Launching Science Science Opportunities Provided by NASA's Constellation System (2009) / Chapter Skim
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2 Analysis of Space Science Mission Studies
2 Analysis of Space Science Mission Studies
Pages 20-66
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From page 20... ...
The committee is not endorsing any specific mission team or approach and recognizes that, because of their preliminary nature, any mission concept that is pursued may require significant revision. BACKGROUND AND APPROACH In 2004, to extend analyses of potential future space science missions and to identify precursor technology requirements, NASA funded studies for a variety of advanced missions referred to as the space science Vision Missions. These missions were inspired by a series of NASA roadmap activities conducted in 2003 and were not connected to the Vision for Space Exploration announced by President George W
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From page 21... ...
, • 8-Meter Monolithic Space Telescope, • Exploration of Near Earth Objects via the Crew Exploration Vehicle, • Solar Probe 2, and • Super-EUSO (Extreme Universe Space Observatory)
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In view of the Constellation System architecture, the committee evaluated the mission concepts using two criteria: 1. Does the concept offer a significant advance in a scientific field?
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As indicated in the table, the committee identified 5 missions that it determined are "more deserving" of further study. Recommendation: NASA should conduct further study of the following mission concepts, which have the most potential to demonstrate the scientific opportunities provided by the Constellation System: 8-Meter Monolithic Space Telescope, Interstellar Probe, Neptune Orbiter with Probes, Solar Polar Imager, and Solar Probe 2.
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earliest black holes and galaxies. development and operations Modern Universe Enabled Has disparate UV/optical science goals; High for instruments Deserving Space Telescope unclear what the scientific impact will be.
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requirements for different locations in the Earth-Moon system and Lagrangian points. NOTE: E-M L1, Earth-Moon libration point L1; GEO, geostationary orbit; GTO, GEO transfer orbit; LEO, low Earth orbit; LLO, low lunar orbit; LTO, lunar transfer orbit; Low-T, low thrust; High-T, high thrust; S-E L1, Sun-Earth libration point L1; S-E L2, Sun-Earth libration point L2; ΔV, delta-v.
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From page 26... ...
THE SUN-EARTH LAGRANGIAN POINT Several of the mission concepts evaluated in this report (e.g., ATLAST, 8-Meter Monolithic Space Telescope, MUST, Gen-X, Stellar Imager) would operate at the Sun-Earth Lagrangian point L2.
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From page 27... ...
The impressive capabilities anticipated for ground-based observatories in the coming decade will redefine the existing synergy between ground and space telescopes. Space will, however, remain an optimal environment for optical observations that require any combination of very high angular resolution over fields of view larger than ∼1 arc minute (arcmin)
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Because the 16-m mission is larger and more technically complex than the 8-Meter Monolithic Space Telescope, it is expected to cost significantly more. Should This Concept Be Studied Further as a Constellation-Enabled Science Mission?
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From page 29... ...
A potential The first two subsections are based on material in H Philip Stahl, "Design Study of 8 Meter Monolithic Mirror UV/Optical Space Telescope," in response to request for information by the Committee on Science Opportunities Enabled by NASA's Constellation System, May 2008.
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Relative Technical Feasibility of the Mission Concept The NASA MSFC study indicates that it is feasible to launch a 6- to 8-meter-class monolithic primary mirror UV/visible observatory with a 10-m Ares V launch vehicle, have it survive launch, and place it into a halo orbit around the Sun-Earth L2 point. Specific technical areas studied included structural, thermal, and optical design and analysis; launch vehicle performance and trajectory; spacecraft; operations and servicing; mass and power budgets; and system cost.
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No existing launch vehicle has sufficient fairing volume or lift capacity to launch an 8-m monolithic space telescope into orbit. The scientific impact of this mission is similar to that for the ATLAST proposal in many respects.
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Lazio, for the DALI team, "The Dark Ages Lunar Interferometer (DALI) ," in response to request for information by the Committee on Science Opportunities Enabled by NASA's Constellation System, May 2008.
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SOURCE: Courtesy of NASA Goddard Space Flight Center. In simple interferometry, signals from two receivers are brought to a common location and combined.
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SOURCE: Joseph Lazio, Naval Research Laboratory, "Dark Ages Lunar Interferometer," presentation to the Committee on Science Opportunities Enabled by NASA's Constellation System, June 10, 2008. The fundamental receiving element for celestial radio signals will be stations, each composed of 100 individual dipole antennas.
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This period, known as the Dark Ages, represents the last frontier in cosmology, the era between the genesis of the cosmic microwave background and the formation of the first stars and galaxies. The technical maturity for the DALI mission is rated as medium for the rovers and interferometrics and low for the need to reduce array mass and for deploying and operating in a remote location.
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From page 36... ...
