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The Role of Small Missions in Planetary and Lunar Exploration: Chapter 3 The Role of Small Missions in Planetary and Lunar Exploration 3 Technological and Programmatic Aspects COST OF CAPABLE SMALL MISSIONS According to NASA's current guidelines, Discovery missions are budgeted at less than $150 million (FY 1992 dollars) exclusive (at the time of writing) of launch vehicles and mission operations and data analysis, and are to be chosen from competitive, peer-judged proposals. Based on COMPLEX's preliminary evaluation of the Clementine mission, the NEAR mission now being executed, and the many Discovery-class concepts that were presented at a 1992 workshop,1 $150 million is a reasonable cost cap for limited-scope planetary missions capable of returning significant results. Yet it must be remembered that planetary spacecraft must be somewhat more sophisticated than those of other space science disciplines because they have to survive and transmit valuable REPORT MENU data across interplanetary distances. Thus, COMPLEX believes that to NOTICE accommodate the required broad spectrum of focused missions, a large fraction MEMBERSHIP (approximately half) of the selected projects will need to be funded near this $150 PREFACE million level. Any attempt to impose a significantly lower cost cap would not be EXECUTIVE SUMMARY cost-effective because it would seriously impair the ability of the program to CHAPTER 1 address important science goals. CHAPTER 2 CHAPTER 3 CHAPTER 4 It is vital that a high ratio of science return per dollar spent be maintained CHAPTER 5 on all missions selected; it makes little sense to develop a mission merely APPENDIX because it is cheap. Since Discovery is proposed to be a long-standing program, the cost cap should increase with the relevant inflation rate; otherwise the scientific capabilities may be seriously compromised. Despite the obvious limitations of such a cost constraint, enthusiasm among planetary scientists for a program of this nature is high, judging by the many new, creative and innovative mission concepts proposed to date. THE NEED TO ESTABLISH A PROGRAM file:///C|/SSB_old_web/smlch3.html (1 of 11) [6/18/2004 1:48:20 PM]
The Role of Small Missions in Planetary and Lunar Exploration: Chapter 3 Although planetary exploration has largely been made up of a series of Mariner (including Voyager) and Pioneer missions to individual planets, there has not been any direct analogue to the Explorer program of missions that have served the space physics and astronomy communities so well for decades. Despite differing widely from one another in terms of scientific goals, instrumentation, and implementation approach, Explorer missions have constituted a continuing program in that they have been planned and carried out as a predictable line item in NASA's budget. Especially for missions constrained to be implemented within fixed schedules and capped budgets-the premise of the Discovery program-one essential attribute is that NASA make, and keep, its commitments to provide a stated funding profile for the definition, design, and implementation phases; predictable budgets are the key to management effectiveness. When externally driven changes are minimized, full responsibility and accountability for mission success can remain with the principal investigator and the project manager, who are then better able to deliver a successful mission than in the current system where budget stability is rare. It is the predictability of the program funding that will permit NASA's Office of Space Science the flexibility to plan a sequence of high-quality missions that together adequately address the scientific and other programmatic goals of solar system exploration. Moreover, managers will be in a much better position than otherwise to deal with occasional failures-of whatever kind-that are an inherent part of space exploration and a recognized element of the increased risk associated with small missions. A reflight of a high-priority small mission can be incorporated into the stream of missions at a point chosen to minimize the externally driven change so detrimental to disciplined program management. Even though a small-missions program may include different types of missions to various solar system objects, the program should be treated as an integrated whole rather than as a series of discrete, independently funded missions. Funding of a continuing program is necessary for a cost-effective, rational, long-term plan. Most Discovery missions are expected to be short, no more than a few years in duration. The missions must be phased appropriately for the available resources to be used efficiently. The program approach would ensure that development of instruments for future missions, support of missions in their development phases, and funding of operations for nominal and extended missions are appropriately balanced against each other to ensure maximum return from the whole program. By appropriately sequencing missions and funding different mission phases, the program approach may also be used to maintain a level budget profile, rather than the pulsed profile that would normally develop if a series of missions were funded independently. Reserves would be managed in a manner most effective for preserving program goals. In addition, funding for the development of instruments would be judged within the context of overall program objectives, rather than the goals of specific missions. Another important reason for initiating a line of Discovery missions is to file:///C|/SSB_old_web/smlch3.html (2 of 11) [6/18/2004 1:48:20 PM]
