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U.S.-European Collaboration in Space Science (1998)

Chapter:3 Case Studies of U.S-European Missions

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Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

Case Studies of U.S.-European Missions

This study seeks to help facilitate successful future international ventures in space. It is based primarily on the joint committee's evaluation of the cooperation and collaboration in space that has existed between the United States and Europe. The joint committee has tried to extract the crucial items that either facilitated or hampered each cooperative project. Among the joint ventures that have been selected for this study, some have been considered successes, others failures, or even a success by one partner and a failure by the other.

Because the disciplinary base may highlight different components of the issue of international cooperation, this chapter accounts for the particulars of each discipline—Earth science, space science with its subdisciplines (astrophysics, space physics, and planetary science), and microgravity research and life sciences—by examining a few selected missions from each area. Selection of these case studies was made so that a cross section of the approaches and experiences (both positive and negative) in the respective disciplines could be achieved. The rationale for this choice within each discipline is presented below (Table 3.1). Given the large variety of missions and types of cooperation, selection was also made to cover the greatest number of situations, as shown in Table 3.2.

In this chapter, the missions selected as case studies in each discipline are characterized briefly with emphasis on specific problems that arose from their international makeup. The findings by discipline follow the case studies; Chapter 4 presents the integrated findings and conclusions of the joint committee.

The following are among the questions that guide these considerations:

  1. What were the scope and nature of the agreement? How did the agreement evolve, and how was it finalized? How long did it take to plan the mission?
  2. How was the cooperation initiated (e.g., by scientist-to-scientist or agency-to-agency contact)? What was the role of each partner and agency? Were the motivations the same for all partners?
  3. What were the expected benefits each partner offered?
  4. What were the extent and practical mechanisms of cooperation? At what level, if any, did hardware integration of multinational components take place? How were communications maintained? Was the project structured to minimize friction between international partners?
  5. What was the net impact of internationalization of the mission in terms of costs, schedule, and science output?
  6. What external influences affected the mission during its life cycle? What were their effects? Were problems caused by different internal priorities or by external (e.g., political, financial) boundary conditions (such as budget cycles)?
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

TABLE 3.1 Missions Used as Case Studies in This Report, Selected by Discipline



NASA-European National Space Agencies




Planetary sciences

Cassini-Huygens, GMM


Space physics

ISPM [Ulysses], ISEE


Earth sciences

EOS—Polar platforms


Microgravity research and life sciences

IML-1, 2

IML-1, 2

TABLE 3.2 Missions Used as Case Studies in This Report, Selected by Type

Mission Type


NASA-European National Space Agencies

Observatory type, large facility shared


IML-1, 2

Programs with several satellites or missions

GMM, ISPM [Ulysses], ISEE


Missions with few instruments



Missions with large number of instruments

SOHO, INTEGRAL, Cassini-Huygens, EOS—Polar platforms


Initiated by principal investigator



NOTE to Tables 3.1 and 3.2: AMPTE = Active Magnetospheric Particle Tracer Explorer; EOS = Earth Observing System; ESA = European Space Agency; GMM = Generic Mars Mission; HST = Hubble Space Telescope; IML = International Microgravity Laboratory; INTEGRAL = International Gamma-Ray Astrophysics Laboratory; ISEE = International Sun-Earth Explorer; ISPM = International Solar Polar Mission [renamed Ulysses]; NASA = National Aeronautics and Space Administration; ROSAT = Roentgen Satellite; SOHO = Solar and Heliospheric Observatory; TOPEX = (Ocean) Topography Experiment; UARS = Upper Atmosphere Research Satellite.

a SOHO is used by both astrophysicists and space physicists. Its mission addresses both disciplines. For the purposes of this study, SOHO was analyzed as an astrophysics mission.

  1. Were there issues of competition versus cooperation? Did the desire to protect technological leadership create problems?
  2. What benefits did the cooperation actually produce?
  3. Which agreements succeeded and which did not, in both scientific and programmatic terms?

The questions are not formally asked and answered for each mission case study but serve instead as guideposts. In the end, the joint committee sought to know and present the lessons learned and how they can be applied in the future.


The four missions selected—the Hubble Space Telescope (HST), the Roentgen Satellite (ROSAT), the Solar and Heliospheric Observatory (SOHO), and the International Gamma-Ray Astrophysics Laboratory (INTEGRAL)—span a wide range of involvement by the National Aeronautics and Space Administration (NASA) and by space agencies in Europe. They also involve a variety of subdisciplines, mission sizes, and degrees of complexity.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
  • HST. This major mission for astronomy, with a European Space Agency (ESA) share of 15 percent, has had very high-visibility for both the astronomy and astrophysics community and the public at large. Particularly since it was repaired, the scientific productivity and impact of the Hubble have been enormous. As an example of international cooperation on such a high-visibility mission, HST has been quite successful. It may have suffered (in the United States at least) from not having been widely recognized as involving significant contributions and participation from outside NASA.
  • ROSAT. This is an example of a mission based on a national program (Germany), rather than ESA, and that has produced a highly successful cooperation among Germany, NASA, and the United Kingdom (UK). The mission was greatly enhanced by the international cooperative effort, which provided both key instruments (the High-Resolution Imager [HRI] and Wide Field [WF] Camera) and mission launch. This is a principal investigator (PI) based mission that illustrates agency-national and interpersonal collaboration.
  • SOHO. The SOHO mission is currently providing the most powerful and complete view of the Sun ever obtained. It epitomizes international planning and execution, with more than a dozen separate instruments provided by laboratories across Europe and the United States. SOHO demonstrates that even the wide-ranging breadth of instrumentation desirable for a modern mission with a wide variety of capabilities can be executed by international agreements and planning. As a ''cornerstone" mission of Horizon 2000, SOHO also represents a case of long-term planning and cooperation.
  • INTEGRAL. As the next major gamma-ray astronomy mission planned for a 2001 launch, INTEGRAL represents a contrast in its international planning from the first three (operating) missions. The long planning process led by ESA was disrupted by significant reduction in NASA's contribution from, originally, the major share of one of the two primary instruments—the spectrometer—to only a token involvement. This can be partly traced to a lack of strong, broad community support in the United States, concerns about the priority of the proposed U.S. instrument, and the rapidly changing outlook for funding within NASA.

Hubble Space Telescope


The Hubble Space Telescope has had the greatest impact of any observatory type facility available in space. The two main reasons for placing a large optical telescope in orbit are to escape the degradation of images caused by atmospheric turbulence and to allow high-resolution imaging and spectral analysis in the ultraviolet (UV) range. Moreover, achieving significant gains over ground-based instruments requires a large collecting power and high-precision optics. These demands create a heavy, complex, and expensive satellite. HST's history is consequently long, complex, and expensive.

The HST is the result of international cooperation between NASA and ESA. NASA has led this effort and provided the spacecraft, the telescope, and four of the five original instruments as well as the ground segment and launch. ESA contributed one instrument, the solar panels and their mechanisms, and support for some scientific and technical staff at the Space Telescope Science Institute (STScI), which operates the HST from its facilities on the campus of Johns Hopkins University in Baltimore, Maryland. This is described in further detail below.

HST consists basically of a reflecting 2.4-m telescope that collects and focuses light on one or more scientific instruments. The current instrument package includes two direct-imaging cameras—the Wide Field and Planetary Camera Second Generation (WFPC2)1 and the Faint Object Camera (FOC)—and the Near-Infrared Camera and Multi-Object Spectrometer (NICMOS) and the Space Telescope Imaging Spectrograph (STIS).2 The optics reflect


The original WFPC was replaced in the 1993 servicing mission by WFPC2, which is similar but includes a revised set of filters that have been improved for the far UV, a new type of charge-coupled device, and corrective optics for the spherical aberration in the primary mirror.


NICMOS permits imaging in the wavelength range between 1000 and 2500 nm and spectroscopy between 1000 and 3000 nm using three grating spectrnmeters. Three cameras simultaneously observe different portions of the field of view. The detectors and part of the optics are cooled to 60 K by solid nitrogen, with an anticipated lifetime of 2 years. On the other hand, STIS is able to replace the performance nf GHRS and FOS by using a 2,000 × 2,000 pixel multimode microchannel array detector providing 8,000 times the elements or its predecessors.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

light adequately with wavelengths between about 115 and 3000 nm, from the UV to the near-infrared (NI). Pointing stability is met by using three interferometric Fine Guidance Sensors (FGS) on the field of view's periphery, which are also operated as an additional scientific instrument.

The original instrument package included the WFPC, the FOC, the Faint Object Spectrometer (FOS), and the Goddard High-Resolution Spectrograph (GHRS). As a result of discovering a manufacturing flaw in the primary mirror on the observatory, NASA conducted a servicing mission in December 1993 and installed the corrective optics package, Corrective Optics Space Telescope Axial Replacement (COSTAR). After COSTAR was installed, the blurred vision of the original HST was restored; this repair required removing the original high-speed photometer. In addition, the STIS (which replaced the FOS and the GHRS) was also installed and the WFPC was upgraded. The NICMOS was added during a second servicing mission in 1997.

Historical Background

The potential advantages of carrying out astronomical observations from space, beyond Earth's atmosphere, were first pointed out by the German rocket pioneer Hermann Oberth in 1923.3 The original idea for HST evolved from the pivotal paper by Lyman Spitzer in 19464 in which he discussed the need for and many advantages of a large space telescope for optical and UV observations of the universe. The primary goals of such a mission were to achieve near-diffraction-limited imaging and spectroscopy in the UV optical (120-700 nm) range with a telescope aperture large enough to allow observation of faint objects.

More than a decade later, between 1962 and 1965, NASA sponsored several studies of a large orbiting telescope.5 The concept began to take a specific form and dimension, and during the early 1970s, studies of a NASA mission concept for a 3-m Large Space Telescope (LST) were carried out.6 These led to definitive studies between 1973 and 1976 establishing parameters for the basic mission. The LST study concept included four scientific instruments (camera, spectrograph, photometer, and astrometric camera) for spectrographic and photometric observations between 120 nm in the UV and 1,000 nm in the IR. The outline of the mission scenario anticipated a 1982 launch date.

The U.S. astronomy community rallied behind the space telescope as the highest priority objective of the decadal study for astronomy for the 1970s, the Greenstein Report published by the National Academy of Sciences in 1972,7 and reaffirmed its priority in the next decadal review, the Field Report, in 1982.8 The actual selling of the project to a reluctant U.S. Congress (because of the cost) was accomplished due to the expressed consensus of this community and the pivotal leadership of a number of leading astronomers.


From the start, European astronomers were willing to join their American colleagues in this important effort. The issue of cooperation was first formally raised in 1973 when ESA's Astronomy Working Group (AWG) recommended that Europe consider and explore the possibility of participation in LST. ESA conducted long negotiations with NASA for this purpose. The selection was narrowed down to the FOC through a series of


Jakobsen, P., and Laurance, R.J., Oberth Paper, ESA Bulletin 58:91, 1989.


Spitzer, L., Astronomical Advantages of Extraterrestrial Observatory (Project RAND Report), Douglas Aircraft Co., 1946.


National Academy of Sciences, A Review of Space Research (Publ. No. 1079), NAS, Washington, D.C., 1962.


In May 1975, NASA decided, for cost reasons, to reduce the size of the telescope primary mirror from 3 to 2.4 m, and the term "large" was dropped from the mission's title. The name Hubble was added by NASA in 1983, in honor of the American astronomer Edwin P. Hubble.


Astronomy Survey Committee, National Research Council, Astronomy and Astrophysics for the 1970s, National Academy of Sciences, Washington, D.C., 1972.


Astronomy and Astrophysics Survey Committee, National Research Council, Astronomy and Astrophysics for the 1980s, Washington, D.C., National Academy Press, 1982.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

discussions within the AWG and with NASA.9 The decision was prompted, in part, by the FOC requirement of a detector imaging system that could work in a so-called photon-counting mode to exploit the space telescope's potential to the fullest. At the time, Europe had a lead in this area, since University College London had developed the only photon-counting imaging system then in routine use for optical astronomy.

In June 1975, a NASA-ESA working group was charged with establishing common ground regarding the basis of eventual cooperation on the LST. This working group proposed that along with the FOC, a continuing European contribution to the telescope's operation and the provision of a major subsystem would be appropriate. This would allow ESA to secure a significant share of the observing time for European astronomers during the then planned 10 years of operations. It was proposed that ESA help to staff the Science Operations Facility, later renamed the Space Telescope Science Institute (STScI). Later, ESA was to set up its own Space Telescope-European Coordinating Facility (ST-ECF) at the European Southern Observatory (ESO) site in Garching, Germany. The major spacecraft subsystem to be provided by ESA was the solar arrays.

For ESA, the project's feasibility study, or Phase A, was completed, and subsequent discussions led ESA's Science Programme Committee (SPC) to accept a proposal presented in October 1976, subject to satisfactory negotiation of the Memorandum of Understanding (MOU) with the United States. The HST project thus evolved into a joint NASA-ESA mission. The U.S. Congress approved a "new start" for the project in the summer of 1977, and a formal MOU between NASA and ESA was signed on October 7, 1977. No less than 15 percent of the observing time available would be guaranteed to European astronomers in exchange for the solar panels; one of the main scientific instruments, the FOC; and 15 positions at the STScI.

The cooperation was formalized to include active ESA participation in mission planning and data analysis. At the time of the establishment of STScI at Johns Hopkins University and the appointment of its first director in July 1981, the links were well established. ESA personnel were already on-site at STScI, with ESA involvement ensured by representation on the Space Telescope Institute Council (STIC). Indeed, the previous chair of the STIC was from an ESA member state.

The original launch date of late 1983 was postponed several times until late 1986 because of funding and technical delays. Furthermore, the Space Shuttle Challenger accident in January 1986 caused an additional delay of more than 3 years.

HST was finally launched by the Shuttle mission STS-31 from Kennedy Space Center in April 1990. During the commissioning period, a flaw was noted in the manufacturing of the primary mirror. Despite this setback, a large number of astounding phenomena and objects were discovered using HST, even though its mirror was flawed. As is now well known, HST recovered its full imaging and spectroscopic capability as a result of a highly successful repair mission in December 1993. During this first servicing mission, the solar arrays were replaced with new ESA-provided systems; the original WFPC was replaced by a new, more effective WFPC2 (including its own corrective optics); and COSTAR was introduced as a focal plane "instrument" (instead of the original high-speed photometer) to correct the optical beam incident on FOS, GHRS, and FOC. ESA actively participated in the definition and testing of COSTAR. Since the servicing mission, HST has been regarded as an overwhelming success by both the public and the scientific user community and must be acknowledged as a superb example of inter-agency cooperation and planning.

From the beginning it was NASA's intent to open its Announcement of Opportunity (AO) to the entire scientific community. The MOU guaranteed 15 percent for Europeans, and this was considered a built-in check of juste retour (fair return). In reality, European astronomers currently obtain approximately 20 percent of the available observing time after selection through the peer review system. Observations selected in the seventh


The FOC instrument is sensitive in the wavelength range from 115 to 650 nm and is capable of operating in two basic modes: direct imaging with different magnifications, and the so-called long-slit spectrographic mode. Whereas the WFPC provides a slightly undersampled image of a wide region of the sky, the FOC is designed to fully exploit the unique imaging capability of the HST and provide images of the highest possible resolution and limiting sensitivity, although the fields or view or the three nominal imaging modes are very small. Moreover, the WFPC operates best at longer wavelengths, while the FOC is most sensitive in the blue and UV regions. It will be replaced in the third servicing mission (1999) by the Advanced Camera for Surveys (ACS) being developed by Johns Hopkins University with NASA funds.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

observing program (cycle 7) are being performed following the second maintenance and refurbishment mission (STS-82) in February 1997.10

Additional servicing missions to HST are planned for 1999 and 2002, and a series of studies are being carried out for the continuation of the mission beyond 2005, the nominal termination of the HST 15-year lifetime. The ESA-funded FOC will be replaced during the 1999 mission by the NASA-approved Advanced Camera for Surveys (ACS). Solar arrays will again be replaced, and HST will be reboosted to a higher orbit to compensate for the orbital decay expected during the next solar maximum cycle.

The planned replacement of solar arrays by NASA (rather than, as originally supplied, by ESA) in the 1999 servicing mission has raised some concerns about ESA's role or hardware share in the extended HST mission. ESA's SPC approved procurement of the Solar Array Drive Mechanism (SADM) for the 1999 servicing mission. Given that the FOC will also be removed from the space telescope, the European contribution to the mission will be significantly reduced. In 1995, a joint ESA-NASA working group was set up to identify a potential HST instrument for the 2002 servicing mission, which could be provided by ESA to NASA. Two potential instruments—three-dimensional imaging spectrographs—to be provided entirely by ESA, were identified at an early stage. However, this approach for a complete ESA instrument was abandoned following budget reductions in the aftermath of the ESA Ministerial Conference in October 1995 at Toulouse. In October 1996, NASA released an AO for the provision of advanced instruments to be installed at the time of the 2002 (probably final) servicing mission; a NASA instrument (Cosmic Origins Spectrograph) was selected. Despite funding problems to accommodate further contributions to the cooperative program, ESA was able to respond to the AO through a collaboration between U.S. and European institutes with a 50-50 participation in proposing the HSTJ instrument, which incorporates Superconducting Tunnel Junction (STJ) detectors.

In the meantime, both ESA and NASA have begun to consider extending the current MOU beyond 2001, the present date of expiration. HST operations are funded on the NASA side to 2005, and mission extension beyond this date is possible, although not yet decided. In this case, a final servicing mission might take place in 2005. ESA also plans to contribute to NASA efforts to develop a Next Generation Space Telescope (NGST). On June 27, 1996, the NASA associate administrator for space science met with the ESA science program director and invited ESA to participate in the study of the "origins" program, which includes, among several missions, the NGST and an infrared interferometer. Formal working-level contacts are now being established, and a task force on NGST has been formed within ESA.

Finally, it is useful to consider the scope of HST. The cost to ESA is accounted as 462 million accounting units (MAU) in 1994 European Community Units (ecus), the equivalent of $547.4 million in 1994 U.S. dollars. The total mission cost to NASA (in real dollars) from inception is $4 billion or more, certainly the most expensive astronomical mission ever carried out and among the most expensive single scientific facilities yet constructed.11


The cooperation on HST between U.S. and European astronomers has worked very well. The fact that NASA had a leading position in the mission was never disputed; however, some European scientists have complained that NASA did not present the mission as truly cooperative and international in its public outreach on both the mission and its results. In addition, it was clearly important to have a well-defined MOU established at early stages. Drafting these kinds of MOUs was found, nevertheless, to be a lengthy process that does not include mechanisms for easily modifying or extending the mission. Europe's significant contribution to the scientific payload also proved crucial, not only to the spacecraft but also to HST operations at the STScI. This cooperation at STScI in the


Cycle 7 is the seventh selection of the observing program, solicited by competitive peer review (approximately 7:1 oversubscribed) on an approximately annual schedule.


Bahcall, J.N., and Odell, C.R., "Scientific Research with the Space Telescope," SEE N80-22130 12-88, 1979, p. 5; Laurence, R.J., "The History of the Hubble Space Telescope and ESA's Involvement," ESA Bulletin 61:9-12, 1990; Smith, R.W., The Space Telescope: A Study of NASA, Science, Technology, and Politics, Cambridge University Press, Cambridge, England, 1989; Wilson, A., ed., Interavia Space Directory, International Space Programmes, 1994, p. 163.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

United States and the links to ST-ECF in Germany have ensured that HST has been conducted highly visibly and successfully on both sides of the Atlantic.

Roentgen Satellite


The Roentgen Satellite is an x-ray telescope mission to provide the first soft x-ray (0.2-2.5 keV) (1 keV = 103 electron volts) all-sky imaging survey, as well as an observatory for detailed study of individual sources. ROSAT mission goals were twofold: (1) Using the scan mode, a complete all-sky survey was to be carried out over 6 months with imaging telescopes to detect sources at x-ray and extreme-ultraviolet (XUV) energies, to measure their positions with an accuracy of less than 0.5 arc minute, and to obtain fluxes and broadband spectra. (2) In the pointing mode, the goal was to study selected sources in detail with respect to spatial extent, temporal variability, and spectral properties. Pointed observations with the High-Resolution Imager (HRI) also were to allow more precise (~5- to 10-inch) positions and structures to be measured. ROSAT was launched in June 1990 and provided a higher-sensitivity and higher-resolution follow-up to the Einstein X-Ray Observatory operated by NASA from 1978 to 1981 (with European participation in its grating spectrometer). It will have provided the highest spatial resolution x-ray imaging capability to date until the planned launch of the Advanced X-Ray Astronomy Facility (AXAF) in late 1998. ROSAT is a German-U.S.-UK project.12

Historical Background

ROSAT resulted from a proposal made by the Max-Planck-Institut für Extraterrestrische Physik (MPE) to the Bundesministerium für Forschung und Technologie (BMFT) in 1975. This was one of three projects selected from 20 proposals for "big projects" across a wide range of natural sciences. The original version of the project entailed an all-sky x-ray survey to be carried out with a moderate angular resolution (roughly 1-inch) imaging telescope. Between 1977 and 1982, extensive studies were conducted by German space companies in the pre-Phase A and Phase A stages. Following the regulations of the ESA convention, BMFT offered cooperation on ROSAT to ESA member states in 1979. This resulted in three proposals, one of which was successful.

The University of Leicester (UK) led a proposal for a Wide Field XUV Camera (WFC) to be flown together with the X-Ray Telescope (XRT) to extend the spectral band pass to lower energies. A formal proposal for UK funding was made by the WFC Consortium to the Science and Engineering Research Council (SERC)13 in August 1981. After discussions between the University of Leicester and MPE and negotiations between BMFT and SERC, the MOU between these two parties was signed in 1983.

U.S. involvement in ROSAT was first discussed at the Uhuru Memorial Symposium in December 1980 when a German scientist talked about ROSAT plans and outlined the possibilities of international cooperation. Individuals at the Harvard Smithsonian Astrophysical Observatory (SAO) and an x-ray astronomer at NASA's Goddard Space Flight Center (GSFC) became interested, and further discussions among scientists at GSFC, SAO, and MPE, and between BMFT and NASA, led to a MOU signed in 1982. NASA agreed to provide the HRI for the focal plane of the XRT, as well as the ROSAT launch with the Space Shuttle in 1987. The HRI was developed at SAO as an improved version of the detector, which had been originally developed for the Einstein Observatory.

The Challenger accident of January 1986 brought about a significant change in the ROSAT project. In December 1987 it was decided that ROSAT would be launched on an expendable launch vehicle (Delta II) in 1990 instead of on the Space Shuttle. This required late changes to the satellite hardware, which fortunately were


As an international project, ROSAT was conceived and executed on a nonexchange of funds basis. Because offers from UK industry did not fully comply with requirements set by the management of Deutsches Zentrum für Luft-und Raumfahrt-Projektträger (DLR-PT), a transfer of funds took place from the United Kingdom to Germany.


In April 1994, U.K. research councils were reorganized and SERC's responsibilities were shared between the Natural Environment Research Council (NERC) and the Particle Physics and Astronomy Research Council (PPARC).

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

modest despite the advanced stage of the project. On NASA's side, the launch required a modified shroud of the Delta II to accommodate ROSAT. The launch finally took place on June 1, 1990, from Cape Canaveral.


The heart of the cooperative effort was science, instruments, and data. The instrument contributions by SAO, UL and British institutes, and MPE were conducted separately. The institutes and agencies (particularly MPE, DLR-PT, and DARA) provided program management and scientific oversight, with science planning led by MPE. Many partners and entities shared responsibilities for scientific analysis software for guest observers and guest observer support and for preparation of the Announcement of Opportunity. Moreover, the data management, sharing, and analysis were developed and conducted in a distributed fashion involving most of the partners.

Instruments and Associated Data Systems. The ROSAT payload consists of two telescopes: the XRT with the position-sensitive proportional counter (PSPC), and the HRI, which was mounted on a carousel in the focal plane behind the XRT mirror assembly14 and the WFC.

Overall direction of the science project was carried out as a PI mission at MPE, whereas the ROSAT project as a whole was managed by DLR-PT until 1990 and by Deutsche Agentur fär Raumfahrt Angelegenheiten (DARA) thereafter. The main satellite contractor in Germany was Dornier System, with Messerschmitt-Bölkow-Blohm as a subcontractor. The Carl Zeiss Company developed and built the x-ray mirror system.

The U.S. contributions to ROSAT were the HRI, mission launch on a Delta II, and significant analysis software. For the pointing phase of the mission, NASA has conducted the observing proposal solicitation for input to the International ROSAT Users Committee (IUC). U.S. participation in ROSAT was managed at GSFC, which supported scientific planning as well as data reduction and distribution to the U.S. astrophysics community. GSFC also developed and maintains the ROSAT data archive for NASA and coordinates solicitation and review of observing proposals submitted by the U.S. community. The ROSAT Science Data Center (RSDC) is operated at SAO, where the HRI detector, telescope aspect software, and HRI data analysis software were developed. SAO also monitors the condition as well as the calibration of the HRI in flight.

