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Space Studies Board 4 Short Reports During 1998, the Space Studies Board and its committees issued three short reports, which this section presents in full in chronological order of release. 4.1 On ESA's FIRST and Planck Missions On February 18, 1998, Claude R. Canizares, chair of the Space Studies Board, Robert Dynes, chair of the Board on Physics and Astronomy, and John Huchra and Thomas Prince, co-chairs of the Committee on Astronomy and Astrophysics, sent the following letter to Dr. Wesley T. Huntress, Jr., NASA associate administrator for space science. In July 1997, the Task Group on Space Astronomy and Astrophysics (TGSAA), chaired by Patrick Thaddeus, released its report A New Science Strategy for Space Astronomy and Astrophysics (National Academy Press, Washington, D.C., 1997). The top science priority of the Thaddeus report is the “[d]etermination of the geometry and content of the universe by measurement of the fine-scale anisotropy of the cosmic microwave background radiation,” and the second priority is “[i]nvestigation of galaxies near the time of their formation at very high redshift” (p. 2). The TGSAA did not comment on specific missions to address the high-priority science objectives discussed in its report. Recently, however, the Committee on Astronomy and Astrophysics (CAA) took up this issue. The CAA concluded that both the NASA Microwave Anisotropy Probe (MAP) mission and the European Space Agency (ESA) Planck mission will make significant contributions to the measurement of the cosmic microwave background radiation (CMBR) and should therefore have the highest scientific priority. The CAA also concluded that the ESA FIRST mission and the Next-Generation Space Telescope (NGST) directly address the question of galaxy formation at high redshift in a highly complementary fashion and therefore also have very high scientific priority. MAP is an Explorer-class mission that will take a critical step in the measurement of the CMBR. Its angular resolution is substantially better than that of the earlier Cosmic Background Explorer (COBE) and will make possible the measurement of several of the most important cosmological parameters to high accuracy. The ESA Planck mission will have even better angular resolution than MAP because it will have high- as well as low-frequency receivers. Together the two missions will be able to reap the full science benefits of CMBR studies in accord with the Thaddeus report's highest science priority. Planck promises as much of an advance over MAP as MAP does over COBE. The NGST is a major component of NASA's 2000-2005 strategic plan for space science, The Space Science Enterprise (NASA, November 1997). It would be sensitive to the red-shifted near-infrared radiation from the early
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Space Studies Board period of galaxy formation. The ESA FIRST mission would complement the capabilities of the NGST by looking at far-infrared and submillimeter wavelengths. FIRST will be able to detect the highly luminous infrared emission associated with the high rates of early star formation in dust-enshrouded galaxies. NASA participation in the ESA Planck and FIRST missions could be crucial to realizing the full science potential of these missions, which address the top two science priorities in space astronomy identified by the Thaddeus report. The science return to the U.S. science community will be significant and NASA's investment highly leveraged. In particular, NASA has a key role to play in developing enabling technologies and indeed has already made significant contributions to both of these missions by its support of suborbital flight opportunities from which relevant technologies have been developed. Since the technology for both Planck and FIRST is not yet fully developed, a steady, adequate flow of technology funding is likely to be critical to the ultimate success of these missions. The CAA is concerned that the NASA investment should be commensurate with the very high priority science of both these missions. We urge that the NASA investment be used to ensure that the science goals articulated in the Thaddeus report are fully met. Signed by Claude R. Canizares Chair, Space Studies Board Robert Dynes Chair, Board on Physics and Astronomy John Huchra Co-chair, Committee on Astronomy and Astrophysics Thomas Prince Co-chair, Committee on Astronomy and Astrophysics
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Space Studies Board 4.2 On Climate Change Research Measurements from NPOESS On May 27, 1998, Claude R. Canizares, chair of the Space Studies Board, and Mark Abbott, chair of the Committee on Earth Studies, sent the following letter to Dr. Ghassem Asrar, Jr., NASA associate administrator for earth science, and Mr. Robert S. Winokur, NOAA, director of the National Environmental Satellite, Data, and Information Service. The Committee on Earth Studies would like to share with you some early results from our study, “Integration of Research and Operational Satellite Systems.” The committee has met four times thus far concerning this topic. The first meeting included briefings by John McElroy, Jerry Mahlman, and others who provided a scientific and historical context for the research and operational Earth-observing missions. In addition, the committee heard reports on the status and plans of NASA/Office of Earth Science (OES) and on the National Polar-orbiting Operational Environmental Satellite System (NPOESS). The committee also heard from the Polar-orbiting Operational Environmental Satellite (POES) and Geostationary Operational Environmental Satellite (GOES) program offices as well as from NOAA and NASA on plans for advanced geostationary platforms. At the end of the first meeting, the committee decided an appropriate study strategy would be to evaluate specific satellite-derived long-term data series that have important applications to Earth science. Particular emphasis was placed on climate research, given the unique potential of NPOESS. At its second and third meetings, the committee examined