The Role of Small Missions in Planetary and Lunar Exploration: Chapter 3 ensure that flight opportunities are allocated on a competitive basis following the Announcements of Opportunity process. While peer review played no role in the selection of the Clementine and NEAR missions (see Chapter 4), COMPLEX believes that such competition should be an essential element of a successful Discovery program. Maintenance of a schedule of reasonably frequent launches is essential to the viability of a small-missions program. Discovery missions are intended to address highly focused goals. Some may go to comets, others to the surfaces of the terrestrial planets or the Moon, others to asteroids, and yet others to probe atmospheres of the outer planets. Each mission will add incrementally to the science in a particular area. Instead of comprehensive data returns from large missions once a decade or less frequently, small but, it is hoped, more frequent inputs of data will be received from a spectrum of objects. One launch per year is highly desirable to maintain a reasonable data flow on a breadth of topics. Such a launch rate would permit a variety of science goals to be addressed as well as allow follow-up missions to a similar, or the same, object within a decade if warranted. One cometary mission might, for example, be followed several years later by a second mission designed to address questions raised by the first. The goals of the program could shift with time in response to the slow but steady stream of new information. A launch rate of one per year also has programmatic implications. An essential property of the small-missions concept is that the time between initial selection and launch of an individual mission is short, between three and five years. Because this time is brief, the dollars spent by any single mission from one year to the next changes substantially. Thus, the maintenance of an approximately level overall funding profile requires frequent launches, and one launch per year is a reasonable goal. With launches every year, some missions would be ramping up as others were ramping down, but the funding level of the whole program would be roughly constant. RISK PHILOSOPHY Space exploration-especially, long flights to the planets-has always been a risky enterprise in which failures are expensive and embarrassing. As discussed above, the desire to minimize risk has led to substantial management overhead and, indeed, to a positive feedback loop relating increased cost with supposed risk reductions. After repeated iterations, the space program seems to have reached a situation where much of the management overhead creates only the illusion of risk reduction. COMPLEX notes that failures have not been absent from more expensive missions; rather than using additional funds to reduce risk, such programs merely carry more hardware and software, which are available to fail. It is essential, therefore, to break this vicious circle and to try a new approach. The recommendations returned to NASA by its advisory management groups with respect to the Discovery program reflect the need for such a change. file:///C|/SSB_old_web/smlch3.html (3 of 11) [6/18/2004 1:48:20 PM]
The Role of Small Missions in Planetary and Lunar Exploration: Chapter 3 The recent, largely successful, Clementine mission demonstrates that a different management approach (not unlike that of NASA itself in its early days) can be effective. But the Clementine mission, which failed before achieving one of its primary technological goals (autonomous, real-time tracking of a cold asteroid during a flyby many months after launch), also points out a potential risk in some low-cost enterprises. Clementine's tight schedule, stringent budget, and the unavailability of sufficient contingency funds shortly before launch each may have been indirect causes of the software error that ultimately led to the spacecraft's demise.2 It is essential to recognize, however, that failures will occur in the future, as they have in the past, and that the ability to deal with such disappointments must be integral to the new NASA philosophy. Taking a risk means being prepared to face a loss. (COMPLEX again notes that failures are not absent in more expensive missions.) First, a commitment to an adequate launch rate must be sustained, not allowing any single