The WFC was designed and built by a consortium of British institutes led by the University of Leicester.15 The ROSAT UK Data Centre (UKDC) is located at the Rutherford Appleton Laboratory, Oxfordshire, whereas the ROSAT UK Guest Observer Centre (UKGOC) is located at the University of Leicester. Between them, the UKDC and UKGOC act as a link between U.K. observers and MPE's ROSAT Data Centre. The UKDC processes all WFC data and distributes pointed x-ray data (received from MPE) and WFC data to U.K. guest observers. It also sends all German WFC GO data to the German XUV Data Centre (at the University of Tübingen). The UKGOC provides general user support for ROSAT to U.K. guest observers (GOs). Analysis of the WFC all-sky survey has been the responsibility of the ROSAT UK Survey Centre at Leicester. The all-sky survey database has since been archived at the Leicester Database and Archive Service.

ROSAT was launched on June 1, 1990. After the initial calibration period, ROSAT performed an all-sky survey in a continuous 6-month period using the PSPC in the focus of the x-ray telescope and in two XUV wave bands with the WFC. Following the all-sky survey, ROSAT has been used for pointed observations using the PSPC or HRI. All of the observing time in the pointed phase is made available to guest investigators through an international, competitive peer review.


The XRT telescope and the PSPC were developed by MPE in Garching, Germany, in collaboration with Carl Zeiss Company; the HRI detectors were developed by SAO in the United States.


In addition to Leicester, the other institutions in the United Kingdom that had a major role were the Rutherford Appleton Laboratory, Mullard Space Science Laboratory of University College London, the University of Birmingham, and the Imperial College of Science and Technology London.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

The Investigator Program. There are no restrictions regarding the amount of ROSAT observing time guest investigators may have, the percentage of observing time spent on long versus short investigations, or the number of targets requested in GO proposals.16 Proposals submitted to each of the three agencies (BMFT, NASA, and PPARC)17 are evaluated independently by the respective national proposal evaluation committees. The available observing time is shared in the ratio 50:38:12 among NASA, BMFT, and PPARC. Each agency approves enough proposals to cover about 150 percent of its nominally available national observing time. All proposals approved by each agency are grouped into one of four categories: two-sevenths for programs with highest priority, two-sevenths for programs with medium priority, three-sevenths for programs with low priority, and those that are not approved.

The three participating agencies (BMFT, NASA, and PPARC) independently define their national proposal lists. The IUC's task is to combine the three national programs into the ROSAT observing program. This observing program should be devoid of unnecessary duplication among nationally defined observing programs; redundant proposals are removed so that the national observing programs are changed as little as possible. To select between competing proposals, the IUC uses the priority and observing time allocated by national selection committees. The IUC recommends a final ROSAT observing program to BMFT and reports back to the national committees about any changes to individual national observing programs. As a result, a nationally approved proposal may be rejected on the international level because of a competing proposal. BMFT approves the ROSAT observing program on the basis of IUC recommendations.18


On the whole, cooperation on ROSAT has worked very well. Many hundreds of guest investigators have used the telescope during more than 7 years of operation. When problems have occurred (e.g., failure of several gyros), they have been solved through joint efforts.

Excellent communication has been central to ROSAT's success. There were, of course, the usual project reviews to monitor progress during the hardware phase. Numerous project meetings dealt with specific questions as well. This ensured constant communication among the engineers, scientists, and managers. At a higher level, there were the national ROSAT committees (for Germany, the United States, and the United Kingdom) and the IUC (eight members). The national and international users committees met several times before launch, and after launch they met at each AO cycle (eight times thus far). In addition, data management, sharing, and analysis, which are done in a distributed but concerted fashion (MPE, GSFC, University of Leicester [UL] with RAL), have been optimal, resulting in an excellent data service for a wide community. There was ample lead time: the data analysis effort at MPE started 8 years before launch; in the United States, it began 4 years before launch and in the United Kingdom about 6 years before launch.

ROSAT has been a highly successful mission that has made fundamental discoveries and many important observations. It provided the United States (and the world) with the only high-resolution (a few arc seconds) x-ray imaging observatory since the demise of the Einstein Observatory (1981) and until AXAF (1998). As an example of international cooperation, it must be regarded as a great success.


Pointed observation data are subject to proprietary data rights for a period of 1 year after the data have been made available to the PI.


With the reorganization of U.K. research councils in April 1994, PPARC took over SERC's responsibilities for funding ROSAT in the United Kingdom.


The ROSAT observing time is significantly oversubscribed (by a factor or four to seven). The most important criterion for assessment by national evaluation committees is the scientific merit of the proposed research. However, the feasibility or the observations, as well as observational constraints that may overburden the ROSAT system, also figure in the selection.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

Solar and Heliospheric Observatory


The Solar and Heliospheric Observatory is the most comprehensive space mission ever devoted to the study of the Sun and the heliosphere. From the vantage point of a halo orbit around the first Lagrangian point, L1, SOHO's 12 scientific instruments observe and measure structures and processes that occur inside as well as outside the Sun and reach well beyond the Earth's orbit into the heliosphere. The two extremes of this data, the deep core and the outermost layers of the convection zone, are unobtainable except from space.

The SOHO mission involves international cooperation among ESA, European national authorities, and NASA. ESA took the lead in the cooperation between the two large space agencies by procuring the spacecraft (including integration of the 12 instruments and environmental testing of the satellite) from European industry. Instruments were built under the leadership of PIs,19 nine of them funded by European national entities and three by NASA.20

EUV and UV imagers and spectrographs have yielded the first comprehensive view of the outer solar atmosphere and corona. For the first time, the temperature, density, and velocity evolution of the solar atmosphere can be observed from the photosphere out through the far corona. Observations are continuous. Although SOHO is a single mission, experiments on board SOHO can be divided, according to their area of research, into three main groups: helioseismology instruments, solar corona instruments, and solar wind in situ instruments. The helioseismology instruments provide high-precision and high-accuracy measurements of solar oscillations. The solar corona instruments produce the data necessary to study dynamic phenomena in the upper solar atmosphere. The solar wind in situ instruments measure the composition of the solar wind and energetic particles.

NASA supplied the SOHO launch vehicle (an Atlas-2AS) and provides ongoing mission operations including communications with the satellite via the Deep Space Network (DSN). Overall responsibility for the mission remains with ESA. After its launch on December 2, 1995, SOHO reached its location near Lagrangian point L1, 1.5 × 106 km from Earth and was injected into the halo orbit on February 14, 1996.

Historical Background

Although the SOHO mission is a cooperative effort between European agencies and NASA, its origins at the agency level were in Europe. However, because of the range of well-developed scientific cooperation between the space communities on both sides of the Atlantic, the scientific parenthood was clearly shared.

SOHO was proposed 13 years before its actual launch and, less than 3 years after being proposed, had become part of an ESA Horizon 2000 cornerstone. The foundations of SOHO were laid in earlier studies, namely those of GRIST (Grazing Incidence Solar Telescope) and DISCO (Dual Spectral Irradiance and Solar Constant Orbiter). It is the combined capabilities and objectives of both of these project proposals that constitutes the core of the SOHO mission.

The GRIST proposal and Phase A study foresaw a grazing incidence telescope (feeding several focal-plane instruments) to be mounted on the Instrument Pointing System (IPS) and flown as part of a Spacelab payload. One of the merits of GRIST was that the wavelength range accessible through grazing incidence optics is particularly powerful for spectroscopic diagnostics of the hot outer solar atmosphere. Spectroscopy in this domain had long been neglected on major solar satellites, partly because of experimental difficulties.

In July 1980 in response to an ESA call for mission proposals, a group of French and Belgian scientists proposed a mission, DISCO, dedicated to the study of spectral irradiance and the solar constant. This was considered an important, broad objective, in part because of the possible climatic effect of a long-term variation in


For the purposes of this report, a PI conceives of an investigation, is responsible for carrying it out and reporting on the results, and is responsible for the scientific success of the mission investigation.


The 12 international PI consortia involved 39 institutes from 15 countries: Belgium, Denmark, Finland, France, Germany, Ireland, Italy, Japan, the Netherlands, Norway, Russia, Spain, Switzerland, United Kingdom, and the United States.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

solar irradiance. At almost the same time, in the austral summer of 1979-1980, a group of French and American physicists observed the Sun continuously from Antarctica between December 31, 1979, and January 5, 1980. They succeeded in measuring global velocity oscillations of the Sun with an unprecedented signal-to-noise ratio. These historic observations led to the decision to include helioseismology velocity observations on board DISCO.

In addition, the potential for helioseismology of solar brightness oscillations, as evidenced by the high-quality of the solar constant data obtained by the Solar Maximum Mission (SMM), offered a unique asset to that mission, which could for the first time attempt to detect the Sun's global oscillation modes and shed new light on the intriguing solar neutrino deficit issue. An instrument measuring brightness oscillations would therefore add a substantial helioseismology assessment capability to the radiance and irradiance instruments. Accordingly, DISCO's model payload was extended to contain a set of photometers and absolute radiometers to perform measurements of the total and spectral irradiance in selected bands and detect solar oscillations in visible light.

An assessment study for SOHO was approved by ESA in December 1982. To create a larger scientific base for an eventual project, the Solar System Working Group recommended that a particle payload segment be included in the model payload. During the initial study phase, it became clear that SOHO should be a multidisciplinary mission, which implied the following: (1) helioseismology should be added to the set of spectroscopic solar telescopes forming the original payload; (2) SOHO should be placed in a halo orbit around L1 in order to be compatible with the helioseismological objectives; and (3) the particles-and-fields instruments should be devoted to solar wind composition measurements, the study of solar energetic particles, and the investigation of waves in the interplanetary medium.


The studies of DISCO and SOHO coincided with cancellation by NASA of its probe in the International Solar Polar Mission (ISPM) and its aftermath. This created tension between the space physics communities in Europe and the United States and explains why DISCO and SOHO were studied as purely European missions in their assessment phases. Despite inter-agency tension, the scientific communities on opposite sides of the Atlantic continued to cooperate in studying missions whose objectives were quite similar. At a regular ESA-NASA consultation meeting in June 1983, it was agreed that an integrated view should be taken of the large number of missions under study in the United States, Europe, and Japan in the area of solar-terrestrial physics. NASA and ESA therefore organized a preparatory meeting in September 1983, to which the Japanese Institute for Space and Astronautical Science (ISAS) was invited.

After extensive discussion and a rather painful rationalization process, the International Solar-Terrestrial Physics (ISTP) program was formulated. It embodied a reduced version of NASA's previous program, Origins of Plasmas in the Earth's Neighborhood (OPEN), consisting of four spacecraft: Wind, which measured the solar wind and space plasma properties near Langrangian point L1; Equator and Polar in near-Earth orbits; and Geotail. New add-ons to the ISTP were Cluster and SOHO. In the preparatory meeting it was argued that SOHO and Cluster should be flown together. Both were addressing the same physical structures and processes by remotely sensing the coronal plasma through in situ measurements of the solar wind and in situ investigations in three dimensions of the magnetospheric plasma.

SOHO As Part of Horizon 2000. Formulation of the ESA science long-term program, later known as Horizon 2000, was a substantial community effort. It was guided and finally produced by a survey committee composed of senior European space scientists, including the ESA Space Science Advisory Committee (SSAC).

At the final meeting of the survey committee in May 1984 in Venice, Italy, only three cornerstones were originally foreseen. It was therefore a surprise when a fourth, consisting of the SOHO and Cluster missions, was introduced by the chairman of the Solar System Working Group. Inclusion of this cornerstone, however, balanced the Horizon 2000 program among the disciplines represented by active researchers at the time. This cornerstone was called the Solar-Terrestrial Science Program (STSP)21 to make it a distinct element of the much larger International Solar-Terrestrial Physics program.


Originally called the Solar-Terrestrial Physics Cornerstone.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

The dialogue with NASA achieved progress along several avenues, including the following:

  • Provision by NASA of the SOHO launch using an Expendable Launch Vehicle (ELV);
  • Agreement by NASA to transfer implementation of SOHO flight operations from the European Space Operations Center to NASA-GSFC, including use of the DSN for data retrieval;
  • Provision by NASA of several spacecraft hardware items such as tape recorders, high-power amplifiers for both SOHO and Cluster, and Sun sensors for SOHO; and
  • Provision by NASA of flight model environmental test facilities for SOHO (an option subsequently not taken up by ESA).

There were several problem areas for SOHO, which is natural for such a large cooperative project. For example, running a joint ESA-NASA AO for SOHO investigations proved extremely cumbersome.22 There were scheduling delays, specification failures, and late deliveries of some of the hardware (tape recorders and detectors). In addition, the division of responsibility between ESA and NASA on the development of space and ground elements of the mission caused some initial problems and required that both parties adapt. In the end, these problems were solved satisfactorily for all involved and confirmed the need for clean interfaces in cooperative missions on all levels, from the experimenters to the agencies.

The scientific output now being demonstrated by the SOHO mission clearly shows how the insistence and will of a cooperative spirit eventually bears fruit. SOHO as it exists today could not have been carried out in a timely manner without cooperation between ESA and NASA. The contributions from national funding agencies in Europe and from the scientific and technical communities on both sides of the Atlantic were crucial. Finally, the cooperative effort on SOHO was exemplary, especially because it emerged in a climate where agency level cooperation was at its coldest.23

International Gamma-Ray Astrophysics Laboratory


The International Gamma-Ray Astrophysics Laboratory (INTEGRAL) mission was selected by ESA in June 1994 as the second medium-size mission (M2) of the Horizon 2000 long-term plan for space science. INTEGRAL, now planned for launch in 2001, is a high-energy observatory for fine spectroscopy and imaging in the energy range between 15 keV and 10 MeV. The payload consists of two main gamma-ray instruments; the Spectrometer on INTEGRAL (SPI) and the Imager on Board the INTEGRAL Satellite (IBIS); and two monitoring instruments, the Joint European X-ray Monitor (JEM-X), and the Optical Monitoring Camera (OMC). Design of the INTEGRAL instruments is largely driven by the requirement to establish a scientifically compatible payload.

Each of the main gamma-ray instruments, SPI and IBIS, has both spectral and angular resolution, but they are optimized differently to complement each other and achieve overall excellent performance. The two monitoring instruments, JEM-X and OMC, will provide complementary observations of high-energy sources at x-ray and optical energy bands.

Historical Background

The selection cycle in Europe followed a two-step competitive process, beginning with an initial call in June 1989 for new mission proposals in the ESA framework of the second selection cycle (M2) of the Horizon 2000 long-term plan. These proposals were narrowed down to six candidate missions in February 1990. The INTEGRAL mission concept arose from an earlier concept, GRASP (Gamma-Ray Spectroscopy and Positioning),


The joint AO process was replaced by coordinated AOs for Cassini.


Large parts of this write-up are based on published materials by M.C.E. Huber et al. in ESA Bulletin, May 1996, and articles in the special volume "The SOHO Mission," Solar Physics 162, 1995.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

which had been studied by a consortium of European gamma-ray astronomers (primarily from the United Kingdom, France, Germany, and Italy). GRASP was submitted to ESA in response to a call for new mission proposals issued in July 1985. Phase A was carried out from December 1987 to October 1988; it was presented in April 1989 to the scientific community, but the mission was not selected by ESA.

The renewed discussions of INTEGRAL in Europe following the rejection of GRASP stemmed in part from the NASA Explorer competition of 1989 in which a U.S. gamma-ray spectroscopy mission, the Nuclear Astrophysics Explorer (NAE), had been selected for a Phase A study but then was not selected for flight. The early definition of INTEGRAL attempted to combine the best features of the two earlier gamma-ray missions studied on both sides of the Atlantic: GRASP (continuum spectroscopy and imaging) and NAE (nuclear line spectroscopy).


In June 1989, in response to the ESA call for new mission proposals, INTEGRAL was proposed jointly by individuals at the University of Southampton and the University of California, San Diego, on behalf of a consortium of institutes and laboratories in Europe and the United States. It was envisioned as a fully shared ESA-NASA partnership, a view supported by NASA Headquarters.

INTEGRAL was proposed with the same objectives as GRASP but with new designs for the instruments (fine spectroscopy was proposed as a separate instrument). International participation in INTEGRAL was widened with the addition of new U.S. and European institutes. As mentioned previously, INTEGRAL was among the six candidate missions selected by ESA in February 1990 for an assessment (pre-Phase A) study. An assessment study team was assembled mostly from astronomers in the United Kingdom, France, Germany, Italy, and the United States in approximately equal numbers. This team, together with ESA and NASA engineers, carried out a joint ESA-NASA assessment study that identified two options for an ESA-NASA cooperative mission, one in which ESA would provide the spacecraft and NASA the launch vehicle (Titan-class would be required), and the other in which NASA would provide the spacecraft and ESA an Ariane launch. In both options the scientific payload would be shared between ESA and NASA and would consist of two primary instruments: a cesium iodide imager (from ESA) and a germanium spectrometer (from NASA). These instruments would be supplemented by x-ray and optical monitors supported mainly by ESA member states.

In April 1991, INTEGRAL, together with other candidate ESA missions, was presented to the scientific community at large; it was subsequently recommended for a Phase A study with the highest priority by both the AWG and the SSAC. In June 1991, the SPC approved the selection of INTEGRAL with three more candidate missions for Phase A studies. In the same time frame, NASA confirmed its support of a Phase A study activity on INTEGRAL. NASA also indicated that the anticipated U.S. participation in the INTEGRAL mission would be proposed in response to its next Delta-class Explorer AO. If selected as M2 by ESA, NASA would seek an appropriate launch vehicle to lift INTEGRAL into the desired orbit.

In December 1991, the Russian Academy of Sciences offered to provide a Proton launcher, free of charge, as a contribution in exchange for a share of the observing time. This offer relieved NASA of launch vehicle responsibility and must have been viewed with relief. At the time, the United States was involved in supplying INTEGRAL's spectrometer (about $70 million) and possibly a Titan III launch. The launch issue was perhaps considered unrealistic.

The joint Phase A study was performed in 1992. As a result of its offer and because of cost considerations and optimized scientific return, Russia participated as a full partner in the study, with the Proton as a preferred launch option (since it would allow a higher orbit)24 and an Ariane as a backup. In the early phases, various cooperative scenarios were considered. However, it soon appeared that the only feasible scheme was that ESA would provide the spacecraft, operations, and ground segment and would assume overall mission responsibilities. A highly eccentric orbit was selected, which allows use of the XMM (X-Ray Multi-Mirror Mission) spacecraft, thus


The Titan launcher would provide for a 48-h orbit (28.5 degrees inclination, 40,000 km perigee, 117,000 km apogee), whereas the Proton rocket would give a 72-h orbit (51.6 degrees inclination, 48,0000 km perigee, 115,000 km apogee).

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

reducing the cost of the mission. NASA's contribution would consist of one main instrument (the spectrometer) and one or two additional ground stations.

At a public presentation of M2 Phase A results in April 1993, NASA reaffirmed its support for INTEGRAL and its strong desire to participate in the mission, if selected by ESA. Funding would be sought through the international payload line, which had recently been established (although not permanently) at about the $10 million level per year. The stability of this budget line was somewhat uncertain at the outset. Moreover, NASA had not previously identified INTEGRAL in its overall mission planning. Given this uncertainty, NASA was unable to make a firm commitment. More importantly, the international payload line could not support the full cost of the spectrometer. It was already mortgaged for other programs (e.g., U.S. instruments on the Russian Spectrum X-Gamma mission), and the spectrometer was expensive (almost $70 million) relative to the size of the funding line. A suspicion arose within the U.S. space science community that funding the spectrometer would require that funds be derived from the Explorer line.

Again, within ESA's advisory structure, INTEGRAL was recommended for selection by the AWG and subsequently by SSAC. At ESA's June 1993 meeting, the SPC approved INTEGRAL as ESA's M2 mission, based on an international cooperation in which Russia would provide the Proton launcher and NASA the spectrometer instrument, as well as a contribution to the ground segment. At this time NASA was informed of the INTEGRAL situation, including the major role of U.S. teams in the spectrometer, which was similar in overall design to the instrument studied for Phase A of the NAE mission.

During the preparation (1993 to 1994)25 of the AO for the instruments, ESA and NASA discussed the form of the AO and agreed that it would be an ESA AO open to the U.S. community for a possible NASA-funded spectrometer proposal. During the period leading to release of the AO, the possible level of NASA support for the spectrometer became increasingly uncertain. The INTEGRAL mission had still not garnered broad U.S. support or a vocal constituency in the NASA space science advisory process for several reasons: (1) the perception that INTEGRAL had never passed the required peer review in the Explorer competition, because the underlying rationale for U.S. participation (the spectrometer based on NAE) had not been selected for flight in the earlier (1989) Explorer competition; (2) its significant strain on the budgets of both the Explorer and the international payload line (which could have effectively bypassed the Explorer queue) in the NASA budget; and (3) early concerns of some astrophysicists that the lack of detection of bright discrete sources of line emission (e.g., 511 keV) by the Oriented Scintillation Spectrometer Experiment (OSSE) instrument on the Compton Gamma-Ray Observatory (CGRO), which had not confirmed at least one source claimed by SIGMA and, more importantly, had not found new line emission sources, implied that the spectrometer planned for INTEGRAL might not be sensitive enough. It therefore soon became clear that NASA would not (and could not) support the spectrometer at the level needed to have a principal investigator from the United States on the mission and that NASA participation would decrease significantly.

The AO was released on July 1, 1994, with proposals due by December 5, 1994. During the autumn of 1994, a meeting was held in France at which a NASA representative presented the astrophysics program. INTEGRAL was not included as a U.S. international program. Despite attempts by ESA and the U.S. and European scientific communities to change this situation, it became increasingly clear that NASA could not support INTEGRAL at the $70 million level expected by U.S. PIs. Possible levels of NASA participation ranged between $6 million and $20 million. Finally, in September 1994, a meeting between ESA and NASA led to the conclusion that NASA could not support the U.S. spectrometer PI. In the time remaining for preparation of the proposal, the French and German groups, originally involved with the principal investigator from the United States, prepared a European-only proposal for the spectrometer that just met the deadline.

This proposal was made possible because the Centre National d'Études Spatiales (CNES), the French national space agency, agreed to assume the financial burden resulting from NASA's withdrawal on the spectrometer, thus


A first version of the Science Management Plan (SMP) was issued at the beginning of 1994, but SPC asked to reconsider the share of time between the principal investigator and guest observer for this observatory mission. An agreement was reached, and SMP was issued with a 6-month delay in June 1994.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

safeguarding the scientific integrity of the INTEGRAL mission. Finally, NASA confined its reduced participation in INTEGRAL to small involvement in three instruments and the provision of one or two ground stations (still currently under negotiation with ESA).26


The withdrawal of NASA support for the development of INTEGRAL instrumentation was a near fatal blow for the mission. European PI teams were determined to recover the missing resources from their national funding agencies and keep the mission alive. Instrument teams were reorganized—in the cases of the imager, spectrometer, and optical monitor, with new PIs. New coinvestigators were added to replace lost resources. ESA organized a series of meetings whose purpose was to secure commitments from the national delegations that funding would be made available to the hardware teams. Each PI was responsible for lobbying the coinvestigator group. Although some funding problems remain, each instrument has successfully completed Phase A and B studies and flight hardware is now being developed. Despite the difficulties of obtaining broad consensus with the U.S. astronomical community, the gamma-ray community has provided considerable support and shared technology (e.g., for the germanium detectors and coolers). NASA is formally represented in the INTEGRAL Science Working Team by a mission scientist and also supports several coinvestigator scientists who are directly involved in developing the instruments. These coinvestigators have made significant contributions in each case.

Lessons Learned

Astronomy is an inherently international science with a long tradition of shared observations and joint planning. This cooperation developed from the need to observe objects over the full sky and at all times of day (or night). Thus, astronomers have long traveled to observatories around the world and in both hemispheres and have arranged for joint campaigns to observe and study objects regardless of local time zones. In the era of space astronomy and astrophysics, there has been this heritage to draw on. The space astronomy communities in the United States and Europe are also well integrated and accustomed to using joint facilities (e.g., HST, ROSAT, SOHO) for research, regardless of the program or agency originally responsible for the mission. However, this natural and historical set of connections has not always meant that planning for missions is as smooth as it might be in an era where large missions will increasingly require international cooperation. Astronomy is special in this regard; also by virtue of the need either to observe increasingly faint objects or to obtain even finer resolution (both spectral and spatial), astronomy research conducted in space will require larger missions for many of its long-term objectives. An understanding of the cosmos cannot be simply squeezed into a larger number of ever-smaller missions (although many opportunities for cutting-edge science on Explorer-class missions still remain), and large observatories or facilities (e.g., interferometers) will be needed in space. The astrophysics lessons learned, as described below, will therefore be critical not only to the future of international cooperation in space in general but also for progress in space astrophysics in particular.