several such data sets, including sea surface temperature, atmospheric ozone and aerosols, sea surface elevation, global temperature, terrestrial vegetation, clouds, Earth's radiation budget, and ocean winds. For each time series, the committee explored issues related to sensor performance and calibration, data access, and data consistency. The fourth meeting continued these discussions with a specific focus on how to leverage the NPOESS satellites to better meet key data needs for the climate research community. The committee was also briefed by Berrien Moore, Eric Barron, and Tom Karl on related studies that are under way within the National Research Council's Board on Sustainable Development and Board on Atmospheric Sciences and Climate. At this point, the committee is now prepared to discuss its initial impressions on issues related to the development and application of NPOESS. The committee wishes to thank you and your staffs for their considerable help in this initial phase, and we look forward to continuing our strong relationship with you. Please feel free to contact us at any time if you wish to discuss any of these issues in more detail. Signed by Claude R. Canizares Chair, Space Studies Board Mark Abbott Chair, Committee on Earth Studies
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Space Studies Board Interactions Between Research and Operational Earth Observation Systems: Initial Steps General Issues The current schedule for NPOESS shows that specific instrument concepts will be selected for most of the major sensors in the next 2 years. During this time period, NASA will be completing its mission planning for the second series of Earth Observing System (EOS) missions. Therefore, if the recommendations of the Committee on Earth Studies are to be useful in the planning process, it is urgent that they be forwarded at this time, and the committee has chosen this abbreviated format to achieve that purpose. There is a clear distinction between measurements related to climate monitoring and those related to understanding climate variability and processes. In the first case, the variables used to document climate change require a high level of accuracy, precision, consistency, and traceability over time. In the second case, the requirements are somewhat less stringent though no less important. Although some variables can fall into both categories, it is useful to recall the distinction between them, particularly as we begin to move toward the use of operational satellite systems for climate studies. It is clear to the Committee on Earth Studies that NASA, through its Earth Science Enterprise (ESE), and NOAA, through its operational environmental satellite programs, fulfill important roles in Earth system research. As noted in the report to the NPOESS Integrated Program Office (the Mahlman and Karl report—NOAA, 1997), climate research (both monitoring studies and studies of climate-related processes) must build on both the long-term stability provided by an observing system such as NPOESS and the flexibility provided by programs within NASA/ ESE. No single approach will work; instead, we must have the capability to collect long time series of science-quality, integrated data sets to study both climate change and climate-related processes and the flexibility to take advantage of new science and new technology. The European Meteorological Satellite platform, METOP-3, is a critical component of the NPOESS program and illustrates the kind of coordinated international missions that will be needed as we move toward a global observing strategy. The committee is strongly supportive of these efforts, while recognizing that there are potential programmatic risks that may need to be overcome. One of the hurdles in achieving the goals of an integrated climate observing system is the lack of a clear federal charter to either NASA or NOAA for the requisite work. The committee notes that the NPOESS program is currently aimed at addressing short-term operational requirements associated with NOAA (and DOD) needs for weather-related information and weather prediction, whereas NASA's EOS and associated programs in the ESE are focused primarily on scientific research without operational constraints. As long-term climate monitoring and climate research do not fall under the purview of either agency, it has been difficult to obtain the necessary budget authority to meet these needs. Ranking of Climate Observables Numerous scientific committees have identified and described the variables that should be included in any climate observing system. However, many of these attempts have not separated the measurements needed to document global change from the measurements needed for understanding specific processes. It has also been difficult to rank these variables in a manner based on scientific understanding. The committee has begun to discuss with other National Research Council committees the idea of an optimization study (perhaps conducted as a series of workshops) to characterize satellite-based climate measurements in terms of their maturity, stability, and sensitivity to gaps. The study would support a systems engineering approach by evaluating measurement quality (including spatial and temporal resolution, calibration requirements, and the effect of measurement errors) and its impact on climate models and predictions. Such knowledge could then be used to rank the various observables in much the same way that observables are ranked in the area of weather prediction. The committee recognizes that the present state of climate research will make this a difficult task, but now is the time to start this study. This process would result in a set of defensible requirements that could be used to evaluate in part how climate research and monitoring requirements could be met through a combination of research and operational sensor systems. Consideration of the complementary in situ measurements is also essential in this effort. This optimization process should act as a reference point to evaluate the overall balance of an integrated observing strategy.
