Opening New Frontiers in Space: Choices for the Next New Frontiers Announcement of Opportunity (2008)

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1 Overview and Top-Level Findings and Recommendations This chapter presents only the committee’s top-level findings and recommendations for the New Frontiers Program. The individual missions are described and mission-specific recommendations presented in Chapter 2. BACKGROUND The New Frontiers Program was created by NASA as a direct result of the recommendations made in the 2003 National Research Council (NRC) report New Frontiers in the Solar System: An Integrated Exploration Strategy. That report, referred to as the solar system exploration decadal survey, established science priorities for the period 2003-2013. The New Frontiers Program is a budget line program, similar to the Discovery- and Mars Scout-class missions, meaning that Congress and the White House have agreed to support the existence of this class of missions, and NASA does not have to seek special approval for each individual mission. However, New Frontiers is essentially a hybrid program that incorporates aspects of both the Discovery-class solar system missions and the much larger flagship-class missions. New Frontiers missions are led by a principal investigator and are selected competitively like Discovery-class missions, but, like flagship missions, New Frontiers missions are expected to answer the fundamental scientific questions defined in the decadal survey. In effect, they must achieve a significantly higher quality of science than Discovery-class missions and cannot simply offer Discovery- class science that has grown too expensive for that mission line. The overall goal of New Frontiers missions is to enhance scientific understanding of the solar system by producing high-quality science return through focused scientific investigations. At a minimum, New Frontiers missions must address one or more goals specified in the decadal survey, whereas no such requirement exists for Discovery missions. Principal-investigator-led New Frontiers missions are intended to encourage innovation and competition and to accomplish the main science objectives developed by the scientific community in the solar system decadal survey. Competing for the mission award, various teams led by a principal investigator (and including not only other scientists, but also an institutional base and an industry partner) propose missions to NASA. The scientific community strongly believes that this competition produces better missions and clever solutions to problems, as the two New Frontiers missions selected to date, and discussed below in this report, demonstrate. National Research Council, New Frontiers in the Solar System: An Integrated Exploration Strategy, The National Academies Press, Wash- ington, D.C., 2003.  

OVERVIEW AND TOP-LEVEL FINDINGS AND RECOMMENDATIONS  The committee strongly believes that the New Frontiers Program is a valuable and vital part of NASA’s solar system exploration program. The committee’s philosophy was to provide NASA with sufficient options and to provide potential proposers with sufficient flexibility in their proposals to enable NASA to select a mission that can be done within the constraints of the New Frontiers Program, particularly the cost cap. The health of the New Frontiers Program was an overriding priority for the committee. New Frontiers has so far been successful in selecting missions that accomplish science that is not possible under the Discovery Program. These missions will make fundamental contributions to scientific understanding of the formation and evolution of the solar system. NEW FRONTIERS MISSION OPTIONS To develop a list of candidate missions for the next New Frontiers Announcement of Opportunity, the Com- mittee on New Opportunities in Solar System Exploration: An Evaluation of the New Frontiers Announcement of Opportunity considered the missions discussed in the decadal survey. The decadal survey recommended five mission candidates and ranked them according to priority: • Kuiper Belt Pluto Explorer, • South Pole-Aitken Basin Sample Return, • Jupiter Polar Orbiter with Probes, • Venus In Situ Explorer, and • Comet Surface Sample Return. To date there have been two New Frontiers missions selectedthe New Horizons mission to Pluto and the Kuiper Belt and the Juno mission to orbit Jupiter. The decadal survey listed five additional missions that were not recommended for reasons of “mission sequenc- ing, technological readiness, or budget.” These missions, listed in the following order in the decadal survey, were not ranked according to scientific priority: • Network Science, • Trojan/Centaur Reconnaissance, • Asteroid Rover/Sample Return, • Io Observer, and • Ganymede Observer. LESSONS LEARNED FROM THE PREVIOUS COMPETITION The New Horizons mission to Pluto (Box 1.1) was approved during the decadal survey and was essentially “grandfathered” into the New Frontiers Program. Launched in early 2006, New Horizons conducted a successful Jupiter flyby in February 2007 en route to a Pluto flyby in 2015 and is to conduct another flyby of a Kuiper Belt object sometime later. The second New Frontiers mission, the Juno mission to Jupiter (Box 1.2), was selected in 2005 and originally scheduled for launch in 2009. The launch date was delayed due to cost-phasing problems at NASA, and this delay substantially increased the cost of the overall mission. Juno will now launch in 2011 for arrival at Jupiter in 2015. Both New Horizons and Juno were the result of lengthy efforts that predated the New Frontiers Program itself. New Horizons benefited from nearly a decade of studies of Pluto missions. Juno resulted from three previously proposed Discovery-class missions. The committee was impressed by this fact and the lesson that successful proposals are the result of a lengthy process of study, refinement, competition, and scientific and technological advances. In order for the New Frontiers Program to remain healthy into the future, the committee encourages not New Frontiers in the Solar System, p. 197. 