Brissenden, Smithsonian Astrophysical Observatory, and the other members of the Gen-X Study Team, "Generation-X Vision Mission Study Report," March 2006; and R Brissenden, Smithsonian Astrophysical Observatory, "The Generation-X Vision Mission," presentation to the Committee on Science Opportunities Enabled by NASA's Constellation System, February 21, 2008.
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From page 37... ...
Gen-X has a 50 m2 collecting area and uses thin foils with on-orbit figure adjustment of shape to reduce the mass. The Ares V launch vehicle would simplify the mission concept because of the large payload fairing and mass to L2 capability.
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In summary, although the potential scientific impact of Gen-X is high, very challenging technical maturity issues place the mission in the "deserving of further study" category. Modern Universe Space Telescope16 Scientific Objectives of the Mission Concept The Modern Universe Space Telescope is a 10-m, diffraction-limited optical-ultraviolet telescope (Figure 2.6)
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Characteristics of the Mission Concept as Developed to Date MUST would be a "next-generation Hubble Space Telescope" in many ways. Some of the technologies follow on from JWST in terms of large-mirror technology and construction and placement at L2.
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. MUST concentrates on science themes that are addressed largely by other observatories, such as JWST and ALMA, and that were the main themes of a similar mission, Space Telescope 2010, proposed during the 2001 astronomy and astrophysics decadal survey.18 The Space Telescope 2010 project was not highly ranked, owing to the limited advances of UV/optical performance when compared with less mature fields such as far-infrared astronomy, and also owing to the relative maturity of UV-unique observations when compared with emerging fields.
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From page 41... ...
Carpenter and the Stellar Imager Vision Mission Team, "SI -- The Stellar Imager: A UV/Optical Deep-Space Telescope to Image Stars and Observe the Universe with 0.1 Milli-arcsec Angular Resolution," NASA Goddard Space Flight Center, Greenbelt, Md., September 2005; K.G. Carpenter, NASA Goddard Space Flight Center, "Stellar Imager (SI)
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From page 42... ...
Stellar Imager would be composed of 20 1-m primary mirrors on a virtual surface (formation flying) that can have their baseline varied from 100 m up to 1,000 m depending on the target requirements.
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would be possible with a single Ares V launch vehicle, but it is currently not possible to estimate cost. As discussed above, Stellar Imager is technically challenging, and as such, the initial cost estimate is likely to be too low.
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The Stellar Imager mission concept is worthy of further study as a Constellation-enhanced science mission. A large launch vehicle such as the Ares V could allow for the full concept to be placed in orbit with a single launch, thereby reducing launch risks.
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Roberts, NASA Goddard Space Flight Center, "Solar Probe 2," in response to request for information by the Committee on Science Opportunities Enabled by NASA's Constellation System, May 2008. See footnote 1 above.
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The 2005 Solar Probe Science and Technology Definition Team established the following detailed Solar Probe science objectives: determine the structure and dynamics of the magnetic fields at the sources of the solar wind, trace the flow of the energy that heats the solar corona and accelerates the solar wind, determine what mechanisms accelerate and transport energetic particles, and explore dusty plasma phenomena and their influence on the solar wind and energetic particle formation. Characteristics of the Mission Concept as Developed to Date The Solar Probe 2 mission concept retains the technological advancements developed for the Solar Probe and Solar Probe Plus missions.
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From page 47... ...
Benefits of Using the Constellation System's Unique Capabilities Relative to Alternative Implementation Approaches The use of Constellation System vehicles as described in this mission concept proposal would enable a Solar Probe 2 mission. Ares I or Ares V launch vehicles, together with gravity assists by Venus, would get the probe into the 4 to 7 solar radii position.
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Further study should be narrowly focused on evaluating the ability to use the Ares V to obtain the desired orbit. Interstellar Probe24 Scientific Objectives of the Mission Concept The heliosphere, the bullet-shaped bubble created by the interaction of the solar wind and solar magnetic field with the interstellar medium, shields our solar system from most interstellar plasma, cosmic rays, and dust.
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From page 49... ...
the Interstellar Probe, one employing nuclear reactor technology25 and one using solar sails.26 Although a final report was written only for the nuclear option, the committee received a presentation from R.L. McNutt on three others: a Delta IV launch vehicle with a spacecraft using a solar sail (the original Vision Mission proposal prepared by McNutt)
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All four implementations have propulsion technology issues. The nuclear reactor option described in the Vision Mission report by Zurbuchen and the ISP Vision Mission Team is the more complex of the missions because of the low technology readiness level of the nuclear reactor and the relatively low technology readiness level of the nuclear electric propulsion options.
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The Interstellar Probe mission concept is worthy of further study as a Constellation-enabled science mission. Using an Ares V, the mission may provide a very significant improvement over earlier mission concepts.
