3
Summaries of Major Reports

3.1 An Assessment of the Solar and Space Physics Aspects of NASA’s Space Science Enterprise Strategic Plan

A Report of the Committee on Solar and Space Physics and the Committee on Solar-Terrestrial Research1

SUMMARY OF CSSP/CSTR’S SCIENCE STRATEGY

CSSP/CSTR’s Science Strategy recommends the major directions for scientific research in space physics for the coming decade. As a field of science, space physics has passed through the stage of simply looking to see what is out beyond Earth’s atmosphere. It has become a “hard” science, focusing on understanding the fundamental interactions between charged particles, electromagnetic fields, and gases in the natural laboratory consisting of the galaxy, the Sun, the heliosphere, and planetary magnetospheres, ionospheres, and upper atmospheres.

The several subfields of space physics share the following objectives:

  • To understand the fundamental laws or processes of nature as they apply to space plasmas and rarefied gases both on the microscale and in the larger, complex systems that constitute the domain of space physics;

  • To investigate the links between changes in the Sun and the resulting effects at Earth, with the eventual goal of predicting the significant effects on the terrestrial environment; and

  • To continue the exploration and description of the plasmas and rarefied gases in the solar system.

CSSP/CSTR’s Science Strategy identifies five scientific topics to be addressed in space physics research in the coming decade:

  1. Mechanisms of solar variability. The Sun is a variable star on time scales of milliseconds to centuries or more. Its emissions vary throughout the electromagnetic spectrum, as do its particle (thermal plasma and energetic) outputs. The solar magnetic field, generated in the Sun’s interior, holds many of the keys to understanding these variations that influence Earth’s space environment and its climate.

1  

“Summary of CSSP/CSTR’s Science Strategy” reprinted from An Assessment of the Solar and Space Physics Aspects of NASA’s Space Science Enterprise Strategic Plan, National Academy Press, Washington, D.C., 1997, pp. 1–3.



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 33
Space Studies Board Annual Report 1997 3 Summaries of Major Reports 3.1 An Assessment of the Solar and Space Physics Aspects of NASA’s Space Science Enterprise Strategic Plan A Report of the Committee on Solar and Space Physics and the Committee on Solar-Terrestrial Research1 SUMMARY OF CSSP/CSTR’S SCIENCE STRATEGY CSSP/CSTR’s Science Strategy recommends the major directions for scientific research in space physics for the coming decade. As a field of science, space physics has passed through the stage of simply looking to see what is out beyond Earth’s atmosphere. It has become a “hard” science, focusing on understanding the fundamental interactions between charged particles, electromagnetic fields, and gases in the natural laboratory consisting of the galaxy, the Sun, the heliosphere, and planetary magnetospheres, ionospheres, and upper atmospheres. The several subfields of space physics share the following objectives: To understand the fundamental laws or processes of nature as they apply to space plasmas and rarefied gases both on the microscale and in the larger, complex systems that constitute the domain of space physics; To investigate the links between changes in the Sun and the resulting effects at Earth, with the eventual goal of predicting the significant effects on the terrestrial environment; and To continue the exploration and description of the plasmas and rarefied gases in the solar system. CSSP/CSTR’s Science Strategy identifies five scientific topics to be addressed in space physics research in the coming decade: Mechanisms of solar variability. The Sun is a variable star on time scales of milliseconds to centuries or more. Its emissions vary throughout the electromagnetic spectrum, as do its particle (thermal plasma and energetic) outputs. The solar magnetic field, generated in the Sun’s interior, holds many of the keys to understanding these variations that influence Earth’s space environment and its climate. 1   “Summary of CSSP/CSTR’s Science Strategy” reprinted from An Assessment of the Solar and Space Physics Aspects of NASA’s Space Science Enterprise Strategic Plan, National Academy Press, Washington, D.C., 1997, pp. 1–3.

OCR for page 33
Space Studies Board Annual Report 1997 The physics of the solar wind and the heliosphere. The solar wind, the extended atmosphere of the Sun that reaches beyond the solar system, is responsible for a host of effects on all planetary bodies and on the local interstellar medium. It is still not known what drives this wind and its variations. Extreme solar-wind disturbances cause the most severe “space weather” around Earth. The structure and dynamics of magnetospheres and their coupling to adjacent regions. The distortions of planetary magnetic fields caused by their interaction with the solar wind are responsible for the “magnetospheric” effects that contribute to space weather. All manifestations of this coupling, from the auroral emissions that appear in the polar regions of the upper atmosphere to the radiation environments of our Earth satellites, vary continually in response to the changing boundary conditions produced by the Sun. This complex, three-dimensional system is also constrained by the atmosphere and ionosphere at its innermost boundary. Synergistic observations and modeling efforts are revealing the manner in which these near-planet space systems work. The middle and upper atmospheres and their coupling to regions above and below. The lower boundary region of near-Earth space is constantly buffeted by variable energy inputs from the Sun and the magnetosphere above, and from the lower atmosphere below. Significant deficiencies exist in our knowledge of the internal workings of this region and its role in determining magnetospheric response to solar wind variations. These deficiencies result from both the difficulty of making measurements there and the region’s intrinsic complexity. Plasma processes that accelerate very energetic particles and control their propagation. Galactic cosmic rays are samples of matter from outside the solar neighborhood that provide clues to subjects ranging from particle acceleration processes in the cosmos to the physics of stellar interiors. For each of these topics, CSSP/CSTR’s Science Strategy presents the scientific background, discusses why the topic is important, describes the current program for research on the topic, and then recommends high-priority research activities for the future. As the Science Strategy points out, “The specific programs required to obtain answers to the questions raised under each of the [above] key topics…are quite different. However, they are united by four common elements or themes that the CSSP and the CSTR consider to be the most important research emphases for space physics in the next decade.”2 These themes, paraphrased from the Science Strategy (pp. 6–7), are as follows: Complete currently approved programs. The space physics community must reap the benefits of the nation’s investment in existing approved programs by enhancing data analysis and interpretation efforts and by supporting essential observational programs that require long-duration databases. A stable program of research permits the most efficient management and execution of high-priority research. Older missions that are productive and competitive in their scientific return should not be terminated prematurely. In addition to the obvious scientific return, ongoing programs provide the basis for developing future research directions. Exploit existing technologies and opportunities to obtain new results in a cost-effective manner. Much technology is already in place to take the next observational steps required to address many of the important questions outlined in CSSP/CSTR’s Science Strategy. However, adaptation of instrumentation to the new generation of smaller spacecraft requires special support. Ground-based facilities, suborbital platforms, and opportunities for space physics pay loads to “hitchhike” on other spacecraft are valuable means for achieving space physics science objectives, as are extended and/or redirected missions. Develop the new technology required to advance the frontiers of space physics. To achieve several high-priority objectives, or to lower the cost of projects, the limits of technology must be pushed. Areas for development include global and high-resolution imaging techniques, high-temperature-tolerant devices for operation near the Sun, and methods to enable access to difficult-to-reach regions of the middle atmosphere. Support strongly the theory and modeling activities vital to space physics. The importance of modeling and theory in both stimulating and interpreting space physics measurements must be recognized. From models of space weather to models of the microscopic behavior of plasmas involved in the triggering of solar flares and magnetospheric disturbances, state-of-the-art work is being done that increases our scientific understanding in step with measurements made in space, while developing the necessary framework for future missions. 2   Space Studies Board and Board on Atmospheric Sciences and Climate, National Research Council, A Science Strategy for Space Physics, National Academy Press, Washington, D.C., 1995.