 OPENING NEW FRONTIERS IN SPACE BOX 1.1  The New Horizons Mission The New Horizons mission to Pluto and the Kuiper Belt (Figure 1.1.1) was selected by NASA in late 2001 in response to an announcement of opportunity issued by NASA in January 2001 for a principal- investigator-led Pluto/Kuiper Belt mission. The 2001 announcement of opportunity, developed with guidance from a Science Definition Team, provided a prioritized list of specific science objectives and measurement objectives that should be addressed by the mission, and the New Horizons payload (visible imaging, far- ultraviolet and near-infrared imaging spectroscopy, plasma spectrometers, and radio science) was tightly focused toward achieving those objectives. Because a Pluto/Kuiper Belt mission was recommended as a top priority medium-class mission by the decadal survey, New Horizons was a good fit to the New Frontiers Program and was funded by New Frontiers after that program was created in 2002. The New Horizons mission, using a small radioisotope thermoelectric generator (RTG)-powered spacecraft, was launched on an Atlas V rocket in January 2006. A gravity-assist flyby of Jupiter in early 2007 has demonstrated New Horizons’ ability to produce high-quality science data, and a Pluto flyby is scheduled for July 2015. An extended mission, if funded, will enable New Horizons to encounter one or more additional Kuiper Belt objects sometime before the mid-2020s. The success of the New Horizons mission demonstrates the feasibility of principal-investigator-led missions and RTG-powered missions in the New Frontiers mission class. In the case of this mission, with its relatively simple architecture, the prioritized science goals and measurement objectives given in the announcement of opportunity were invaluable in providing a level playing field for proposers and in guiding spacecraft and mission design. FIGURE 1.1.1  NASA’s New Horizons spacecraft will fly past Pluto in 2015. New Horizons was the first of the New Frontiers missions recommended in the decadal survey. SOURCE: Courtesy of NASA. 