Clearly Defined and Significant Mission Responsibilities

During the SOHO mission development phase, a clear understanding arose between NASA and ESA of how responsibilities were to be shared. The costs of SOHO were to be shared nearly equally between ESA and NASA


Ballmoos, P., Dean, A.J., and Winkler, C., "Proceedings of the 17th Texas Symposium," Ann. New York Acad. Sci. 759:401, 1995; Carli, R., et al., Proceedings of the 2nd INTEGRAL Workshop (ESA SP-382), European Space Agency, Paris, 1997, p. 581; Courvoisier, T., "The Astronomical Community and the INTEGRAL Mission," Proceedings of the 2nd INTEGIRAL Workshop (ESA SP-382), European Space Agency, Paris, 1997, p. 581; Gehrels, N., et al., "The INTEGRAL Core Programme," Proceedings of the 2nd INTEGRAL Workshop (ESA SP-382), European Space Agency, Paris, 1997, p. 587; Matteson, J.L., Dean, A.J., and Winkler, C., "Proceedings of the 2nd Compton Gamma-Ray Observatory Symposium," AIP 294:89, 1994; Winkler, C., ed., "Report on INTEGRAL Phase A Study," ESA SCI 93:1, 1993; Winkler, C., "INTEGRAL: Overview and Mission Concept," ApJSS 92:327, 1994; Winkler, C., "Proceedings of the 4th Compton Gamma-Ray Observatory Symposium" (in press).

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

to cover the development of the spacecraft on eventual mission operations. ESA retained overall responsibility for implementation of the SOHO project, which proved to be a determining factor in mission success. ESA took the lead in developing and integrating the spacecraft, whereas NASA undertook launch and mission operations. Interfaces between the agencies were extremely clean with well-defined responsibilities. Although the joint AO for instruments was difficult to implement, the determination of the PIs and the agencies overcame the difficulties. In addition, contributions from national agencies in Europe and from scientific and technical communities on both side of the Atlantic proved crucial.

Clear definitions of mission responsibilities also contributed greatly to the success of ROSAT development. For example, the direct access the U.K. project team had to the spacecraft contractor (Dornier), to GSFC, and to MPE minimized unnecessary levels between personnel on each side of the various interfaces. For formal and informal communications between the German and U.K. project teams, there were straightforward, clearly defined points of contact with neatly delineated responsibilities. In Germany, scientists were responsible for the science, including design, construction, and testing of the instruments. Managers at DLR-PT were responsible for controlling industry and funds; and the scientific-technical aspects were supported by MPE. There was a free flow of technical interactions between MPE and industry, along with good relations and cooperation between scientists and managers in all phases of the project. Moreover, for ROSAT, the modest added cost of the HRI by NASA greatly extended mission scope and utility.

For HST it is clear that ESA's responsibility not only for the solar arrays but also for an important instrument (FOC) helped solidify the mission in Europe and, even more importantly, strengthened the bond between NASA and ESA.27

Public Perceptions

Particularly since Hubble's repair with the Shuttle servicing mission in December 1993, HST has been a public space spectacular. This may have been a two-edged sword. NASA and U.S. scientists have received much credit for the success, whereas ESA and European scientific users have not been lauded as widely. This is true in both the United States and Europe and reflects a limited public understanding that space missions can be truly cooperative and international.

It is unclear that ESA will be able to support the development of a replacement instrument for the FOC, which could be supplied in the final servicing mission planned for 2002. (NASA has committed to providing the Cosmic Origins Spectrograph as a follow-on to the FOC.) Without a follow-on instrument from ESA, or significant contribution to HST hardware, will the Hubble remain a truly international mission? Planning at both the mission and the agency levels should include provisions for possible changes in mission status.

Strong Community Support Coupled with Broad Community Participation

ROSAT has been an enormously successful mission—not only because of its scientific successes, but also because of the huge numbers of participants outside of the hardware producers who have taken part in the observing program and have used data archives. In terms that appeal to scientific managers, ROSAT was a cost-effective mission. This result was anticipated when the mission was planned and played a key role in its selection by funding authorities in the United States and Europe.

The SOHO mission was, from its inception, strongly supported by the astrophysics communities in the United States and Europe. The mission payload was developed over a period of years during which concepts for complementary instrumentation presented scientific possibilities richer than the sum of individual components would imply. In addition, there was solid support for the mission within NASA and ESA. The HST effort was generally consistent with this experience, whereas INTEGRAL shows what happens when this broad and strong community support is not enjoyed on both sides of the Atlantic.


ESA also participated in the Science Operations Facility at the Space Telescope Science Institute in the United States and set up its own Space Telescope-European Coordinating Facility (in Garching, Germany), which further clarified mission responsibilities.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

The European high-energy astrophysics community was solidly behind INTEGRAL. Although the predecessor U.S. Explorer-class mission, NAE, was favorably mentioned in the decadal study (Bahcall report),28 the broad astronomical community either was generally unaware or had not been persuaded that NAE, as reconstituted in INTEGRAL, should be the next Explorer-class mission. NASA initially supported the mission (e.g., U.S. participation in the Phase A study) without having identified the resources necessary to carry it through. The mission did not receive as high a recommendation from NASA's internal advisory bodies as it did in ESA; moreover, the breadth of support appears in hindsight to have been lacking, and this could not be offset by strong support in Europe. The fact that NAE had not been selected meant that many in the U.S. community did not believe that a significant NASA role in INTEGRAL had passed peer review and was therefore justified.

In the United States, the INTEGRAL mission had a more limited community. What was presented as an observatory mission with extensive possibilities for drawing in large segments of the ground- and space-based observing communities was not perceived this way by U.S. astrophysicists because of the long observing times typical of gamma-ray observations. This meant that relatively few observations would be carried out in the course of the mission and appears to have been a factor in the NASA decision to withdraw from INTEGRAL. In any case, it was clear that only a relatively limited community would likely make observations with the INTEGRAL observatory. In addition, as noted above, some segments of the U.S. astrophysical community were concerned that the nuclear line sensitivity achieved with INTEGRAL would simply not be enough to achieve the desired breakthroughs and a future, more sensitive mission was needed instead.

Strong National Ties

ROSAT is a case mission showing that nation-to-nation international cooperation can be successful and sometimes easier to manage than NASA-ESA missions. For the ROSAT mission, strong and well-organized scientific groups existed in each of the participating countries (Germany, the United Kingdom, and the United States). The European high-energy astrophysics community had been involved in all NASA missions since the first x-ray satellite, the Small Astronomical Satellite 1 (SAS-1), called Uhuru, the Swahili word for "freedom." British scientists had worked on their own ARIEL series of missions and were also hardware providers for AXAF instrumentation. German scientists had developed x-ray technology through a series of rocket flights. Both groups had participated in the development of ESA's European X-Ray Observatory Satellite (EXOSAT) mission. NASA was kept apprised of these activities by the U.S. community. The ROSAT cooperative effort resonated strongly with U.S. government policy with respect to two long-term allies in Europe, Germany and the United Kingdom. Does this mean that nation-to-nation missions are more successful than NASA-ESA missions? This study unearthed no firm evidence for such a generalization; nation-to-nation cooperation may fail, as demonstrated by the Comet Rendezvous Asteroid Flyby (CRAF) mission (United States-Germany), which is mentioned in the next section on planetary sciences. INTEGRAL, SOHO, and HST, for example, show that ESA-NASA cooperation can be highly successful and lead to top-level research.

Long-Term Commitment—The Memorandum of Understanding

The HST project was originally planned as a 15-year mission with an MOU that guaranteed ESA 15 percent observing time in exchange for supplying the FOC instrument, solar panels, and ESA staff at the STScI. Extension of the MOU is currently being negotiated between ESA and NASA and is complicated by the uncertainty inherent in mission lifetime, as well as by the provision of a replacement instrument for the FOC. In a cooperative major mission such as HST, there should be provisions for extensions of the MOU in the original mission agreements. The planned lifetime of the HST extended beyond the term of the first MOU. Both parties could have considered, in general terms, what to do to extend the cooperation while still allowing for potentially altered circumstances


National Rescarch Council, The Decade of Discovery in Astronomy and Astrophysics, National Acadcmy Press, Washington, D.C., 1991.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

within the partnership, including the inevitable changes in both agencies of personnel who may have negotiated the original agreements.

Inconsistent or Misaligned Schedules for AOs or Planning

The INTEGRAL experience shows that there may well be a fatal problem if schedules are not well aligned. ESA and NASA were at different places in their funding cycles and their plans to release AOs for new missions. Whereas ESA is fully committed to carry through on a mission once it has been chosen by the competitive selection process after the presentation of Phase A studies, a corresponding NASA decision would require that the mission be prioritized within an ongoing NASA selection process. The INTEGRAL Phase A study was carried out in response to an invitation from ESA, without an initial solicitation on the NASA side. After supporting the invited U.S. members of the Science Working Team and prospective U.S. PI team throughout the INTEGRAL study and Phase A processes, NASA withdrew support at about the time the AO was issued because there was no current mechanism for the mission to compete against other opportunities in astrophysics.

The difficulty inherent in the misalignment of schedules was apparent most recently on the Rosetta mission (see following section), where NASA had to shift its commitments to other components of the mission simply because it could not provide assurances on the schedule deemed necessary by ESA.

Need for Appropriate Budget Lines

INTEGRAL may highlight a gap in NASA's budget lines, but other missions (particularly with the new theme of "smaller, faster, cheaper") may point to similar difficulties in ESA.

It remains unclear how NASA can respond to an international call for mission participation. The closest it has, at present, is in "missions of opportunity." An investigator can now propose a mission of opportunity with a cap of $20 million under the Explorer line. This will be peer reviewed along with the normal Explorer proposals, which are asking for full funding. This mission of opportunity line is not a de facto international payload line; it could also respond to opportunities from other parts of the federal government as well as the private sector. The joint committee notes, however, that the cap would have been too low to support the INTEGRAL spectrometer.

Planetary Sciences

Planetary science has a rich history of international scientific partnerships that could justify a separate report. However, there have been few planetary missions of international cooperation, defined in this report to mean the combined efforts of two or more countries in an integrated project (large or small) to reach a common goal. Most international planetary projects to date have been executed by one country or entity, with minor contributions of hardware, software, and engineering and scientific expertise from another. The withdrawal of a minor participant would not have been catastrophic.

For the purposes of this report, two missions have been selected that are representative of international cooperation in planetary science in the fullest sense: (1) the Cassini mission with the Huygen probe, which is an ongoing joint project of NASA, ESA, and Agenzìa Spaziale Italiana (ASI, the Italian Space Agency) and (2) a generic Mars mission, which represents the failure to instigate a successful joint Mars mission over the past decade despite many attempts.

The Cassini mission is distinctive in that both ESA-ASI and NASA are making major contributions to the project in a respective cost ratio of 30 percent to 70 percent, and the ultimate success of this mission requires that each participant meet its commitments, even though the United States has overall responsibility for the mission. By comparison, Galileo and CRAF were essentially NASA missions. The German space agency (DARA) was initially going to provide the propulsion systems for CRAF and Galileo, one science instrument for CRAF, and three for Galileo. Following the cancellation of CRAF, the Galileo part of this plan was successfully implemented. The cometary missions Giotto and Rosetta are essentially ESA-led projects. NASA had a minor involvement in Giotto to provide DSN support and may provide instruments for the Rosetta orbiter as well as DSN support.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

Cassini Mission with the Huygens Probe


Cassini is a joint U.S.-European mission to the Saturn system with emphasis on its largest satellite, Titan. The mission consists of a Saturn orbiter, provided by the United States; the Huygens probe, provided by ESA; and telecommunication and microwave systems, provided by ASI. In addition, individual ESA member states and the United States contributed a total of 18 instruments for the Cassini orbiter and the Huygens probe. The scientific objectives are to conduct orbital remote sensing of Saturn's atmosphere, icy satellites, and rings; in situ orbital measurements of charged particles, dust particles, and magnetic fields; and detailed measurements with six instruments on the Huygens probe during descent through Titan's dense, nitrogen atmosphere to the surface. In addition, if the probe survives after landing, it will conduct surface science measurements. The Cassini mission will address scientific issues raised by the highly successful Voyager 1 and 2 flybys in 1980 and 1981. A representative summary of fundamental science issues follows:

  • The thermal structure and composition of the atmosphere of Saturn and their possible impact on theories of formation of the solar system, evolutionary histories of the planet, the rings, and the satellite system;
  • Atmospheric dynamics and the general circulation of a rapidly rotating planet, which obviously exhibits significant differences from Jupiter;
  • Dynamo theory and the generation of the axially symmetric magnetic field;
  • The configuration and dynamical evolution of the ring system and its interrelation with the satellite system;
  • The nature of the surface of Titan and its atmospheric composition leading to important constraints on theories of formation of the Saturn system;
  • The detection of prebiotic molecules in Titan's atmosphere, and possibly the determination of physiochemical processes that lead to their formation;
  • The formation, internal configuration, and surface processes of icy satellites as well as their comparative study; and
  • The configuration, composition, and dynamics of the magnetosphere of Saturn and its interactions with the solar wind, the satellites, and the rings.29

The Cassini mission was launched on October 15, 1997, on a Titan IV-Centaur vehicle. The trajectory requires Venus-Venus-Earth-Jupiter gravity assists to deliver the Cassini spacecraft to Saturn in June 2004. The Huygens probe will be released on the first orbit after orbital insertion approximately 22 days before the first Titan encounter-flyby. The primary orbiter mission lasts 4 years (approximately 60 orbits around Saturn).

Historical Background

The historical origins of the Cassini mission can be traced back to the Space Science Board (SSB) [Space Studies Board as of 1989] of the National Research Council (NRC) and its Committee on Planetary and Lunar Exploration (COMPLEX), which recommended in its 1975 report an in-depth exploration of the Saturnian system subsequent to the Pioneer and Voyager flyby encounters.30 In 1980 the NASA Advisory Council formed the Solar System Exploration Committee (SSEC) to address the high cost of planetary programs and their long development times. During the summer of 1982, the SSB and the Space Science Committee (SSC) of the European Science Foundation (ESF) established the Joint Working Group (JWG) on Cooperation in Planetary Exploration for the


Joint Working Group on Cooperation in Planetary Exploration, National Research Council, United States and Western Europe Cooperation in Planetary Exploration, National Academy Press, Washington, D.C., 1986, pp. 91-92.


Space Science Board, National Research Council, Report on Space Science—1975, National Academy of Sciences, Washington, D.C., 1976.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

purpose of creating a framework for joint space missions to planets and primitive bodies. Also in 1982, a French scientist initiated discussions of the possibility that France and the United States could join forces to conduct a mission to the Saturnian system in a manner analogous to the U.S. Galileo mission to Jupiter. Mission costs to France were too expensive, and the French scientist teamed up with a German researcher, along with 27 other European scientists, to propose to ESA a Saturn orbiter and Titan probe mission to be conducted jointly with NASA and referred to as Project Cassini.

In January 1983 the SSEC issued its report with four core missions recommended: the first, the Venus Radar Mapper (1988 launch); the second, a Mars Geoscience and Climatology Orbiter (1990 launch); the third, Comet Rendezvous Asteroid Flyby (CRAF)—the first mission to use the Mariner Mark II spacecraft; and the fourth, a Titan Probe-Radar Mapper using a modified Galileo probe. The latter could be combined with a Saturn orbiter mission based on the Galileo spacecraft. However, it became evident in early 1983 that NASA was unwilling to proceed with a U.S.-only mission to the Saturnian system. The principal reason was the high cost; only 3 years earlier, the SSEC had been formed to recommend cheaper, more cost-effective planetary missions, and a Galileo spacecraft gave the mission a "Cadillac-Mercedes" cost image.

The JWG set up an Outer Planets Study Team (OPST) in February 1983 to "construct plans for candidate Saturn system missions to be jointly carried out by ESA and NASA." A joint ESF-NRC assessment study by OPST was conducted during 1983 to decide on scientific objective for the proposed mission (which were essentially the Project Cassini objectives) and to recommend a mission concept, model payloads, required technologies, launch opportunities, schedules, and costs for various orbiter spacecraft and probe designs. The OPST gave its highest priority to using the spare Galileo spacecraft, with ESA taking the lead in developing a new lightweight Titan probe. This recommendation was based on "the exceptional capabilities of the Galileo spacecraft, extensive altitude coverage with a lightweight probe, and the low mission cost associated with use of an existing spacecraft."31

Although this approach made sense financially, it was politically unacceptable because the SSEC report had just come out and proposed the generic Mariner Mark II spacecraft for deep-space missions to hold down costs. The Mariner Mark II spacecraft was never built, but the concept was attractive enough to encourage abandoning the spare Galileo spacecraft approach and, when coupled with subsequent funding problems, to delay a new start for the Cassini mission until the end of the decade. However, the Cassini project incorporated a significant heritage from developmental work on the Mariner Mark II spacecraft (which yielded reduced costs to the mission). It should also be noted that in these initial stages of international discussions and assessments, a European-supplied orbiter and a U.S.-provided Titan probe based on Galileo probe development were also considered as possible contributions to a joint Cassini mission.

After the culmination of OPST activity in 1983, a large group of scientists headed by a French researcher submitted a mission proposal to ESA in response to one of its periodic calls for proposals. A joint ESA-NASA assessment study was carried out in 1984-1985; meanwhile, executives of the ESA science program obtained approval of the Horizon 2000 long-term program. A new call for mission ideas was issued to select mission concepts for a Phase A study. Because of the lack of a NASA commitment, the Cassini mission was put on hold in the ESA system while a number of other missions were being assessed. This move by ESA to mesh schedules proved precisely the right action, given the political and budget realities. At the end of 1986, new candidates to become the first "medium mission" had to be selected, and solar system science was given the possibility of studying two missions at the Phase A level.

The Solar System Working Group recommended to the ESA executive that two Phase A studies be carried out during 1987-1988: one for an asteroid-comet mission called Vesta in cooperation with Russia and France (this mission resembled very closely the present international Rosetta mission), and Cassini. A few days later ESA's Space Science Advisory Committee (SSAC) met to select a maximum of four Phase A studies covering both astronomy and solar system disciplines. The Cassini-Titan probe was eventually recommended pending a final NASA commitment to the mission.


United States and Western Europe Cooperalion in Planetary Exploration, 1986, pp. 88-128.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

Meanwhile during 1986, COMPLEX stated that "highest priority for outer planet exploration in the next decade is intensive study of Saturn—the planet, satellites, rings, and magnetosphere—as a system."32 With this endorsement, NASA was able to initiate a joint Phase A study with ESA. The results of this study, initiated in 1987, were published in the so-called ESA red report33 in October 1988. On November 25, 1988, SSAC and SPC selected the Huygens project as the first medium mission in the Horizon 2000 long-term plan as ESA's part of the joint Cassini mission. The competing ESA missions were VESTA, LYMAN (a UV space observatory), QUASAT (a radio, very long baseline interferometer satellite), and the Gamma-Ray Spectroscopy and Positioning (GRASP) telescope. On the U.S. side, NASA continued definition studies on the CRAF and Cassini missions and advanced development work on the Mariner Mark II spacecraft during 1987-1988. Cassini was paired with CRAF as a single mission in early 1988 for a proposed new start in FY 1989. It was included in the president's FY 1990 budget request to Congress, and Congress finally approved the CRAF-Cassini missions in November 1989. NASA's budget for Cassini in FY 1990 was reduced from the initial request of $40 million to $30 million, and further cuts in the FY 1991 budget used up all contingency funds for that year.


In October 1989, two separate but coordinated AOs were issued by ESA and NASA for selection of the Titan Huygens probe and Saturn orbiter instruments, respectively. This was the first instance of separate AOs being issued for a joint mission, which was done to avoid the legal problems that characterized payload selection for the SOHO mission caused by the issuance of a joint AO. ESA selects payloads on behalf of its member states who finance flight instrument construction; NASA selects and pays for the instruments. This creates completely different legal environments. Since then, all ESA-NASA cooperative efforts have been implemented through separate but coordinated selections.

Originally in August 1988, in the new start presentation to then NASA Administrator James Fletcher, the launch date for Cassini was April 1996, after the scheduled launch of CRAF (set for August 1995), which allowed the Huygens probe to be tested at the Jet Propulsion Laboratory (JPL). (Subsequent changes in launch dates required direct delivery of the Huygens probe to Cape Canaveral.) The CRAF-Cassini Baseline Confirmation Review in January 1991 found a way to reduce the total development phase by having Cassini launch on November 28, 1995, and CRAF on February 6, 1996. On September 26, 1991, the U.S. House-Senate conference allocated $117 million34 less than the amount needed for the CRAF-Cassini mission in 1992, which delayed the launch date for Cassini until October 1997 and CRAF to April 1997, with a total development phase cost of $1.85 billion. On January 29, 1992, the president submitted his budget without CRAF. Given the financial situations for both NASA and DARA (reunification of Germany created inherent financial problems), the German space agency made the inevitable mutual decision with the United States to cancel CRAF.

Budget realities also precipitated a request from NASA Headquarters to reduce all development phase costs associated with the Cassini spacecraft and resulted in several simplifications, including elimination of the scan platform in April 1992 for a savings of $250 million from the previous budget of $1.68 billion. The Cassini mission was restructured deliberately to have negligible impact on ESA's Huygen's probe and was presented to NASA on April 23, 1992, by JPL; NASA authorized the Cassini mission at its current budget of $1.4 billion and schedule on May 22, 1992. One then current hope in terms of the ordered reduction in development phase costs by NASA Headquarters was that "non-time mandated development costs," which could be moved to the mission operations and data analysis (MO&DA) phase, could be recovered later. However, this proved to be wishful thinking. The MO&DA budget of Cassini was reduced from $1.5 billion to $1.32 billion in July 1992 by the


Space Science Board, National Research Council, A Strategy for Exploration of the Outer Planets: 1986-1996, Committee on Planetary and Lunar Exploration, National Academy Press, Washingtnn, D.C., 1986, p. 5.


Cassini Phase A Report ScI 88:5.


All budget figures for the Cassini mission have been kindly supplied by Ronald Draper, Jet Propulsion Laboratory, deputy project manager of the Cassini mission.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

NASA Blue Team–Red Team Review. The Cassini project then reexamined the architecture and philosophy of MO&DA and at the MO&DA preliminary design review in November 1993 presented a restructured, cost-effective approach that reduced the budget to $976 million. It is difficult to project the impact of the reduced MO&DA budget on science objectives.

The Cassini mission almost suffered the "budget ax" in preparation for the president's FY 1995 budget request to Congress in January 1994 and during congressional deliberations in the summer of that year. Here, the international aspect of the Cassini mission was an extremely important factor in reversing almost certain cancellation of the mission. In a subsequent review (Recertification Review 3) of MO&DA costs, funding was reduced to $755 million in June 1994 and in NASA program operating plans for 1995 and 1996; this was then reduced further to its present $700 million for the JPL-managed total. However, when NASA Headquarters taxes and contingency costs are added to the JPL total, the overall Cassini mission funding is still $755 million.

The Cassini mission is a complex undertaking involving 16 European countries and the United States in supplying technology, hardware, software, and engineering and scientific expertise. To carry out this cooperative venture, a number of agreements were formalized, including (1) an MOU between NASA and ESA signed on December 17, 1990, and (2) an MOU between NASA and ASI signed on June 14, 1993 (an agency-to-agency agreement); to secure funding, this was elevated to a government-to-government agreement via the exchange of diplomatic notes in mid-1994, for design, development, and delivery of four Cassini orbiter components. The components are (1) the High Gain Antenna-Low Gain Antenna-1 Assembly, (2) a significant portion of the radio-frequency instrument subsystems, (3) about half of the Cassini radar, and (4) the visible channel of the visible and IR mapping spectrometer hardware and personnel. The two and one-half year separation between the two MOUs reflects the active role of JPL's Cassini management in working with ESA, whereas Italian contributions to Cassini escalated over time in response to additional NASA requests and significant delays in defining the terms of cooperation. Several reimbursable agreements were negotiated between NASA and individual European member nation agencies for unique space-qualified components for Cassini, which were not available on the open market. In the Cassini AO (NASA), scientists were encouraged to bring in international partners on their instrument teams to reduce costs to the United States. The science payload selected has 18 instruments, with 2 to 10 countries providing parts of each instrument. Letters of financial endorsement had to be requested from every country involved in the development of each instrument.