OCR for page 33
Space Studies Board Annual Report 1997 3.2 Mars Sample Return: Issues and Recommendations A Report of the Task Group on Issues in Sample Return1 EXECUTIVE SUMMARY As stated in NASA Management Instruction 8020.7, the Space Studies Board of the National Research Council (NRC) serves as the primary adviser to the National Aeronautics and Space Administration (NASA) on planetary protection policy, the purpose of which is to preserve conditions for future biological and organic exploration of planets and other solar system objects and to protect Earth and its biosphere from potential extraterrestrial sources of contamination. In October 1995 the NRC received a letter from NASA requesting that the Space Studies Board examine and provide advice on planetary protection issues related to possible sample-return missions to near-Earth solar system bodies. In response, the Space Studies Board established the Task Group on Issues in Sample Return to address the following concerns: The potential for a living entity to be included in a sample to be returned from another solar system body, in particular Mars; The scientific investigations that should be conducted to reduce uncertainty in the above assessment; The potential for large-scale effects on the environment resulting from the release of any returned entity; The status of technological measures that could be taken on a mission to prevent the unintended release of a returned sample into Earth’s biosphere; and Criteria for controlled distribution of sample material, taking note of the anticipated regulatory framework. The key findings and recommendations of the task group are listed below. Although focused on sample-return missions from Mars, the recommendations can be generalized to any mission that could return a sample from an extraterrestrial object with a similar potential for harboring life. FINDINGS • Although current evidence suggests that the surface of Mars is inimical to life as we know it, there remain plausible scenarios for extant microbial life on Mars—for instance in possible hydrothermal oases or in subsurface regions. The surface environment of Mars, from which early samples are most likely to be returned, is highly oxidizing, is exposed to a high flux of ultraviolet radiation, is devoid of organic matter, and is largely devoid of liquid water. It is unlikely that life of any kind, as we currently understand it, either active or dormant, could survive in such an inhospitable environment. If active volcanism, or near-surface liquid water, is discovered on Mars, or if the subsurface environment is found to be considerably less oxidizing and wetter than the surface, the occurrence of extant life on the planet becomes more plausible. • Contamination of Earth by putative martian microorganisms is unlikely to pose a risk of significant ecological impact or other significant harmful effects. The risk is not zero, however. In the event that living martian organisms were somehow introduced into Earth’s environment, the likelihood that they could survive and grow and produce harmful effects is judged to be low. Any extant martian microorganisms introduced into Earth’s biosphere would likely be subject to the same physical and chemical constraints on their metabolic processes as are terrestrial organisms. Thus, extraterrestrial organisms would be unlikely to mediate any geochemical reactions that are not already catalyzed by Earth organisms. They would be unlikely to be able to compete successfully with Earth organisms, which are well adapted to their habitats. 1   “Executive Summary” reprinted from Mars Sample Return: Issues and Recommendations, National Academy Press, Washington, D.C., 1997, pp. 1–7.

OCR for page 33
Space Studies Board Annual Report 1997 Because pathogenesis requires specific adaptations to overcome the extensive defenses possessed by all Earth organisms, virulent extraterrestrial pathogens are unlikely. Subcellular disease agents, such as viruses and prions, are biologically part of their host organisms, and so an extraterrestrial source is extremely unlikely. Conceivably, putative extraterrestrial organisms could be capable of opportunistic infections or toxicity, as are some terrestrial bacteria, but such a risk can be eliminated by standard laboratory control procedures. The potential for large-scale effects, either through pathogenesis or ecological disruption, is extremely small. Thus, the risks associated with inadvertent introduction of exogenous microbes into the terrestrial environment are judged to be low. However, any assessment of the potential for harmful effects involves many uncertainties, and the risk is not zero. • Uncertainties with regard to the possibility of extant martian life can be reduced through a program of research and exploration that might include data acquisition from orbital platforms, robotic exploration of the surface of Mars, the study of martian meteorites, the study of Mars-like or other extreme environments on Earth, and the study of returned samples. However, each returned sample should be assumed to contain viable exogenous biological entities until proven otherwise. A program of Mars exploration is outlined in a recent NASA strategy document, An Exobiological Strategy for Mars Exploration (NASA, 1995). The Space Studies Board task group strongly endorses NASA’s strategy. Such an exploration program, while likely to greatly enhance our understanding of Mars and its potential for harboring life, nonetheless is not likely to significantly reduce uncertainty as to whether any particular returned sample might include a viable exogenous biological entity—at least not to the extent that planetary protection measures could be relaxed. RECOMMENDATIONS Sample Return and Control Recommendation. Samples returned from Mars by spacecraft should be contained2 and treated as though potentially hazardous until proven otherwise. No uncontained martian materials, including spacecraft surfaces that have been exposed to the martian environment, should be returned to Earth unless sterilized. While the probability of returning a replicating biological entity in a sample from Mars, especially from sample-return missions that do not specifically target sites identified as possible oases,3 is judged to be low and the risk of pathogenic or ecological effects is lower still, the risk is not zero. Therefore, it is reasonable that NASA adopt a prudent approach, erring on the side of caution and safety. Recommendation. If sample containment cannot be verified en route to Earth, the sample, and any spacecraft components that may have been exposed to the sample, should either be sterilized in space or not returned to Earth. The engineering and design of any sample-return mission should incorporate some means of verifying sample containment during transit and prior to return to Earth. Means should also be available to sterilize the sample, and any spacecraft components that may have been exposed to it, in flight or to prevent their return to Earth in the event that containment cannot be verified. Recommendation. Integrity of containment should be maintained through reentry of the spacecraft and transfer of the sample to an appropriate receiving facility. 2   The words “contained” and “containment” are used herein to indicate physical and biological isolation. 3   Locations that exhibit active volcanism or where the presence of liquid water is indicated.

OCR for page 33
Space Studies Board Annual Report 1997 The points in a mission where loss of containment is most likely to occur include operations on the martian surface; intervehicle transfer of sample material; vehicle reentry, descent, and landing; and subsequent transfer of the sample container to a receiving facility. Techniques and protocols that can ensure containment at these vulnerable points should be designed into the mission. Recommendation. Controlled distribution of unsterilized materials returned from Mars should occur only if rigorous analyses determine that the materials do not contain a biological hazard. If any portion of the sample is removed from containment prior to completion of these analyses, it should first be sterilized. Returned samples should be considered potentially hazardous until they have been reasonably demonstrated to be nonhazardous. Distribution of unsterilized sample material should occur only after rigorous physical, chemical, and biological analyses confirm that there is no indication of the presence of any exogenous biological entity. If any portion of the sample is removed from containment prior to this determination, it should first be sterilized. The development of effective sterilization techniques that preserve the value of treated material for other (nonbiological) types of scientific analysis should be the subject of research by NASA and by the science team associated with the sample-receiving facility. Recommendation. The planetary protection measures adopted for the first Mars sample-return missions should not be relaxed for subsequent missions without thorough scientific review and concurrence by an appropriate independent body. Samples returned from the martian surface, unless returned from sites specifically targeted as possible oases, are unlikely to harbor life as we know it, and there may be some pressure to reduce planetary protection requirements on subsequent sample-return missions if prior samples are found to be sterile. Presumably, however, subsequent missions will be directed toward locations on Mars where extant life is more plausible, based on data acquired from an integrated exploration program, including prior sample-return missions. Thus, planetary protection measures may become more rather than less critical as the exploration program evolves. At some point it may be reasonable to relax the requirements, but this should only be done after careful scientific review by an independent body. Sample Evaluation Recommendation. A research facility for receiving, containing, and processing returned samples should be established as soon as possible once serious planning for a Mars sample-return mission has begun. At a minimum, the facility should be operational at least two years prior to launch. The facility should be staffed by a multidisciplinary team of scientists responsible for the development and validation of procedures for detection, preliminary characterization, and containment of organisms (living, dead, or fossil) in returned samples and for sample sterilization. An advisory panel of scientists should be constituted with oversight responsibilities for the facility. It was evident from the Apollo experience that the science team, and therefore the lunar receiving facility as a whole, would have been more effective if the team members had had prior experience working together as a group on common problems before receiving lunar samples. During the preliminary study of those samples, loss of containment and compromise of quarantine occurred on several occasions. Some of these occurrences might have been avoided had the science team and the receiving facility been operational well before return of the samples. To avoid similar problems during the initial investigation of returned martian samples and to provide sufficient time to develop and validate the requisite life detection, containment, and sterilization technologies, the receiving facility and its associated science team should be established well in advance of the launch of any sample-return mission. The facility should include appropriately stringent biological containment capability and be staffed by a broadly multidisciplinary team of scientists. When fully constituted, the science team should strive to include diverse expertise in such areas as effective biological containment, geological and biological sample processing and curation, microbial paleontology and evolution, field ecology and laboratory culture, cell and molecular biology, organic and light stable isotope geochemistry, petrology, mineralogy, and martian geology.

