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Assessment of Solar System Exploration Programs 1991 (Chapter 9) Assessment of Solar System Exploration Programs 1991 9 General Programmatic Issues In this section we address several general issues that have a substantial impact on NASA's planetary science programs. PLANETARY FLIGHT PROGRAMS Small Missions Program for Planetary Exploration NASA's Solar System Exploration Division is developing a new initiative, named the Discovery Program, for carrying out small, low-cost spacecraft missions. Potential aspects of this program would cover a triad of "small REPORT MENU missions," "mission partnerships," and "mission participations." The small NOTICE missions portion of the program would consist of simple, small spacecraft costing MEMBERSHIP under $100 million. Mission partnerships could include joint missions or FOREWORD collaboration on building instruments, whether between government agencies in SUMMARY the U.S. or with other countries. Mission participations might involve the provision CHAPTER 1 of instruments, of spacecraft subassemblies, and of self-contained mission CHAPTER 2 components such as surface probes. CHAPTER 3 CHAPTER 4 CHAPTER 5 This program has similarities to the Explorer Program in the Astrophysics CHAPTER 6 and Solar and Space Physics divisions, and to the new Earth Probes line in the CHAPTER 7 Earth Science and Applications Division. We note here some of the reasons for CHAPTER 8 the past successes of the Explorer Programs as stated in three Space Science CHAPTER 9 Board reports: Strategy for Earth Explorers in Global Earth Sciences (SSB, REFERENCES 1988c), The Explorer Program for Astronomy and Astrophysics (SSB, 1986a), and A Strategy for the Explorer Program for Solar and Space Physics (SSB, 1984). These reports found that such small mission programs promote frequent access to space; support specific, well-defined scientific objectives; enhance programmatic flexibility because of their small size and shorter lead-time requirements than larger missions; provide data not obtainable from the ground, yet not acquired in larger missions; provide opportunities for international file:///C|/SSB_old_web/ssep91ch9.htm (1 of 5) [6/18/2004 1:58:56 PM]

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Assessment of Solar System Exploration Programs 1991 (Chapter 9) cooperation; and augment training for science and engineering students at universities. A Discovery Program could bring many of these advantages to the planetary exploration program. The mission and program structure should be such that no single element absorbs the program resources for more than two years. The selection process ought to be structured so that a large investment in engineering design is not required. The data from the missions should be delivered to scientific archives in a timely manner, and adequate funding for data analysis and related theoretical modeling must be available. While the desire to provide additional diversity and breadth to the planetary program is worthy in itself, particularly with regard to program balance, the Discovery Program needs to carefully choose objectives and goals that are worthwhile, largely unattainable by other means, and within its resources. A major requirement of proper implementation is an adequate and steady source of funding directed at carefully chosen scientific objectives. Discovery missions to near-Earth asteroids and to Pluto have been considered. The committee supports further investigation of these and other missions for the Discovery Program. Reserves for Flight Missions The provision of adequate reserves for flight missions is vital to the delivery of instruments and spacecraft systems on schedule and within cost. The lack of adequate reserves on a year-by-year basis can lead to more—not less—cost growth, as there is a tendency to push problems into later years when remedies may be more costly and more drastic. The scientific integrity of a mission may be threatened by cost-saving measures, or funding may be transferred from other activities such as R&A programs, producing unanticipated and detrimental effects on program science. In extreme cases, instruments may be sacrificed, not because they have low priority, but simply because their funding for a single year matches a mission deficit for that year. To avoid these problems, missions need to be planned carefully and carry adequate reserves for each year. When year-by-year caps are imposed, whether by NASA or by Congress, the mission budgets must reflect accurately the schedule of work to be done at the instrument and spacecraft assembly level, and must include adequate reserves. RESEARCH AND ANALYSIS PROGRAMS The scientific achievements of planetary exploration are not limited to the time of the nominal mission. Significant advances in understanding occur during extended mission phases, post-mission data and analysis programs, thematic file:///C|/SSB_old_web/ssep91ch9.htm (2 of 5) [6/18/2004 1:58:56 PM]