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Socker, U.S. Naval Research Laboratory, for the Solar Polar Imager Vision Mission Study Team, "Solar Polar Imager: Observing Solar Activity from a New Perspective," presentation to the Committee on Science Opportunities Enabled by NASA's Constellation System, February 21, 2008.
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From page 53... ...
The Solar Polar Imager will have a Doppler-magnetograph imager, a white light coronagraph, an extreme ultraviolet imager, a total solar irradiance monitor, an ultraviolet spectrograph, a magnetometer, a solar wind ion composition and electron spectrometer, and an energetic-particle instrument. In the original Vision Mission study, the spacecraft used a Delta IV launch vehicle and required 6.7 years of flight time to reach its science orbit.
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In comparison, the Solar Polar Imager orbit would provide measurements of the poles every 4 months, closer to the Sun, and with more complete diagnostics. Although Solar Polar Imager is not mentioned by name in the NRC's 2003 solar and space physics decadal survey, a multi-spacecraft mission to provide imaging of the poles of the Sun is described as an important next step in providing understanding of the solar structure, magnetic field, and dynamics, and a multi-spacecraft mission is a possible enhanced version of the Solar Polar Imager mission.32 The committee believes that this mission does offer a significant advance in its scientific field, but it will have to be further reviewed in a future decadal survey.
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The Solar Polar Imager mission concept is worthy of further study as a Constellation-enhanced science mission. The Ares V launch vehicle could allow the elimination of the unproven solar sail technology.
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In summary, the Solar Polar Imager's combination of clearly defined, high-priority science goals and mature instrument technology places this mission in the "more deserving of further study" category. Further study should be primarily narrowly focused on evaluating the ability to use the Ares V to obtain the desired orbit and on answering the question of whether additional satellites could be launched simultaneously to provide multipoint observations.
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ANALYSIS OF SPACE SCIENCE MISSION STUDIES 57 FIGURE 2.11 Illustration of an Orion spacecraft approaching a near-Earth object. SOURCE: Hyabusa image courtesy of JAXA.
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The upper-bookend option is a dual-launch scenario most like the proposed lunar architecture, with spacecraft similar to an Altair Lunar Surface Access Module atop an Ares V vehicle and an Ares I rocket carrying an Orion. Defining studies need to be made to enable the proper choice of a launch vehicle or vehicles for this mission concept.
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From page 59... ...
Assessment of the Mission Concept for Further Study The Exploration of Near Earth Objects via the Crew Exploration Vehicle mission is enabled by the Constellation System. Each of the four mission concept options considered requires the Orion crew vehicle in conjunction with some combination of Ares I and Ares V launch vehicles.
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From page 60... ...
Ingersoll, Caltech, "Aerocapture Implementation of NASA's ‘Neptune Orbiter with Probes' Vision Mission," presentation to the Committee on Science Opportunities Enabled by NASA's Constellation System, February 20, 2008; and B Bienstock, The Boeing Company, and D
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Of the two missions reviewed by the committee, only the non-nuclear version can fly on a Delta IV Heavy launch vehicle, according to the current Delta IV Payload Planners Guide.40 Using the performance characteristics given in the 2002 Delta IV Payload Planners Guide,41 the proposers concluded that, if a lander were to be deployed, a Delta IV Heavy would be inadequate. However, the more recent Payload Planners Guide claims an increased payload capability, and this should be sufficient for all stated mission options.
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A Triton surface lander would enable direct measurement and sampling of the atmosphere and surface for purposes of the study of surface-atmosphere interactions, and might allow direct seismic probing of Triton's interior. Relative Technical Feasibility of the Mission Concept The technical maturity of the instrument complement for the Neptune Orbiter with Probes mission concept is high, whereas the necessary propulsion options are relatively immature.
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Levine, NASA Langley Research Center, "Titan Explorer: The Next Step in the Exploration of a Mysterious World," Final Report for NASA Vision Mission Study per NRA-03-OSS-01, June 2005; and J.S. Levine, NASA Langley Research Center, "Titan Explorer: The Next Step in the Exploration of a Mysterious World," presentation to the Committee on Science Opportunities Enabled by NASA's Constellation System, February 21, 2008.
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From page 64... ...
Figure 2.13.eps Includes low resolution bitmap image may reveal answers to questions about the chemical evolution on early Earth. The Titan Explorer mission focuses on nearly a dozen scientific questions, including the following: • What is the chemical composition of the atmosphere, including the trace gases?
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The use of an Ares V launch vehicle could eliminate the requirement for aerocapture. The Titan Explorer would provide a significant improvement in the knowledge of the evolution of prebiological chemistry.
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Although a Titan science mission could have significant impact on science, the science goals of the Titan Explorer as presented to the committee are obsolete, having become outdated following a new understanding of Titan with the results of the Cassini mission and the Cassini Equinox Mission (Cassini's extended mission)
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