OCR for page 33
Space Studies Board Annual Report 1997 Program Oversight Recommendation. A panel of experts, including representatives of relevant governmental and scientific bodies, should be established as soon as possible once serious planning for a Mars sample-return mission has begun, to coordinate regulatory responsibilities and to advise NASA on the implementation of planetary protection measures for sample-return missions. The panel should be in place at least one year prior to the establishment of the sample-receiving facility (at least three years prior to launch). Although NASA is the lead agency on matters pertaining to the exploration of space and extraterrestrial bodies, other federal agencies, such as the U.S. Department of Agriculture, may have a regulatory interest in the return of samples from Mars or other solar system objects. To coordinate regulatory and other oversight responsibilities, NASA should establish a panel analogous to the Interagency Committee on Back Contamination that coordinated regulatory and oversight activities during the lunar sample-return missions. To be effective, planetary protection measures should be integrated into the engineering and design of any sample-return mission, and, for an oversight panel to be in a position to coordinate the implementation of planetary protection requirements, it should be established as soon as serious planning for a Mars sample-return mission has begun. For the panel to be able to review and approve any plans for a Mars sample-receiving facility, the panel should be in place at least one year before the sample-receiving facility is established. Recommendation. An administrative structure should be established within NASA to verify and certify adherence to planetary protection requirements at each critical stage of a sample-return mission, including launch, reentry, and sample distribution. The best-laid plans are only as effective as their implementation. An internal administrative structure, with clearly defined lines of authority, is required to verify and certify adherence to planetary protection requirements at each critical stage of a sample-return mission, including launch, reentry, and sample distribution. The certification should be sequential. That is, the mission should not be allowed to proceed to the next stage until planetary protection requirements for that stage and each preceding stage have been met. For example, reentry should not be authorized unless containment has been verified or the material to be returned has been sterilized. The required internal structure is already partly in place at NASA, but the lines of authority should be more clearly specified and a certification process should be implemented for each mission stage. Recommendation. Throughout any sample-return program, the public should be openly informed of plans, activities, results, and associated issues. Significant changes have occurred in the public decision-making realm since the return of lunar samples during the Apollo program. More open review processes now allow for citizen involvement in nearly all aspects of governmental decision making, most notably under the National Environmental Policy Act. Scientific and technical decisions about mission hardware and operations, while still made by groups of experts, now are openly scrutinized by other governmental bodies, the general public, advocacy groups, and the media. The array of environmental and health and safety laws enacted during the past three decades often provides ample opportunity for public involvement in many parts of the decision-making process that previously were conducted in private. The possibility of legal challenges always exists. In light of the public’s past response to other controversies involving science and technology, it is possible that environmental and quality-of-life issues will be raised in the context of a Mars sample-return mission. If so, it is likely that the adequacy of NASA’s planetary protection measures will be questioned in depth. The most effective strategy for allaying fear and distrust is to inform early and often as the program unfolds. Acknowledging the public’s legitimate interest in planetary protection issues, and thereby keeping the public fully informed throughout the decision-making process related to sample return and handling, will go a long way toward addressing the public’s concerns.

OCR for page 33
Space Studies Board Annual Report 1997 3.3 Space Weather: A Research Perspective A Report of the Committee on Solar and Space Physics and the Committee on Solar-Terrestrial Research This report is an online tutorial on space weather and is available at <http://www.nas.edu/ssb/cover.html>.

OCR for page 33
Space Studies Board Annual Report 1997 3.4 A New Science Strategy for Space Astronomy and Astrophsyics A Report of the Task Group on Space Astronomy and Astrophysics1 EXECUTIVE SUMMARY The half-decade since the publication of The Decade of Discovery in Astronomy and Astrophysics, the 1991 report of the National Research Council’s (NRC’s) Astronomy and Astrophysics Survey Committee chaired by John Bahcall, has been one of the most productive periods in the history of astronomy. Remarkable advances in understanding have been achieved, in no small part owing to the successful operation of space facilities such as the Hubble Space Telescope (HST), the Compton Gamma-Ray Observatory (CGRO), and several smaller missions including the Cosmic Background Explorer (COBE). The community consensus embodied in the Bahcall and earlier decadal surveys has proved to be a major factor in the initiation of many of NASA’s space astronomy missions. But at a critical phase in NASA’s planning cycle and midway between decadal surveys, the list of unexecuted consensus missions was too small to serve as the foundation for NASA’s next strategic plan for the space sciences. Accordingly, in December 1995, NASA’s Office of Space Science (OSS) requested that the Space Studies Board (SSB) update the scientific priorities for space astronomy and astrophysics in the context of recent discoveries and the likelihood that all but one of the space missions recommended by the Bahcall report will have been started before the year 2000. To undertake this study, the SSB early in 1996 established the Task Group on Space Astronomy and Astrophysics (TGSAA), under the aegis of the NRC’s Committee on Astronomy and Astrophysics (CAA). To encompass the wide range of topics relevant to a study of astronomy and astrophysics beyond the solar system, TGSAA organized itself into four panels: Planets, Star Formation, and the Interstellar Medium; Stars and Stellar Evolution; Galaxies and Stellar Systems; and Cosmology and Fundamental Physics. Forty-six experts (including 10 of the CAA’s 13 members) were selected to serve on these panels. The work of the four panels was coordinated by a steering group consisting of the chairs of the four panels, the two co-chairs of the CAA, an at-large member, and the chair of TGSAA. From among the leading topics for study identified by each of the four panels through debate, discussion, and a series of ballots, the steering group established a draft series of final priorities based on scientific goals. These priorities were later ratified in the same way at a joint meeting of TGSAA’s steering group and the CAA. Thus, as input to OSS’s development of its 1997 strategic plan, this report poses and prioritizes what TGSAA considers to be the most important scientific questions for researchers in space astronomy and astrophysics to address during the remainder of this decade and the beginning of the next. Astrophysicists employ a broad variety of tools to study electromagnetic radiation over the entire spectrum as well as energetic cosmic-ray particles. As a result of this diversity of techniques, TGSAA considered a wide range of space-based astrophysical opportunities. From among the many options, TGSAA identified four particularly important and timely priorities in space astrophysics for the early years of the coming decade. In ranked order these recommended priorities are as follows: Determination of the geometry and content of the universe by measurement of the fine-scale anisotropy of the cosmic microwave background radiation; Investigation of galaxies near the time of their formation at very high redshift; Detection and study of planets around nearby stars; and Measurement of the properties of black holes of all sizes. The second and third priorities were given virtually the same weight. 1   “Executive Summary” reprinted from A New Science Strategy for Space Astronomy and Astrophysics, National Academy Press, Washington, D.C., 1997, pp. 1–3.