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Assessment of Solar System Exploration Programs 1991 (Chapter 9) study programs, and basic R&A. Such programs are essential for fully realizing the scientific potential of each mission and for establishing critical objectives for future exploration. Results from the Mariner 10, Viking, and Voyager missions have all underscored the importance of extended mission phases. Follow-on encounters of Mercury by Mariner 10 acquired multiple data sets of the near-Mercury environment. The extended Viking mission allowed high-resolution imaging of the surface that profoundly affected our understanding of surface processes. Without the extended Voyager mission, Uranus and Neptune would remain unexplored. Magellan's nominal mission will not provide gravity data for Venus, fill in gaps left by solar conjunction, or allow for a search of short-term changes on the planet's surface. Therefore, the committee strongly recommends approval for the extended mission for Magellan. Post-mission data analysis programs not only capitalize on unique and ephemeral expertise gathered during the mission, but also maximize the overall scientific return by involving new perspectives, techniques, and approaches from the science community at large. In general, COMPLEX expresses its support for the development within the Solar System Exploration Division of an ongoing sequence of data analysis programs, each of approximately three years' duration and focused on the analysis of data from specific missions. These programs serve to broaden the involvement of the planetary science community at an early date and also provide opportunities for new researchers to enter into the NASA R&A program. Interdisciplinary thematic studies also have proven effective for broadening our understanding of the planets. Just as post-mission data analysis programs capitalize on expertise and excitement associated with a mission, finite (e.g., three-year) thematic programs build on timely scientific issues related to planetary research. In view of the importance of this facet of NASA's R&A program, COMPLEX expresses concern for the delays in implementation of such programs in recent years. In the 1990 Update to the Strategy for Exploration of the Inner Planets, COMPLEX recommended "that NASA should support a vigorous program of data analysis, basic research, and scientific instrument development." Basic R&A provides essential continuity and backbone for achieving NASA's goals. As emphasized in the 1990 report, significant advances have come not only from new mission data, but also from new ideas and unexpected discoveries made possible by a vigorous program of basic R&A. Examples include the discovery of meteorites from the Moon and Mars in Antarctica; geochemical cosmic signatures on Earth at times of dramatic biologic and climatic change; advanced computational models allowing tests and constraints for the origin of the Moon by a catastrophic collision on the Earth; the first imaging of an asteroid by Earth- based radar; and new insights for Pluto that have dramatically challenged our view of the last planet in our solar system yet to be explored by a spacecraft. The Committee on Planetary and Lunar Exploration acknowledges the sincere efforts by NASA to preserve a balanced research program, but it is deeply concerned by NASA's view of the R&A program as a financial reserve for file:///C|/SSB_old_web/ssep91ch9.htm (3 of 5) [6/18/2004 1:58:56 PM]

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Assessment of Solar System Exploration Programs 1991 (Chapter 9) fixing fiscal crises in its flight programs. This practice is harmful to the continuity and long-term stability of the R&A activities. Moreover, it significantly reduces the number of young scientists in a field with a median age approaching 50. Research and analysis programs should not be viewed as another source for mission reserve funds and need to be insulated from mission cost overruns. GROUND-BASED AND EARTH-ORBITAL ASTRONOMY The committee notes that currently there are several projects in various stages of planning that have a favorable impact on the goals outlined in this report. They are as follows: SIRTF (Space Infrared Telescope Facility)—a cryogenically cooled infrared telescope planned for a high Earth orbit. It will be capable of studying planetary atmospheres, primitive bodies, interplanetary dust, and potential extrasolar planetary systems. The inclusion of planetary scientists on the planning team has helped assure that the telescope will be capable of observing planetary objects. COMPLEX strongly recommends the completion of this project. SOFIA (Stratospheric Observatory for Infrared Astronomy)—an aircraft- based telescope facility proposed to replace the Kuiper Airborne Observatory (KAO). A significant portion of the KAO time has gone to planetary projects, and the committee urges NASA to provide similar opportunities with the SOFIA. OPT (Orbiting Planetary Telescope)—a 1-meter orbiting telescope proposed as a joint ESA-NASA project. It will be dedicated to planetary projects at multiple wavelengths. Excellent planetary research has been done with the International Ultraviolet Explorer in the past and the OPT would continue this trend. Second Keck 10-Meter Telescope—primarily for the detection of extrasolar planetary systems and proposed as a joint NASA-Keck observatory facility. It will be operated in an interferometric mode with the first Keck 10-meter telescope. This would be a potent instrument for search for extrasolar planets. COMPLEX recommends the development of these and other interdisciplinary projects. The inclusion of planetary scientists in the planning of telescope facilities helps in the establishment of critical planetary observational capabilities. NASA should be commended for including planetary scientists with relevant expertise on astronomy projects in the past, and the committee strongly supports the continuation of this practice. file:///C|/SSB_old_web/ssep91ch9.htm (4 of 5) [6/18/2004 1:58:56 PM]