OVERVIEW AND TOP-LEVEL FINDINGS AND RECOMMENDATIONS  only the generation of new mission ideas and concepts, but also their continued growth and development beyond the next announcement of opportunity. The committee heard from members of both the New Horizons and the Juno teams on their perspectives on the overall program as well as their thoughts about the next announcement of opportunity. In particular, those who proposed missions for the last New Frontiers selection felt that the degree of mission specification (archi- tecture), and to a lesser extent the cost profile, had an impact on their creative efforts in approaching problems in the announcement of opportunity. For example, one mission defined in the decadal survey was a “Jupiter polar orbiter with probes.”  However, the developers of the Juno mission determined that it was not possible to design both an orbiter and atmospheric probes and still stay within the required cost cap for the mission. They chose instead to utilize only a microwave sensor to determine the water content of Jupiter’s atmosphere—the scientific goal of the probes specified for the mission. Initially this decision made it difficult for the developers of the proposal to find sponsors for their proj- ect. Potential sponsors were concerned that omitting a key aspect of the mission as defined by the decadal survey (i.e., the probes) would make it impossible for the mission to compete successfully. However, the Juno developers ultimately were able to convince a sponsor of the wisdom of their decision and were also able to convince NASA’s selection team of the utility of a microwave instrument over the costly atmospheric probes. The lesson that the committee learned from the Juno mission was that being too specific about how to obtain desired scientific data not only hampers ingenuity, but also can place an otherwise excellent proposal at risk even before it can be submitted for evaluation by NASA. For this reason the committee agreed to limit specifying how data should be collected and instead defined what data are required. The committee adopted this approach as much as possible throughout this report. COMMITTEE FINDINGS AND RECOMMENDATIONS There are several threats to the viability of the New Frontiers mission line. The committee heard from various experts that one potential threat was that the announcement of opportunity could be so tightly constrained that it would produce no viable competitors. Certainly, as the number of candidate mission options is reduced (from the original five to the present threeSouth Pole-Aitken Basin Sample Return, Venus In Situ Explorer, and Comet Surface Sample Return), the possibility increases that no viable contenders for the New Frontiers Program will emerge. But another constraint was the one identified above—overly defining the method of acquiring scientific data rather than leaving the methods to the proposers. Because of the committee’s desire to maintain the viability of the New Frontiers line and because of the statements by several persons who briefed the committee, the com- mittee recommends that NASA should focus more on the science to be returned rather than on specific methods for achieving it. The committee believes that scientific justification is fundamental to the health and future of the New Frontiers Program. New Frontiers is a strategic component of the planetary flight program, and the first recommendation is intended to ensure that the announcement of opportunity will be based on the mission science priorities from the decadal survey and that the strategic nature of the New Frontiers Program is maintained. Recommendation 1: In drafting the rules for the next New Frontiers announcement of opportunity, NASA should emphasize the science objectives and questions to be addressed, and not specify measurements or techniques for the implementation. Compared to the larger 12-month decadal survey involving dozens of members working on several panels, the study done by the Committee on New Opportunities in Solar System Exploration had less time and depth of expertise. As a result, the committee sought to adhere to the guidance of the decadal survey as closely as possible while still recognizing the limitations of the original decadal survey and remaining cognizant of advances in space science and technology since the decadal survey was produced 5 years ago. The committee identified several features of the decadal survey that limited the committee’s work. These New Frontiers in the Solar System, p. 16. 

10 OPENING NEW FRONTIERS IN SPACE BOX 1.2  The Juno Mission The Juno team proposed a low-risk, innovative approach to probe the magnetic and gravitational fields and map the water and cloud distribution of Jupiter (Figure 1.2.1). Despite resistance from institutional man- agement and others who feared that the mission would be rejected because it did not adhere to the strawman architecture established in the decadal survey, the team abandoned the direct entry probe and chose to utilize a microwave spectrograph with six frequency bands that sound to different atmospheric depths to address the question of water abundance and distribution at different altitudes. This approach could be accommodated by a spin-stabilized spacecraft in an elliptical, nearly atmospheric grazing, 11-day polar orbit, which would allow sampling of the magnetic and gravitational fields over a wide range of radial distances. The orbital period would be synchronized with the rotation of the planet so that the entire planet can be longitudinally sampled within 16 orbits, providing early yield in a hazardous environment. The spin-stabilized spacecraft would be operated in a passive mode for greatest sensitivity in determining gravitational fields, or oriented perpendicular to its orbital motion, allowing the microwave radiometers to scan in a latitudinal direction. With this mode, the spectrometer would view a given area of the cloud deck from multiple observational angles, providing vertical discrimination of the abundance of water and cloud structure. The committee notes that the Juno mission is particularly strong because it addresses fundamental science questions raised in three National Research Council decadal surveys (solar system exploration, astronomy and astrophysics, and solar and space physics).1 Even though the Jupiter polar orbiter was not the highest-ranked New Frontiers mission in the solar system decadal survey, by selecting it NASA was also able to address sig- nificant goals of the solar and space physics and astronomy and astrophysics communities. Global sensing of Jupiter’s gravitational and magnetic fields and water content will yield more detailed knowledge of the internal mass distribution, the inner magnetic field, and the water content of Jupiter. For astrophysics, a better under- standing of the water content and mass distribution is needed to determine how Jupiter and extrasolar planets formed. Because data related to near-planet, high-latitude magnetic field structure are needed to understand basic magnetospheric processes, the solar and space physics community assigned a Jupiter polar orbiter a high priority. 1 National Research Council, New Frontiers in the Solar System: An Integrated Exploration Strategy, The National Academies Press, Washington, D.C., 2003; National Research Council, Astronomy and Astrophysics in the New Millennium, National Academy Press, Washington, D.C., 2001; and National Research Council, The Sun to the Earthand Beyond: A Decadal Research Strategy in Solar and Space Physics, The National Academies Press, Washington, D.C., 2003. included the fact that the decadal survey identified and ranked five New Frontiers missions, and identified but did not rank the five additional medium-size missions. Another limitation was that the decadal survey (and the 2003 NASA New Frontiers announcement of opportunity that was based on it) was overly specific about how to answer scientific questions, selecting options for how to address a science goal rather than leaving most of such details to the proposers. In addition, the committee concluded that the decadal survey used unrealistic cost models, meaning that, if implemented as described in the decadal survey, the missions described would cost more than was predicted by the decadal survey. The committee determined that the next announcement of opportunity should state a candidate list of mis- sions, as was done with the previous round, but with an important caveat that is discussed below. The committee See NASA, “New Frontiers Program and Missions of Opportunity Announcement of Opportunity,” available at http://research.hq.nasa. gov/code_s/nra/current/AO-03-OSS-03/main.html. 