OCR for page 33
Space Studies Board Annual Report 1997 Four additional scientific objectives were judged by TGSAA to be of high priority but to be less urgent at this time than the primary four listed above, or less achievable in terms of possible space missions. These recommended secondary objectives, unranked, are the following: Study of star formation by, for example, high-resolution far-infrared and submillimeter observations of protostars, protoplanetary disks, and outflows; Study of the origin and evolution of the elements; Resolution of the mystery of the cosmic gamma-ray bursts; and Determination of the amount, distribution, and nature of dark matter in the universe. TGSAA places determination of the fine-scale structure of the cosmic microwave background radiation at the top of its list of priorities because of the enormous impact of COBE’s observations. Not only have these observations provided confirmation of the hot big bang cosmological model, but they also have yielded new information on the primordial seeds responsible for the large-scale distribution of matter in the universe. Moreover, there is a very strong likelihood that moderate follow-on missions with higher-resolution instruments can, in the fairly near term, solve some of the deepest, and hitherto intractable, problems of cosmology and physics. TGSAA believes that NASA would be making a mistake of major proportions if it did not thoroughly and vigorously exploit the great breakthroughs achieved by COBE. The required observations are clearly defined, the necessary technology exists, and the costs appear to be fairly modest and well constrained. TGSAA’s recommendation for the study of galaxies near their time of formation in the early universe has a similar motivation. HST’s observations in this field and in deep extragalactic research, in general, have been especially successful. Studies performed by HST and the Keck 10-meter, ground-based telescope are providing researchers with their first direct look at the evolution of galaxies only a few billion years after the beginning of the universe. Astronomers now have, as never before, the ability to build instruments allowing detailed observation of galaxy formation—one of the major missing links in current understanding of cosmic evolution. Additional work in this field will certainly be one of the central facets of astronomical research over the next few decades. Observations from space will be crucial to this enterprise, and the HST, the Space Infrared Telescope Facility (SIRTF), and possible successor instruments will be at center stage. TGSAA’s recommendation for a concerted search for extrasolar planetary systems and black holes should be intelligible to any reader of Science or Nature, or even the daily newspaper. At least 10 planets, all very massive compared to Earth, have now been detected around nearby stars. Study of these objects and many more can probably be conducted with optical or infrared interferometers in space. Such an endeavor will be a major scientific activity bridging the interface between astronomy, astrophysics, and the planetary sciences. TGSAA’s recommendation for the detection and study of extrasolar planetary systems is a broad one, calling for a census of the most readily observed planets whatever their type. In TGSAA’s judgment it would be premature to focus attention solely or primarily on terrestrial planets at this time. The detection and study of planets like Earth are very difficult tasks that should be viewed as constituting the culmination, not the beginning, of the process of extending our knowledge of planetary bodies beyond the confines of the solar system. Black holes have long been thought to power the central engines of quasars and to be responsible for the x-ray emission from a handful of somewhat problematical binary stars. In the last few years these conjectures have been confirmed. Improved observations of active galaxies, combined with the discovery of new black hole candidates in binary systems, have brought about a wide consensus that black holes have, in fact, been detected. Confirmed examples have masses ranging from a few times that of the Sun, for those in binary systems, to about a billion times greater, for those in active galaxies. Thus, within a few years, the status of these bizarre objects has gone from hypothetical entities predicted by general relativity—whose existence was doubted by many—to important constituents of the universe. A systematic study of black holes across the spectrum is extremely timely and, in the judgment of TGSAA, should be a central theme in space research during the coming decade. Detailed justifications for TGSAA’s recommended priorities are given in Chapters 2 through 5, each of which was contributed by one of TGSAA’s four panels, and in the concluding Chapter 6. The panels’ chapters discuss recent progress and current problems in a wide variety of astrophysical topics, among which the recommended priorities listed above are judged to be the most scientifically important, the timeliest, and the most plausible as the centerpiece of NASA’s program in space astronomy and astrophysics during the start of the decade ahead. The additional key activities listed in Chapters 2 through 5 serve a number of roles, including providing scientific

OCR for page 33
Space Studies Board Annual Report 1997 justification and support for small missions that could be proposed by individual principal investigators, offering guidance to peer-review panels that will select small missions, and suggesting a focus for technology development efforts that will enable future space astronomy and astrophysics missions. Throughout its deliberations TGSAA assumed that all currently approved NASA astrophysical missions either would be operational by the early years of the coming decade or would be approaching launch. Missions of particular importance include the Advanced X-ray Astrophysics Facility (AXAF), SIRTF, the Stratospheric Observatory for Infrared Astronomy (SOFIA), and the Far-Ultraviolet Spectroscopic Explorer (FUSE). Although TGSAA was not asked to make explicit recommendations about missions to address the scientific priorities outlined above, planned or proposed missions are implicit in the priorities recommended by TGSAA. Thus the Microwave Anisotropy Probe (MAP), approved by NASA while TGSAA’s deliberations were under way, and the Planck mission (formerly COBRAS/SAMBA), a European Space Agency project with possible U.S. participation, are both dedicated to studying the anisotropy of the cosmic microwave background radiation.

OCR for page 33
Space Studies Board Annual Report 1997 3.5 Reducing the Costs of Space Science Research Missions: Proceedings of a Workshop A Report of the Joint Committee on Technology for Space Science and Applications, a committee of the Space Studies Board and the Aeronautics and Space Engineering Board1 SUMMARY OF FINDINGS The workshop participants concluded that the challenge in reducing space science mission costs is that there is no one “prescription” that can be applied to the wide variety of circumstances associated with the public funding of science. This report summarizes two days of discussions and the findings of the four working groups. A synopsis of each working group’s findings is included in Appendix D. The invited papers in Appendix C contain much of the data used by workshop participants in their analyses. The workshop participants also had access to the results of many previous studies and workshops that had addressed the issue of cost reduction for space science research; these materials are listed in Appendix E. The workshop results are categorized under the major topics of policy, the national space science mission, mission requirements, programmatics and acquisition strategies, recognition and management of risk, and the influence of new technology. These topics are addressed in descending order of importance and influence on the cost of space science research missions as agreed by the workshop participants. EFFECT OF POLICY MANDATES Behind all missions is a fundamental belief that public investment in creating new knowledge is a worthwhile objective. Science missions usually begin with the basic objective of advancing scientific knowledge rather than enhancing national prestige or promoting societal benefits. This approach to mission objectives, preferred by scientists, may not demonstrate clearly the value of the public investment to nonscientists or provide a basis for articulating national space science policy. Mission definitions are influenced strongly by national policy as defined by the executive and legislative branches of the federal government. Interpretation of the policy by the procuring agency, particularly the definition and acceptability of risk, can affect the mission definition. Also at play may be parallel agendas in government agencies, the Congress, or the scientific community. Perhaps the foremost example was the short-lived national policy of the early 1980s that the Space Shuttle would be the sole U.S. launch system and that expendable launch vehicles would no longer be available for scientific payloads (NSDD, 1981, 1982). Often policies that have a worthwhile objective result in unintended consequences when they are applied inflexibly. Examples include policy decisions affecting launch vehicle selection, such as the Space Shuttle policy mentioned above or restricting the use of non-U.S. launch vehicles. This policy can have a negative effect on mission cost. In this context, the consensus of the workshop and of the steering committee was that “buy American” policies frequently preclude mission savings that might be otherwise achievable. All four working groups believed that when national policies and political mandates impose requirements on individual scientific missions, there must also be serious consideration of longer-term scientific goals. Only then can there be major reductions in mission costs. UNDERSTANDING THE NATIONAL SPACE SCIENCE MISSION An articulated national policy and plan that identifies both near-term and long-range goals for the gradual exploration of space and the enhancement of the body of space science knowledge can provide a framework for increased public acceptance of and congressional support for the science program (NRC, 1995a). The scientific 1   “Summary of Findings” reprinted from Reducing the Costs of Space Science Research Missions: Proceedings of a Workshop, National Academy Press, Washington, D.C., 1997, pp. 7–14.