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Space Studies Board This study approach must be broadly based, and the committee recommends that it include both modelers and satellite remote sensing experts. It would provide a firm basis from which to evaluate various trade-offs in sensor design and performance while also establishing a method for evaluating new operational requirements for climate observing systems. The optimization study does not need to be limited solely to polar-orbiting missions, but may include missions that use geostationary, low-inclination, or other orbits as well. The Committee on Earth Studies will begin working with other NRC committees to define the study in more detail and begin the organization process. The committee recognizes that considerable planning will be necessary in advance of any study. The purpose is not to restructure the plans for NPOESS and EOS, but instead to provide a framework for building a climate observing system—one built on the foundation that already exists. The committee will work closely with the NASA 's Office of Earth Science (OES) and the NPOESS Integrated Program Office (IPO) throughout this process. Actions for NOAA and NASA NPOESS The NPOESS program presents enormous opportunities for climate research. The committee acknowledges the importance of the program's primary focus, which is short-term environmental predictions and assessment. However, the committee believes that there may be small changes in mission architecture, sensor performance, and operations that would greatly enhance the use of the NPOESS satellites for climate research and prediction, particularly in cooperation with NASA. Such changes will require involvement by the science community throughout the development and operations of NPOESS, as opposed to involvement limited to the program's initial design phases. The committee recommends that NOAA and the NPOESS IPO address the needs for climate research by: Ensuring that a knowledgeable climate advocate participates in the continuing design and implementation of NPOESS. An expanded role for NASA in the IPO may meet the need for this advocate for climate research. Ranking the measurements identified by the optimization study and establishing a science team for each of the high-priority measurements that have analogs in NPOESS. These measurement-focused teams would provide input on only the climate-related aspects of these data sets and would examine the entire end-to-end system from this vantage point. The committee recommends that these teams be established as soon as possible after the optimization study is completed. Examining critically its approach and its interactions with EOS. The present schedule for NPOESS sensor acquisition and development may limit the opportunities to learn from pre-NPOESS missions such as AM-1 and PM-1, as well as from polar-orbiting operational environmental satellite missions such as NOAA-N′. The committee envisions one science team for each climate-critical variable. Below, it lists some issues that the teams should consider. This list is not comprehensive, but merely shows the scope of the activities. Flexibility in the NPOESS program: Current plans include weight and power growth allowances to enable testing of new sensor concepts and designs on the NPOESS platforms. The committee strongly supports this approach as it will provide opportunities for new measurements as well as a mechanism for cross-validation between different sensor designs. Other approaches to enhance flexibility might be the use of sensor designs that can be easily upgraded, or the use of small satellites as part of the operational observing system, or for technology demonstration. Replenishment strategies: Gaps in the data record could seriously reduce the utility of the NPOESS operational datasets for climate studies and for monitoring climate change. The committee recommends that the IPO consider strategies to reduce the impact of gaps in the data record, including strategies for overlap and/or replenishment of NPOESS sensors. Instrument/platform design: The present plan is to use on-board propellant to maintain a fixed equator-crossing time for the NPOESS satellites. This is a significant improvement for the application of NPOESS measurements to climate research. However, in addition, an overall system architecture failure analysis of the sensors and satellite bus should be performed to identify whether there are small changes that might be made to
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Space Studies Board increase system redundancy and reliability. The results of the committee 's optimization study should also be considered for developing specific strategies for monitoring instrument stability. Data processing and distribution: It is essential that the complete archive of raw sensor observations be maintained and organized in a manner to facilitate reprocessing. This archive must include information related to sensor design, construction, testing, and operations in order to build a consistent time series. Early planning will enhance the ability of the global change community to use these data sets for research. Although the science teams would focus initially on NPOESS sensor systems, they should not be constrained to the polar-orbiting missions. In particular, geostationary platforms have many advantages for some types of climate research, and the science teams should also consider these and other orbits as part of the observing strategy. ESE The Earth System Science Pathfinder (ESSP) approach is emerging as the model that NASA will use to select and develop future missions as part of the Earth Observing System. In addition to the present approach for ESSP, the committee believes that future EOS missions must also focus on the following objectives: Improving NPOESS sensors through the use of new technology or new approaches; Filling gaps in critical data sets between NPOESS and the first set of EOS missions; and Continuing observations of critical variables that will not be measured (or not measured with sufficient quality) by NPOESS. As with the NPOESS measurements, the optimization study described above can help identify and rank the critical variables. The Operational Satellite Improvement Program (OSIP), which was operated by NASA until the early 1980s, may serve