failure to jeopardize the whole program. Second, the ability to recover quickly from failure must be built into the program. Finally, the experience gained in failures must be used to estimate future risks reliably, as well as to learn how to decrease hazards; such a strategy is only justifiable if the flight rate is appreciable. Facing risk during the development phase must also be considered, since one feature of a small-missions program should be that a mission may be canceled if the projected milestones and budget are not within their proposed envelopes. It should be kept in mind, nonetheless, that innovation could either increase or decrease risk for a particular mission, and this aspect will have to be judged on a case-by-case basis. Other types of risk also need to be considered. A small mission, with a single scientific objective, may fail if that narrow objective is ill-conceived, or if its experiment is unsuccessful for reasons that could not be predicted in advance. Nonetheless, science may occasionally still benefit: for example, in the former case of an ill-conceived objective, an incorrect hypothesis may be eliminated (as with the null result obtained by the Michelson-Morley experiment); in the latter case, other unexpected results may sometimes be obtained (as with the Active Magnetospheric Particle Tracer Explorer (AMPTE), where chemical releases were not detected as planned but the charge composition of the magnetospheric plasma was determined). COMPLEX notes that, with missions of broader scope having multiple goals, it should be expected that at least some objectives will be satisfied unless a spacecraft failure occurs. INFRASTRUCTURE The extensive infrastructure required for large, complex missions is unnecessary for small missions. For a program of small missions, infrastructure should exist only because of mission requirements rather than by tradition or file:///C|/SSB_old_web/smlch3.html (4 of 11) [6/18/2004 1:48:20 PM]
The Role of Small Missions in Planetary and Lunar Exploration: Chapter 3 administrative edict. Cost-effectiveness should be sought through competition rather than through false hopes of obtaining economics of scale by requiring common equipment for all missions in the program. Specifically, a program of small missions should emphasize innovative ways to maximize science return for minimum cost without placing restrictions on (1) the launch vehicle, (2) the spacecraft bus, (3) the payload, (4) the data rate, (5) a specific management structure, or (6) a specific institution to run mission operations. SUPPORTING TECHNOLOGY The success of a small-missions program will depend in part on the availability of low-cost, small, capable science instruments. Such instruments cannot be developed within individual missions because of the time needed for a concept to mature. NASA's Planetary Instrument Definition and Development Program (PIDDP) is currently the only significant source of funds for development of new planetary science instruments. But this program is limited and has traditionally been able to support development of only a few instruments at a modest level. Because of the diverse goals of the proposed Discovery program, the range of instruments expected to fly is large. Moreover, the constraints on instrument mass and power are likely to be tight. The availability of previously classified, capable, lightweight sensors and spacecraft systems that Clementine carried was an important factor in keeping the cost of this mission reasonably low. Department of Defense technology is now more readily available for transfer to and exploitation by space scientists.3 Thus COMPLEX recommends that the PIDDP program be expanded and that a significant fraction of its resources be devoted to the development of instruments necessary to make the Discovery program a reality. An alternative would be to have within Discovery a precursor advanced technology development program, such as was the case with the Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX)-the first of NASA's Small Explorers. Either approach would be consistent with the objective of supporting new technology. COMPLEX does not recommend that parts of the existing Discovery budget be set aside for development of spacecraft components. Due to its limited resources, the Discovery program as currently conceived is an inappropriate source of funds for advanced spacecraft design. The role of NASA's Office of Space Access and Technology is to support advanced design, as it is doing with the Lewis and Clark Earth-observation satellites; this expertise should be brought to bear on the Discovery program's needs. SUBSIDIARY GOALS An important characteristic of a small-missions program is its focused file:///C|/SSB_old_web/smlch3.html (5 of 11) [6/18/2004 1:48:20 PM]