OCR for page 33
Space Studies Board Annual Report 1997 introducing commercial off-the-shelf elements into military specification systems is also relevant (Wertz and Larson, 1996; Sarsfield, Appendix C). Although concerns over government procurement systems are not new, participants believed it was worthwhile to rearticulate them in light of the current government emphasis on eliminating bureaucratic waste. Revisions in the Federal Acquisition Regulations could facilitate multiyear funding to meet the demands of rapid deployment and cost control. This was successfully demonstrated as a cost-savings strategy in the development of the Global Positioning System (NRC, 1995b). Workshop participants agree that such revisions are highly desirable for programs involving space science missions. RISK-INFORMED DECISIONS Failures in science missions can result from a variety of causes, such as a spacecraft failure (Mars Observer), a launch failure (Mars ’96), or a budgetary problem (Comet Rendezvous/Asteroid Flyby). In some cases, mission capabilities can be seriously degraded by simple mechanical failures that occur after launch (for example, the Galileo high gain antenna). The current NASA Strategic Plan states that the space science program can accept higher levels of risk in order to lower mission costs (NASA, 1996). Although program managers are ostensibly encouraged to apply new techniques and advanced hardware and software, they and spacecraft engineers are often reluctant to put their program and their careers at risk by using new technologies. They prefer to minimize risk and mitigate against failure by relying on older, proven technologies and occasionally by overengineering the spacecraft. Innovation in technologies and design can be realized only in a climate of mutual trust, with acknowledgment by all parties, including Congress and the procuring agencies, that space missions are inherently risky and that, despite all precautions, some losses will occur. Some risks inherent in space missions are unique. Plans that do not recognize and articulate these risks make it extremely difficult to assign proper value to space science investments. The consensus of the workshop and this committee is that risks should be stated clearly and that risk mitigation plans be identified early. The risk mitigation plans may both define the acceptable level of risk in a given mission and establish methods for addressing risk throughout the program. The working groups believed that risk assessments could be expanded to include not only technical risks but also programmatic risks (e.g., changes in national policy and congressionally mandated budget cuts, schedule delays, and unforeseen expenses). Risk-informed decisions are possible when there are clear mission goals and when a well understood risk evaluation framework is in place. INCLUSION OF ADVANCED TECHNOLOGY The major cost drivers in spacecraft are size, weight, and power. The continual search for and recent emphasis on space technology that will support the development of lighter weight, smaller systems have resulted in a diverse inventory of space-qualified technologies (Wertz and Larson, 1996). Workshop participants noted that small spacecraft missions in such programs as Discovery, Pathfinder, and Explorer can be considered forerunners. In NASA’s recent generation of small satellites, the agency has taken advantage of past technology investments, including investments by the Strategic Defense Initiative Organization, the Ballistic Missile Defense Organization, and industry. In addition, NASA’s New Millennium program is intended to fill the need for new technology testing and application (Redd, Appendix C). However, the reduction of budgets dedicated for technology research and development budgets raised general concern among workshop participants about the future of research and development in this area. Workshop participants pointed out that even though a small spacecraft may be launched on a less expensive launch vehicle than a large spacecraft, the cost saving may be offset by the cost of technology miniaturization and packaging, as well as by capital investments for tooling, new facilities, and training and certification. Miniaturized technology in the space science context connotes costly investments in research and development. Thus, small spacecraft with scientific capabilities comparable to their larger counterparts may not always be cheaper, even including savings in launch costs. Multiple spacecraft in constellations may distribute the risk among several spacecraft and launch vehicles but may not actually cost less than a large spacecraft with the same scientific capability (NRC, 1994). The working groups also agreed that smaller spacecraft should not necessarily be expected to deliver the same science for less money. There are two factors that may prevent an improvement in the cost-benefit ratio when

OCR for page 33
Space Studies Board Annual Report 1997 reducing the size and cost of space science research. The first is that some instruments cannot be reduced in size within current funding constraints. For example, to obtain a specific optical resolution, the mirrors or lenses on a space telescope must meet or exceed the size set by the diffraction limit and the technology available at the time. Thus, some important studies cannot be performed by small spacecraft because of physical limits and a lack of funds for new technology development. Second, economies of scale may be achieved on large spacecraft. That is, the science performance-cost ratio may be higher for large spacecraft than for small spacecraft, despite higher launch costs (Sarsfield, Appendix C). One participant noted that if the “best” science involves sending ten instruments to a planet, then co-locating all ten on one platform may well be cheaper than sending them on ten small spacecraft. A widespread concern is the transition of available advanced technology into operational missions. Project managers are reluctant to specify non-space-qualified subsystems for their missions because of the risk of failure. Funding for proof of concept and space qualification has been, and remains, difficult to obtain. The upcoming availability of the International Space Station for engineering research may help alleviate the problem of space qualification in some areas. (This is discussed in detail in the 1996 NRC report, Engineering Research and Technology Development on the Space Station.) In general, because technology advances require significant up-front investment in research and development, workshop participants believe that consideration ought to be given first to existing technology (worldwide) and then to new technology that will reduce cost, enable new or better capabilities, or facilitate scientific results (Redd, Appendix C). Workshop participants noted that utilizing standardized mechanical and electronic architectures at the interface level—as opposed to the spacecraft bus level—can reduce costs substantially without overly constraining design options. Standardization can significantly reduce nonrecurring engineering and design expenses while permitting the development of unique or specialized instruments. Flexible designs within standard architecture and interface formats can allow early integration of hardware, software, and computers. The ground-based infrastructure required for satellite control and mission data retrieval represents a major component of mission costs over the life cycle of the program. The participants noted that ground control and data retrieval costs can exceed the costs of space hardware development and launch. Therefore, savings in launch costs may represent a small fraction of the total mission cost. Workshop participants noted that a mission’s ground control and, thus, life-cycle costs could be reduced by on-board systems that increase satellite autonomy (NRC, 1994). Although technologies to support both simple autonomous operations (e.g., routine, repetitive processes, such as orbit and attitude determination) and more complex operations (such as problem detection, identification, and resolution) are advancing, autonomous satellite operation has not achieved the degree of acceptance that will be necessary to realize major cost savings. This is directly related to the problem of risk acceptance (discussed above). In addition to the use of more advanced technologies, possible cost-reduction strategies include out-sourcing, using available commercial installations, and consolidating program facilities to realize economies of scale (Larson, Appendix C, and Sarsfield, Appendix C). REFERENCES NASA (National Aeronautics and Space Administration). 1996. Strategic Plan. Washington, D.C.: NASA. NRC (National Research Council). 1994. Technology for Small Spacecraft. Panel on Small Spacecraft Technology, Committee on Advanced Spacecraft Technology, Aeronautics and Space Engineering Board. Washington, D.C.: National Academy Press. NRC. 1995a. Managing the Space Sciences. Committee on the Future of Space Science, Space Studies Board. Washington, D.C.: National Academy Press. NRC. 1995b. The Role of Small Missions in Planetary and Lunar Exploration. Committee on Planetary and Lunar Exploration, Space Studies Board. Washington, D.C.: National Academy Press. NRC. 1996. Engineering Research and Technology Development on the Space Station. Committee on the Use of the International Space Station for Engineering Research and Technology Development, Aeronautics and Space Engineering Board. Washington, D.C.: National Academy Press. NSDD (National Security Decision Directive) 8. 1981. Space Transportation System. Washington, D.C., November 13. NSDD 42. 1982. National Space Policy. Washington, D.C., July 4. Wertz, J.R., and W.J.Larson. 1996. Reducing Space Mission Cost. Torrance, Calif.: Microcosm Press, and Dordrecht, The Netherlands: Kluwer Academic Publishers.