Since the Cassini mission is ongoing, it is not possible to give a postmission assessment of how well the cooperative efforts worked. Instead, the basic management structure of the Cassini mission and some preliminary perspectives from the European and U.S. points of view are described. NASA established a program office at its headquarters, headed by the Cassini program manager along with the program scientist.35 The program manager is responsible for overall management of the mission and coordination with ESA. NASA also established a project office at JPL headed by the Cassini mission project manager36 with overall responsibility for mission management and implementation. ESA established a Huygens project office at the European Space Research and Technology Centre (ESTEC) headed by the Huygens project manager with overall responsibility for management and implementation of the Huygens probe. The primary group for science advice to NASA and ESA project managers is the Cassini Project Science Group (PSG) co-chaired by the Cassini and Huygens probe project scientists. All principal investigators, interdisciplinary scientists, and team leaders (along with project scientists and NASA's program


For the purposes of this report, a program manager is an individual responsible for cost, schedule, and technical performance of a multior single-project program and who oversees the project managers for integrated program planning and execution. A program scientist defines the policy and scientific direction of a program, establishes the mission science and applications objectives, and guides the science team to ensure that the scientific objectives are met.


For the purposes of this report, a project manager manages the design, development, fabrication, and test of a project. A project scientist is the scientist who coordinates with the program/project manager to ensure that the science requirements of an investigation are met.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

scientist) are members of the PSG. In addition, an equivalent group, the Huygens Science Working Team, serves the same function for the Huygens probe. The PSG meets about three times a year; the ESA-NASA MOU specifies that at least one of these meetings must be in Europe. Unfortunately, although the letter of the MOU has been satisfied on this requirement, the spirit has not, in part because NASA foreign travel regulations restrict the number of U.S. scientists and engineers who can attend any given international meeting on NASA travel funds. Given the complexity and diversity of the various contributions from 16 European countries and the United States to the Cassini mission, the PSG has served scientists acceptably as a format to optimize scientific return and resolve the usual conflicts between the engineering and science sides of a mission.

From the U.S. perspective, ESA and ASI have provided highly dedicated personnel as well as excellent hardware and software for the Cassini mission, with considerable cost savings to the U.S. government and taxpayers and the potential for much greater scientific return from the mission. The overall costs of Cassini are shared, approximately 70 percent by the United States and 30 percent by European member nations. From a European point of view, Cassini gives the European planetary community an outstanding opportunity to be deeply involved in one of the major missions of solar system exploration. The Cassini mission enjoys broad-based scientific support because its objectives cover most of the important scientific issues concerning the Saturnian system and thus involves the entire planetary science community. In times of crisis, international MOUs have provided strong support for continuance of Cassini.37

Finally, as pointed out in the case study, the scientific community is fortunate that the Cassini mission with the Huygens probe was launched successfully on October 15, 1997. There were several occasions at which cancellation of the mission may have occurred. Both NASA and ESA took actions to maintain phasing of the mission within their decision process rules and constraints; where there is a strong will, such actions are possible. The successful launch of Cassini-Huygens was regarded as a miracle by some involved in the mission: The mission was very ambitious and its implementation was risky.

Generic Mars Mission


The generic Mars mission (GMM) differs from most of the other missions in this study by being not a single specific mission, but a sequence of mission concepts—all of which were studied in detail (in four cases, right through Phase A in ESA)—none of which came to fruition. This discussion focuses on why so much effort was expended on designing a series of international missions to Mars without a positive outcome.

Within the solar system, Mars has long had a special appeal because of its resemblance to Earth, the variety of science issues it poses, the possibility that life might have appeared there, and its potential for eventual human exploration. As a result, all space agencies involved in planetary exploration have always been interested in participating in Mars exploration.

In recent years, an International Mars Exploration Working Group initiated by the Inter-Agency Consultative Group (IACG) has examined the science goals of Mars exploration, currently approved missions of different agencies, and the constraints on and desires of those agencies in terms of participating in future Mars exploration. The working group has formulated a tentative plan for Mars exploration for the next decade, which includes multiple missions to Mars at every launch opportunity and culminates in a broadly international network of stations at the 2003 launch opportunity.

At the time of this writing, different elements of the plan are in various stages of implementation. In 1996, Russian launch of a complex mission to Mars (Mars-96), including an orbiter, two small landers, and two penetrators, ended in failure. In late 1996, the United States launched Mars Surveyor, an orbiter that should


Ronald Draper, Jet Propulsion Laboratory, deputy project manager of the Cassini Mission, and Dr. Dennis Matson, Jet Propulsion Laboratory, Cassini project scientist, are acknowledged for their help in providing general information and facts on the Cassini-Huygens mission.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

recover most of the original Mars Observer objectives,38 and Mars Pathfinder, a highly successful small lander with a robotics rover that landed on the surface on July 4, 1997. More broadly, Congress has approved a Mars Surveyor program with multiple launches at subsequent opportunities. In 1998, the Japanese will send a spacecraft to characterize the interactions of Mars with the solar wind (Planet-B). Discussions are also under way to design a Russian-launched mission in 1998 that includes a U.S. orbiter, a French balloon (recently withdrawn), and a Russian rover. For nearly a decade, ESA has been studying how an international network mission (i.e., a pattern of small landers on the surface, with similar or identical payloads) might be implemented in 2003, with NASA as the primary partner.

Historical Background

NASA missions to Mars extend to Mariner 2 in 1962 and concluded, temporarily, with the outstanding success of Viking in 1976. Europe came on the scene in 1980, when a Mars Orbiter mission called Kepler was successfully proposed to ESA as a Phase A study. At about the same time, NASA undertook a study of a similar mission called Mars Geoscience Climatology Orbiter and later known as Mars Observer. In 1985, a decision was made to link Mars Observer and Kepler to produce the first attempt at an international Mars mission, the so-called Mars Dual Orbiter.39

In 1993 a new ESA Phase A study was completed on a more ambitious joint mission with NASA, called Marsnet, to place surface stations on the red planet. A revamped version of the same project was studied in 1994-1996 under the name Intermarsnet. Other Mars missions were studied by NASA: Mars Aeronomy Orbiter, Mars Environmental Survey (MESUR), and Mars Rover Sample Return. Each involved considerable guest participation from Europe.

Thus, over a period of about 15 years, three fully cooperative missions to Mars (in the sense of having nearly equal proposed contributions) were studied to a high level. In addition, several studies either were carried out at a low level or were not truly joint because most of the funding was to come from a single international partner.

The GMM includes international aspects of all of these missions, which had the same destination and broadly similar or overlapping scientific objectives.

Description of Four Missions Kepler was to be a spin stabilized orbiter in a highly eccentric polar orbit about Mars. Mars Observer was a three-axis stabilized polar orbiter in a close, circular orbit, 360 km above the Martian surface. The Kepler orbit was to come in so low that direct sampling of the upper Martian atmosphere would have been possible five times a day. The latitude of periapsis changed by about 1 degree per day, to give good global coverage during the course of the mission, including both polar regions. Launch of both spacecraft was planned for September 1993, but this target was achieved only by Mars Observer. Some argued for joint science objectives on the premise that two spacecraft would be required to operate simultaneously; however, the missions were independent, although coordination would have been beneficial.

The Marsnet mission was to consist of a network of small stations on the surface of Mars. The main scientific goals were determination of the internal structure of the planet, chemical and mineralogical analysis of Martian rocks and soils, study of atmospheric circulation and weather patterns, and determination of the exobiological conditions existing on the surface. The expanded Intermarsnet mission was to consist of a network of stations to be landed on the Martian surface, but it later included an orbiter around Mars carrying scientific instruments in addition to its data relay function for the landers. Complementary data obtained from orbit would have included atmospheric sounding and imaging, roughness radar measurements, and plasma environment monitoring. The main scientific goals of the mission would have been to study the internal structure of the planet; the surface


The Mars Observer, launched in 1993, failed to reach Mars orbit and lost contact with ground control. NASA's current plans call for two Mars missions every two years.


European Space Agency, KEPLER: An Interdisciplinary Mars Orbiter Mission (ESA Document No. SCI[82]5), ESA, Paris, 1982; European Space Agency, KEPLER Mars Orbiter (ESA Document No. SCI[85]6), ESA, 1985; European Space Agency, MARSNET (ESA Document No. SCI[93]2), ESA, Paris, 1995; European Space Agency, INTERMARSNET (ESA Document No. SCI[96]2), ESA, Paris, 1996.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

morphology and geology at the landing sites; the geochemical and mineralogical analysis of Martian rocks, soils, and volatiles; the atmospheric circulation, structure, and weather patterns; the magnetic field and geodesy of the planet; and exobiological conditions during the planet's history.

Cooperation Attempts

Cooperation in the exploration of Mars is perhaps discussed more than any other large international space project, and it is the one with the highest public profile.

The Mars Dual Orbiter (Mars Observer and Kepler) concept originated from the Terrestrial Planet Study Group (TPSG) of the JWG of the National Academy of Sciences–National Research Council (NAS-NRC) and the ESF. This group, which worked from 1982 to 1984, endorsed a Mars Dual Orbiter mission based on two independent mission proposals that were considered separately by NASA and ESA. These were the NASA Mars Geoscience and Climatology Orbiter, later named Mars Observer, and the ESA Kepler Mars Aeronomy Orbiter mission. The study team argued that by flying both of these missions in close coordination and simultaneously around Mars for a significant period, enhancements of the overall science return would be achieved. The missions went forward as a pair of single-agency projects, with the intention of obtaining the benefits of coordination if both were selected. The Mars Dual Orbiter failed because of a lack of reciprocal support and the need for each partner to contribute. However, it represented a failure of international coordination rather than international cooperation because each contribution could have been carried out independently.

Marsnet was a community proposal in Europe, submitted to ESA in response to a call for new mission proposals for the next medium-size project (M2). The call was issued in June 1989 by the director of scientific programs in the framework of the new selection cycle of the Horizon 2000 long-term plan. After evaluating all proposals concerning solar system missions, the Solar System Working Group (SSWG) recommended Marsnet for a Phase A study, following the assessment study in 1990-1991. This recommendation was subsequently endorsed by the SSAC. The Phase A study was coordinated with NASA, in view of possible future cooperation on a joint ESA-NASA Mars network mission. NASA, in parallel, studied similar landers in the framework of the MESUR mission. The Marsnet and MESUR study teams kept each other informed and exchanged representatives at their respective meetings. However, neither MESUR nor Marsnet ever reached fruition.

Nevertheless, the concept of a network mission to Mars is still a scientific priority. The practical benefits of cooperation stem mainly from sharing the costs of comprehensive scientific investigations on Mars. The surface network, in particular, requires a large launch vehicle and a relay-mapping orbiter, plus sophisticated landing systems. The surface network approach is therefore intrinsically a fairly expensive venture for which cost sharing not only makes sense but may also be the only way to proceed cost-effectively. Thus, the Intermarsnet began immediately after cancellation of Marsnet. The Intermarsnet mission was submitted to ESA in response to a call for new mission proposals for the next medium-size project (M3) issued in November 1992. After evaluation of all proposals concerning solar system missions, the SSWG recommended Intermarsnet for a Phase A study following the assessment study performed in 1993-1994. This recommendation was subsequently endorsed by the SSAC and the SPC.

The Phase A Study was conducted jointly with NASA, with the specific goal of a joint mission to be launched in June 2003. NASA's component was drawn from the Mars Surveyor program, which already had congressional approval. A joint ESA-NASA Intermarsnet Science Working Group was formed to support Phase A activities during 1994-1996 with engineering and industrial teams. A successful International Workshop on Intermarsnet was held on September 28-30, 1995, in Capri, Italy, to demonstrate a fundamental, deep interest in Mars exploration among the wide international scientific community. Before conclusion of the Phase A study, the new budget for the ESA science program was approved by the European ministers with a reduction of 10 percent (possibly becoming 15 percent) over 5 years. The need for cost reduction of the mission to be selected put the Intermarsnet mission in severe difficulties vis-à-vis competing missions. ESA's budget squeeze threatened to delay the European part of the project, whereas NASA believed it could proceed only if the original launch date was adhered to. The less complex, cheaper, and ESA-only COBRA-SAMBA mission40 was eventually selected in place of


The COBRA-SAMBA has been renamed the Planck Surveyor.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

Intermarsnet as the third medium-size mission of the Horizon 2000 long-term program. Once again, ESA's involvement in the exploration of Mars was postponed. As consolation for the solar system community, the promise was made to reserve the next medium mission budget for planetary science disciplines.


None of the Mars missions described actually came into being as a cooperative project; therefore, no actual cooperation (on flight systems at least) can be described. Yet in scientific communities, and to a certain extent within the space agencies that conceived and developed mission proposals and carried out design studies, great enthusiasm and goodwill resulted in highly effective cooperation. This derived from mutual recognition of the importance, interest, and timeliness of the science goals for Mars, as well as interest in using a cost-benefit analysis of cooperation to achieve a sweep of objectives too expensive for one partner under most circumstances.

The reason for the ultimate failure of cooperation is much harder to diagnose. It should be noted that this was not the isolated failure of a desirable project but the failure of a whole sector of a high-profile section of space science that was pursued diligently over an extended period in several different forms by many committed people.41 The following factors were among those that contributed to the unsuccessful cooperation:

  • Inadequate coordination within the European planetary community;
  • Distraction by domestic pressures to achieve other objectives, not specifically targeted by the joint mission, especially Mars Rovers (mainly in France, affecting Kepler) and Mars Sample Return (mainly in the United States, affecting Intermarsnet); and
  • Serious difficulties in matching the mechanics of the selection process on the two sides of the Atlantic to achieve a realistic program.

Lessons Learned

The planetary science community is strong only in some of the large European countries, and U.S. solar system missions competing for ESA new starts face strong competition from astronomy missions. Averaged over all of Europe, the European astrophysics community is considerably stronger and more cohesively organized than its planetary science community. Even in the United States, where NASA revolutionized the discipline, planetary scientists must compete against a well-organized astrophysics community noted for decadal implementation studies that clearly lay out future directions for astronomy and are highly valued by Congress. In Europe especially, the planetary sciences community is not well coordinated and cannot practice the ''cartel" approach used by astronomers. International cooperation in planetary science operates within this competitive space science environment. Any lessons learned must be understood in this context.

In October 1982, the JWG on Planetary Exploration of NAS-NRC and ESF formed the TPSG, which recommended the development of a Mars Dual Orbiter mission. Four months later, JWG formed OPST, which endorsed the Cassini mission as the priority for the next major planetary probe. Thus, Mars and Saturn system missions started on equal competitive footing with well-defined science objectives. Both missions progressed to Phase A studies (Kepler in 1982, Cassini in 1987-1988) and ended by competing against each other and two astronomy missions (Quasat and Lyman) for the ESA Horizon medium mission selection in 1988. In this competition, Cassini benefited from the extraordinarily successful Voyager and its heritage of international cooperation. Voyager had established strong working relationships among European and U.S. scientists as coinvestigators associated with the 11 instruments on board each spacecraft. Unlike some missions portrayed in this report, at the time of Horizon medium mission selection the Cassini and Kepler missions could not be faulted for inadequate preparation. In fact, both missions were well-defined in terms of science, instruments, and orbits. Hence, by any standards, the proposals that emerged from strong joint working groups formed in 1982-1983 were mature and solid.


The comments and suggestions of Professor P. Masson, Université De Paris-Sud, and Dr. Marcello Coradini, ESA Headquarters, Paris, regarding the Mars mission studies are gratefully acknowledged.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
"Sink or Swim Together"

One thing that distinguishes the Cassini mission from the Dual Orbiter mission is the philosophy of international participation. Cassini was constructed as an international cooperative effort in a mode of sink or swim together. In contrast, the Kepler mission was constructed as an international coordination project in which ESA and the United States would separately pursue Kepler and MGCO (Mars Observer), respectively, but with enhanced science return if done concurrently. The two components of the Dual Orbiter mission went independently through their agencies' selection procedures, and the result is well known. The Mars Observer was launched and Kepler failed to materialize. Kepler's direct competition with Cassini involved the same scientific community, and lack of synchronization with the Mars Observer timeline led to the failed cooperative effort.

The Cassini mission in its sink-or-swim-together mode generated strong "lobbying and support" efforts on both sides of the Atlantic. This partnership ensured that the importance attached to this cooperative enterprise was communicated to individual space agencies, ESA, and the U.S. government. In particular, the European lobbying and support effort was extremely important and effective in attaining a new U.S. start for Cassini in FY 1990 and averting near cancellation of the Cassini mission during FY 1994. The letter ESA Director General Luton to U.S. Vice President Gore was an essential action at a crucial stage in the mission and illustrates the potential importance of international cooperation for mission success (Appendix G). For the Europeans, a total expenditure of almost $0.5 billion on the Huygens probe and Saturn orbiter would have been wasted if the United States had failed to honor its international agreements. In this context, an important lesson learned about U.S. financial support of space science, with its annual budget cycles, is never to assume that an individual space mission is safe from budget reductions or elimination. A vigorous educational lobbying effort is needed every year, particularly when a new U.S. president assumes office. This lesson is now evident as a result of the events that occurred in late 1993 through the summer of 1994, when Cassini was in deep trouble.

Clearly Defined and Significant Responsibilities

The sink-or-swim linkage on Cassini was complemented by clean interfaces and significant mission responsibilities. For the Europeans, Cassini provided an outstanding opportunity for the European planetary community to be deeply involved in a major solar system exploration mission. From an engineering point of view, clear technical interfaces allowed ESA management to maintain independence and full control of Huygens probe development. For scientists, the construction of space instruments in the framework of worldwide consortia is nothing new and resulted in no specific Cassini-related problems. Although the total cost of this mission could be construed as greater for all the taxpayers of participating countries, the current economic and political realities are that an individual country can no longer pay for a Cassini-class planetary mission alone.42 Thus, missions on this scale require international cooperation to share the cost. Given a choice between going it alone without a mission or international cooperation with one, the choice for space scientists is obvious.

Broad Community Support and Mission Cost

To put it simply, as the cost of a major mission escalates, the breadth and strength of community support for the mission must also escalate. Marsnet and Intermarsnet were both fairly expensive missions and could not be carried out by ESA alone, except perhaps as cornerstone missions. These occur only about every 5 years and are in a highly competitive environment with other disciplines requiring access to space. A mission on the scale of Marsnet or Intermarsnet might not have attracted sufficient support in Europe as a cornerstone because of the inbred commitment of a majority of European space scientists to experiments on small bodies, particles and fields, and dust. Given the strength of the astronomy community as well, it seemed likely that cooperation with the


In other words, the cost to taxpayers in any one country is certainly less in a cooperative mode than it would be for that country to conduct the project without international partnerships.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

United States was not just desirable but absolutely essential to the success of a Mars network mission. On the American side, there was concern in some quarters that by putting pressure on the budget line, support for Intermarsnet in 2003 might indirectly jeopardize its top priority, a Mars sample return mission in 2005. Despite strong and sincere support for Intermarsnet on both sides in the selection showdown, lack of a single-minded approach among the communities on both sides of the Atlantic, combined with the relatively high cost that was threatening to delay the launch date, in the end proved fatal.

In formulating the extension to the long-term ESA program now called Horizon 2000 Plus, European Mars exploration suffered incredibly from rapidly evolving international interest and scientific objectives. The search for life has been an underlying motive in Mars exploration and research for years, but the negative results from the Viking landers required the advocacy of Mars missions to be more circumspect. In 1994, European planetary scientists also had to propose a Mars mission scenario that could guarantee scientific originality 13 to 15 years after its conception. The United States, on the other hand, had the capacity to carry out a network mission unaided but, in the current climate of massive cost-cutting, saw clearly the fiscal benefits of international cooperation. Cost, then, was a main factor driving cooperation on the later joint Mars missions, although there was also a strong desire among scientists to work together to maximize the scientific return for a given level of expenditure, and to exploit the scientific expertise available from many countries that did not reside in any one nation alone. But it is fair to say that the mentality established during the Mars Dual Orbiter Mission of international coordination, rather than the Cassini partnership of "sink or swim together," has permeated subsequent planning for ESA-NASA Mars missions.

Schedule Alignments and the Mission Approval Process

In the ESA system, the Marsnet failure could also be attributed to the lack of approval of the NASA component at the time of ESA selection. The different ESA-NASA mission selection processes and schedules are especially difficult for missions that only require coordination. The recent selection of an ESA astronomy mission instead of a Mars mission could illustrate a potential problem in flight selection procedures for accomplishing U.S.-European cooperation. NASA selection is subject to an intense political and scientific process, which can often take years for a mission to reach NASA's highest space science priority, and still be subject to revocation. In contrast, ESA makes a permanent selection decision based on a kind of tournament at which all interested parties gather and campaign. On a positive note, ESA "slowed down" its process in 1983-1985 during the development of the Cassini mission and thereby better matched the schedule on the other side of the Atlantic. This proved very beneficial to the development and approval of the Cassini mission.

Space Physics

Investigations in space physics—whether experimental or theoretical—are largely devoted to specific phenomena in space such as the physics of acceleration of charged particles, entrainment of magnetic fields by the solar wind, shocks of various types traveling in the interplanetary medium, radiation trapped in planetary magnetospheres, and elemental and isotopic composition of energetic particles from the galaxy that can be investigated only in a space environment. These and other basic mechanisms cannot be brought down to the scale of Earth laboratories; however, they are the "ground truth" for explaining phenomena on larger astrophysical scales such as the galaxy.

Space physics is also unique in that the instruments required are relatively small and are usually derived from the culture of experimental physicists working alone or in small teams. This culture also reflects the end-to-end approach with PI-based teams that design and build their instruments, participate in testing and launching, supervise data processing, carry out their research, and publish their findings. Thus, this is generally a different background from the astronomer relying on common instrument facilities (e.g., the HST) built and operated by others—in this case, their investigations begin after the facility is in space flight. These differences in culture are often reflected in how investigators and their institutions approach international opportunities.

Because space physics missions extend to the planetary magnetospheres (e.g., Mercury, Earth, Jupiter, Saturn) or to the outer reaches of the interplanetary medium and heliosphere in three dimensions, the spacecraft that carry

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

a typical mix of space physics instruments can be costly. Consequently, international cooperative missions—including those by ESA and NASA, or nation to nation—represent the potential for significant cost sharing. It should also be noted that in space physics it is easier and often more effective to form international partnerships with individual instrument teams than in the case of large, complex, facility-class instruments.

From a historical perspective, the subdiscipline of space physics has a strong tradition of international cooperation, beginning in the early 1960s with Ariel-I and Ariel-II and the early Explorers. To date, there have been some 45 such missions that have had at least a partial focus on space physics. Perhaps the height of the modern era of this tradition, when the balance between European and U.S. participation within a given project reached contributions at the spacecraft level from both sides, along with closely integrated science, begins with the International Sun-Earth Explorer (ISEE-1, 2, and 3) program, launched in 1977-1978. Space physics on both sides of the Atlantic has benefited greatly from this cooperation, with subsequent projects such as the Active Magnetospheric Particle Tracer Explorer (AMPTE) and the ISTP as positive examples of such cooperation. Some programs have failed to live up to expectations, usually because of a breakdown in support for the program on one side or the other, a prime example being the ISPM, which was to have consisted of two spacecraft flown simultaneously over opposite poles of the Sun. The failure of this cooperation both shocked and dismayed participants on both sides of the ocean, who had considered the international aspect to be a buffer against just such a descope. The scaled-back version of this mission, Ulysses, has been very successful in its own right, but only for some of the goals of the original program.

In space physics, three missions have been chosen for discussion, from which different lessons may be taken. The ISEE-1 and ISEE-2 program, based on joint NASA-ESA cooperation, is a good (if perhaps historical) example of the mutual benefit, good-faith cooperation, and strong scientific product that can be achieved. The AMPTE program is likewise a highly positive example of a relatively small mission, in this case conducted bilaterally and later trilaterally (the United States and Germany at first, with the later addition of Great Britain), in which institutional relationships played the dominant role in the interaction. The third mission discussed is the ISPM, a program of ambitious scale that provides the first historical example of a breakdown in the teaming of NASA and ESA. The ISTP would have important, more current lessons to contribute, but it is not included here primarily because it is still going on and because unlike the three missions that are covered, the coordination is much looser, with responsibility concentrated in a particular agency at the spacecraft level. (This arrangement may, in fact, be considered the result of lessons learned from earlier cooperative ventures such as ISPM.) SOHO (an element of the ISTP) is, however, discussed as one of the examples in the section on astrophysics.

International Solar Polar Mission


The heliosphere is a vast region totally enclosing the solar system and extending to approximately 100 to 120 astronomical units (AU) (one AU is equal to the distance between the Sun and Earth). The heliosphere is produced by the radial outflow of the solar wind plasma from the Sun, carrying outward with it an extension of the solar magnetic field. This three-dimensional electrodynamical "bubble" interfaces with and is contained by the interstellar medium. Understanding of the physical processes occurring within the heliosphere was based, until 1992, on observations from Earth and spacecraft located within about 7° from the heliospheric equator. Only two spacecraft, Pioneer-11 and Voyager-1, reached 16° and 30° latitude, respectively, in the distant heliosphere. Thus, until spacecraft could undertake observations over a latitude range in the inner heliosphere extending from pole to pole of the Sun and heliosphere, the essentially two-dimensional world in the ecliptic zone had to be extrapolated, with assumptions used to make theoretical models for a three-dimensional heliosphere.