OVERVIEW AND TOP-LEVEL FINDINGS AND RECOMMENDATIONS 11 FIGURE 1.2.1  The Juno spacecraft which will travel to Jupiter and conduct measurements of its magnetosphere among other science objectives. Juno is unique as the first spacecraft to be designed to operate at Jupiter distance from the Sun and operate on solar panels. This opens the possibility of other missions at this distance also using this technology. SOURCE: Courtesy of Scott Bolton, Southwest Research Institute and Jet Propulsion Laboratory. further concluded that the candidate missions should include the three remaining medium-size missions from the previous announcement of opportunity and the five additional nonprioritized missions developed for the decadal survey. As with prior competitive mission opportunities, NASA should select from this set of eight missions based on both science quality and overall mission viability. Recommendation 2: NASA should expand the list of potential missions in the next New Frontiers announce- ment of opportunity to include the three remaining candidate missions—South Pole-Aitken Basin Sample Return, Venus In Situ Explorer, and Comet Surface Sample Return—and also the five additional medium- size missions mentioned in the decadal survey: Network Science, Trojan/Centaur Reconnaissance, Asteroid Rover/Sample Return, Io Observer, and Ganymede Observer. There is no recommended priority for these missions. NASA should select from this set of missions based both on science priority and on overall mis- sion viability. 

12 OPENING NEW FRONTIERS IN SPACE The committee concluded that each of these eight missions still has scientific merit, and in the past 5 years no additional scientific objectives have emerged that can be accomplished within the New Frontiers cost con- straints. The committee received input from various persons about the merits of preparing a mission list versus making the competition open to all proposals. However, given the limitations of this study, the committee could not sample all of the potential mission ideas from the entire community. The committee rejected the option of developing a candidate list based on science themes from the decadal survey because the New Frontiers Program requires greater focus than the decadal survey science themes would provide. The committee’s charge asked the committee to determine if a list of science themes would be more appropriate than a list of potential missions. The committee concluded that because the New Frontiers line is competed, must meet cost constraints, and requires that proposals be ready in time for the next announcement of opportunity, a candidate list of missions (with their respective science goals drawn from the decadal survey), rather than a list of science themes, would be of greater value to the proposers. These five additional missions were not recommended in the decadal survey for reasons of “mission sequenc- ing, technological readiness, or budget.” The decadal survey did not state what issues were relevant to which missions. The committee was not asked to evaluate the technological readiness or budget feasibility of any of these missions and lacked the time and resources to conduct such assessments. In some cases new technology or novel technological approaches may make some of these missions more achievable now than they were 5 years ago. However, the committee acknowledges that for all of the missions, including the three remaining from the original prioritized list, these factors may still pose some major challenges. For this reason, the committee chose to introduce greater flexibility into mission architecture (i.e., how to accomplish the mission) and the science requirements, and to adopt the general approach that within each mission, the decision about which science goals to pursue should be left to a competitor to select and to justify. The eight candidate missions are more fully described in Chapter 2. For each mission option, the committee introduces the mission, provides background on why it is important, quotes sections of the decadal survey that called for such a mission, and explains how scientific advances made since 2002 affect the mission. In addition, the committee provides mission-specific recommendations for each. Although the decadal survey did not make a specific recommendation for a Mars mission within the New Frontiers line, the inclusion of Network Science as one of the mission categories leaves a potentially attractive option for a Mars Network mission (Figure 1.1). The decadal survey did refer (in Table ES.2) to a Mars Network mission as the second-highest priority for a medium-size Mars mission after the Mars Science Laboratory.  Such a mission would be important for comparative planetology and is not currently part of the Mars Exploration Pro- gram, which is focused on the search for water and life and sample return. The committee was wary of making any Mars mission recommendations that could potentially upset the Mars Exploration Program, which it considers to be a carefully planned, integrated, and highly successful program to date. The committee concluded that the prominence of a Network Science mission in the New Frontiers line and the Mars Network mission in the Mars section of the decadal survey clearly warrants the inclusion of a Network Science mission in the next New Frontiers announcement of opportunity. Furthermore, the committee concluded that the meteorological component identified under the Mars Long-Lived Lander Network was also important, but that it should not be a requirement for such a mission. See Chapter 2 for further details. In describing these different mission options, the committee sought to identify the original language justifying them in the decadal survey but found that not all of the missions were defined in the decadal survey at the same level of detail. Therefore, the committee sought to add further information about potential science objectives of these missions, clearly delineating that this information was not from the decadal survey. The committee believes that if these missions are included in the next decadal survey, it will be most helpful to future prospective propos- ers if that decadal survey provides greater discussion and definition than they have previously received. This will assist not only the proposers but also NASA in its selection of future New Frontiers missions. New Frontiers in the Solar System, p. 197. New Frontiers in the Solar System, p. 5. 