The Role of Small Missions in Planetary and Lunar Exploration: Chapter 3 science objectives. Adding other goals to the basic scientific mission will, of course, increase the cost. If other goals-such as education and new technology- are among the criteria used to judge a program, their costs, as listed in the proposal, should be separated from the basic scientific component so that review panels can understand clearly the expense of each component of the project. Ideally, separate funding sources should be identified to support any subsidiary goals. One benefit of reducing the scale of missions is that they can involve smaller institutions such as universities. Incorporating a larger section of the community should, through competition, lead to reduced costs and will enhance opportunities for both new technologies and education. Technology While the complexity and expense of planetary missions have been growing, high-technology industries outside NASA have been creating new products with improved capabilities at lower cost. The most striking example is, of course, the computer industry. We have learned to expect that capabilities in that field will grow rapidly even as prices decline dramatically. Another advancing field is materials science, which creates the prospect of lighter yet more capable spacecraft. In space-mission design there have been striking examples of innovative technology, some of which were incorporated in Clementine, in part as a result of the Strategic Defense Initiative of the 1980s. Unfortunately, not all the advances in these and other fields have been put to use in civil space missions.4 The Lewis and Clark programs, initiated under the Small Spacecraft Technology Initiative program of NASA's Office of Space Access and Technology, is designed to accelerate this transfer of technology. As with Lewis and Clark, Discovery missions are capped in cost and weight, and will, in many cases, benefit from new technology. But any substantial development of new technology within a particular mission would certainly increase the final price of that mission. Ideally, mission requirements and competition, not an administrative dictum, should be the judge of what, and how much, new technology should be incorporated into any mission. The new technology may enable richer scientific returns from the mission as well. New technology may also heighten the risk of failure, and insurance against this risk should be part of the mission plan. If the development of new technology is to be a significant aspect of the Discovery program, its role must be clearly and consistently stated. In other words, does the program seek to stimulate new technology? Or does the program wish to avoid new technology so as to keep unknowns to a minimum? Education file:///C|/SSB_old_web/smlch3.html (6 of 11) [6/18/2004 1:48:20 PM]
The Role of Small Missions in Planetary and Lunar Exploration: Chapter 3 Small missions provide a variety of opportunities for education at K-12 levels. There are several examples of extensive educational outreach programs associated with, for example, the Hubble Space Telescope and less expensive activities such as the Extreme Ultraviolet Explorer and the Kuiper Airborne Observatory. Such missions, both large and small, employ educators with strong scientific backgrounds to coordinate activities with local Space Grant colleges, teachers' colleges, and local school teachers; these groups bring the space missions into the classroom, public libraries, and museums (via electronic media, audio-visual materials, interdisciplinary projects, and so on) as well as organize school visits to witness the development and construction of a spacecraft and the operation of a mission center (such as Clementine's "Batecave"). The involvement of universities in small missions is also an excellent chance to train scientists and engineers. The aim is not to produce more planetary scientists, but to use the opportunity to excite and inspire students in various disciplines at both undergraduate and graduate levels and to provide technical, scientific, and managerial experiences that might be extremely valuable for a wide variety of careers. The most desirable missions for student participation are those that are completed in at most a few years, so that a student can be a part of the entire mission-not just analyze data obtained a decade earlier. Examples of successful student involvement in small missions are provided by the Solar Mesosphere Explorer at the University of Colorado and the Extreme Ultraviolet Explorer at the University of California, Berkeley. While the involvement of a motivated student work force may reduce mission costs, an effective educational outreach program will need additional funds. Such outreach programs might be funded through NASA's present education grants. In addition, it is important to include the costs of evaluating the effectiveness of educational programs. Nevertheless, it must be recognized that relatively few dollars could yield enormous benefits to the nation's educational system. INTERNATIONAL COOPERATION A program of small planetary missions could include participation in non- U.S. flights. Opportunities