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FIGURE 1.1â NASAâs New Horizons spacecraft will fly past the outermost planet in the solar system, Pluto, in 2015. SOURCE: NASA.
1 Introduction The exploration of our solar system using Earth-based tools, robotic spacecraft, and, at times, people has been a human endeavor for hundreds of years. From Galileoâs first observations of Jupiter through an early telescope to the Galileo flight mission to Jupiter, solar system exploration has been a rich scientific field encompassing biology, chemistry, geology, physics, meteorology, and many other disciplines. The solar system exploration community and its principal supporter, NASAâs Science Mission Directorate (SMD), have worked together over the years to determine the direction and scientific rationale and goals for both a space-based and a ground-based program of exploration. They have then worked to develop a set of missions to achieve these goals. In 1994, the National Research Council (NRC) through the Space Studies Board produced a 15-year strategy for solar system exploration, An Integrated Strategy for the Planetary Sciences: 1995-2010. Since that report was issued, a number of important developments and changes in circumstances for the program necessitated a new strategy. Adopting the model of decadal surveys used successfully by the astronomy and astrophysics community since the 1960s, NASA requested a decadal survey encompassing all of the elements of solar system exploration, including the major scientific questions to be addressed and recommendations for flight missions and ground-based activities. The result of this effort was the 2003 report New Frontiers in the Solar System, generally referred to as the solar system exploration decadal survey. The committee notes that whereas the astronomy and astrophysics community has a long and successful history of decadal surveys, the solar system exploration community is still relatively new to this process and not all community members fully recognize or acknowledge the importance of the decadal survey. The committee stresses that the solar system decadal survey is the primary process for establishing scientific priorities for the exploration of the solar system. Only the decadal survey process involves broad-scale community involvement and input and a careful vetting process. Five years into the decade covered by the survey (2003-2013) and in preparation for the next survey effort, Congress asked NASA to engage the community through the NRCâs Space Studies Board in assessing progress toward the scientific and mission goals recommended in the decadal survey and in a similar NRC report on the National Research Council, An Integrated Strategy for the Planetary Sciences: 1995-2010, National Academy Press, Washington, D.C., 1994. National Research Council, New Frontiers in the Solar System: An Integrated Exploration Strategy, The National Academies Press, Wash- ington, D.C., 2003. 13
14 GRADING NASAâS SOLAR SYSTEM EXPLORATION PROGRAM Mars Exploration Program, Assessment of NASAâs Mars Architecture 2007-2016. This midterm progress report follows a similar assessment completed in early 2007 of the astronomy and astrophysics decadal survey and will be followed by similar efforts in heliophysics and Earth science. The committee recognizes that the decadal survey represents the first time that the solar system science com- munity has done such a broad community survey to produce a strategic path forward for solar system exploration. It is a positive and welcome development that the committee enthusiastically supports as a way of operating in the future. The committee also recognizes that these âmidterm gradesâ represent an assessment of work in progress. It has endeavored to accumulate evidence and information to back up its performance assessment as well as to provide guidance for future activities in the context of the current decadal survey and in preparation for the next decadal survey, scheduled to start in late 2008. NASAâS SOLAR SYSTEM EXPLORATION PROGRAM NASAâs Planetary Science Division (PSD) is one of five divisions that make up NASAâs Science Mission Directorate. In fiscal year (FY) 2007, SMD had a total budget of $5.251 billion, of which $1.391 billion was allocated to the PSD. Within the $1.391 billion, $626 million, or 45 percent of the budget, was used for Mars exploration. The remaining 55 percent was split among the Discovery ($177 million) and New Frontiers ($156 million) programs, technology development ($72 million), and planetary science research ($275 million). See Figure 1.2 for details on how this money is divided by projects in the FY 2008 budget. The Planetary Science Division is currently overseeing more than a dozen space-based missions (Table 1.1). These missions are studying the solar system from the inner-most planet Mercury outward to beyond Pluto and the edge of the Kuiper Belt, and almost everywhere in between (see Figures 1.1 and 1.3). The operations are conducted by a fleet of sophisticated robots that orbit, land on, drive over, and even collect samples from planetary