OVERVIEW AND TOP-LEVEL FINDINGS AND RECOMMENDATIONS 13 1.3 rt top Mars.eps 1.3 rt mid Mars.eps 1.3 rt btm Mars.eps FIGURE 1.1  A Network Science mission was identified as a possible New Frontiers mission in the decadal survey, and the Mars Long-Lived Lander Network was also identified as a high-priority mission for the Mars program. SOURCE: Courtesy 1.3 left Mars.eps of Jet Propulsion Laboratory, California Institute of Technology. OPPORTUNITIES FOR NEW SCIENCE The committee acknowledges that scientific developments since 2002 require some reinterpretation of the New Frontiers Program’s goals. New technological developments have also occurred in that time. For example, prior to the selection of the Juno mission, it was commonly accepted wisdom within the scientific community that solar power was inadequate for a spacecraft at Jupiter. Although Juno is constrained by its limited power using solar cells, the mission demonstrates the potential for solutions that have not yet been considered. Furthermore, the committee was also impressed by the wealth of ideas for other missions and other important science that could be conducted within the solar system that bear on decadal survey science goals. For these reasons and because of its limited knowledge, the committee determined that NASA should provide an “open option” so that mission developers with innovative ideas are given the opportunity to propose them to NASA. In particular, considerable new scientific information has been obtained by missions and ground-based obser- vations since the decadal survey was prepared. In addition, advances in technology may enable missions that were not considered, or were considered infeasible in the decadal survey, but that might now be feasible within the New Frontiers constraints. Therefore, a mission proposed under New Frontiers could take advantage of new scientific discoveries as well as new ideas. However, the committee believes that any mission proposed under this more open option should meet a very high standard of scientific content: it cannot simply be a Discovery-class mission that scores high for its limited costs but relatively low scientifically—it must answer fundamental questions established in the decadal survey. The New Frontiers Program is a strategic program and its missions must be strategic in conception. A proposal targeted to a lower standard would undercut the justification for the New Frontiers Program as distinct from the Discovery Program. 

14 OPENING NEW FRONTIERS IN SPACE The committee emphasizes that the success of future New Frontiers missions after the currently planned announcement of opportunity requires that new ideas and innovations be constantly generated, and that they go through successive rounds of review, evaluation, and critique in order to become stronger and more competitive. Recommendation 3: NASA should consider mission options outside the three remaining and five additional medium-size missions described in the decadal survey that are spurred by major scientific and technologi- cal developments made since the decadal survey. As with any New Frontiers mission, these proposals must offer the potential to dramatically advance fundamental scientific goals of the decadal survey and should accomplish scientific investigations well beyond the scope of the smaller Discovery Program. Both mission- enabling technological advances or novel applications of current technology could be considered. However, NASA should limit its choices to the eight specific candidate missions unless a highly compelling argument can be made for an outside proposal.