Because there are differences between the north and south hemispheres (e.g., solar activity, coronal magnetic fields) over the 11- and 22-year solar activity cycle, it was obvious that heliospheric dynamics would be neither static nor necessarily uniform over both hemispheres. Consequently, these time- and space-dependent asymmetries would require simultaneous investigations over both hemispheres of the Sun and heliosphere for observations of the solar wind, magnetic fields in the heliosphere, or incoming galactic cosmic rays, among other phenomena.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

With these factors in mind, ISPM was planned to consist of two spacecraft, passing to and over opposite heliospheric hemispheres simultaneously in order to separate time and spatial changes that could complicate the analysis of heliospheric dynamics in three dimensions.

Ultimately, only one international spacecraft—Ulysses—was launched. It reached 80.2° south latitude in 1994, passed perihelion in March 1995, and reached 80.2° north latitude in mid-1995 under conditions approaching the solar minimum of the approximately 11-year solar cycle. The many diverse scientific investigations on Ulysses were hugely successful, and the resulting discoveries in many fields of space physics drastically changed many concepts that had been based on extrapolations from the two-dimensional world.

Historical Background

In the early years of scientific investigations in space it became increasingly clear that dramatic solar and interplanetary discoveries made near the ecliptic plane of the Sun and heliosphere could be fully understood only by extending observations to the polar regions of the Sun and heliosphere. However, in the 1960s—in both the United States and Europe—only a minor portion of the scientific community was concerned with this three-dimensional goal for space flight. This is understandable because of a major technical difficulty. In the 1960s, there was no propulsion system for a direct launch from Earth that could overcome the orbital angular momentum of Earth, which was necessary for a spacecraft launch out of the ecliptic to a high solar latitude.

By the early 1970s, driven by the goals of U.S. programs to investigate Jupiter and develop a galactic probe, scientists and engineers had solved the principal technical problems for a future out-of-ecliptic (OOE) mission. These solutions included the following:

  • The radioisotope thermoelectric generator (RTG), instead of solar panels, for spacecraft power;43
  • A gravity assist for a swing-by of Jupiter;44 and
  • Development of radiation-resistant electronics for penetration of the Jovian radiation belt.45

Attempts between 1972 and 1974 to convince NASA administrators to use the spare (backup) Pioneer spacecraft for an OOE failed (Appendix B) but did lead the administrator to discuss a possible international OOE mission with the ESA director general. In Europe, the method proposed in the 1960s and early 1970s for OOE was the development of a solar-powered ion propulsion engine to launch a spacecraft directly from Earth. When it became apparent that there would be no support for such engine development, there was strong motivation for ESA member states in 1973 to be interested in international cooperation with the United States.

To investigate the feasibility of a cooperative program between the European Space Research Organization (ESRO, now ESA) and NASA, ESRO appointed three European scientists and NASA appointed four U.S. scientists in 1974. This study group held alternating meetings in Europe and the United States in 1974 and 1975. A dual spacecraft mission was proposed that would maintain clean interfaces. This proposal, which became the ISPM, was accepted by ESA and NASA. The ESA spacecraft would be spin stabilized, whereas NASA's would be stabilized to accommodate a coronagraph. AOs to propose scientific investigations were issued by ESA and NASA in April 1977.


With a dual launch planned for the February 1983 window of access to Jupiter, ESA and NASA moved swiftly before U.S. congressional approval of ISPM to obtain spacecraft contractors, identify investigators, and define the instrument payload. The joint announcement in early 1978 of experiments selected for the two spacecraft revealed


Studies of RTG radiation on charged particle telescopes; Letters from J. Epstein, Goddard Space Flight Center, 1962, to Simpson and final report, May 1966.


The success or Pioneer 10 in the December 1973 swing-by of Jupiter proved that this approach for an OOE mission would be successful.


This problem persisted throughout the 1960s. Resolution or the problem enabled Pioneers F and G, now called 10 and 11, to be launched to Jupiter in 1972 and 1973, respectively.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

the magnitude of interest in ISPM by the science community. More than 200 scientists from 65 universities and research institutions in 13 countries were associated with ISPM. The selection of experiments in early 1978 included a mix of ESA and NASA investigations on each spacecraft. The investigators moved ahead with enthusiasm, apparently unaware—until it was too late—of impending difficulties that would culminate in cancellation by NASA of the U.S. spacecraft containing both European and U.S. experiments.

In January 1978, the budget request for FY 1979 submitted by the president to Congress included the ISPM as one of five new starts. Congress approved it but effectively cut $5 million from the $13 million ISPM request to cover overruns in Space Shuttle development costs. NASA signed an MOU with ESA in March 1979 (Appendix C), but by year's end the chairman of the Senate Appropriations Subcommittee for Housing and Urban Development and Independent Agencies (which has budgetary jurisdiction over NASA) was suggesting to the NASA administrator that ISPM be delayed 2 years since Shuttle development was behind schedule and the interim upper stage (IUS), still to be developed for the Shuttle, probably could not launch the dual spacecraft. In response to this difficulty, it was recommended that the Centaur upper stage replace the IUS. Nevertheless, no action was taken to alter the mission until President Carter submitted an amended budget for FY 1981. This amended budget maintained the U.S. craft but proposed a postponement of the mission for 2 years, moving the launch from 1983 to 1985.

With the election of President Reagan came a change of White House policies in the Office of Management and Budget (OMB). The White House, under the usual practices of a new administration, recast the Carter budget in line with Reagan administration objectives. When the revised budget was released, OMB called for overall budget reductions within each NASA budget category for FY 1982, which resulted in $107 million less for the Office of Space Science and Applications (OSSA).46 NASA chose to absorb a good portion of these cuts by eliminating the $43 million originally slated for ISPM in FY 1982. After initial release of the FY 1982 budget request in which these cuts were outlined, NASA made a token request for funds for ISPM that was turned down (see Appendix D).47 Soon thereafter, Acting Administrator Hans Mark rejected the two-spacecraft option. This led to cancellation of the U.S. spacecraft, finalized by the conference vote on NASA's budget in late September 1981.

When the new NASA administrator, James Beggs, arrived in June 1981, it was essentially too late—his options to save ISPM were lost. This may seem somewhat confusing since Congress was still interested in an ISPM mission. In November 1980, Congress (at the urging of scientists) had requested that NASA have the National Academy of Sciences-National Research Council study ISPM mission options—options to be reported back to Congress before September 11, 1981. Congress expected this review to consider the scientific merits and all costs of the two-spacecraft options. Because the timing of the decision was critical, the congressional conferees expected to be briefed by the review panel on its recommendation by September 11, 1981.

Throughout late 1980 and early 1981, NASA staff prepared five options for an OOE mission, extending from a single ESA spacecraft to the full ISPM dual spacecraft mission, with cost estimates for NASA funding (estimates from $110 million to $460 million; see Appendix E). Unfortunately, the NRC committee did not meet until July 1981 to consider these five options. Its report was submitted on September 9, 1981.48 This tardy response to Congress was too late to serve the new NASA administrator. ESA was informed by Administrator Beggs on September 4, 1981—without prior consultation with ESA and before the expected congressional review—that NASA would not include a request for funds for the U.S. ISPM spacecraft in its FY 1983 budget proposal to be submitted to OMB.49


The cooperative effort for a dual mission obviously failed. There may have been a lack of belief in the community that the mission required two spacecraft, in other words, that it was essential to acquire bipolar solar


Johnson-Freese, J., "Canceling the US Solar-Polar Spacecraft," Space Policy, February 1987, p. 24.


Letter from the Office of Management and Budget to NASA, June 22, 1981 (see Appendix D).


National Research Council, Committee on NASA Scientific and Technological Program Changes, The International Solar-Polar Mission: A Review and Assessment of Options, National Academy Press, Washington, D.C., 1981.


As a result, only the first option of the five given in Appendix E—the single ESA spacecraft—was still viable.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

data simultaneously. Specific factors also contributed to the unsuccessful outcome of NASA-ESA cooperation. Administration and congressional changes led to personnel turnover and the loss of several key administrators in 1980–1981. Consequently, these changes contributed to a lack of understanding of the importance of ISPM and of the consequences of cancellation of the U.S. spacecraft. Misunderstandings arose in Europe from a lack of understanding of the U.S. budgetary process. Although the MOU contained caveats indicating possible cancellations by NASA, it never clearly stated that the mission depended on yearly action by Congress. In addition, there were communication gaps among the scientists selected to perform experiments, the agencies, and Congress. Since the selection and mixing of ESA and NASA experiments on each of the two spacecraft had been completed in early 1978, scientists involved in the mission believed until early 1981 that ISPM was secure. Moreover, contractors for scientific instruments and spacecraft had made substantial cost commitments to ISPM, on both sides of the ocean, before the mission was submitted to Congress for approval. These investments resulted in large losses, both scientific and financial, when the spacecraft was canceled. Communications problems were further exacerbated when ESA was not consulted in the decision-making process on canceling ISPM. The hurt experienced by scientists and officials, especially in ESA states—both real and perceived—created a contentious atmosphere that influenced later cooperative efforts.

Finally, by early 1982, ESA and NASA decided to move ahead with the single ESA spacecraft containing the original 1978 mixture of ESA-U.S. investigations. NASA delays in launch vehicle development, followed by the Challenger accident, postponed launch of the ESA spacecraft until 1990. The mission, renamed Ulysses, resulted in important discoveries in its solar pole-to-pole passage in 1994 and 1995. NASA fulfilled its other commitments—12 ESA personnel, supported by ESA, are at JPL in charge of mission operations. An extended mission to return Ulysses to the solar polar regions in 2000–2001 was approved by ESA unconditionally in 1994 and by NASA in 1996, with a year-by-year caveat of possible cancellation (Appendix F).

Active Magnetospheric Particle Tracer Explorer


The Active Magnetospheric Particle Tracer Explorer program was a three-nation, three-spacecraft mission. It was designed to study the sources, transport, and acceleration of energetic magnetospheric ions and the interaction between clouds of cool, dense, artificially injected plasma and the hot, magnetized, rapidly flowing natural plasmas of the magnetosphere and solar wind. The three AMPTE spacecraft were the NASA Charge Composition Explorer (CCE), the Federal Republic of Germany's Ion Release Module (IRM), and the United Kingdom Subsatellite (UKS), so termed because of its close proximity to the IRM and its launch configuration acting as the flange between the IRM and the booster. The three were launched together on August 16, 1984, into near-equatorial elliptical orbits. All contained extensive instrumentation supported by a diverse team of investigators, with the CCE and IRM providing the only complete data set existent on energetic ion spectra, composition, and charge state throughout the near-Earth magnetosphere. In addition, the IRM carried out either major active ion releases—two clouds of lithium ions in the solar wind in front of the magnetosphere; two barium "artificial comet" releases in the dawn and dusk; and two releases each of lithium and barium ions in the near magnetotail. The UKS, which malfunctioned after 6 months, provided plasma, magnetic field, and plasma wave measurements. This satellite flew in close proximity to the IRM and was expected to provide information on the spatial scale of physical processes associated with ion releases.

Historical Background

The AMPTE mission was conceived in the early 1970s as a logical next step in understanding the energetics of Earth's magnetosphere. Composition studies had been going on for some years in high-energy cosmic rays. New and exciting results showed that many elements were represented, not just protons and electrons, and there were hints that charge states might be important and not necessarily as simple as expected.

In the magnetosphere, the radiation belts had been explored to the extent that the locus and energy distribut-

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

tions of ions and electrons were fairly well determined, with the plasma sheet mapped to a much lesser extent. Virtually nothing was known about the composition of the ions, their sources, their charge states, and the mechanisms that accelerated them to high-energy (either from solar wind energies or ionospheric energies). This was the next logical step in the exploration of the near-Earth space environment.

Along with the development of new time-of-flight techniques for measuring ion composition and charge state, the release of gases into the ionosphere and magnetosphere had been developed by German scientists at MPE. In these experiments conducted from rockets, fast-ionizing materials—mostly barium atoms—were released. For painting auroral magnetic field lines, shaped charges were used. Releases were timed so that while ground observers were in darkness, the gases expanded into sunlight where they were quickly ionized. A host of scientific applications existed for these artificial plasma releases, such as tracing the otherwise invisible magnetospheric convection or DC electric fields, tracing or even generating instabilities and the formation of ionospheric irregularities, and verifying the existence of electrostatic acceleration in the auroral region.

This combination of developments, it was argued, could be employed in experiments that combined the release of gases (barium and lithium, which do not occur naturally in the magnetosphere, ionosphere, or solar wind) with tracing of the ions, by use of a separate satellite with excellent instrumentation. The strategy was to release ions in the source regions for the magnetosphere (i.e., solar wind and geomagnetic tail) and place the tracing satellite well within the outer magnetosphere. In this way, it was hoped that the transfer efficiency through respective magnetospheric boundaries, as well as acceleration and transport processes, could be established.

Complementary to the magnetospheric particle tracing was the second objective, the diagnostics of the interaction between the natural plasma environment (solar wind, plasma sheet) and the dense, heavy ion population of the release gas clouds, by both in situ and remote (ground-based) sensing. There was particular interest in releases in the solar wind, because these would simulate the creation of cometary plasma tails (artificial comet experiments). A third objective was to use the plasma and field diagnostic instrumentation on both spacecraft to monitor the magnetospheric and solar wind environment with model instrumentation, particularly the newly developed ion composition and charge state techniques.

The mission was considered an attractive concept, both because of its novelty and promise of ushering in a new, powerful technique for actively exploring space plasmas as well as for its timely goal of measuring the composition and charge state of the hot plasmas in the magnetosphere. Although no trace of any of the releases from the IRM was ever detected at the CCE, the release experiment gave rich information on the interaction between environmental and injected plasmas, owing both to on board diagnostics on the IRM and the UKS and to remote sensing from various ground stations and airplanes. The detailed composition and charge state measurements throughout most of the equatorial middle magnetosphere by the CCE, and the assessment of dynamical processes in the near-Earth tail and at the magnetopause made by instruments of the IRM, remain valuable resources today.


The most important characteristics of the AMPTE mission from an organizational perspective were that it was led by two principal investigators (one from the Johns Hopkins University Applied Physics Lab [APL] for the United States and one from MPE for Germany) and that the spacecraft were developed in these institutions under the control of the PIs. At the same time, the PIs were responsible for their respective spacecraft, each of which carried multiple instruments (the UKS was, under this arrangement, considered an instrument of the IRM). Given this architecture, the PIs were better able to drive the science agenda and thereby foster and impose a common set of science objectives and collaborations. NASA oversaw the AMPTE project under the manager of international programs at GSFC, who was known for his strong management and his facility in moving AMPTE funds.50


The AMPTE manager at GSFC set aside 15 m 20 percent as contingency funds and forced APL to spend more money to make the spacecraft more robust—for example, two transponders, redundant power converters, and a cold-gas altitude system in addition to magnetic torquing. Thus, the project contingency was used up-front for robustness, at the direction of the government.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

The program also employed a new paradigm regarding data rights. Data from any instrument were available to any other and easily accessible through the AMPTE Real-Time Science Data Center, operated by the APL data reduction and analysis team. The data center was designed according to guidelines dictated by data rights and by the obligation to provide data equally to the entire science team.51

The mission began in 1971 as a concept expressed in two letters sent by APL to the magnetospheric physics chief at NASA. In the time between these two letters, Germany became involved, and the mission proceeded for several years as an extended study on both sides of the Atlantic. In 1976, the mission proposal was submitted to NASA in response to Explorer AOs 6 and 7. In 1977 it was selected jointly along with the Solar Mesospheric Explorer (SME) and the Infrared Astronomical Satellite (IRAS). Because of IRAS cost overruns, hardware building for AMPTE was delayed on the U.S. side until 1981 when the start of Phase C/D was funded by NASA.

Germany had begun building the previous year, and the MOU between Germany and the United States was signed in the fall of 1981. The UKS was conceived, after the failure of the Firewheel Ariane launch, to enhance in situ diagnostics during the gas release phases, as well as at natural boundaries such as the magnetopause. British participation interfaced with the project through Germany. According to the MOU, the UKS was formally considered an IRM experiment.

The three spacecraft were launched in 1984 aboard a Delta and were successfully placed in their intended orbits. The UKS failed 6 months into the mission; the CCE and IRM survived and completed the primary mission.


With its state-of-the-art composition and charge state instrumentation, AMPTE was very successful in its science goals of investigating the composition and charge state of the energetic ions throughout the inner and middle magnetosphere, in determining the dynamical processes at the interface between the solar wind and the magnetosphere, and in exploring the near-Earth magnetotail. Although initially conceived as a highly focused and modest space physics mission, like the successful ISEE mission, the CCE and IRM spacecraft proved to be important tools in the exploration and long-term monitoring of interaction processes between the solar wind and Earth's magnetosphere and atmosphere, and the resulting changes of particle populations and field configurations. The scientific success of the AMPTE mission was due, in part, to the science data system, which originally allowed on-line access to all of the data by all coinvestigators and guest investigators. Today, it is open to general access by the space physics community and is still being used very actively (more than 500 publications have been based on the AMPTE data set, with more being submitted every year).52

Good communications between and among mission participants, agencies, and political entities contributed to AMPTE's success. Educating and maintaining contact with political players also proved critical. Efforts by mission leaders in the United States to foster political support and work with both Senate staff and NASA management helped secure start-up funding for AMPTE. Similarly, the PIs' political involvement was important in keeping the mission on track. They acted effectively at a congressional level when trends adverse to the mission arose.


Although data were accessible by all the Pls, their use in publications was subject to the individual instrument team leader's permission. This permission request was, for the most part, simply a courtesy but was always observed. The practice was viewed as a safeguard against people analyzing data they did not fully understand and interpreting as actual geophysical events what might be instrumental glitches.


The section on AMPTE was compiled from the following sources: interview with Dr. Stamatios M. Krimigis, department head, Space Department, the Johns Hopkins University Applied Physics Laboratory, Laurel, Md., 1996; John Dassoulos, AMPTE Program Manager, the Johns Hopkins University Applied Physics Laboratory; and contributions from Prof. Gerhard Haerendel, PI, Max Planck Institute für Extraterrestrische Physik, Garching, Germany. Other references include the AMPTE website,<; IEEE, Transactions on Geoscience and Remote Sensing (GE-23), 1985; Memorandum of Understanding Between the United States National Aeronautics and Space Administration and the Federal Minister for Research and Technology of the Federal Republic of Germany on the Project of the Active Magnetospheric Particle Tracer Explorers, October 15, 1981; Department or Housing and Urban Development, "Independent Agencies Appropriations Bill 1981 Report," which accompanied H.R. 7631, specifically appropriating start-up money for AMPTE; letters from S. M. Krimigis to Dr. E. R. Schmerling, Magnetospheric Physics Chief, NASA, June and September 1971.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

International Sun-Earth Explorer Mission


The International Sun-Earth Explorer mission introduced a novel feature into solar-terrestrial and space plasma research, a dual spacecraft approach to the measurement of crucial boundaries or small-scale plasma structures, plus monitoring of these conditions about 1 hour ahead of their arrival at Earth's magnetosphere, where the spacecraft pair was operating. The spacecraft pair ISEE-1 and ISEE-2 were launched jointly on a Thor Delta 2914 from the Eastern Test Range in October 1977. The apogee was 146,000 km and the perigee 700 km, with about 30-degree inclination. ISEE-3 was launched in August 1978 and inserted into a halo orbit around the libration point 1.5 × 106 km upstream of Earth. Later it was placed in the far tail and was finally redirected as the International Cometary Explorer (ICE) to intersect the tail of comet Giacobini-Zinner in September 1985. The ISEE-1 and ISEE-3 spacecraft were built by NASA, based on the very successful Interplanetary Monitoring Platform (IMP) design; ISEE-2, a smaller spacecraft, was built by ESA and carried the thrusters for station keeping with ISEE-1. The payloads of all three spacecraft were carefully adjusted to each other for optimum coverage of all relevant plasma, field, and high-energy particle parameters. The instrument PIs on all three spacecraft were from the United States and Europe. From a total of 80 proposals, 31 instruments were selected by a joint NASA-ESRO selection committee. The mission was extremely successful and led to many discoveries and to deeper understanding of crucial plasma processes. For years the total production of papers arising from this effort exceeded 100 annually. Even as late as 1996 there was still a steady flow of papers based on ISEE data.

Historical Background

The origin of the two-spacecraft concept can be traced to 1968-1969 when discussions began in the United States on the possibility of realizing a satellite pair IMP K-K'. At the same time, a British scientist was trying to promote in Europe the idea of a cluster of satellites. The NASA project scientist on ESRO II at the time brought this idea to ESRO, and soon the idea of a joint NASA-ESRO mission was born. In early February 1971, during a joint NASA-ESRO program review in Washington, D.C., the idea was officially discussed and introduced into the ESRO scientific advisory system. With positive recommendations from the respective advisory bodies on both sides of the Atlantic, a joint NASA-ESRO AO was issued in mid-1972 for the now renamed mother-daughter mission. This was contrary to ESRO's standard procedure, because it had not yet approved the mission, but it was done to have time to incorporate this project into the International Magnetospheric Study 1976-1979 (IMS) for which ESRO was developing the GEOS (geostationary satellite), launched in 1977, and GEOS-2, launched in 1978.


The IMS was proposed as a concerted effort to acquire coordinated, ground-based balloon, rocket, and satellite data for enhanced understanding of the magnetosphere and its response to the solar wind. Many programs were begun worldwide in support of the IMS and coordinated through a central information exchange office. Information on satellite position was provided by the Satellite Situation Center at GSFC. As data became available, coordinated data analysis workshops were held with great success. The IMS helped stabilize the mission, which was finally named ISEE.

On ESRO's side, the ISEE mission was selected jointly with the x-ray mission HELOS, which was to be renamed European Space Agency's X-Ray Observatory (EXOSAT) in early 1973. After completion of a competitive Phase B in 1974, the contract for ISEE-2 was placed with Dornier Systems in late 1974. The joint launch of ISEE-1 and ISEE-2 in October 1977 occurred only 12 days later than had been predicted 3 years before.

ISEE was the first ESRO-NASA project in which hardware as well as software contributions were intimately intertwined. Thus, there was little experience with carrying out such an enterprise and determining the best organizational form. On either side of the Atlantic were a project manager and a project scientist (who were

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

thought to represent and protect the rights of investigators). These four made up the JWG responsible for running the project. The PIs formed a science working team (SWT) that advised the JWG. The latter met every 3 months, the SWT twice a year. The MOU which covered these organizational relationships, laid down the general responsibilities of the two agencies.


There were probably three reasons ISEE became such an outstanding scientific success beyond the excellent technical work done by spacecraft contractors. First, at the time of the AO, integrated teams with the participation of scientists from several laboratories on either side of the Atlantic had formed and were seriously competing against each other. The teams were formed on the basis of mutual appreciation of similar or complementary expertise and often on already existing personal friendships. The established multiplicity of human ties proved to be a great help in problem solving and decision-making in the SWT.

In addition, the two project managers for ISEE-1 and ISEE-2 (on which this discussion concentrates because of the symmetry between both sides of the Atlantic) were well suited for a cooperative project. Both leaders had strong personalities and a similar sense of humor; they respected each other and had a strong commitment to finding the most practical interfaces between their respective activities and products. They were equally and appropriately unimpressed sometimes by certain contradicting formal requirements. For example, they jointly opposed (successfully) the imposition of NASA specifications on European industrial contractors. A similarly harmonious relationship developed between project scientists at NASA and ESA. The value of people with a strong dedication to international cooperation, a commitment to solving problems, and a sense of humor should not be underestimated.

Finally, as mentioned above, the ISEE project was a fundamental (and probably the most important) element in the IMS. It was embedded in a highly motivated, worldwide activity. Coordinated ground-based observations and measurements of other satellites with ISEE were commonplace. The scientific community preparing for and subsequently working with ISEE data and producing supporting theories was steadily growing throughout the 1970s and early 1980s. A crisis in the project was hardly conceivable and never occurred. Altogether, ISEE is one of the outstanding examples of harmonious and successful transatlantic cooperation.

Lessons Learned

In space physics, a long-lasting tradition of cooperation between scientists from either side of the Atlantic, which accelerated with the availability of access to space starting in the 1960s and has continued ever since, created a solid foundation for successful international cooperation on the mission level. Although there was fierce competition in some cases (not necessarily between scientists on different continents), in general it did not result in protective actions with the aim of excluding the other side from participation in a particular mission. In most cases the advantages of cooperation were recognized clearly because the multiparameter nature of mission objectives made combining the individual expertise of various laboratories almost a necessity. Complete coverage of measurement parameters was more important than geographic balance or national pride.