as a model for the interaction between the research satellite programs developed by NASA and the operational satellite programs developed by NPOESS. OSIP had its roots in scientific research and technology development to develop and test new sensor concepts in the context of weather forecasting. A similar process may be possible in the area of climate research and monitoring. In addition to its support of NASA missions, the Research and Analysis (R&A) program within the Earth Science Enterprise should provide a solid scientific basis for analysis and reprocessing of NPOESS and geostationary satellite data sets. As noted in the Mahlman and Karl report (NOAA, 1997), long time series require continued analysis and reworking to identify errors and to improve data quality. Such reprocessing efforts also may require more stable funding beyond the traditional 3-year funding cycle. Experience with reprocessing and analysis of long time series of satellite data (such as the NASA Pathfinder program) has shown that while ongoing review is necessary, a typical 3-year research grant is not sufficient to accomplish this complex set of tasks. The R&A program should continue to support improved algorithms for climate research. This includes forging partnerships with other agencies to maintain the global ground-based validation networks that are essential for climate monitoring through the use of satellite-based measurements. It also includes support for physically based algorithms and algorithms based on multiple sensors (as opposed to algorithms based on empirical relationships). In some cases, long time series can be developed serendipitously by combining measurements from a variety of sensors and missions—such research should be encouraged. Climate Research and Monitoring The committee recommends that NOAA and NASA establish an active, coordinated management structure that will focus on the needs for both climate research and climate monitoring. Although there are existing agency linkages, there needs to be a particular focus on long-term measurements for climate research that is accompanied by a stronger, continuing science involvement. The committee is concerned that neither NASA nor NOAA has clear leadership or responsibility for climate-related measurements. If we are to achieve an integrated system that can both monitor climate change and be used to study climate processes, then there must be a strong advocate for these science requirements. The committee recommends that in coordination with NASA/OES the IPO immediately extend its responsibilities to include the potential climate research and monitoring capabilities of the NPOESS satellites. This will enable a systemwide view of both NOAA and NASA missions in the context of an integrated climate-observing system.
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Space Studies Board While the present schedule for NPOESS includes opportunities for inserting new technology, as well as risk reduction through the flight of pre-NPOESS sensors, the strategy could be improved through better coordination with NASA's EOS program. For example, the committee is concerned that the test flight of a new atmospheric sounder may occur shortly before a final decision is made on the specifics of the planned NPOESS sounder. This will leave limited time in which to evaluate the pre-NPOESS sensor. Similarly, the committee is concerned that decisions regarding measurements of vector winds over the ocean using passive microwave radiometry may be made without the benefit of a thorough analysis because of constrained schedules. These potential problems arise in large part because the long-lead-time activities of NPOESS may lock in particular technologies far in advance of actual deployment in space. In contrast, NASA's EOS missions are moving toward a much more rapid accommodation of science and technology infusion. Overall coordination of these two activities could lead to a better balance between needed operational continuity and technology infusion. The scheduled launch of the second series of EOS satellites in 2004 will result in sensor concepts being selected during the next 2 years. Currently, NASA's plans for continuity with AM-1 are based in part on expectations for NPOESS. However, to realize the scientific goals established by NASA for EOS, there must be extensive coordination between NASA/OES and the NPOESS IPO. This must include coordination not only at the management level, but also at the scientific level as well. The committee recommends that NASA and NOAA establish a science advisory group that will ensure that the two programs remain integrated to meet the scientific needs of climate research (including studies of climate change as well as climate processes). Such a group will also ensure that the programs can respond in a coordinated manner to changes in science, technology, or budgets. Next Steps for the Committee on Earth Studies Over the next year, the Committee on Earth Studies will continue its investigation of issues related to the integration of operational and research satellite systems. The committee will continue its analysis of existing long time series of satellite measurements as well as the needs of data assimilation models that rely on satellite data. In addition, it will study how various mission architectures, including geostationary systems and small satellites, might be used and how they would affect sampling strategies. The committee also intends to study the present status of physically based algorithms, especially those that rely on multiple sensors. Calibration and validation are essential components of Earth systems science, and the committee will investigate both the on-board and ground-based strategies that are needed. Lastly, the committee will work with other appropriate NRC committees in the area of data systems to better understand how they may be optimized to support reprocessing of long time series for climate research. Reference National Oceanic and Atmospheric Administration (NOAA). 1997. Climate Measurement Requirements for the National Polar-orbiting Operational Environmental Satellite System (NPOESS), Workshop Report, Herbert Jacobowitz (ed.), Office of Research and Applications, National Environmental Satellite, Data, and Information Service, National Oceanic and Atmospheric Administration , 77 pp.
