FIGURE 3.1 Europa above the clouds of Jupiter, as imaged by the New Horizons spacecraft. Europa was the top-priority flagship mission for the decadal survey. SOURCE: Jet Propulsion Laboratory.



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FIGURE 3.1 Europa above the clouds of Jupiter, as imaged by the New Horizons spacecraft. Europa was the top-priority flagship mission for the decadal survey. SOURCE: Jet Propulsion Laboratory.

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3 Flight Missions Some of the major recommendations of the decadal survey New Frontiers in the Solar System concern how to select and fly space missions to the planets.1 The decadal survey makes recommendations for mission classes of different sizes and proposes a list of targets for the largest mission in the flagship and New Frontiers classes. Flagship missions are the largest, having a cost that was defined in New Frontiers in the Solar System as greater than $650 million, but in reality costing more than a billion dollars. The decadal survey recommends a flagship mission to Jupiter’s moon Europa as the highest priority. This committee reiterates that recommendation, and commends NASA for studies of other future possible flagship missions now under way. To meet the recom- mendation in the decadal survey, NASA should start the Europa flagship mission in this decade. NASA has succeeded in initiating a New Frontiers program of principal-investigator-led, moderate-cost mis- sions. In order to fulfill the decadal survey recommendations, NASA should increase the rate of selection and launch of New Frontiers missions. The Discovery missions are smaller still, and also competitively selected. Although the flight rate of Discovery missions is less than expected in the decadal survey, these missions provide a valuable contribution to the program of planetary exploration. However, to ensure that the Discovery program continues with appealing, low-cost, and low-risk planetary missions, the next decadal survey should examine closely the rationale, achievements, and direction of the program. Flight Missions OVERALL ASSESSMENT: Grade: B Trend: ➜ The lack of the start of the Europa flagship mission and new Discovery missions has led the committee to give the flight missions area a grade of B. The committee assessed this area with a downward trend because of the lack of new Discovery opportunities. The flagship flight missions recommended by the decadal survey for 2003-2013 are listed in Table 3.1. 1National Research Council, New Frontiers in the Solar System: An Integrated Exploration Strategy, The National Academies Press, Wash- ington, D.C., 2003. 27

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2 GRADING NASA’S SOLAR SYSTEM EXPLORATION PROGRAM TABLE 3.1 Mission Concepts for 2003-2013 Proposed by the New Frontiers Decadal Survey Panels Missiona Status at Midterm Review Large, Flagship Missions 1 Venus Sample Return No detailed study or study plans 2 Mercury Sample Return No detailed study or study plans 3 Comet Cryogenic Sample Return No detailed study or study plans 4 Neptune Orbiter with Probes Two funded “Vision Mission” studies; no future study plans 5 Saturn Ring Observer No detailed study or study plans 6 Uranus Orbiter with Probes No detailed study or study plans 7 Europa Geophysical Explorer Now undergoing detailed study 8 Europa Lander Studied as part of Jupiter Icy Moons Orbiter and Europa studies 9 Titan Explorer Two funded “Vision Mission” studies; now undergoing detailed study in parallel with Europa Geophysical Explorer 10 Neptune Orbiter/Triton Explorer See (4) above 11 Mars Sample Return Now entering early study Medium Missions 12 Venus In Situ Explorer In last New Frontiers Announcement of Opportunity 13 South Pole-Aitken Basin Sample Return In last New Frontiers Announcement of Opportunity 14 Kuiper Belt-Pluto Explorer Implemented as New Horizons (launched January 2006) 15 Comet Surface Sample Return In last New Frontiers Announcement of Opportunity 16 Trojan/Centaur Reconnaissance Flyby No known current studies or plans 17 Asteroid Rover/Sample Return No known current studies or plans 18 Jupiter Polar Orbiter with Probes In last New Frontiers Announcement of Opportunity; implemented without probes as Juno (planned launch 2011) 19 Io Observer No known current studies or plans 20 Ganymede Orbiter Now undergoing detailed study with (7) and (9) on flagship list (above) aMission concepts summarized from National Research Council, New Frontiers in the Solar System: An Integrated Exploration Strategy, The National Academies Press, Washington, D.C., 2003. In the recommendations quoted below from New Frontiers in the Solar System,2 the Solar System Exploration Survey (SSE Survey) referred to is called simply the decadal survey in the present report. The grade and trend assigned by the Committee on Assessing the Solar System Exploration Program in its midterm review of efforts to address the recommendations appear to the right of the quoted recommendations. 2National Research Council, New Frontiers in the Solar System: An Integrated Exploration Strategy, The National Academies Press, Wash- ington, D.C., 2003.