A stabilizing factor was that mission ideas were often subjected to a competitive selection process during which cooperating teams formed even before an AO was issued for the proposal of science instrumentation. In the accompanying study phases, all scientific objectives and their experimental implementations were thoroughly analyzed. Hence, international teams and agreements on goals were being formulated long before formal MOUs were drafted between the respective agencies. The relatively modest size of many of the missions in space physics amplified this PI-collegial mission development and hence the possibility for successful international cooperation. This is particularly true in NASA-European national space agency cooperation as opposed to NASA-ESA cooperation.

As a consequence, it is no surprise that the problems that arose rarely originated from the group of individual scientists but from the agencies instead.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Small Scale and PI Based

AMPTE was basically a two-PI mission, one on each side of the Atlantic, but both responsible for the scientific objectives of the entire mission. In addition, they were responsible to their respective funding agencies for production of the hardware and proper use of the funds, as was the lead scientist for UKS. ISEE, although larger and with multiple PIs, still had the principal investigator in a central role.

ISEE and AMPTE were motivated by well-defined science goals. Principal control of the program was through PIs. This was particularly true of AMPTE, which was relatively small, but also of ISEE. At all stages of the program, science was the overriding issue. Individuals made all final decisions; these were not made by committees.

  • AMPTE and ISEE were well served by a low-cost, easily accessible ground data system. Data distribution was simple.
  • Minimization of international red tape helped significantly in the evolution of the design and the correction of some technical problems. National agencies did not overmanage the program. For example, the MOU for AMPTE was quite broad and flexible, allowing for changes late in the program.
Clean Lines of Authority and Excellent Communication

For AMPTE, since NASA was to provide the launch, the NASA project manager had the overall responsibility for flight worthiness of the three-spacecraft stack. The two European spacecraft were represented by a German project coordinator whose attention was focused on smooth interfaces across the Atlantic and on internal milestones and cash flow. On ISEE, excellent personal relations between the two project managers amplified the value of clean boundaries and minimized difficulties when they occurred.

  • Simple interfaces (both in management and in engineering) were an important element of the success of AMPTE and ISEE.
  • In the ISEE and AMPTE missions, there were excellent U.S.-European communication and rapport. There was great confidence in the reliability and competence of the partners. Excellent communication among engineers, scientists, and technicians within each national team, as well as between these teams, was the norm. Sharing technical (engineering and technology) information across the Atlantic was crucial to the success of AMPTE.
  • There was a breakdown in communication in ISPM. Various parties in the cooperative process—scientists, agency officials, and congressional figures, for example—were not privy to critical information on mission status and budget. This was especially proven in the U.S. failure to consult Europe once budget pressures put ISPM in jeopardy. Europe's lack of understanding of the U.S. mission approval and budget process exacerbated misunderstandings.
Strong Joint Working Groups

In AMPTE, the two PIs headed the joint SWT, assisted by excellent project scientists for the representative satellites. All scientific goals, the approaches to their realization, the construction of scenarios for magnetospheric tracing experiments, the data sharing policy, the command structure, and mutual consultations in the actual execution of plasma releases were jointly planned by the SWT. Many friendships developed in the course of the mission, which helped glue the teams together, not only on the level of participating scientists but also among many of the technical personnel. No wonder that free access to the data of any instrument by all participating investigators was easily agreed-upon, while individual rights to data were respected. This basic structure and the fact that all of the spacecraft were developed and built in scientific institutions under the control of the respective PIs (or U.K. lead scientist) and their spacecraft managers created a stable atmosphere of mutual trust and technical assistance on all working levels.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

In ISEE, there was an intensity of cooperation within smaller interdisciplinary teams that is rather remarkable and that contributed to its overall success.

Element of a Larger International Program

The ISEE project was a fundamental element and probably the single most important one in the International Magnetospheric Study 1976-1979. It was part of a highly motivated worldwide activity in which coordinated ground-based observations and measurements of other satellites with ISEE were commonplace. The value of this approach is seen elsewhere (e.g., with the Ocean Topography Experiment [TOPEX-POSEIDON] in the World Ocean Circulation Experiment).

The Budget Process: The ''Good" News

On the U.S. side, AMPTE was accomplished by funding through the Explorer line item budget, which had a history of continuity. On the German side, the entire contribution was funded at the level of a typical scientific instrument, and funds were entirely within the control of the institute. Similarly, this Explorer-class aspect kept the ISEE within budget lines, kept development schedules short, and forced partners to adhere to schedules. (If ISPM had been an Explorer-class mission as well, it might not have encountered the budgetary problems that beset the mission.)

  • The ISEE and AMPTE mission, once into the hardware phase, enjoyed stable sources of funds on both sides of the Atlantic.
  • With AMPTE, NASA's help in purchasing key components for the European partner kept costs under control. Help with customs regulations was also useful to both sides.

At some stage, strong political connections stabilized the AMPTE program budget.

Budget Process: The "Bad" News

Cancellation of an international cooperative space mission is more likely in the United States than Europe. The ISPM experience highlights this possibility. The reasons for this are rooted in the existing budget and agency processes:

  • The annual congressional review and approval of NASA's budget may result in the refusal to fund any program in any given year;
  • NASA's funding priorities can change, especially with a change of administration;
  • NASA's budget is more integrated than ESA's, so that if NASA's highest priority program has serious budgetary difficulties, other NASA programs can be at risk. This is less likely in Europe, where the mandatory science program is not at risk if, for example, the Ariane launcher program should require additional funding; and
  • If negative budgetary pressures are strong enough in Europe, cancellations could occur there as well. Thus, unilateral cancellation of an international program remains possible because there is no guaranteed protection against such an action being taken.
Warning Signs

Warning signs of dangers of cancellation of an ESA-NASA program are often interpreted differently by NASA and ESA. This appears to have been the case on ISPM. Communication is essential, and such warning signs must be heeded.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Role of the Memorandum of Understanding

The joint committee recognizes that the MOU is an imperfect process for cooperation and can hardly be the basis for international cooperation. However, it remains an important process and can be a crucial stabilizing factor. From the ISPM experience, certain lessons emerge:

  • If a mission plan includes uncertain technical development issues, the MOU must explicitly address these elements and the associated risks. It must include provisions for unfulfilled technical expectations.
  • MOUs are more easily implemented and followed if instrumentation and other engineering issues are in an advanced stage of development.
  • An important element in any MOU should be the obligation for early consultation of partners in case of crisis. This is particularly important when unilateral action would harm the partnership.
  • Cancellation or other significant perturbations in the ISEE and AMPTE programs were not avoided because of a better MOU. What was important to the successful completion of these missions was that the partners shared an "early warning system," a political networking that functioned better than in the case of ISPM.
Being International Does Not Ensure Support

The common belief that multinational missions will provide enhanced protection against cancellation is obviously invalid. Over the years there have been a number of cancellations; CRAF and ISPM are but two. For ISPM, there may be a lesson: Namely, it is not clear that full participation was necessary to achieve an important scientific contribution. Full participation would have provided additional science in ISPM, but significant science achievements might result from a one-spacecraft mission, as was proven eventually by Ulysses. This lack of essential and close coupling of both parties may have been a weakness in ISPM. It should be noted, of course, that the loss of the second spacecraft carried with it not only the loss of contemporaneous measurements of the other solar pole but, perhaps more importantly, the loss of the instruments (European and U.S.) that were canceled along with the U.S. spacecraft. It appears that the two spacecraft were far more coupled in the ISPM than in the Mars orbiting spacecraft discussed earlier (i.e., Kepler and Mars Observer), yet a similar fate was realized (one spacecraft was canceled while the other proceeded on the mission).

In the AMPTE and ISEE missions, loss of the scientific objective if one side canceled its contribution was more obvious (more real) than in the case of ISPM.

Earth Sciences

There is a broad, multidimensional context that influences Earth observation missions and the characteristics and dynamics of international cooperation.

  1. One aspect of this context is the myriad interests and objectives of Earth observation: scientific, operational, commercial, political, and military. The historical development of Earth remote sensing at NASA illustrates operational objectives. Aside from the operational meteorological satellites, it is clear that the early Earth observation satellites were "operations driven." The scientific community used the data without a predefined scientific program governing the observations actually achieved. The first Earth observation satellite that was "scientifically driven" and included a predefined scientific program was the Upper Atmosphere Research Satellite (UARS) launched in 1991.53

    This multidimensional context continues today, when nonscientific reasons may provide significant impetus for Earth observation missions. Moreover, these various interests can confuse the process of defining the goals of an international cooperative mission. The importance of operational and practical applications of Earth observation data has led governments and agencies to create international coordination mechanisms such as the Coordination Group for Meteorological Satellites, the Committee on Earth Observation Satellites (CEOS), and the
  2. 53  

    Even in naming the mission, it was considered necessary to use the word "research."

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
  1. Earth Observation-International Coordination Working Group (EO-ICWG). Overall, however, Earth observation for Earth sciences remains an emerging process.

    From the opposite perspective, the set of data acquired from a given NASA, ESA, or European Earth observation mission may used for several different purposes. For example, data from meteorological satellites can be used for scientific as well as operational purposes; data sets from scientific satellites have operational, commercial, and military uses. These secondary beneficiaries of Earth observation data can lead to restrictions on how the data are used. Consequently, policies on data use in Earth science are extremely important and often difficult to implement. Differences in establishing these policies continue to affect international cooperation in Earth science.
  2. In a similar vein, the development of more technologically advanced observing instruments and more efficient algorithms to extract useful information from the observations can have commercial and industrial benefits as well as scientific advantages. This "technology push" can introduce conflicts of interest in existing or planned international cooperation where none previously existed.
  3. In addition, Earth science disciplines vary widely and have different antecedents: atmospheric sciences (physics, [bio]chemistry); oceanography (physics, chemistry, biology); and land surface studies (hydrology, plant physiology, agronomy, soil sciences, geology, ecology, geography, etc.). There is hardly a single Earth science community.54 The use of space observations in these disciplines and their level of sophistication in terms of modeling differ in part because of the intrinsic emphases of the disciplines, which reflect differences in the underlying processes themselves. For instance, models of the ocean and atmosphere are based to a certain extent on the application of basic hydrodynamic equations, whereas a corresponding basis for analysis of the terrestrial system is not available. The requirements for observations, even of the same variable, vary by discipline and therefore can easily change over time. This can appear confusing or redundant when, in fact, it is neither.
  4. Unlike some of the space sciences, there is a wealth of data in the Earth sciences at spatial and temporal scales far finer than the pixel scales of the remotely sensed data from space science research. This allows and demands a suite of important associated activities—field programs, validation campaigns, calibration experiments, and assimilation efforts—to blend data types. Such experiments lead to particular types of international cooperation as well as a set of external schedules and requirements, often with an international flavor, that must be met by the space-based program.

    To probe certain Earth phenomena such as the climate system, relatively long-term observations are necessary. Yet measurements with different spatial and shorter temporal resolutions are necessary to examine other types of problems. Often, however, the same geophysical quantity (or a similar one) is of interest. The myriad interests and data needs of a particular geophysical property can therefore lead to conflict in determining the requirements for an Earth observation mission. Furthermore, serving these multiple interests can necessitate the collection of huge data sets by a variety of international agencies.
  5. Finally, for some of the space agencies, Earth science and space science programs follow different processes for mission definition, approval, and financing. ESA is a case in point: Earth observation is an optional program, whereas the ESA space science program is mandatory, with secured funding. At the same time, the European Union has a much greater interest in Earth observation than in space science disciplines because of its potential applications.

The Case for Cooperation

There are strong reasons for international cooperation in Earth science missions. The nature of Earth observing satellites leads almost automatically to international cooperation and data sharing, because the space-


However, there is an increasing recognition of the interactions between different Earth science fields as well as an awareness of the importance, for instance, of coupling models of the atmosphere to models of the ocean and land.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

based observations are inherently global. Associated with this shared observation, the history of data exchange within Earth sciences spans more than a century: International data exchange has existed since the earliest days of the space program, often within the framework of preexisting agreements for environmental data exchange. Many of the scientific spacecraft systems have been justified partly on the basis of contributions to international programs (e.g., the Global Atmospheric Research Program [GARP] or the World Ocean Circulation Experiment [WOCE]). The international scientific community has therefore been involved from the beginning in setting the goals of space missions in Earth observation.

There are at least three types of space-based international cooperation in Earth science:

  1. Missions designed with scientific objectives defined in an international cooperation (e.g., TOPEX-POSEIDON, UARS);
  2. International data exchanges for scientific purposes in which the hardware is essentially produced on one side of the Atlantic (e.g., the European Remote Sensing Satellite [ERS] and the upcoming Earth Observing System [EOS] from NASA and the Environmental Satellite [ENVISAT] from ESA); and
  3. Missions with operational or commercial objectives (e.g., the National Oceanic and Atmospheric Administration [NOAA] spacecraft, the European Geostationary Meteorological Satellite [METEOSAT] and the Geostationary Operational Environmental Satellite [GOES] or the Système Pour l'Observation de la Terre [SPOT] satellite).

    It is worth noting that there are no NASA-ESA missions or cooperative activities in Earth science (despite an initial major effort with EOS and ENVISAT) and only a few U.S.-European bilateral missions—NASA with one (TOPEX-POSEIDON) or two (UARS) European nations. As there are lessons to be learned from such bilateral and trilateral cooperation, the lack of NASA-ESA multilateral cooperation may have something to impart as well.

Case Mission Choice and Rationale

Two missions and the polar platform activities have been chosen as cooperative examples for this study.

UARS is the first Earth observing mission based on a scientific program that was conceived and executed through international cooperation among four countries, namely the United States, the United Kingdom, and France, along with Canada. The hardware was designed to meet scientific requirements and was provided by each of the participating countries; data were shared more broadly.

TOPEX-POSEIDON is an example of a space mission that was jointly conceived and funded by the United States and France to contribute to solving a well-identified scientific problem. Elements of the mission (including hardware) were provided on both sides, and data were shared with the wider scientific community.

The polar platform venture is an example of an ambitious joint NASA-ESA program, combining scientific and operational applications. It was proposed at the agency level, in part to create a more efficient global monitoring system with the corresponding data distribution program. Although this joint activity did not come to fruition, it provided an important prelude to the current cooperative activity between NOAA and the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) on the future EUMETSAT-Meteorological Operational Satellite (METOP) and the NOAA-DOD polar orbiting satellites.

The history of meteorological missions might have been considered here, but this study has limited its review to the science side of the issue.55 Cooperation on meteorological satellites presents at least two additional interesting aspects, namely, data sharing and sharing of the satellites themselves. The topic of international cooperation for operational purposes is a rich and important one and merits further study.56


Although these are not strictly scientific missions, the data they provide are very useful to the scientific community.


The issue of convergence will make this topic even more important in the future.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

Upper Atmosphere Research Satellite


The mid-1970s were exciting times in stratospheric research. The furor over the potential impact of the Supersonic Transport (SST) aircraft on the ozone layer was fading when a newly noted chemical reaction involving chlorine and ozone became the subject of focus in scientific journals. It was proposed that chlorofluorocarbons (e.g., CFC-11, CFC-12), otherwise known as Freon® and previously assumed inert, would eventually drift up to the stratosphere, photolyze by UV radiation, and release chlorine. When the chlorine was subsequently oxidized to chlorine monoxide (CIO), it would destroy ozone at a rate much faster than molecules such as nitrogen oxides (NOx), the product of SSTs. The scientific community was challenged to study the impact of CFCs on the stratosphere, project the loss of ozone, and assess the impact of the transmission of biologically harmful UV radiation to Earth's surface.

NASA had a problem of its own. It was suggested that emission gases from Shuttle launches, which contained chlorine, would aggravate ozone loss in the stratosphere. This subject was hotly debated by NASA advisory committees, within NASA itself, and at several boards and committees of the U.S. National Academy of Sciences. It became clear that because there would be only a few Shuttle launches (one or two per month), their effect on ozone destruction would be minimal compared with that of CFCs. But the debate continued on the magnitude and spatial distribution of ozone loss over time that would result from the buildup of CFCs. Although stratospheric research models were being effectively developed, data on the chemistry and dynamics of the stratosphere that could be used to check these models were almost nonexistent.

Historical Background

Scientists inside and outside NASA began to push the agency to launch a comprehensive mission to study the linked physical and chemical dynamics of the stratosphere. The conjuncture was just right. Scientists who had been involved with NASA's program on planetary exploration were ready and available to work on research related to Earth's stratosphere. Similarly, stratospheric scientists could benefit from instruments being prepared for launch on Pioneer-Venus to study its stratosphere, which provided an excellent heritage of scientific knowledge.

NASA's Office of Space Science and Applications (OSSA) set up a Stratospheric Science Advisory Committee to define a mission that would address the fundamentals of stratospheric science rather than just measure chlorine, NOx, and ozone. U.S. and European stratospheric scientists had been working together over the years, so NASA invited the Europeans to join the committee. The mission was extraordinarily well conceived scientifically.


UARS was launched in September 1991. The observatory, 10 m long and more than 6 metric tons, carried nine large scientific instruments: seven from the United States, one from the United Kingdom, and one from a Canadian-French consortium. The success of the mission became clear as precise measurements were made not only of ozone but also of molecules that play critical roles in ozone chemistry, such as ClO, NOx, and nitric acid (HNO3). To understand the physics, radiation measurements were carried out to great precision, while the study of middle atmosphere temperature and dynamics got a big boost from using measurements made by a variety of instruments.

An important feature of this mission was its science team, which included 9 instrument PIs, 12 theoretical and collaborative PIs, and an interdisciplinary team leader. Each member had instant access to the data of other investigators and, as such, could look collectively at the stratosphere in evolution. By pooling talent on both sides of the Atlantic, the mission provided data and insights that enabled the scientific community to discard theories that did not support the data. At the same time, the cooperative effort vastly improved knowledge of the physical and chemical processes occurring in the stratosphere.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

The UARS mission is innovative both in the comprehensive and unique data set it has provided and for some of the organizational procedures it has implemented. The UARS science team includes a wide range of PIs, theoretical and collaborative investigators, and guest observers.57 UARS data are processed at the Central Data handling Facility using software provided and maintained by the science team. These data are available to the scientific community through the GSFC Distributed Active Archive Center.58

In addition to data from UARS instruments, meteorological data from the U.S. National Meteorological Center and the U.K. Meteorological Office are included in the UARS Central Data Handling Facility. These meteorological data have been extremely valuable both for processing UARS instrument data and for scientific analyses.

Data validation has been an essential part of the UARS program. A comprehensive correlative measurements program, involving ground-based, aircraft, and balloon instruments, has been integral to UARS. Several international validation workshops were held following the UARS launch and before data were first publicly released to the scientific community. This was done to ensure that the data were adequately understood and documented before their general use in scientific analyses. These workshops considered the internal consistencies of individual UARS data sets, comparisons among UARS instruments measuring the same parameters, and comparisons with data from the UARS correlative measurements program and with data from other satellites. These cross-calibrations and data inspections generally have been a hallmark of the UARS international team.

In 1997, UARS continued to provide valuable data far beyond its primary goal of observing two Northern Hemisphere winters. Five northern winters have been observed to date, and 8 of the 9 mission instruments continue to operate (Cryogenic Limb Array Etalon Spectrometer [CLAES] measurements stopped in April 1993 after the cryogen was depleted, and Improved Stratospheric and Mesospheric Sounder [ISAMS] measurements stopped in July 1992 after the chopper failed).59 The observatory is currently being operated in a reduced-power mode with time sharing of instrument observations.


UARS was planned with the involvement of European scientists and has included investigators from several European countries and instruments from Britain, France, and Canada. The data were analyzed jointly by teams of scientists and guest investigators from both sides of the Atlantic. The extensive array of papers being published in peer reviewed journals attest to the high-quality of science the mission has produced. This was made possible by two hitherto unique arrangements that were enacted to enhance the teamwork. First, data systems were organized so that each instrument team member had access to other instruments' data products, which enabled scientists to make diagnostic checks on their findings. In addition, before papers were sent out for publication, they were refereed and reviewed by the entire science team. As a result, the very first set of papers published on the results of UARS still remain standard references in stratospheric science.60

Ocean Topography Experiment (Topex-Poseidon)


The Ocean Topography Experiment (TOPEX-POSEIDON) is a cooperative project between the United States and France to develop and operate an advanced satellite system dedicated to observing Earth's oceans. The


The UARS science team has recently been augmented by about 60 guest investigators.




Microwave Limb Sounder [MLS] stratospheric water vapor measurements stopped after April 1993 following failure of the 183-GHz radiometer (MLS continues measurements of ozone, ClO, temperature, HNO3, and upper tropospheric water).


UARS missit'm and instrumentation papers in J. Geophys. Res. 98(D6), June 20, 1993; Reber, C.A., et al., "The Upper Atmosphere Research Satellite (UARS) Mission," J. Geophys. Res. 98:10643-10647, 1993.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

mission provides global sea-level measurements with unprecedented accuracy. Data from TOPEX-POSEIDON are used to help determine global ocean circulation and understand how the oceans interact with the atmosphere. This understanding is essential to improving the understanding of global climate and other aspects of global environmental variability and change.

For this joint mission, NASA provided the satellite bus and five instruments with their associated ground elements. JPL has been responsible for project management; it operates and controls the satellite through NASA's Tracking and Data Relay Satellite System. France's Centre Nationale d'Études Spatiales (CNES) furnished two instruments with their associated ground elements and provided a dedicated Ariane launch. Both CNES and NASA provide precision orbit determination and jointly process and distribute data to 38 science investigators from 9 nations, as well as other interested scientists. The management approach for this mission included two program managers, two project managers (for their respective share of the project), and two project scientists (co-chairing the TOPEX-POSEIDON Science Working Group) who share in the selection of PIs for calibration and validation of the data and for data evaluation and analysis.

Historical Background and Cooperation

In February 1980, NASA established a TOPEX Science Working Group to consider the scientific usefulness of satellite measurements of ocean topography, especially for the study of ocean circulation. A report of the group's findings was published in March 1981.61 At the same time, a group of French scientists studied essentially the same topics and proposed the POSEIDON mission in a report of its findings to CNES in October 1983.62 The primary finding of the two groups was that satellite altimeter observations of ocean topography can provide the global information on ocean dynamics necessary for studying many important oceanographic problems.63

During the following years, NASA and CNES refined the requirements for an altimetric satellite mission and studied the feasibility of a joint mission. These studies resulted in an MOU that was drafted by the NASA-CNES study team and approved by both organizations. It covered programmatic and scientific subjects and is widely regarded as the agreement that put the mission on the path to success. French scientists persuaded the director general of CNES to help their U.S. colleagues convince the NASA administrator that TOPEX-POSEIDON would make an important contribution to oceanography. In return, U.S. scientists and NASA managers kept the momentum going when TOPEX-POSEIDON faced financial difficulties during changes of administration in the French government.64

The initial success of the cooperation was also enhanced by the strong interest in altimetry that both sides had developed. They were able to contribute significantly in required areas of expertise such as oceanography, altimetry, orbit calculations, and satellite technology. Yet national pride and their advanced status in altimetry made some participants reluctant to cooperate and share their technical knowledge. Some managers did not want to relinquish a perceived technical lead to other countries. Furthermore, an Ariane launch was not acceptable to NASA for political and scientific reasons (NASA wanted to see the Space Shuttle used for the launch, believing that carrying out altimetry from a SPOT spacecraft bus with its Sun-synchronous orbit would introduce error into certain tidal measurements). Eventually agreement was reached to use an Ariane launch with the bus provided by the United States.65


TOPEX Science Working Group, Satellite Altimetric Measurements of the Ocean, Jet Propulsion Laboratory, Calilfornia Institute of Technology, Pasadena, Calif., March 1981.


Centre National D'Études Spatiales, POSEIDON, CNES, Toulouse, France, October 1983; interview with Michel Lefebvre, formerly with CNES, Toulouse, September 22, 1996.


Interview with Stanley Wilson, Assistant Administrator, National Oceanic and Atmospheric Administration, Washington, D.C., April 12, 1996.


Interview with Charles Yamarone, Jet Propulsion Laboratory, TOPEX-POSEIDON project manager at Pasadena, Calif., March 18, 1996; interview with Chester Koblinsky, NASA/Goddard Space Flight Center, Beltsville, Md., head, Oceans and Ice Branch, March 20, 1996.


See footnote 64.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

In the summer of 1992, TOPEX-POSEIDON was launched into orbit by an Ariane rocket from ESA's Guiana Center for Space in Kourou, French Guiana. From its orbit 1,336 km (830 miles) above Earth's surface, TOPEX-POSEIDON makes sea-level measurements along the same path every 10 days using the dual-frequency altimeter developed by NASA and the CNES single-frequency solid-state altimeter. This information is used to relate changes in ocean currents to atmospheric and climate patterns. Measurements from NASA's microwave radiometer provide estimates of the total water vapor content in the atmosphere, which is used to correct errors in altimeter measurements. These combined measurements allow scientists to chart the height of the seas across ocean basins within an accuracy of about 5 cm.