may arise to place instruments on, or otherwise participate in, international missions at costs comparable to, or less than, those of a typical Discovery mission. As a general rule, COMPLEX favors international participation and cooperation as a means of optimizing the scientific return of planetary missions against the resources being applied by individual countries.5 A full discussion of the complications and pitfalls inherent in major international collaborations raises issues far beyond the scope of this study and COMPLEX's competence to address. A simpler issue, and one that COMPLEX did discuss, is the use of Discovery funds for the provision of instruments of opportunity on foreign planetary missions. CONPLEX's guiding principle in such cases is that it file:///C|/SSB_old_web/smlch3.html (7 of 11) [6/18/2004 1:48:20 PM]
The Role of Small Missions in Planetary and Lunar Exploration: Chapter 3 is essential that such participation be competitive and consistent with the attributes of small missions listed above. For example, one essential property of Discovery missions is that they are to be implemented quickly, and yet international participation may require accommodation to the budget and planning cycles of partner nations, which may well be significantly longer than the planning cycles of typical Discovery missions. Nonetheless, international programs, as illustrated by the plans for Japan's Planet-B mission, can sometimes satisfy COMPLEX's suggested guidelines. Planet-B is scheduled for launch in August 1998 and will enter orbit around Mars in October 1999. In addition to some dozen Japanese experiments, the spacecraft will carry a U.S. mass spectrometer designed to investigate the density profile and composition of the martian thermosphere and lower exosphere. Since the scope and development schedule of Planet-B are broadly consistent with the philosophy of the Discovery program, COMPLEX would have few reservations about having future opportunities, such as this one, openly compete for Discovery funds. NASA's planned involvement in the European Space Agency's Rosetta mission is a possible counterexample to Planet-B. This major mission, approved by ESA in late 1994 and scheduled for launch no sooner than 2003, will rendezvous with, and deploy an experimental package on, the nucleus of a comet some years later.6 If successful, Rosetta will recover some, if not all, of the science lost with the cancellation of NASA's Comet Rendezvous/Asteroid Flyby (CRAF) mission. A mission of this type has been and remains of the highest priority to COMPLEX.7 However, COMPLEX is not in favor of a U.S. contribution to Rosetta (in the form of, for example, the surface science package) being funded as a Discovery mission. A commitment to participate in Rosetta now would tie up Discovery funds in a mission that would not be launched for almost a decade-a clear violation of the rapid-development aspect of the Discovery philosophy. On the other hand, deferring commitment to participate in Rosetta until closer to launch would, almost certainly, be unacceptable to ESA. Although not discussed at length, one concern of COMPLEX is that potential uses of Discovery funds, including international cooperation, compete fairly against each other. Occasionally in the past, an international opportunity has arisen, and time has not permitted normal competitive processes to be followed to meet the opportunity. The same rationale applies to other potential applications of Discovery funds. The program should not be considered as a fund to support a miscellany of projects or external objectives, but rather should be used only to finance quick, low-cost flight opportunities judged in open competition. Another concern is that differences in national cultures, practices, and mechanisms by which missions are approved may lead to misunderstandings that could sour future relationships. A prime example is NASA's failure to formally participate in ESA's International Gamma-Ray Astrophysics Laboratory (INTEGRAL) mission. file:///C|/SSB_old_web/smlch3.html (8 of 11) [6/18/2004 1:48:20 PM]
The Role of Small Missions in Planetary and Lunar Exploration: Chapter 3 PROGRAM ISSUES Mission Operations The wide variety of types of small planetary missions will lead to a range of ways of operating the missions. Some missions may require extensive use of the Deep Space Network and the infrastructure provided by NASA's Jet Propulsion Laboratory. Others will be able to operate an entirely independent ground station or have a small student-run operations center linked to the spacecraft via a NASA center. Moreover, a mission that involves monitoring a target from Earth-orbit over months or years will have very different operational requirements than a probe returning data at a high rate for a brief interval as it flies by an asteroid or descends through a planet's atmosphere. Thus, it is impossible for one mode of operation to suit all missions. Pls should be encouraged to find