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2 FLIGHT MISSIONS New Frontiers Recommendations Results of Midterm Review “The SSE Survey recommends that flagship (>$650 million) missions be developed and flown at a rate of about one per decade. In addition, for large missions of such inclusive scientific breadth, a broad cross section of the community should be involved in the early planning stages.” (pp. 2, 193) Grade: D Trend: ➜ “Rather than compete large-class missions with missions in other cost classes, the SSE Survey recommends flying large-class missions at an appropriate frequency (i.e., roughly one per decade), independent of the issues facing new starts in other cost classes.” (p. 196) NASA has not initiated a new flagship mission this decade, resulting in the low grade of D. The agency has tasked four science definition teams to study future flagship mission concepts. The reports of these teams were finished in August 2007 but not publicly released until later. Until NASA actually funds a new flagship mission, the committee cannot assess an upward trend. In NASA planning, flagship missions are considered separately from missions in lower cost categories, as suggested by the decadal survey. However, budgetary concerns and the long lead time between approval and launch of a flagship mission make it difficult for NASA to support launches once per decade. (The last flagship mission, Cassini, was launched in 1997.) Overruns of large mission budgets inevitably would limit the launch rate and could cause budgetary problems for other parts of the NASA science program. Recommendation: To ensure that flagship mission costs do not negatively impact missions in other cost classes, NASA should apply sufficient resources to obtain good cost estimates in the earliest phases and rigorously review mission costs before selection. New Frontiers Recommendation Results of Midterm Review Grade: B Trend: ➜ “The SSE Survey recommends that NASA conduct a series of advanced studies of Flagship mission concepts with broad community participation over each 10-year period prior to decadal surveys.” (p. 193) The Outer Planets Analysis Group (OPAG) is providing ongoing community input to NASA planning for future missions. The four science definition team flagship studies conducted from 2006 to 2007 responded to this recommendation. NASA also needs to consult with the Mars Exploration Program Analysis Group (MEPAG) and the Venus Exploration Analysis Group (VEXAG) on future flagship missions. The current flagship mission studies can be advocated to only 4 of the 10 proposed targets listed in the decadal survey. New missions to Venus and Mercury, listed in the decadal survey, are not being studied at this time, but NASA consultation with appropriate advisory groups is under way, and the committee hopes that this effort proceeds to formal studies. Recommendation: NASA should continue studying possible flagship missions to both the inner and the outer planets as input to the next decadal study. New Frontiers Recommendation Results of Midterm Review Grade: D Trend: ➜ “The SSE Survey endorses the current recommendations for a mission to orbit Europa. However, given the high cost of the Europa Geophysical Explorer mission, the Survey considers it essential that the mission address both the Group 1 and Group 2 science objectives described by the Europa Orbiter Science Definition Team.” (p. 196)