Three independent techniques determine the satellite altitude. NASA's laser retroreflector array is used with a network of 10 to 15 satellite laser ranging stations to provide baseline tracking data for precision orbit determination and calibration of the radar altimeter bias. The Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) system, demonstrated by the French SPOT-2 mission, provides an alternate set of tracking data using microwave Doppler techniques. The system is composed of an on board receiver and a network of 40 to 50 ground transmitting stations, providing all-weather global tracking of the satellite. NASA's Global Positioning System demonstration receiver provides a new technique for precise, continuous tracking of the spacecraft.


One reason TOPEX-POSEIDON became a scientific and cooperative success was that it originated at the grassroots of the scientific community and involved many key scientists on both sides in a careful planning effort. Some team meetings were attended by as many as 250 scientists; this breadth enhanced the team's creativity. Detailed mission planning took about 2 to 3 years. Delays in a new start in the United States were translated into time for improved mission definition.

The MOU for TOPEX-POSEIDON was a significant agreement between CNES and NASA. The upfront planning and specific joint management teaming between international partners led to the signing of an effective MOU between NASA and CNES and their success in implementing the TOPEX-POSEIDON mission. It was drafted by a joint study team over several years and was reviewed and approved by NASA and CNES after lengthy and constructive debate. It clearly covered both programmatic and scientific subjects and constituted a major cornerstone for French-U.S. scientific cooperation.

Though the MOU coordination on science AOs was spelled out in sufficient detail, which was important to mission success, the MOU and other original agreements did not specifically outline how altimetry data were to be shared and what calibration information was to be provided. As a result, there were occasional problems with using one another's data because of the lack of engineering and calibration information provided by other team members. (Some U.S. scientists have stated that even now they do not understand the details of the French altimetry system.)

During the development phase, both CNES and NASA had events that required increased resources and considerable risk taking. A joint steering group dealt with such situations effectively.

Another important element in this cooperative effort was the level of cost sharing. CNES agreed to cover about 30 percent of the total cost of the project, including the launch, a 13.6-GHz altimeter (in addition to NASA's dual-frequency instrument operating at 13.6 and 5.3 GHz), and the DORIS microwave Doppler tracking system, which had proven successful on the French SPOT-2 mission. One estimate claims that the internationalization of TOPEX-POSEIDON saved the United States at least $250 million.66

Data sharing, other than the details on altimetry and calibration data, was ensured not only by the MOU and other agreements but also by the fact that TOPEX-POSEIDON is a vital part of an international research effort to explore ocean circulation and its interaction with the atmosphere. The mission was timed to coincide with and complement a number of international oceanographic and meteorological research efforts, including WOCE and


Interview with Charles Yamarone, Jet Propulsion Laboratory, TOPEX-POSEIDON project manager at Pasadena, Calif., March 18, 1996; interview with Chester Koblinsky, NASA/GSFC, Beltsville, Md., head, Oceans and Ice Branch, March 20, 1996.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

the Tropical Ocean and Global Atmosphere (TOGA) program, both of which are sponsored by the World Climate Research Program. TOPEX-POSEIDON completed its 3-year mission and is currently in an extended observation phase; a joint NASA-CNES follow-on mission, Jason-1, is planned for 2000. Results from TOPEX-POSEIDON are building the foundation for a continuing program of long-term observations of ocean circulation from space and for an extensive ocean monitoring program in the next century.

Earth Observing System


During the early 1980s, interest in Earth observation from space was growing rapidly, thanks to the successful operations of Landsat and NOAA satellites, METEOSAT, the future programs of ERS and SPOT in Europe, and the programs prepared cooperatively between the United States and European countries (i.e., UARS and TOPEX-POSEIDON, discussed above).67 At the time, the United States was engaged in the design of a Space Station, which included a human-tended polar orbiting platform along with a co-orbiting science platform. This was an infrastructure-driven, all-embracing approach that assumed big, serviceable polar platforms for scientific and operational purposes.

NASA's Earth science program took advantage of the polar orbiting platform for its design of a global Earth observation system. Following President Reagan's decision to build a Space Station, the United States invited Europe to participate. ESA accepted this invitation, which fit with its new approach for Earth observation:

  • Multidisciplinary payloads;
  • In orbit intervention for servicing, repair, and addition of new payloads;
  • Contribution to and shared use of the new capability of the Earth observation system by different nations; and
  • Combination of operational, experimental, and research instruments.

This approach also interested the operational agencies. The convergence of interests led the concerned agencies to joint in building a system that could meet their objectives by improving the monitoring capabilities of space systems and by reducing their own financial contribution through cost sharing. Thus the concept of permanent polar platforms for international global Earth observation was born.68

Historical Background

In the United States, the case for an Earth observing system based on a set of polar platforms emerged in the early to mid-1980s, when scientists and engineers created a new perspective on how to conduct future NASA Earth observation programs. Three studies—known as the Goody, Friedman, and Bretherton reports, and issued by NASA, NRC, and the Earth System Sciences Committee, respectively—were pivotal in developing the new vision69 leading


Space Studies Board, National Research Council, Earth Observations from Space: History, Promise, and Reality, National Academy Press, Washington, D.C., 1995.


Quoted from N. de Villiers, Working Group on Earth Observation Requirements for the Polar Orbiting Platform Elements of the International Space Station, ESA-SP 266, ESPOIR, November 1986.


Report of a NASA workshop, Global Change: Impacts on Habitability, A Scientific Basis for Assessment, chaired by Richard Goody at Woods Hole, Mass., June 21-26, 1982, submitted on behalf of the Executive Committee, July 7, 1982 (Jet Propulsion Laboratory, Pasadena, Calif., 1982); report of a National Research Council workshop, Toward an International Geosphere-Biosphere Program: A Study of Global Change, chaired by Herbert Friedman at Woods Hole, Mass., July 25-29, 1983 (National Academy Press, Washington, D.C., 1983); reports of the Earth System Sciences Committee chaired by Francis Bretherton: Earth System Sciences Committee, NASA Advisory Council, Earth System Science Overview: A Program for Global Change, NASA, Washington, D.C., 1986; Earth System Sciences Committee, NASA Advisory Council, Earth System Sciences: A Closer View, NASA, Washington, D.C., 1988.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

to the so-called Mission to Planet Earth (MTPE) program and provided the foundations upon which MTPE was built. (MTPE has been renamed the Earth Science Enterprise at NASA.) The early discussions within the science and engineering communities began to have a strong influence on federal programs well in advance of the formal publication of these reports. NASA published a two-part report in 198470 and another report in 198771 that included a series of volumes describing the principal instrument concepts and associated investigations.

At the same time, the NRC Space Science Board (as of 1989, Space Studies Board) continued its work and published a series of strategy and assessment documents.72 The latest report, while offering suggestions for improvement, endorsed the overall concept of the MTPE and urged (as previous reports had) that the intermediate-class platforms of the Earth Observing System (EOS) be complemented by an expanded set of smaller satellites.

Similarly, in Europe, there were several agency initiatives to prepare a contribution to this polar platform system. Beginning in 1983, ESA had undertaken a series of three studies, known as European Utilization Aspects (EUA) studies, under a contract with the German aerospace research establishment, DLR, to define the European platform. This first approach was the responsibility of industries. Scientific communities and future users would be involved only as providers of potential applications; therefore, the resulting propositions were not based on a well-defined and coordinated scientific program.73 This European effort was undertaken with the United States. A first joint utilization workshop was held at Woods Hole, Massachusetts, in 1984. Then, to finalize scenarios prepared on both sides of the Atlantic, an ESA-NASA-NOAA group was set up, and an extensive joint effort between ESA and NASA was organized.

After the first three studies, ESA—assisted by a working group of experts, the Earth Observation Advisory Committee (EOAC, established in 1981)—initiated a study to outline Earth observation requirements for the Polar Orbiting Platform Element (POPE). For the purpose of this study, the scientific community was directly involved through EOAC with representatives of the EUA study group. The study produced a scenario with two serviceable polar platforms (a morning one under ESA's aegis and an afternoon one under NASA's) that would accommodate a combination of operational, experimental, and research instruments. Following this first definition, in June 1986, ESA invited about 80 scientists from all ESA member states to a workshop, the European Symposium on Polar Platform Opportunities and Instrumentation for Remote Sensing (ESPOIR). The agency aimed to develop a consensus of the Earth observation scientific and applications user community on the requirements, priorities, and content of missions to be flown on the polar platforms.74 This preparation was going on in parallel with development of the ERS-1, which focused on ocean and ice application because of the strong commitment of the oceanic scientific community, and with the work of the International Polar Orbiting Meteorological Satellite (IPOMS) working group, which was focusing on atmospheric applications. The Earth science community also held a preparatory meeting under ESA's sponsorship in March 1986 to review the objectives and requirements of the land science community.75 (The atmospheric and ocean science communities, which already had missions planned, were better prepared than the land science communities to respond to these studies.)


National Aeronautics and Space Administration, Earth Observing System, Science and Mission Requirements Working Group Report, vol. I, parts 1 and 2 (NASA Technical Memnrandum 86129), Goddard Space Flight Center, Greenbelt, Md., 1984.


National Aeronautics and Space Administration, From Pattern to Process: The Strategy of the Earth Observing System, EOS Science Steering Committee Report, vol. II, NASA, Washington, D.C., 1987.


Committcc on Earth Seiences, Spacc Seience Board, National Research Council (NRC), A Strategy for Earth Science from Space in the 1980s—Part 1: Solid Earth and Oceans, National Academy Press, Washington, D.C., 1982; Committee on Earth Sciences, Space Science Board, NRC, A Strategy for Earth Science from Space in the 1980s and 1990s—Part II Atmosphere and Interactions with the Solicl Earth, Oceans, and Biota, National Academy Press, Washington, D.C., 1985; Task Group on Earth Sciences, Space Science Board, NRC, 1988, Space Science in the Twenty-First Century (7 vols.), National Academy Press, Washington, D.C., 1988; Committee on Earth Sciences, Space Studies Board, NRC, Strategy for Earth Explorers in Global Earth Sciences, National Academy Press, Washington, D.C., 1989; Space Studies Board, NRC, Space Studies Board Position on the NASA Earth Observation System, National Academy Press, Washington, D.C., 1991; and Committee on Earth Studies, Space Studies Board, NRC, Assessment of Satellite Earth Observation Programs, National Academy Press, Washington, D.C., 1991.


The International Land Surface Climatology Prnject (ILSCP) was established under the leadership of S.I. Rassol and H.J. Bolle in 1983 and included U.S.-European cooperation in field experiments.


Duchossois, G., ESPOIR—ESA Workshop, Avignon, France, June 16-18, 1986 (ESA SP-266), November 1986,


SESAME (ESA-SP 1080), 1986.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

The coordination efforts of ESA, NASA, and NOAA were aimed at defining the principles, content, and possible schedule for this international cooperative endeavor, particularly for preparing closely coordinated AOs by NASA and ESA. These AOs, with NOAA's and EUMETSAT's cooperation, were published in 1988 and included a description of the types of instruments that were to be on board the two platforms:

  • Operational instruments provided and/or operated by governmental entities (e.g., meteorological sensors flown on NOAA's TIROS-N series) and possibly by commercial entities (i.e., Landsat TM-type sensor operated by the Earth Observing Satellite Company [EOSAT] in the United States, or the SPOT High-Resolution Visible (HRV)-type sensor operated by SPOT-Image in France);
  • Medium-size to large instruments; multipurpose core facilities, which were candidates to be provided by the Space Station partners, such as a high-resolution imaging spectrometer, multifrequency synthetic aperture radar, and high-resolution thermal infrared imager; and
  • Small- to medium-size experimental instruments (non-core instruments), which could be provided nationally through the AO.

A list of more than 30 potential instruments was proposed.

In parallel with these efforts, the serviceable, large polar platform concept began suffering a series of setbacks. In 1986 Challenger forced many NASA programs to non-Shuttle launch designs. The co-orbiting (and hence the polar orbiting) Space Station platforms were abandoned, leaving NASA's then Earth Science and Applications Division with the momentum of large polar platforms (one from ESA and one from NASA), but without the actual platforms. By this time, however, the move toward a global Earth observing system was well under way. In the early 1990s, the planned scenario with two large polar platforms began to be seriously questioned both in the United States and Europe. In the United States, the committee conducting the EOS review recommended that the large polar platform be redesigned—specifically, that the size be reduced from a Titan IV-class launcher to an Atlas 2A class (later to a Delta-1 class platform) to complement these intermediate-size platforms with a larger number of smaller satellites. Furthermore, for budgetary reasons, program costs had to be cut.76 A revised version of MTPE was proposed and approved by Congress in 1992 and included a separation of the operational instruments from the U.S. polar platform. Similarly, in Europe, ESA and the scientific community proposed replacing the polar platform (so-called POEM-1) with two satellites, namely METOP and ENVISAT. This had been recommended by the ESF/ESSC77 and approved by the ESA Ministerial Conference at Granada in 1992. The polar platform venture was thus reduced to a descoped set of platforms and smaller spacecraft on the U.S. side (including EOS-AM1, EOS-PM1, and EOS-Chemistry 1) and ENVISAT on the European side. In Europe, the operational part of the instruments were to be placed on METOP, and in the United States, the operational instruments would be flown by NOAA on separate operational spacecraft.

Although scientific partnerships between U.S. and European scientists continued to grow, the only NASA-ESA cooperation left was reduced to the two instruments, the Clouds and Earth's Radiant Energy System (CERES) from the United States and the Multifrequency Imaging Microwave Radiometer (MIMR) from Europe, which were planned to be flown on both the U.S. and European satellites. However, neither NASA (mainly for financial reasons) nor ESA (mainly for managerial and programmatic reasons) was able to finalize cooperation on these two instruments. As a result, CERES was removed from ENVISAT and MIMR from EOS-PM1 (and even from ENVISAT and/or METOP). Unfortunately, these decisions were made without much consultation.

Ultimately, the cooperative polar platform venture proved too large a step to take, given the size and complexity of the program, the lack of previous experience in U.S.-European land-observing missions, and the emergent state of the interdisciplinary Earth system science approach. Despite the end of this particular NASA-ESA


Moore, B., et al., "The Restructured Earth Observing System: Instrument Recommendations," EOS, Transactions, American Geophysical Union, 72(46):505, 510, 516, 1991; EOS Payload Advisory Panel, Adapting the Earth Observing System to the Projected $8 Billion Budget: Recommendations from the EOS Investigators, Berrien Moore III and Jeff Dozier, eds., NASA, Washington, D.C., 1992; Frieman, E., ed., Report of Earth Observing System Engineering Review Committee, NASA, Washington, D.C., 1991.


EEOP-European Space Science Committee, European Science Foundation, A Strategy for Earth Observation from Space, ESF, Strasbourg, France, September 1992.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

cooperative effort, work on the polar platform venture brought to fruition many successful U.S.-European activities on instrument and science teams and paved the way for a smaller joint activity on the three polar meteorological satellites: The METOP satellite from EUMETSAT will be coordinated with two National Polar Orbiting Operational Environmental Satellite System (NPOESS) satellites, which are managed by a joint Department of Defense-NOAA program in the United States. Many in the Earth sciences community hope that the cooperation can be continued, at least through an appropriate data policy that allows for data exchange and sharing of scientific research.


Cooperation on the polar platforms took mainly a top-down approach, initiated by the agencies. Although many scientists supported the venture, the concept did not have the benefit of good coordination between the scientific communities in the United States and Europe. These communities did not enjoy the same status in their preparation of the platforms and worked independently in each country. In Europe, scientists were used as consultants and were not a driving force in the system. This appears in the asymmetrical objectives of the two AOs.

On the European side, the objectives were as follows:

  • To determine the level of European interest in potential core instruments to be developed by ESA;
  • To provide priorities for European use of different instruments within the payload;
  • To identify AOs for instruments supported by ESA member states; and
  • To identify possible investigations in the various disciplines, as well as interdisciplinary investigations (selection of PIs).

On the U.S. side, the AO had the following objectives:

  • To identify scientific team members and leaders for facility or core instruments to be developed and funded by NASA;
  • To identify a set of interdisciplinary investigations;
  • To identify proposals for non-core instruments for further Phase B studies, which were ultimately to be confirmed for Phase C/D; and
  • To provide guidance for the development of the Earth Observing System Data and Information System (EOSDIS).

Thus, the objectives of U.S. and European science differed, as noted in the dissimilar AO definitions; no joint research programs were proposed, and, at the scientific core of the program, the two communities diverged. This lack of coherence and organization between the two communities made it difficult to lobby decision makers when both the European agencies and NASA faced budget cuts and when financial difficulties arose in the polar platform venture. It was also difficult for NASA and ESA to agree on the necessary descoping of the platform; as a result, cooperation could not result in cost savings. In addition, Earth system science was a new interdisciplinary approach that some scientists took less seriously than traditional disciplines. The structure and hierarchy of the Earth system science program were less familiar, creating additional difficulties for scientists who were working through channels to seek support.78 Finally, there was no agreement on data sharing and distribution; each agency had its own data policy. This remains a point of contention between NASA and ESA.


It is interesting to note that the atmospheric, oceanographic, Earth science, and land subdisciplines or the Earth scientific communities on both sides of the Atlantic did not share the same attitude during this period. The atmospheric community was preparing the UARS mission discussed above, along with an analysis of Advanced Very High Resolution Radiometer (AVHRR), Geostationary Operational Environmental Satellite (GOES), and METEOSAT data. The oceanographic communities in the United States and France were preparing TOPEX-POSEIDON, discussed above; and the oceanographic European community with several U.S. universities took an interest in preparation of the European Remote Sensing Satellite (ERS-1), leading between 1981 and 1983 to a modification of its orbit (a higher orbit better suited for mesoscale circulation measurements by TOPEX-POSEIDON) and of its payload (inclusion of a Ku [12 to 18 GHz] radar altimeter and a precise positioning system, still complementing TOPEX-POSEIDON). Nothing equivalent occurred in the land science communities, which had no specific joint missions being prepared on the European side.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

However, a substantial data exchange and agreement took place among ESA, NASA, and NOAA on the ERS-1. In addition, there was an MOU with NASA to receive data at the Fairbanks ground station; an MOU with NOAA for delivery of ERS-1 Low Bit Rate Fast Delivery products to NOAA for forecasting purposes; and collaboration between the United States and Europe on calibration and validation of ERS-1 instruments and data.79


The history and circumstances leading up to the failure of cooperation on NASA-ESA polar platforms involved many perspectives and interests. There is no simple answer as to why the cooperation unraveled; myriad factors and influences contributed to the unsuccessful result. The beginnings of the polar platforms and Earth Observing System had its roots in the large Space Station program. In promoting the Space Station, the United States attempted to link the polar platforms and Earth observation in general, through a so-called intergovernmental agreement. This top-down approach assumed serviceable platforms for scientific and operational uses and a unified Earth observation data policy discussed under EO-ICWG and CEOS. Moreover, the programmatic decision to use large polar platforms introduced a new, unaffordable approach for Earth observation programs.

Within the space community, scientists supported this approach, not always for scientific reasons, but because they initially were given a platform on a "take-it-or-leave-it" basis. Once work on the program began, the Earth science communities were not well coordinated and not accustomed to working together. There was an inadequate historical basis for joint space-based scientific research on both sides of the Atlantic, at least in land science. The scientific communities in Europe and the United States had different levels of preparation and involvement in defining the polar program. This imbalance created a dissymetry in the relationships among the program managers.

In addition, the conception of the program itself changed early on, as did the context in which the program was conceived. The aftermath of Challenger created uncertainty for all launches; preparation for other missions in ocean and atmospheric sciences led to a variety of motivations among scientific users, as well as a difference in levels of preparation. The fact that the mission's objectives were not focused on a well-defined goal made scientific users unwilling to lobby for it. Furthermore, both Europe and NASA faced budget cuts, had (and still have) difficulties preserving their respective programs, and had to descope them.

In the end, the cooperative effort failed because the polar platform program was not objective driven and because the larger Space Station program from which it had emerged attempted to impose rules on Earth observations that had nothing to do with the International Space Station. Moreover, the original cooperative plan, which was to include not only the Earth science communities with NASA and ESA but also the operational segment with NOAA and EUMETSAT, may have been too ambitious for a first-time NASA-ESA Earth observing activity. The final failure was the result of a small step (the exchange of two instruments), but the initial step taken was far too grand; there was never a clear agreement about objectives and approach.

Lessons Learned

Although there is only a limited range of truly international scientific missions in Earth observation, those that have been developed have been quite successful. For instance, UARS and TOPEX-POSEIDON returned data and information beyond all expectations of the original team of mission planners and designers. The satellites were launched successfully, operated as expected, and provided highly reliable data and new insights into atmospheric processes and ocean dynamics. These achievements came at a significantly reduced cost to each participating country.

For these Earth science missions, data have been successfully distributed to a large number of users and investigators in many countries and across various disciplines. For instance, TOPEX-POSEIDON data have been


Memorandum of Understanding Between the United States National Aeronauties and Space Administration and the European Space Agency Concerning the Acquisition of ERS-1 SAR Data at Fairbanks, January 14, 1986.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

used by several international oceanographic and meteorological programs (e.g., WOCE and TOGA) to obtain significant new insight into ocean dynamics and climatic effects. UARS employed a Central Data Facility where data in all forms (from raw downlink to sophisticated mapped products, plus information to facilitate its use) were available on-line to investigators around the world, following the 1-year proprietary period.

Even though these bilateral and trilateral missions have been largely successful, there has been no formal cooperation between NASA and ESA on an Earth observation mission. The only cooperative activities are between NASA and one nation (e.g., France for TOPEX-POSEIDON) or several (e.g., the United Kingdom and France for UARS). Furthermore, within the Earth sciences, there has not been a cooperative land science mission between either NASA and ESA or NASA and a European country.80 The only cooperation in this domain has been restricted to data exchange, calibration and validation, sharing of receiving stations, or the opportunity to place European instruments on board the Space Shuttle.

Clearly Defined Mission, Significant Responsibilities on Both Sides, Clean Interfaces

The scientific value of missions has been significantly enhanced when scientists from several countries pooled their knowledge and shared their techniques. This applies equally to engineering know-how and to equipment. For instance, in TOPEX-POSEIDON, U.S. and French scientists and engineers shared significant contributions in oceanography, geodesy, altimetry, orbit calculation, and spacecraft engineering. What made this possible in practice and not just in theory was that there were relatively clean boundaries and interfaces in mission design and engineering, and each side made a significant contribution: They needed each other.

On UARS, Europe contributed instruments using techniques not readily available in the United States (e.g., pressure modulation, radiometry for composition measurements, solid-state interferometers for wind sensing); therefore, even though the contribution was not large, it was important, and the interface was clean.

Joint and Early Mission Planning

If an international mission is designed at the outset with the participation of scientists from cooperating countries, the mission has a stronger raison d'être. Experimenters from participating countries competitively bring their own know-how to the program; therefore, the mission is richer in concept than it would be without them. Also, if the experiments chosen complement each other in their quest to achieve the same objectives, the mission is more robust than it would be otherwise. In other words, a cooperative mission in which there is consensus on scientific objectives among partners and experiments that complement these objectives has a better chance of withstanding potential pitfalls than it would otherwise.

Scientists from both sides of the Atlantic must be involved in defining the concept of the mission from the beginning; mission design clearly benefits from these combined talents, but more importantly, a collective buy-in occurs. This happened in the case of UARS, whose design proved optimum to address questions and opposing hypotheses about the stratospheric sciences that were hotly debated at the time.

In TOPEX-POSEIDON there was a lengthy planning process and MOU development. This established a firm foundation for cooperation. In addition, TOPEX-POSEIDON scientists helped their counterparts on the other side of the Atlantic keep the mission planning and implementation process moving forward, even when the political or funding situation deteriorated. Without cooperation between French and U.S. scientists, the TOPEX-POSEIDON mission would never have been approved by NASA or CNES. The support of French scientists was needed for NASA acceptance, and it appears that the scientific pressure applied by U.S. scientists helped persuade CNES to


However, under the new NASA Earth System Science Pathfinder Program, which requires launch within 4 years of project initiation, one or the first two selections may involve U.S.-European cooperation between NASA and DARA on the Gravity Recovery and Climate Experiment (GRACE). Final discussions are under way between the United States and Germany and could involve the purchase of a launch vehicle by Germany.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

support the mission. This was not the case in the polar platform venture, which resulted in failure of the cooperation when less funding became available.

Cost Reduction

Cost sharing helped reduce the mission cost to each individual country, as noted in the TOPEX-POSEIDON example. The international cost contribution to UARS was smaller, consisting of payload instruments worth perhaps $50 million; but the technology contribution, as mentioned, reflected an importance beyond its total monetary value.