bodies. Mars, unlike the other potential solar system targets, has been treated as a special case and is managed as a âprogramâ in its own right, with a set of high-level science goals that individual missions are expected to address. Each new mission to Mars builds on the science and technology resulting from past missions and is expected to operate in concert with the other spacecraft already at Mars to produce a better understanding of that planet as a system. Planetary scientists consider Mars to be the planet in our solar system most similar to Earth and the planet other than Earth that is most likely to have developed life in the past. It is, therefore, a high-priority target. Only one of the current missions in flightâthe initial flight in the New Frontiers program, the New Horizons mission to Pluto and the Kuiper Beltâis the result of a decadal survey recommendation. A second New Frontiers mission, the Juno mission to Jupiter, has been selected for launch in 2011. One mainline Mars mission, the Mars Science Laboratory rover, has been approved, and a down-selection is imminent between two Mars Scout mis- sions, the Great Escape mission and the Mars Atmosphere and Volatile Evolution (MAVEN) missionâboth Mars aeronomy (atmosphere science) missions. No new Discovery missions have been selected for flight in the past 5 years, although two small âmissions of opportunityâ have been approved, EPOXI and Stardust New Exploration of Tempel 1 (NExT), which use spacecraft already in flight that have accomplished their primary missions. The recommended flagship mission, a Europa orbiter, has not been started. All of these current and approved missions address key scientific questions in the decadal survey. National Research Council, Assessment of NASAâs Mars Architecture 2007-2016, The National Academies Press, Washington, D.C., 2006. The first of these assessments, A Performance Assessment of NASAâs Astrophysics Program (The National Academies Press, Washington, D.C., 2007), prepared jointly by the National Research Councilâs Space Studies Board and Board on Physics and Astronomy, was delivered to NASA in February 2007. See http://www.aaas.org/spp/rd/nasa08p.htm#tb. The acronym EPOXI combines Extrasolar Planet Observations and Characterization (EPOCh) and Deep Impact eXtended Investigation (DIXI). Note added in proof: A new Discovery mission, GRAIL, was selected after this report was completed.
INTRODUCTION 15 TABLE 1.1â Current (2007) Planetary Science Missions Mission Type Date Launched Milestones Cassini Flagship October 15, 1997 Saturn arrival: July 1, 2004 Dawn Discovery September 27, 2007 Vesta arrival: 2011; Ceres arrival: 2015 Deep Impact Discovery January 12, 2005 Tempel 1 impact: July 4, 2005 Mars Exploration Rovers Mars Scout June 10, 2003âSpirit Land on Mars: January 4, 2004; Mars Scout July 7, 2003âOpportunity Land on Mars: January 25, 2004 Mars ExpressâASPERA instrument Mars Scout June 2, 2003 Mars arrival: December 26, 2003 Mars Odyssey Mars Scout April 7, 2001 Mars arrival: October 24, 2001 Mars Reconnaissance Orbiter Mars Scout August 12, 2005 Mars arrival: March 2006 Mercury Surface, Space Environment, Discovery August 3, 2004 Mercury orbital arrival: 2011 Geochemistry and Ranging (MESSENGER) New Horizons New Frontiers January 19, 2006 Pluto arrival: July 2015 Phoenix Discovery August 4, 2007 Mars arrival: May 25, 2008 Stardust Discovery February 7, 1999 Sample return: January 15, 2006 Voyager Flagship Summer 1977 NOTE: There are also NASA instruments on the European Space Agencyâs Venus Express and Japanâs Hyabusa spacecraft. ASPERA, Analyzer of Space Plasma and Energetic Atoms. Hayabusa, Rosetta, Cassini Mars Operating Msn Curation, PDS 7% (Phoenix, MRO, MER, Odyssey, 2% MEX) Lunar Research 10% 2% Research (R&A, DAP, Mars) 14% MSL 25% Discovery 2006 AO 10% Discovery Operating Msn (Dawn, M3, MESSENGER, ASPERA-3, Genesis) 4% Scout '11 & Future Mars Msn 6% Technology (Mars, ISP, RPS, AMMOS) Juno 9% 9% New Horizons & Program Mgt 2% FIGURE 1.2â Breakdown of the NASA Planetary Science Division budget for fiscal year 2008. NOTE: Acronyms are spelled out in Appendix E. SOURCE: Jim Green, director, NASA Planetary Science Division, briefing to the committee, Washington, D.C., February 22, 2007. fig 1-2
16 GRADING NASAâS SOLAR SYSTEM EXPLORATION PROGRAM FIGURE 1.3â NASAâs MESSENGER spacecraft is due to arrive at Mercury in 2011. SOURCE: NASA. THE MIDTERM REPORT To assess the current state of solar system science and exploration, the Committee on Assessing the Solar System Exploration Program examined each of the recommendations in the decadal survey and the Mars Archi- tecture report and assigned both a grade and a trend arrow to the NASA effort associated with each. The general meanings of these grades and trend arrows are as follows: AâAchieved or exceeded the goal established in the decadal survey. BâPartially achieved the decadal goal, or made significant progress. CâMade some progress toward meeting the decadal goal, or achieved a supporting objective. DâMade little progress toward meeting the decadal goal. FâRegressed or made no progress toward meeting the decadal goal. WithdrawnâGoal or objective dropped. IncompleteâUnable to make an assessment due to lack of data, inconclusive decision process, or other factors. Trend: âImproving. â Trend: âGetting worse. â Trend: â âNo change. The recommendations are grouped in five major theme areas: (1) science goals and objectives; (2) flight mis- sions; (3) Mars; (4) research and analysis, planetary astronomy, and flight mission data analysis; and (5) enabling technologies. Each of those areas was given an overall rating and trend arrow (see the section entitled âSummary of Major Theme Areasâ in the Summary). In addition, the committee looked at the major scientific questions in