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0 GRADING NASA’S SOLAR SYSTEM EXPLORATION PROGRAM The 2006 Europa Explorer study addresses Group 1 and 2 science objectives articulated in the decadal survey. Although no flagship mission selection has yet been made, the committee believes that after several false starts NASA is now moving forward responsibly toward such a flagship mission selection. NASA has taken seriously the advice in the decadal survey to develop a flagship mission to Europa. (See Figure 3.1.) For several years, studies of a nuclear-powered spacecraft (Jupiter Icy Moons Orbiter, JIMO) were conducted, but they were ultimately terminated as it became clear that technical problems would be extremely costly to solve. For missions requiring standard propulsion, technological problems are also significant, particularly those arising from the intense radiation environment in which this mission will have to operate. If a lander is required as part of the exploration, significant mass must be provided for propulsion. All of these issues are being investigated by a science definition team (SDT) at this time. Another SDT is examining what can be learned about Europa from flybys and remote sensing using a spacecraft orbiting Jupiter but not Europa. The actions taken by NASA to this point have been very responsive, but the committee notes that the decadal survey recommended beginning a flag- ship mission to Europa, and studies of such a mission are not by themselves responsive. Recommendation: NASA should select a Europa mission concept and secure a new start for the project before 2011. New Frontiers Recommendation Results of Midterm Review Grade: A Trend: ➜ “The SSE Survey recommends that NASA establish a procedure for reevaluating the candidate list of large-class missions for the decade 2013-2023. Two possible mechanisms for this procedure include (1) the appointment of a Science Definition Team every 3 years to define candidate missions or (2) a periodic competition for funds to support initial definition studies of mission concepts.” (p. 196) NASA has tasked four science definition teams to consider some candidate flagship missions. There were 10 “large” missions (in addition to a Mars Sample Return mission) listed in the decadal survey (see Table 3.1). The studies under way cover some of the concepts proposed and some that were not suggested. Such studies are vital to the health of the decadal survey process. Because of both cost growth and a better understanding of actual mission costs, some of the “medium-class” missions in the decadal survey may now be above the medium cap and thus really of the flagship class. For example, the Mars Science Laboratory was originally a medium-class mission, but NASA now considers it to be a flagship- class mission. See Table 3.1 for a list of medium-class missions proposed by the decadal survey. New Frontiers Recommendation Results of Midterm Review Grade: C Trend: ➜ “The SSE Survey recommends that NASA engage prospective international partners in the planning and implementation of the Europa Geophysical Explorer.” (p. 196) NASA conducted a bilateral discussion with the European Space Agency (ESA) in the fall of 2007, which demonstrated good progress toward meeting this objective. NASA maintains good communication with ESA on planning for outer planet missions. U.S. investigators are being encouraged to participate in proposing a Europa mission for ESA’s Cosmic Vision selection. A working group established to consider a joint NASA-ESA mission to Europa concluded that collaboration would be very desirable but that separate U.S. and European spacecraft would be required (because of International Traffic in Arms Regulations [ITAR] restrictions). The bilateral meeting mentioned above shows NASA’s continued interest in pursuing international partners.

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1 FLIGHT MISSIONS New Frontiers Recommendation Results of Midterm Review Grade: A Trend: ➜ “The SSE Survey recommends that NASA encourage and continue to pursue cooperative programs with other nations.” (pp. 2, 156) NASA has made use of international partners for the Stardust, Cassini, Rosetta, Mars Exploration Rovers (Spirit and Opportunity), Mars Reconnaissance Orbiter, Mars Odyssey, Dawn, Juno, Phoenix, Mars Science Lander, and the ESA’s Mars Express, Venus Express, and planned Exo-Mars missions. The committee notes that this cooperation has had significant impact. For instance, the direct sharing of data and knowledge between the European Mars Express mission and the U.S. Mars Reconnaissance Orbiter has helped to identify areas on the martian surface of high scientific interest. Despite ITAR’s chilling effect, NASA maintains a good level of international collaboration in planetary exploration and should be commended. Current trends will lead to maintaining this satisfactory level of support. New Frontiers Recommendation Results of Midterm Review Grade: B Trend: ➜ “The SSE Survey strongly endorses the New Frontiers initiative. These spacecraft should be competitively procured and should have flights every 2 or 3 years, with the total cost capped at approximately twice that of a Discovery mission. Target selection should be guided by the list in this report.” (pp. 2, 190) NASA succeeded in initiating a New Frontiers program, and the committee praises the agency for undertaking this effort. The New Horizons mission to Pluto was the first New Frontiers mission. It was selected in 2001 before the writing of the decadal survey (2002). Juno was selected for flight in 2005. Despite these achievements, the rate is half that recommended. NASA is planning to release an announcement for the next selection in FY 2009. Recommendation: NASA should increase the rate of selection and launch of New Frontiers missions. New Frontiers Recommendation Results of Midterm Review Grade: “The SSE Survey recommends an early study to find ways to avoid the potentially Incomplete adverse consequences of conflicts of interest relating to, for example, access to unique expertise and infrastructure at NASA centers.” (p. 191) The decadal survey did not give clear advice about how to underwrite proposal competition, and NASA has not introduced any such process in its selections. The committee is concerned about how this could be implemented and suggests that a better solution would be to focus on the pre-proposal phase. Recommendation: The New Frontiers missions should follow a two-stage development process, starting with (1) an opportunity to submit a proposal for funding for 1 or 2 years to develop mission concepts. This earlier stage would provide for some endorsement of the best ideas so that they can attract industry and NASA center support. Such support, in turn, would (2) allow more concepts to reach a level of maturity required for considering full-scale proposal development. New Frontiers Recommendation Results of Midterm Review Grade: A Trend: ➜ “In order to confirm the readiness of any New Frontier mission concept prior to the issuance of an Announcement of Opportunity and to certify the mission concept’s qualification for this program, the SSE Survey recommends that after the first selection, an independent group conduct a certification review of the mission concept to be solicited, prior to the issuance of any Announcement of Opportunity.” (p. 191)