On the negative side, specific problems have been associated with mission financial support despite the overall success of missions. Because UARS was the first international Earth science mission, it was also a major learning exercise for the project teams and agencies. One of the difficulties arose when a French principal investigator, whose instrument was accepted for the UARS mission, could not get support to develop and construct the instrument in France. It was finally built by Canada with a Canadian PI. There were also said to have been difficulties for a British PI on UARS in delivering his instrument and obtaining travel support to attend science steering group meetings in the United States. Despite these problems, the UARS mission is a major success story in internationalizing Earth science missions from space.

Involvement in a Broader International Agenda

Earth observation missions provide data to more than one discipline or research project. Unlike UARS, where data were restricted to principal investigators for 1 year, TOPEX-POSEIDON data were limited only to a 6-month validation period. Moreover, data sharing for the TOPEX-POSEIDON mission was ensured not only by the MOU and other agreements, but also by the fact that it had become a vital part of an international research effort to explore ocean circulation and its interaction with the atmosphere. The mission was timed to coincide with and complement a number of international oceanographic and meteorological programs, including WOCE and TOGA, both of which are sponsored by the World Climate Research Programme (WCRP). TOPEX-POSEIDON was more than a contribution to WOCE, because WOCE was designed by taking TOPEX-POSEIDON into account. The relationship of TOPEX-POSEIDON to international research programs was, therefore, conceived beforehand.

For UARS, the relationship to international research programs was based on actual observation. UARS had been designed earlier, before Challenger and before the discovery of the hole in the ozone layer in 1985. However, UARS contributed directly to international concerns that were addressing changes in the chemistry of the atmosphere, including ozone depletion due to NOx and CFCs. For example, the Montreal Protocol of 1987 called for international ozone assessments to be done on a periodic basis under the World Meteorological Organization and the United Nations Environmental Program. UARS was critical in verifying the chemistry and dynamics of stratospheric ozone reduction by actually measuring molecules such as ClO. In addition, UARS played a vital role in the development of an international project, Stratospheric Processes and Their Role in Climate, which is now a component of the WCRP.

Data Sharing

The concept of creating a central data handling facility for a given scientific mission so that the data from all instruments are available to all investigators on the mission provides an added benefit of making correlative data sets available to individual investigators. In the case of UARS, this pioneering concept in an Earth science mission helped investigators to compare their measurements with other related parameters in the stratosphere measured by other instruments on UARS and thereby provided excellent diagnostic capability to each of the investigators. In addition, when a central data handling facility is set up from which each participating scientist, regardless of nationality, can reach into and acquire the data of everyone else, common trust is built up faster and the scientific results are likely to be of higher quality. Although a central data facility was one way to collect and distribute

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

mission data in the pre-workstation era, advances in computer technology and networks have made it easier for multiple, decentralized centers to link disparate data sets in a seamless fashion.

In fact, TOPEX-POSEIDON, which ensured data sharing in the original MOU and other agreements, took advantage of this advanced technology. TOPEX-POSEIDON data are processed, distributed, and archived by JPL's Physical Oceanography Distributed Active Archive Center (PODAAC) and by the French Space Agency (CNES) Archiving, Validation and Interpretation of Satellite Oceanographic (AVISO) Data Center in Toulouse, France. At both centers, data are readily requested via the Internet and electronic mail. Data are provided to users primarily in CD-ROM format or by electronic file transfer. Moreover, JPL, which manages the TOPEX-POSEIDON project and operates the satellite, hosts World Wide Web pages with browse files of data and images, access to near-real-time data, and other resources such as tutorials, descriptions of images, examples of oceanographic applications, and a list of investigators. The existence of two processing centers—one in France and one in the United States—with shared responsibilities, stimulated cross-fertilization and was of benefit to the scientific community. The principal investigators for TOPEX-POSEIDON also decided to give up any "proprietary access period" to the data, on the grounds that they had already a significant advantage over general users because of their depth of knowledge of the system and because they calibrated and validated the data without imposing a period of restricted access.

It is relatively easy to implement data exchange agreements for fully dedicated scientific missions with a relatively sharp focus, where the data are used primarily by the scientific community. On the other hand, multiuser, multipurpose missions that have different communities of users with different goals, from science to commercial applications, raise almost insurmountable barriers to developing data exchange agreements and policies. Therefore, it is important that agreement on the purpose of the mission and data policy be achieved very early in the process of cooperation.

To induce scientists or engineers to share their data and technology with other countries, there must be a two-way flow with a clear advantage to all sides. In the case of TOPEX-POSEIDON, each side benefited from the knowledge of altimetry, geology, oceanography, and space technology that the other side provided. However, the original agreements (or MOUs) must clearly spell out how mission data are to be shared and specifically what calibration information is to be provided.

The distribution and cost of data to participants and other users must be agreed on at initiation of the project. For most missions, agreements specify how long PIs have preferential access before the data are released to the public. Financial implications may arise if the data must be obtained through commercial channels. When scientific research has potential applications with commercial and/or industrial interests or when national interests are the driving forces, cooperation may turn into competition. These issues should be clearly addressed during the preparation phase of the mission to avoid "poisoning" the scientific cooperation. It is essential that the role and responsibilities of each partner be clearly identified as early as possible.

International cooperation in analyzing data or organizing field experiments (ground segment) has been much better than the cooperation in defining, designing, and sharing responsibilities for a space mission (space segment). International programs for analyzing the data (e.g., International Geosphere-Biosphere Program [IGBP] and the WCRP) and for organizing field experiments (e.g., WOCE, Hydrological and Atmospheric Pilot Experiment in the Sahel [HAPEX], Boreal Ecosystem-Atmosphere Study [BOREAS]) exist and have proven highly efficient.

Technology Sharing

There were problems with using each other's data due to lack of calibration information from the other side, particularly for altimeter calibration data on TOPEX-POSEIDON. Whether intentional or accidental, this deficiency might not have occurred if the original agreements had more clearly spelled out data were to be shared, and specifically what calibration information was to be provided. Again on TOPEX-POSEIDON, there was considerable reluctance among decision-making NASA officials to share altimeter-related technology for both competitive and security reasons, and similar reluctance on the part of the French to explain details of the French system. There were no corresponding problems on UARS where an excellent spirit of cooperation was achieved throughout.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Lack of Historical Foundation

Finally, there is an implicit lesson in what is missing from our base of international experience; namely, there have been no Earth science missions jointly between ESA and NASA and no joint land missions between NASA and a European country. This area is marked by unsuccessful attempts at cooperation. Most recently, NASA was to provide an Earth radiation budget instrument to ESA's ENVISAT mission, and ESA was to provide a passive microwave instrument for flight on NASA's EOS-PM1 spacecraft. Each canceled its contribution; in both cases, cancellation proved troublesome for the other side and was done with little or no consultation or warning. This last act ended the planned cooperation between ESA and NASA in Earth science.

The reasons for the lack of success appear to be that cooperation in Earth science (as opposed to Earth observation) between NASA and ESA is relatively recent, and the undercurrent of competitive forces still influences Earth observation programs at these agencies. The lack of adequate data exchange agreements between NASA and ESA for their major Earth science missions (e.g., EOS, ENVISAT) reflect this continuing tension. It should be noted, however, that scientific cooperation between the United States and Europe in Earth sciences has increased significantly in the past 15 years, thanks to the IGBP and WCRP and other similar programs.

Microgravity Research And Life Sciences

For microgravity research and life sciences, the future of experimentation in space for the next 20 years depends largely on the International Space Station as the laboratory in space. As is well known, Space Station is a cooperative effort among Canada, Japan, the western European community, Russia, and the United States. Hence, to a great extent, the efficacy of scientific investigations on Space Station depends on the efficacy of international cooperation. One branch of this international cooperation is, of course, efforts between the western European community and the United States.

Within this context, from the various types of missions flown thus far, the International Microgravity Laboratory (IML) missions IML-1 and IML-2 were chosen to represent the nature of international cooperation in microgravity research and life sciences. These missions exhibited characteristics of cooperative endeavors between NASA and the European agencies on Space Station and can be thought of as precursor missions for the International Space Station. IML-1 and IML-2 were particularly distinctive with respect to the variety and intensity of cooperation between Europe and the United States. The nature of the cooperation included sharing of experimental facilities as well as sharing of scientific knowledge. Also, even though a majority of the experimental facilities were provided by Canada, Japan, and western Europe, both experimental facility management and mission management were provided by the United States. Because of the particular characteristics of IML-1 and IML-2, an analysis of the experience and outcome associated with them should provide guidance for the conduct of international cooperation of the space laboratory of the future, the International Space Station.

International Microgravity Laboratory

IML-1 and IML-2 were missions in which foreign partners contributed facilities for use in life sciences or microgravity research experiments in exchange for an opportunity to place the facility aboard the Shuttle to carry out experiments in space.81 The missions involved the CNES, the 14-nation ESA, the Canadian Space Agency (CSA), DARA, the National Space Development Agency of Japan (NASDA), and NASA.

The manifest for IML-1 was composed of 14 experimental facilities equally divided between life sciences and microgravity research. There was an additional facility for measurement of acceleration levels. The latter facility and six of the experimental facilities were provided by NASA. ESA, DARA, and NASDA each provided two experimental facilities; CNES and CSA each provided one facility. The manifest structure and diversity in


Microgravity and life sciences research conducted in the space environment makes use of large facilities, such as glove boxes and furnaces, which investigators share to conduct experiments.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

nationality of facilities for IML-2 was similar to IML-1: There were eight experimental facilities in life sciences and seven in microgravity research; however, most of the actual experimental facilities for IML-2 were new.

Historical Background

The initial planning meeting for IML-1 was held in July 1983. This was followed by the formation of a science working group in October 1983. The payload complement was finalized in December 1984. In 1986 Challenger caused a prolonged delay, within which the launch date was rescheduled nine times. The investigator working group began meeting in January 1987 and met frequently thereafter. IML-1 was ultimately launched on an 8-day mission on January 22, 1992.

Like IML-1, IML-2 had its inception in 1983 when NASA began planning the IML Spacelab missions. The preliminary payload for IML-2 was sketched out in January 1989. The payload configuration was established in October 1989. This was followed by the first meeting of the investigator working group in May 1990. Except for personnel changes, the IML-2 mission management organization was similar to IML-1. IML-2 was launched on July 8, 1994, and landed on July 23, 1994.


The selection of facilities to be included in IML-1 was made by NASA. Each facility was developed and provided, flight-ready, by the space agency that proposed and sponsored it. On the other hand, each space agency was individually responsible for the selection of experiments for a given facility. The responsible space agency covered the costs of the experiments it selected, regardless of the origin of the facility involved. Each major facility had its own project manager who helped coordinate the activities of individual experimenters. NASA provided overall coordination of the mission with a program scientist and program manager at its headquarters, as well as a mission manager and mission scientist at the Marshall Space Flight Center.

The life sciences facilities involved 29 separate experiments. Investigations were conducted in human physiology, space biology, radiation biology, bioprocessing, plant physiology, and human adaptation to low gravity. Three of the facilities were provided by NASA and had only U.S. principal investigators. Facilities provided by DARA and NASDA each had single experiments, with PIs from the country of origin. The facility provided by CSA was used for six experiments, all with Canadian PIs. Only one life sciences facility, the Biorack provided by ESA, was international in scope. PIs from eight separate European countries and the United States conducted 17 experiments.

Thirteen separate experiments were performed in the microgravity research facilities. The areas targeted were casting and solidification technology, solution crystal growth, vapor crystal growth, protein crystal growth, organic crystal growth, and critical point phenomena. The three facilities provided by NASA were used solely by U.S. PIs. The facilities provided by CNES and NASDA were used for single experiments with PIs from the country of origin. Two facilities, the Cryostat provided by DARA and the Critical Point Facility provided by ESA, had an international flavor. In Cryostat, two PIs were from Germany and one was from the United States; the Critical Point Facility included two PIs from France, one from the Netherlands, and one from the United States.

For specific experiments in both the life sciences and microgravity research, additional international cooperation occurred in several instances. In these cases, the nationality of the coinvestigator(s) differed from the nationality of the PI, and the data collected were shared by members of the investigative team. Altogether there were 40 PIs from 11 countries. If coinvestigators are taken into account, 220 scientists from 12 countries participated in IML-1. The countries represented were Switzerland, the United States, the Netherlands, Spain, Germany, Italy, France, the United Kingdom, Denmark, Japan, Canada, and Australia.

IML-2 continued the concept of the contribution of facilities by foreign partners for a NASA-managed Spacelab mission in exchange for the opportunity to carry out experiments in low Earth orbit. The participating agencies were identical to those that took part in IML-1. Payload selection was done by NASA, as earlier. Participating agencies were again responsible for the costs of a flight-ready facility. They were also responsible

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

for the selection of their national experiments and the costs of supporting the experiments selected. However, the lineup of facilities was considerably different from that of IML-1. Only three experimental facilities from IML-1 were reflown on IML-2: the Biorack and Critical Point Facility provided by ESA, and the Biostack provided by DARA. The acceleration measurement facility provided by NASA on IML-1 was also reflown.

Including Biorack and Biostack, a total of eight life sciences facilities were selected for IML-2. Thirty-five separate experiments were conducted in the general areas of space biology, human physiology, and radiation biology. NASDA-provided three facilities and DARA-provided two, including Biostack. ESA, CSA, and NASA each provided one facility. In the latter two cases, PIs were of the same national origin as the facility itself. This was also true for one of the facilities provided by NASDA and one provided by DARA. In somewhat similar fashion, the ESA-provided Biorack had PIs only from ESA member nations; in this case, PIs from six European countries conducted experiments. Hence, PIs whose origin was different from that of the facility were present on only three of these facilities. One U.S. PI and one Swiss PI utilized the DARA-provided Slow Rotating Centrifuge Microscope along with six German PIs. One U.S. PI cooperated with three Japanese PIs to conduct experiments with the Aquatic Animal Experiment Unit provided by Japan. The second NASDA-provided facility, the Thermoelectric Incubator, had a roster of one U.S. PI and two PIs from Japan.

For carrying out experiments in microgravity research, seven facilities were selected for IML-2. Thirty-eight experiments in the general areas of materials science, fluid sciences, and biotechnology were carried out. ESA- provided three facilities, including the Critical Point Facility mentioned previously. NASDA-provided two facilities; CNES and DARA each provided one. NASA did not provide any of the microgravity research facilities, but at least one U.S. PI was included in every facility. In the Electromagnetic Containerless Processing Facility provided by DARA, the experimental team consisted of four U.S. PIs and four German PIs. The Bubble, Drop and Particle Unit provided by ESA involved two U.S. PIs along with four European PIs from three ESA member countries. A second ESA-provided facility, the Advanced Protein Crystallization Unit, involved a U.S. PI cooperating with 10 European PIs from five ESA member countries. ESA's Critical Point Facility included one U.S. PI with three European PIs from three ESA member countries. One French PI and one U.S. PI participated in using the French-provided facility, Applied Research on Separation Methods Using Electrophoresis. Each of the NASDA-provided facilities, the Free Flow Electrophoresis Unit and the Large Isothermal Furnace, accommodated one U.S. PI along with two PIs from Japan.

Three additional facilities flown on IML-2 were dedicated to experiments and measurements for characterization of the microgravity environment and countermeasures. One facility, which had previously flown on IML-1, was provided by NASA. The other two were provided by DARA and NASDA. Four experiments were done. The PIs in each case represented the nationality of the facility-providing agency.

Because of multiple experiments by three PIs, 73 individuals carried out a total of 77 experiments on IML-2. As was true for IML-1, coinvestigators were associated with most of the PIs. Also, like IML-1, in several instances the nationality of the coinvestigators differed from that of the PI. Including coinvestigators, 198 scientists from 13 countries were involved in conducting experiments on IML-2. The countries represented were Switzerland, the United States, the Netherlands, Spain, Germany, Italy, France, the United Kingdom, Japan, Canada, Norway, Belgium, and Sweden.


For both IML-1 and IML-2, a range of experimental and programmatic success was experienced. Some PIs reported complete success, many reported significant success, and others reported relatively minor success or none. The reasons were similar to other areas of successful cooperation in space: clean interfaces, good communication between all parties, favorable cost-benefit ratios, and synergistic effects. Instances of less-than-complete success were often accompanied by situations in which the interfaces and communications were faulty and the scientists were not "in charge."

There are, also, some insights unique to IML, such as the amplification of cooperation through the development of "generic" equipment that different partners must use, although this amplification was not always free of

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

problems. However, it is important to note that many of the same problems that existed, and still continue, on international missions in the life and microgravity sciences also occur on national missions. These problems tend to be magnified in any international undertaking, making them somewhat more complicated to resolve.

Lessons Learned

Benefits Should Clearly Outweigh Costs

One primary benefit was the distribution of costs for performing experiments in low Earth orbit. Both NASA and the European partners provided equipment and selected experiments for the IML missions, whereas NASA provided mission management and launches. Cooperation spread the cost of hardware over a wider base. Neither NASA nor the foreign partners could have provided such a wide spectrum of equipment from their own resources. For U.S. investigators this arrangement provided an opportunity to make use of equipment that would otherwise have not been available to them.

The international missions were an economic advantage to both the United States and the foreign partners. Each country was able to mount important experiments with less total cost to itself. European scientists were able to put experiments into space at a reduced cost, compared with development of their own launch vehicle. For the United States, the availability of "free" hardware in exchange for flight possibilities was an important economic consequence. For example, without this, the IML-2 mission would never have flown, since NASA was unable to provide the budget needed for any hardware development. Another economic benefit is that this collaborative approach to developing hardware has resulted in a larger stock of apparatus available for experiments on subsequent flights. Some of the pieces of hardware have already been used on other flights.


An important benefit of international cooperations is the synergism that develops between and among scientists, scientists and engineers, scientists and managers, and engineers and managers from different countries. A wider range of expertise was available for the generation of equipment concept, development, and implementation, as well as for improving the concept of experiments and experimental protocols. In many cases, the resulting experiments were better than they would have been if participants had been from only a single country. Furthermore, the missions promoted cooperation among scientists from different countries that have resulted in long-lasting scientific collaborations.

The international cooperation in these missions had a major synergistic effect on the science that could be performed. Neither U.S. nor European scientists could have accomplished nearly as many spaceflight experiments without this cooperation. The United States had the only vehicle capable of carrying these experiments into space but relatively limited amounts of equipment or budget to produce such equipment. The Europeans, on the other hand, had no access to space on their own because they had no launch vehicle, but they had both the funding and the interest to provide equipment suitable for these experiments in microgravity research and life sciences. Thus, by combining their efforts, a maximum amount of science was achieved. This lesson has clearly already been learned with regard to the Space Station.

Development of Generic Equipment

It was perceived that the development of multiuser (generic) hardware by a specific national entity would always be valuable to scientists from other nations, who might then be able to use the equipment for their own experiments. To a certain extent this has been true, and equipment proved to be truly generic. However, two problems have occurred. Generic hardware often imperfectly accommodated given experiments within the set of equipment for which the hardware was said to be designed. In addition, some scientists found that generic hardware was insufficient for their needs. In some cases, facilities were not generic in that the hardware was developed for a defined set of experiments. By the time additional international PIs were added, it was usually too late to effect any meaningful changes to the apparatus so as to accommodate other, diverse experiments.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

Given such experiences on the IML missions, PIs should be more closely involved in the definition of facilities and equipment. At present, facilities tend to be designed by committees that try to make the apparatus as multiuser as possible. Although this is a desirable goal, some of the equipment problems might be alleviated if PIs were involved earlier.

Hardware Failings and Communication

The two IML missions conducted 119 experiments. More than 400 scientists participated, including both principal investigators and coinvestigators from 15 countries. There were failures and mixtures of degrees of success, as well as major difficulties encountered by some PIs. In some cases the hardware failed to live up to expectations. Severe difficulties with some of the hardware was brought on in part by insufficient communication between the hardware development engineers and the PIs who were going to use the equipment. Often, hardware development had proceeded too far before international PIs came on board. In addition, there were cases in which communication difficulties between various players were exacerbated by the diversity of nationalities, different agendas of the international entities, and geographic separation of participants. Improvements in communication among engineers and scientists will be important for the Space Station. There is no excuse for flight equipment to be flown that has not been ground tested or does not work properly.

Resource Allocation

PIs also faced the difficulty of resource allocation, which is particularly important on relatively short Shuttle-based mission. It is even more demanding on international missions that may have conflicting agendas.

Because of the wide range of nations involved and an accompanying diversity in scientific priorities, there were myriad experiments on IML-1 and IML-2. In the planning of missions there was no great concern about the overbooking of resources, even though a large number of experiments were to take place. Many believed that the diversity would, in fact, lend itself to compatibility with resources. In particular, the inclusion of both microgravity research and life sciences experiments was thought to be a benefit; the life sciences experiments were expected to be crew intensive, whereas the microgravity research experiments were expected to be power intensive. This outlook proved to be too simplistic. The missions showed that an analysis of mission experiments and resource availability must be conducted down to the subdiscipline level.

The unavoidable conclusion is that on IML-1 and IML-2, the resources were seriously overbooked. This includes data downlinks, direct TV coverage of experiments, and crew time. Crew time was so heavily booked that when some of the crew were unable to perform for periods of time, there was not enough slack in the system to compensate. This problem was exacerbated by the interruptions of crew time for public relations or outreach teaching performances. As a result, in some investigations, critical data points were simply not collected, and the experiments were seriously compromised. The success of scientific experiments should not be jeopardized by the unexpected insertion of public affairs into the time line. Proper planning with the public affairs office will alleviate this issue.

Experience has shown that at times the crew's efficiency in space is lower than when they are on the ground, so it is better to fly fewer experiments and have them all succeed rather than fly too many that end up being incomplete.

Archiving and Accessing Data82

The IML missions contained a wide range of science, experiments, and experimenters from all over the world. Hence, results obtained are published in a variety of journals and conference proceedings. For IML-1 and IML-2, there is no single source summary of scientific results. One has to comb through a considerable number of sources


For more information about archiving, see Committee on Microgravity Research, Space Studies Board, NRC, Archiving Microgravity Flight Data and Samples, National Academy Press, Washington, D.C., 1996.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.

to learn the efficacy of the missions. Then too, many of the experiments may never be published, especially if they were not considered a scientific success by the PI. There is therefore a need for proceedings of international cooperation in microgravity research and life sciences. Moreover, in formulating international missions in microgravity research and life sciences, partners should reach agreements that articulate how the results are going to be disseminated and identify the obligations of all PIs to contribute to a single book on mission results. However, the format of such a publication should be such that the material would not preclude parallel publication in refereed journals.83 An example to be followed is that of the D-2 mission, which published a single volume containing information and basic findings from every experiment on the mission.84


Considering the potential for difficulties in managing these complex international missions, the management succeeded better than anyone could have expected. Some problems arose, and there were too many levels of management between the PI and the mission, but few concrete suggestions were made about ways to improve mission management. There were suggestions, however, about the need for better communication between the agencies. European scientists need to be better informed about NASA's requirements, rules, and procedures. Similarly, U.S. scientists need to understand that the administrative structure for spaceflight experiments is somewhat different in Europe. Improving these types of communication might make it easier for European scientists to adjust to some of NASA's requirements.


IML-1 "Quick Look," documentation dated April 6, 1992; IML-1 Brochure IML-1 payload confirmation documentation; correspondence from Dr. Robert Snyder, mission scientist for IML-1 and IML-2, dated May 13, 1996; IML-2 payload confirmation documentation, dated January 12, 1993.


Sahm, P.R., Keller, M.H., and Schiewe, B., eds., Proceedings of the Norderney Symposium on Scientific Results of the German Spacelab Mission D-2, March 14-16, 1994, Norderney, Germany, Wissenschaffliehe Projcktfuhrung D-2 Mission, Cologne, Germany, 1995.

Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Suggested Citation:"3 Case Studies of U.S-European Missions." National Research Council. 1998. U.S.-European Collaboration in Space Science. Washington, DC: The National Academies Press. doi: 10.17226/5981.
Next: 4 Findings and Recommendations »
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U.S.-European Collaboration in Space Science reviews the past 30 years of space-based research across the Atlantic. The book, which was prepared jointly with the European Space Science Committee (under the aegis of the European Science Foundation) begins with a broad survey of the historical and political context of U.S.-European cooperation and collaboration in space.

The focus of the book is a set of 13 U.S.-European missions in astrophysics, space physics, planetary sciences, earth sciences, and life and microgravity research that illustrate "lessons learned" on the evolution of the cooperation, mission planning and scheduling, international agreements, cost-sharing, management, and scientific output.

These lessons form the basis of the joint committee's findings and recommendations, which serve to improve the future conduct and enhance the scientific output of U.S.-European cooperation and collaboration in space science.

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