OCR for page 33
Space Studies Board Annual Report 1997 3.6 Lessons Learned from the Clementine Mission A Report of the Committee on Planetary and Lunar Exploration1 EXECUTIVE SUMMARY Clementine was a relatively low-cost, technology demonstration mission that, as a secondary objective, was designed to survey the Moon and to fly past an asteroid. After a 22-month development phase, the spacecraft was launched in late January 1994. Operated by the Ballistic Missile Defense Organization within the U.S. Department of Defense (DOD), Clementine was the first U.S. space mission to leave Earth’s vicinity that was not run by NASA. Because of Clementine’s many similarities to NASA’s current drive to carry out space missions that are “smaller, cheaper, and faster,” this document describes some of the mission’s operational features that differ from traditional NASA practice and that might be profitably brought into scientific spaceflights. This report first presents a preliminary assessment of Clementine’s scientific return to date. Although much of the data reduction, calibration, and analysis is yet to be completed, Clementine already appears to have returned interesting and valuable scientific results, especially its identification of the lunar topography, which shows much more relief than anticipated. However, the spacecraft’s limited instrument complement prevented the mission from accomplishing the highest-priority objective for lunar science, namely determination of the Moon’s global geochemistry. This should not be regarded as a failure, because the mission was not motivated by the achievement of any particular scientific objective. Answers to most of the fundamental scientific questions, listed previously by COMPLEX, will come only after further exploration of the Moon by orbiters and landers. Clementine carried several new-technology devices and utilized lightweight spacecraft components. These elements are likely to have considerable application aboard small space science missions. Clementine was operated unlike most of the major space science missions of the past two decades: a small, highly dedicated team was given full responsibility for virtually all phases of the mission from design and construction of the spacecraft through to its launch and subsequent operation. The project stayed close within its budget and the spacecraft was delivered on time. Several aspects of Clementine—its cost, its incorporation of new technology, technological cooperation between NASA and DOD, and the scheme for software development—should be studied by groups more appropriately constituted than COMPLEX. The mission’s success rested to a considerable degree on the operational team’s substantial freedom to make decisions and on the easy access to technology already developed. The tight time schedule forced swift decisions and lowered costs, but also took a human toll. The stringent budget and the firm limitations on reserves guaranteed that the mission would be relatively inexpensive, but surely reduced the mission’s capability, may have made it less cost-effective, and perhaps ultimately led to the loss of the spacecraft before the completion of the asteroid flyby component of the mission. For the most part, within its constrained lunar science objectives, Clementine was successful. Because of various factors, Clementine’s costs were significantly less than most comparable space science missions might be. Since Clementine was not planned originally as a science mission and did not have science as a primary objective, funds were not allocated for instrument development and scientific calibration, or for data reduction and analysis. Nevertheless, Clementine validated the concept that, with proper operational profiles, small missions (such as those in the Discovery and MidEx programs) are capable of accomplishing significant research in space science. Clementine also demonstrated the usefulness to space science of missions emphasizing the testing of innovative technologies, fresh management styles, and new approaches to spacecraft operations. Future missions of this type should be initiated provided that they are capable of achieving first-class science and that the scientific community is actively involved in them as early as possible. The extent to which traditional NASA programs could or should follow this model is unclear at present. What is clear is that Clementine provides an existence proof that a small team of non-NASA researchers can successfully assume the overall responsibility for a deep-space mission. 1   “Executive Summary” reprinted from Lessons Learned from the Clementine Mission, National Academy Press, Washington, D.C., 1997, pp. 1–2.

OCR for page 33
Space Studies Board Annual Report 1997 3.7 Science Management in the Human Exploration of Space A Report of the Committee on Human Exploration1 EXECUTIVE SUMMARY Since the late 1960s, the post-Apollo future of human space exploration has been a subject of ongoing debate, incremental decisions, variable political support, ceaseless studies, and little progress or commitment toward a well-defined long-term goal. In 1989, President Bush attempted to establish a direction by announcing a long-term goal for the U.S. space program of returning humans to the Moon and then voyaging to Mars early in the 21st century. His proposal did not win political support. Indeed, implementation of human exploration of the solar system for a time virtually disappeared from public discussion, largely as a result of greatly increased federal budget pressures and the end of the Cold War, which in combination have brought about a de facto reprioritization of national goals, including an examination of the entire rationale for the U.S. civil space program. Recently, steps have been taken to initiate integrated planning for the exploration of Mars. In parallel, the goals of the international space station (ISS) program include the conduct of life science research and the acquisition of practical operational experience needed to resolve issues related to long-duration human spaceflight. Concurrently, robotic exploration of the Moon and Mars is being pursued by the United States and other countries. The Space Studies Board (SSB) constituted the Committee on Human Exploration (CHEX) in 1989 to examine the general question of the space science component of a future human exploration program. The first CHEX report, Scientific Prerequisites for the Human Exploration of Space,2 addressed the question of what scientific knowledge is required to enable prolonged human space missions. The second CHEX report, Scientific Opportunities in the Human Exploration of Space,3 addressed the question of what scientific opportunities might derive from prolonged human space missions. During the development of these first two reports, it became evident to the committee that the mode of interaction between space science and human exploration has varied over the years, as evidenced by a succession of different NASA organizational structures. The committee reviewed the history of this interaction with the objective of developing a “lessons-learned” set of principles and recommendations for the future. The principles and recommendations thus evolved for managing the science component of a Moon/Mars program, whenever and however it is pursued, transcend political and administrative changes. While this report is not intended to dictate precise organizational models, application of these principles and recommendations should facilitate a productive integration of science into a program of human exploration. PRINCIPLES FOR SCIENCE MANAGEMENT Three broad principles emerged from the committee’s survey of past programs: INTEGRATED SCIENCE PROGRAM—The scientific study of specific planetary bodies, such as the Moon and Mars, should be treated as an integral part of an overall solar system science program and not separated out simply because there may be concurrent interest in human exploration of those bodies. Thus, there should be a single Headquarters office responsible for conducting the scientific aspects of solar system exploration. CLEAR PROGRAM GOALS AND PRIORITIES—A program of human spaceflight will have political, engineering, and technological goals in addition to its scientific goals. To avoid confusion and misunderstandings, the objectives of each individual component project or mission that integrates space science and human spaceflight should be clearly specified and prioritized. 1   “Executive Summary” reprinted from Science Management in the Human Exploration of Space, National Academy Press, Washington, D.C., 1997, pp. 1–4. 2   Space Studies Board, National Research Council, Scientific Prerequisites for the Human Exploration of Space, National Academy Press, Washington, D.C., 1993. 3   Space Studies Board, National Research Council, Scientific Opportunities in the Human Exploration of Space, National Academy Press, Washington, D.C., 1994.

OCR for page 33
Space Studies Board Annual Report 1997 JOINT SPACEFLIGHT/SCIENCE PROGRAM OFFICE—The offices responsible for human spaceflight and space science should jointly establish and staff a program office to collaboratively implement the scientific component of human exploration. As a model, that office should have responsibilities, functions, and reporting relationships similar to those that supported science in the Apollo, Skylab, and Apollo-Soyuz Test Project (ASTP) missions. MANAGEMENT RECOMMENDATIONS In addition to these broad principles, the committee developed a number of specific recommendations on managing space research in the context of a human exploration program. Divided into three general categories, these recommendations are as follows: Science Prerequisites for Human Exploration (Enabling Science) The program office charged with human exploration should establish the scientific and programmatic requirements needed to resolve the critical research and optimal performance issues enabling a human exploration program, such as a human mission to Mars. To define these requirements, the program office may enlist the assistance of other NASA offices, federal agencies, and the outside research community. The scientific investigations required to resolve critical enabling research and optimal performance issues for a human exploration program should be selected by NASA’s Headquarters science offices, or other designated agencies, using selection procedures based on broad solicitation, open and equitable competition, peer review, and adequate post-selection debriefings. NASA should maintain a dedicated biomedical sciences office headed by a life scientist. This office should be given management visibility and decision-making authority commensurate with its critical role in the program. The option of having this office report directly to the NASA Administrator should be given careful consideration. Science Enabled by Human Exploration Each space research discipline should maintain a science strategy to be used as the basis for planning, prioritizing, selecting, and managing science, including that enabled by a human exploration program. NASA’s Headquarters science offices should select the scientific experiments enabled by a human exploration program according to established practices: community-wide opportunity announcements, open and equitable competition, and peer review. The offices responsible for human exploration and for space science should jointly create a formal organizational structure for managing the enabled science component of a human exploration program. Institutional Issues Officials responsible for review of activities or protocols relating to human health and safety and planetary protection on human and robotic missions should be independent of the implementing program offices. The external research community should have a leading role in defining and carrying out the scientific experiments conducted within a human exploration program. A human exploration program organization must incorporate scientific personnel to assist in program planning and operations, and to serve as an interface between internal project management and the external scientific community. Such “in-house” scientists should be of a professional caliber that will enable them to compete on an equal basis with their academic colleagues for research opportunities offered by human exploration missions. Working through their partnership in a joint spaceflight/science program office, the science offices should control the overall science management process, including the budgeting and disbursement of research funds.