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2 GRADING NASA’S SOLAR SYSTEM EXPLORATION PROGRAM NASA is planning to review input from the National Research Council (NRC) before announcing new targets for the next New Frontiers Announcement of Opportunity. NASA reviewed the decadal survey concepts before announcing the 2003 New Frontiers opportunity. The NRC currently has a study effort under way—Opening New Frontiers in Space: Choices for the Next New Frontiers Announcement of Opportunity—that is considering whether the next New Frontiers Announcement of Opportunity should be open to all proposals or should instead include a candidate list of science goals and/or missions. New Frontiers Recommendation Results of Midterm Review Grade: A Trend: ➜ “The SSE Survey recommends that the National Research Council’s Committee on Planetary and Lunar Exploration conduct a review to confirm or modify decadal survey recommendations and priorities for the New Frontiers flight program.” (p. 192) An NRC study is currently under way as a result of NASA’s request, which was based on the decadal survey recommendation quoted above.3 The committee gives NASA high marks for implementing a logical process toward the next New Frontiers program selection. New Frontiers Recommendations Results of Midterm Review “Given Discovery’s highly successful start, the SSE Survey endorses the continuation of this program, which relies on principal-investigator leadership and competition to obtain the greatest science return within a cost cap. A flight rate of no less than one launch every 18 months is recommended.” (pp. 2, 192) Grade: D Trend: ➜ “Recognizing the Discovery program’s success, the SSE Survey recommends that adequate resources be provided to sustain an average flight rate of no less than one launch every 18 months.” (p. 192) No Discovery missions have been selected since 2001. A low grade was assigned because so little progress has been made toward meeting the recommended launch interval of 18 months. The committee notes that the previously selected Dawn and Kepler missions are scheduled for launch in this decade, but this still does not mitigate the fact that none has been selected in the past 6 years. Allowing for the launch of the two already-selected missions and the typical 3-year development time before launch, it would take five mission selections in the next 4 years to satisfy the decadal survey recommendations.4 Recommendation: NASA should select two of the three Discovery missions currently in Phase A studies (if two are sufficiently meritorious to be selectable) and should seek to achieve an 18-month period between selections for the rest of the decade. These steps can help to restore vitality to this important program. New Frontiers Recommendation Results of Midterm Review Grade: A “The SSE Survey supports NASA’s current Senior Review process for deciding Trend: ➜ the scientific merits of a proposed mission extension and recommends that early planning be done to provide adequate funding of mission extensions, particularly Flagship missions and missions with international partners.” (pp. 4, 192) NASA has a regular process for reviewing proposals for mission extensions, and funding was provided to Cassini for planning mission extensions. The committee assessed the trend as downward, however, because the frequency of Senior Reviews has increased for the Mars program from every 2 years to annual reviews. The 3Note added in proof: The report of the study, Opening New Frontiers in Space: Choices for the Next New Frontiers Announcement of Op- portunity, was approved for public release in early March 2008. 4Note added in proof: NASA selected the GRAIL lunar gravity Discovery mission soon after this report was completed.

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 FLIGHT MISSIONS committee concluded that the change from biennial to annual reviews has little or no added value. The time and resources spent on preparing for such reviews every year, on the part of both reviewers and investigators, seems out of proportion to the benefits to mission planning or implementation. The committee also notes that NASA can re-examine the assumptions from the biennial review at any time should major changes occur (e.g., loss of spacecraft capability or an exciting new discovery). Recommendation: NASA should return to conducting Senior Reviews once every 2 years to improve efficiency. New Frontiers Recommendation Results of Midterm Review Grade: A Trend: ➜ “[A] top-level programmatic priorit[y]: Continue approved missions, such as the Cassini-Huygens mission to Saturn and Titan. . . .” (pp. 189-190) NASA has taken steps toward approving a 2-year extension of the Cassini mission. The committee agrees with this choice and believes that it is a sound decision consistent with the intent of the decadal survey and the realities of operating the Cassini spacecraft.