innovative ways to operate missions that optimize the science return for minimum cost. At the same time, COMPLEX recognizes that mission operations is the area where perhaps the greatest contributions can be made to the subsidiary goals of technology transfer and education with the least risk to mission success. One possibility, for example, would be to set up parallel data processing and archiving systems, each embodying a different philosophy and technical implementation. In such an approach, data from the mission would not only be downlinked to a conventional control center, but it would also be directed simultaneously via the Internet to mission scientists' workstations, to classrooms, and to moot control rooms staffed by student volunteers, or even to experimental artificial intelligence systems. Improvements in mission software or instrument control might have broader application than would more sophisticated spacecraft systems or instrumentation. In the past, the cost of mission operations has been considered separately from the costs for mission development and construction. A program of small missions should view mission operations as part of the total mission costs. The past philosophy of costing a mission as "launch plus 30 days" has simply pushed the financial burden into a different part of NASA's budget. A further difficulty arises when a mission survives beyond its initial prime phase; a mechanism needs to be in place for deciding whether extended mission operations should be funded and what the source of those dollars should be. Rather than whittle away at the support scheduled for new Discovery missions, other sources, such as university consortia, should be sought if missions (e.g., Earth-orbital telescopes) are extended beyond their nominal lifetimes. Data Analysis and Archiving The initial products of planetary missions are the data. It is essential that these data be made available to the public and also archived in the Planetary Data System (PDS) in a timely manner. A plan that describes the data to be archived and the schedule for this activity should be included in the original file:///C|/SSB_old_web/smlch3.html (9 of 11) [6/18/2004 1:48:20 PM]
The Role of Small Missions in Planetary and Lunar Exploration: Chapter 3 proposal. Emerging information technologies make both these tasks relatively simple. For example, even today images or data displays (with descriptive text) can be made available through the Internet on the World Wide Web, accessed via an HTML browser such as Mosaic or Netscape, and optical disks have eliminated the need for vast storage rooms full of data tapes. Nevertheless, proper analysis of the data will require the support of scientists either on the original mission team or as guest investigators. In the past, project management has tended to spend funds originally marked for data analysis on coping with cost overruns in design and construction phases earlier in the mission. The rigorous costing required for a successful program of small missions should ensure that sufficient funds remain available for data analysis by the science team. Funds for guest investigator programs and extended analysis programs will have to be made available from the Supporting Research and Technology program. Efforts need to be made early in the program to solicit guest investigators; this should bring young scientists aboard Discovery teams even when Pls are senior investigators. REFERENCES 1. Nash, Doug (ed.), Discovery Program Workshop: Summary Report, San Juan Capistrano Research Institute, San Juan Capistrano, Calif., 1992. 2. Space Studies Board, National Research Council, Lessons Learned from the Clementine Mission, National Academy Press, Washing- ton, D.C., in preparation. 3. Appelby, J. (ed.), Workshop on Advanced Technologies for Planetary Instruments, LPI Technical Report 93-02, Parts I and 2, Lunar and Planetary Institute, Houston, Tex., 1993. 4. See, for example, Aeronautics and Space Engineering Board, National Research Council, Technology for Small Spacecraft, National Academy Press, Washington, D.C., 1994. 5. Space Studies Board, National Research Council, An Integrated Strategy for the Planetary Sciences: 1995-2010, National Academy of Sciences, Washington, D.C., 1994, pages 32-33. 6. Joint ESA/NASA Science Definition Team, ROSETTA: The Comet- Nucleus Sample Return, ESA SP-1125, ESA Publications Division, Noordwijk, The Netherlands, June, 1991. 7. Space Studies Board, National Research Council, An Integrated Strategy for the Planetary Sciences: 1995-2010, National Academy of Sciences, file:///C|/SSB_old_web/smlch3.html (10 of 11) [6/18/2004 1:48:20 PM]
The Role of Small Missions in Planetary and Lunar Exploration: Chapter 3 Washington, D.C., 1994, page 189. Last update 5/22/00 at 1:55 pm Site managed by Anne Simmons, Space Studies Board The National Academies Current Projects Publications Directories Search Site Map Feedback file:///C|/SSB_old_web/smlch3.html (11 of 11) [6/18/2004 1:48:20 PM]