OCR for page 33
Space Studies Board Annual Report 1997 3.8 An Initial Review of Microgravity Research in Support of Human Exploration and Development of Space A Report of the Committee on Microgravity Research1 EXECUTIVE SUMMARY The current organizational structure of NASA includes five strategic enterprises, one of which is the Human Exploration and Development of Space (HEDS). Goals set by the HEDS enterprise include (1) increasing knowledge of nature’s processes by use of the space environment; (2) exploring and settling the solar system; (3) achieving routine space travel; and (4) enriching life on Earth through people living and working in space. The means by which NASA proposes to accomplish these ambitious goals include a combination of scientific research, engineering technology development, and use of the Space Shuttle and the International Space Station (ISS) as microgravity test platforms. The first objective stipulated within NASA’s HEDS Goal 1 is that scientific research should be conducted to understand the roles played by gravity and the space environment in affecting the behavior of biological, chemical, and physical systems. The second objective within HEDS Goal 1 specifies the innovative use of major HEDS facilities, such as the Space Shuttle and the ISS, to achieve breakthroughs in science and technology. This preliminary report of the Committee on Microgravity Research examines those areas of microgravity research that not only support the objectives of Goal 1, but also have the potential to contribute to the eventual development of the new technologies required to accomplish the remaining HEDS goals. An initial appraisal is made of types of exploration technologies that, for development, would require an improved understanding of fluid and material behavior in a reduced-gravity environment. The current microgravity research program at NASA’s Microgravity Research Division (MRD) includes five major disciplines: (1) fluid physics, (2) materials science, (3) combustion, (4) biotechnology, and (5) fundamental physics. In general terms, fluid physics research encompasses the phenomena of heat and mass transport in low gravity and underlies many of the scientific and technological problems associated with long-duration crewed missions exploring the Moon and inner planets. A strong emphasis remains within the MRD program on experimental microgravity fluids studies—as opposed to reliance on computational fluid dynamics (CFD)—because the boundary conditions encountered in many reduced-gravity fluid physics studies are less well understood than in conventional subfields of aerospace research. For example, relatively weak forces, such as thermocapillary tractions and van der Waals interactions, which may be ignored in most terrestrial flow problems, can become dominant in microgravity. Materials science research in the MRD program tends to be focused on basic subjects such as nucleation and growth of solids from melts and on the evolution of microstructures—especially those involving one or more fluid phases. These include the formation of crystal defects and solute segregation in single-phase processing, such as semiconductor crystal growth, as well as research aimed at achieving a better understanding of polyphase microstructures, such as occur in eutectics and monotectics. Microgravity materials research extends to practically important processes such as reaction synthesis and sintering, welding and solidification, and in situ resource utilization (ISRU) for producing structural materials from extraterrestrial bodies. Such materials processes seem particularly relevant to technologies contemplated for future HEDS missions. Microgravity combustion research within the MRD—especially studies on fire safety research at the fractional gravity levels found on extraterrestrial bodies or studies under microgravity as encountered in spacecraft environments during deep-space transit—is critically needed to ensure safety on future HEDS missions, where crew egress might not be an option. Such research includes studies on flammability limits, smoldering, flame spread, and flame stability—all of which contribute both to scientific knowledge and to the engineering know-how needed for successfully pursuing the HEDS goals. Research in microgravity biotechnology is considered essential for understanding and designing reliable life-support systems, for producing nutrients and food for crews during long-duration HEDS missions, and 1   “Executive Summary” reprinted from An Initial Review of Microgravity Research in Support of Human Exploration and Development of Space, National Academy Press, Washington, D.C., 1997, pp. 1–3.

OCR for page 33
Space Studies Board Annual Report 1997 for safely and reliably recycling waste aboard spacecraft for water and oxygen recovery. Current MRD studies include activities on cell culture and bioseparations, which will contribute critically to understanding biological options for nutrient production in spacecraft as well as waste recycling. Low-temperature and atomic physics research using microgravity generally probes certain extreme physical limits in both classical and quantum systems. Research on laser cooling of atoms in microgravity can contribute directly to the development of improved navigational systems for achieving safe, efficient deep-space travel by providing practical atomic clocks with greatly increased accuracy. Although this initial report identifies the general areas of research discussed above as having the potential to make long-term contributions to HEDS technology development, the committee has attempted to prioritize neither the research nor the affected technologies, in part because NASA is currently still in the early stages of identifying its technology needs. As these needs become more clearly defined, it should be possible to identify research that can be profitably emphasized, although the need for flexibility in HEDS mission planning suggests that a strict prioritization of research is likely to remain counterproductive. Nevertheless, it is possible at this early stage to provide a number of initial recommendations, primarily programmatic, derived in the course of this review of microgravity research in support of Human Exploration and Development of Space. MRD should, on a continuing basis, assist NASA in identifying critical technologies that would benefit future HEDS missions and then seek opportunities in microgravity research to contribute to their efficient realization. MRD should, however, remain both flexible and cautious in evaluating such opportunities. Major advances in technology can result from basic research undertaken without regard to current technological priorities, which have yet to be even identified. In addition, the timing of such technological advances is often unpredictable. In supporting HEDS, MRD should continue to focus on maintaining its broad program of microgravity research. Although not all of the technological advances needed for HEDS missions will be the direct result of basic research, the unfolding knowledge base and collective experience of microgravity investigators focused within the MRD program will continue to represent unique NASA resources with which to approach the scientific questions underlying many of the barriers to space exploration. MRD should be prepared to stimulate and support critical microgravity research to help discriminate among competing HEDS technologies, specifically providing information so that NASA can make informed choices among them. The process of gathering and exchanging information relevant to research selections that could support HEDS missions should be strengthened. Specialized workshops, cross-divisional teams, advisory panels, and study groups attended by mission technologists and microgravity scientists are among the suggested mechanisms for achieving this recommendation. Such activities would encourage the exchange of ideas between technologists and scientists, provide better communication and ongoing awareness of the technology needed for MRD, and also allow timely transfer of microgravity research findings to HEDS technologists. The goals of HEDS involve the development of complex technological systems that require integration of microgravity information derived from research in disparate fields of science. MRD may find it advantageous to initiate a limited number of cross-disciplinary projects to develop experience in selecting and managing research projects that operate across traditional boundaries of the microgravity science disciplines. Some HEDS missions will involve operating systems at fractional gravity levels, such as the 0.16 Earth gravity encountered on the Moon or the 0.37 Earth gravity encountered on Mars. It is, however, often unclear as to whether or not thresholds of the gravity level exist at which various physical, chemical, and biological phenomena and processes undergo change. MRD should consider giving more attention to research studies carried out at fractional gravity levels where HEDS technologies might directly benefit from the scientific advances. Knowledge generated from such studies could be used to evaluate the need to provide artificial gravity by using continuous spacecraft rotation. Ongoing investments by NASA in robotics and automation research are expected to benefit both manned and unmanned HEDS missions, which must operate sufficiently far from Earth that highly autonomous operations and control become necessary because of the long transit time of signals. MRD should ensure that microgravity issues in teleoperations and robotics research are given sufficient attention and should maintain an active and current awareness of these issues. The International Space Station (ISS), when available for scientific use shortly after the beginning of the next millennium, should provide MRD with unique long-duration microgravity opportunities for evaluation of

OCR for page 33
Space Studies Board Annual Report 1997 technical systems deemed important to future HEDS missions. MRD should take advantage of the ISS as a microgravity platform for investigating closed-cycle, long-term operation of various physical, chemical, and biological systems considered to be within its research purview. In view of the normally long time-scale needed for the evolution of basic scientific concepts into practical applications, MRD should begin now to study and understand the scope and long-term implications of microgravity research areas relevant to accomplishing HEDS goals. Any adjustments to the emphasis or scope of MRD research must then be carefully assessed with respect to overall program balance, scientific merit, external interest, and HEDS mission relevance. The systematic and periodic application of NASA Research Announcements (NRAs) and peer review has improved the quality and selection of the science supported by MRD. These benefits to NASA and the nation are so extensive that these mechanisms should be preserved to ensure scientific objectives that support and enhance the HEDS enterprise. The recent inclusion of a call for research on ISRU and two-phase flow in the 1996 NRAs for materials science and fluid physics is commended as timely and responsive.