INTRODUCTION 17 the decadal survey and assigned a grade and a trend to the progress made in addressing these questions. All of the results are summarized in Tables S.1 and S.2 in the Summary. For the most part, NASA has done a very good job so far in implementing the recommendations of the decadal survey and Mars Architecture report, but the committee is concerned that further progress will be significantly hampered by several factors, particularly a lack of attention to technology development and research and analysis. Without further investment in technology development in particular, it will not be possible for NASA to achieve many of the goals in the decadal survey. The more detailed assessments that led to the results in Tables S.1 and S.2 are given in Chapters 2 through 6. The committee also offers recommendations for improvements that NASA can make in order to realize as many of the decadal survey and Mars Architecture report recommendations as possible in the remaining time frame addressed in the two reports. In addition, the committee identified four major obstacles (listed below) that stand in the way of the fulfillment of all of the recommendations of the decadal survey by 2013 and of the Mars Architecture report by 2016. MAJOR OBSTACLES TO FULFILLMENT The major obstacles to fulfillment of the recommendations of the decadal survey by 2013 and of the Mars Architecture report by 2016 are these: 1. The uncertain funding situation and reduced expectations for the next several years.â The overall NASA budget is projected to grow at about 3 percent per year for the next 4 years. However, within that total, the budget for the Science Mission Directorate (within which solar system exploration funding resides) is projected to grow at only 1 percent per year over that same period (a rate that is below inflation and thus equivalent to a greater than 10 percent reduction). Projections are not destiny, but the federal budget picture for the foreseeable future is subject to many compelling competing demands; thus, the potential for even modest increases in space science funding as a whole is unknown. Without a significant addition of funds, the activities envisioned in the decadal survey are probably unachievable. 2. Larger liens on the overall solar system exploration program caused by the increased mortgages (cost growth) of missions previously approved and initiated.â This cost growth has had the effect of necessitating reduced investments in research and data analysis and in technology developmentâboth of which help to characterize and reduce (or âretire,â in agency parlance) risk for future missions as well as bolster the future vitality and productivity of the solar system scientific community. 3. The underestimated costs for missions proposed in the decadal survey.â This first-ever solar system decadal survey was conducted within a compressed schedule, with insufficient resources invested in mission concept stud- ies and cost estimates. The New Frontiers missions proposed in the report cannot achieve all of the recommended science objectives for the costs estimated. In addition, NASA did not dispute the costs, highlighting the necessity of an iterative process whereby the agency does not simply accept decadal survey recommendations that it later declares unrealistic. It is hoped that this deficiency will be rectified for the next decadal survey. 4. The increased infrastructure cost to enable the achievement and/or the success of solar system exploration.â The lack of a robust fleet of launch vehicles that is also reasonably affordable has the potential to bring much of the program as currently planned to a halt or to force a radical restructuring both of specific mis- sions and of their scientific goals. The committee could not see a resolution for this issue. The aging and fragile telecommunications infrastructure for deep-space missions needs immediate attention and investment. Taken together, these issues represent a very significant risk to the solar system exploration programâs performance in the future. NASA, NASA FY 2008 Budget, Washington, D.C., 2007. The committee notes that there are unfortunately numerous examples of this, includingâbut by no means limited toâthe Mars Science Laboratory, Juno, and other missions. Although the reasons for this cost growth vary by mission, the end result is the same: insufficient money for new missions and disruptions to the overall program.