OCR for page 33
Space Studies Board Annual Report 1997 3.9 Scientific Assessment of NASA’s SMEX-MIDEX Space Physics Mission Selections A Report of the Committee on Solar and Space Physics and the Committee on Solar-Terrestrial Research1 EXECUTIVE SUMMARY In this report, the Committee on Solar and Space Physics (CSSP) and the Committee on Solar-Terrestrial Research (CSTR) assess how relevant recent Explorer mission selections are to the priority science goals identified in the National Research Council (NRC) report produced by the committees, A Science Strategy for Space Physics (SSB, 1995). Briefings by participants in a variety of Explorer missions, including the recent selections, Transition Region and Coronal Explorer (TRACE) and Imager for Magnetopause-to-Aurora Global Exploration (IMAGE), were made to the committees in June 1996. This report summarizes the committees’ findings and recommendations resulting from their deliberations. In addition, it addresses the broader issue of how well the present cost-capped Explorer program can meet the overall goals of the NRC Science Strategy report in this new era of “faster, cheaper, better” missions for the National Aeronautics and Space Administration (NASA). This report reviews the scientific objectives of TRACE and IMAGE and concludes that both missions will address high-priority goals of the NRC Science Strategy report for the Sun-Earth Connections research program. The principal findings of the committees are as follows: Both the most recently selected Small Explorer (SMEX) and Mid-size Explorer (MIDEX) missions (TRACE and IMAGE, respectively) address high-priority scientific issues fully consistent with the current primary science goals of the solar and space physics discipline, as identified by the NRC Science Strategy report (SSB, 1995). Although the Explorers do an excellent job of focusing on specific scientific objectives, most of the broader top-priority objectives summarized in the NRC Science Strategy report can only be accomplished with larger, more scientifically capable missions. To succeed within their severe cost constraints, Explorer missions cannot afford instruments that require lengthy development or space qualification cycles. Therefore, the use of instruments and/or instrument subsystems that have been developed for previous missions is essential. The present funding cap on SMEX and MIDEX could well prove too restrictive for building scientifically first-rate missions without such instrument “heritage.” Lessons learned from the space physics Explorers demonstrate the importance of instrument and spacecraft heritage in meeting science goals while remaining within cost and schedule limits. The committees support NASA efforts to make the Explorer program more responsive to “missions of opportunity.” However, they are concerned that relaxing current launch vehicle constraints on the Explorer program could attract suborbital and Shuttle-based missions that would previously have been funded under a different line. This could place additional strain on maintaining sufficient Explorer funding. The current operation and management styles of the SMEX program—including mutually beneficial cooperation between NASA and non-NASA participants, reduction of documentation, and flexibility in that class—are fostering opportunities for excellent, high-priority science. The extremely low selection rate (2/50) among the large number of proposed Explorer missions results in much effort spent fruitlessly in proposal preparation. This extra work puts a significant burden on the research community and their industrial partners. As with many other flight missions, Explorer missions can often continue to provide important scientific knowledge well after the scheduled mission termination if appropriate funding is available. The committees recommend that NASA consider the following: 1   “Executive Summary” reprinted from Scientific Assessment of NASA’s SMEX-MIDEX Space Physics Mission Selections, National Academy Press, Washington, D.C., 1997, pp. 1–2.

OCR for page 33
Space Studies Board Annual Report 1997 Establish a line of larger missions, such as Solar-Terrestrial Probes, because most of the broader, top-priority science objectives can only be accomplished with more capable missions. Explorer mission science could then be properly placed in the context of a coherent overall science program. This would include a balance of larger and smaller missions, suborbital projects, and research and analysis (R&A), all working synergistically to accomplish identified scientific objectives. Adapt some of the management style and procedures associated with the SMEX program, as discussed in Finding No. 5 above, in other science programs. Recent spacecraft-Principal Investigator (PI) mode space physics Explorers (such as Solar and Magnetospheric Particle Explorer [SAMPEX] and Fast Auroral Snapshot Explorer [FAST]) successfully demonstrate how high-priority science can be carried out in “faster, cheaper, better” ways. Within NASA’s R&A program, provide for some instrument development opportunities in addition to the suborbital program of rockets and balloons, because of the importance of instrument heritage to the success of many Explorer experiments. With respect to Explorer program proposals, consult the advisory groups before the final-stage proposal review process for a broad range of inputs and suggestions regarding candidates for membership on its all-important technical proposal review panel. This process could have a better chance of finding expert peer reviewers free of conflicts of interest.

OCR for page 33
Space Studies Board Annual Report 1997 3.10 The Human Exploration of Space A Report of the Committee on Human Exploration1 FOREWORD During 1988, the National Research Council’s Space Science Board reorganized itself to more effectively address NASA’s advisory needs. The Board’s scope was broadened: it was renamed the Space Studies Board and, among other new initiatives, the Committee on Human Exploration was created. The new committee was intended to focus on the scientific aspects of human exploration programs, rather than engineering issues. Early on, the committee recognized that an orderly review and clear statement of the role of science in human exploration should include, but distinguish between, science that must be conducted before human exploration beyond the Earth’s immediate environs could be practically undertaken, and science that would be enabled or facilitated by human presence on other worlds. This led to two reports, Scientific Prerequisites for the Human Exploration of Space and Scientific Opportunities in the Human Exploration of Space, published in 1993 and 1994, respectively. While these studies were in progress, the value of a third study that would focus on issues of science management within a human exploration program was recognized; this third topic was taken up after the Opportunities report was completed, and was published this year as Science Management in the Human Exploration of Space. These three reports are collected and reprinted in this volume. During the decade of existence of the Committee on Human Exploration, the prospects for human exploration have ebbed and flowed. On July 20, 1989, President George Bush announced that the U.S. should undertake “a sustained program of manned exploration of the solar system.” Timed to commemorate the 20th anniversary of the first human landing on the Moon, this announcement formalized a deep aspiration that has suffused space enthusiasts and professionals since the very beginning of the rocket era in this century and motivated the formation of the Board’s Committee on Human Exploration and its studies. Cost estimates for interplanetary travel proved very discouraging, however, and NASA’s human flight capabilities were soon focused on the space station program. But the goal of flight beyond the Earth-Moon system has never entirely faded and has remained the subject of dreams and long-range studies at a low level. The present series of reports, eight years in the making from the initial formation of the committee, seems to have been paced exactly right: the subject of human exploration of Mars is coming increasingly to the fore. Significant progress has been made in many scientific areas during this period; for example, in 1996 the Board enlarged on a key topic in the committee’s first report with a detailed survey of research required in the area of biological effects of radiation.2 Also in 1996, possible evidence for ancient Mars life was found in an Antarctic meteorite. Technology too has advanced enormously. As this volume goes to press, the Mars Pathfinder’s Sagan Station is operating on Mars, and its tiny Sojourner rover is conducting the first mobile field geology of another planet. Last fall, a historic partnership was formalized between NASA’s human spaceflight, life science, and space science offices to collaborate in an integrated program of robotic, and ultimately human, exploration of Mars. At the same time, reinvention of NASA over the past five years has renewed commitment to developing and applying new technology and to lowering project costs. A sustained and systematic drive toward the needed science and technology may be bringing the grand challenge of human exploration of the solar system into reach. Claude R.Canizares Chair, Space Studies Board Louis J.Lanzerotti Former Chair, Space Studies Board 1   “Foreword” reprinted from The Human Exploration of Space, National Academy Press, Washington, D.C., 1997, pp. 1–2. 2   Space Studies Board, Radiation Hazards to Crews of Interplanetary Missions: Biological Issues and Research Strategies, National Academy Press, Washington, D.C., 1996.