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Space Studies Board 4.3 Assessment of NASA's Mars Exploration Architecture On November 11, 1998, Claude R. Canizares, chair of the Space Studies Board, and Ronald Greeley, chair of the Committee on Planetary and Lunar Exploration, sent the following letter to Dr. Carl Pilcher, science program director for NASA's Solar System Exploration Division. In your letter of August 12, 1998, you requested that the Committee on Planetary and Lunar Exploration (COMPLEX) assess the approach to Mars exploration advocated by NASA's Mars Architecture Definition Team. COMPLEX understands that you need its remarks by November 15, 1998, to assist in ongoing mission planning and budget deliberations concerning the Mars Surveyor missions scheduled for launch in 2003 and 2005. As you requested, the assessment was conducted at COMPLEX'S September 15-17, 1998, meeting held at the National Research Council 's Georgetown offices in Washington, D.C. The assessment was based on presentations made by members of the Mars Architecture Definition Team, including Dr. Charles Elachi (chair), Dr. Dan McCleese (Chief Scientist of the Mars Exploration Directorate at the Jet Propulsion Laboratory), and Dr. Frank Jordan (Manager of the Mars Planning and Architecture Office at the Jet Propulsion Laboratory). Additional comments and elucidation were provided by Dr. John Rummel (NASA' s Planetary Protection Officer). In the course of its study, COMPLEX reviewed material submitted by the Mars Architecture Definition Team, consulted on recent scientific and technical developments with a select group of experts representing the diverse interests of the Mars science community, reviewed prior relevant reports by COMPLEX and other National Research Council (NRC) committees (e.g., Mars Sample Return: Issues and Recommendations , “Scientific Assessment of NASA's Mars Sample-Return Mission Options” [December 3, 1996], and Review of NASA's Planned Mars Program ), and held extensive discussions in closed session. NASA's presentations emphasized that the implementation aspects of the Mars exploration program will be defined in the next stage of the study. Thus, COMPLEX was unable to provide a detailed, point-by-point technical analysis of the scientific responsiveness of the proposed Mars exploration architecture. The committee was, however, able to provide a general assessment in the light of recommendations made in a variety of previous NRC reports (see attached “Assessment of NASA's Mars Exploration Architecture”). As such, both COMPLEX and the Space Studies Board (SSB) regard this current document as another step in an iterative process that has been in progress for many years and will continue with the evolution of NASA's planning for the implementation of its Mars exploration program and the program's central facet, a series of sample-return missions scheduled to begin in 2005. As you know, COMPLEX and the SSB have consistently emphasized the importance of an intensive study of Mars by spacecraft. An important element of such a program is the return of martian samples to Earth. COMPLEX continues to support this viewpoint. The primary objectives for Mars exploration and sample-return missions have been clearly defined and prioritized by both COMPLEX and other groups. These include, among other high-priority objectives, the search for evidence of possible martian life, past or present. The Mars Architecture Definition Team has done a fine job in designing the program. The incorporation of the return of multiple samples from a variety of diverse sites is a particular strength. Overall, COMPLEX concluded that the program to address the question of life on Mars is sound. There are, however, some concerns to address in the implementation phase as well as some concerns about possible impacts on the program's scientific return. These concerns, described in the attached assessment, led COMPLEX to make the following recommendations: The scientific goals and objectives of NASA's Mars exploration program must be stated in scientifically valid and reasonable terms. That is, the interpretation of biologically relevant observations can be maximized only if the data are gathered in the context of a broad framework of research aimed at understanding the origin and evolution of the martian environment. Thus, an appropriate focus for NASA's Mars program is the comprehensive goal of understanding Mars as a possible abode of past or present life. Moreover, a biologically oriented program must be conducted within the framework of appropriate safeguards against forward and back contamination to maintain scientific integrity and public trust. A Science Definition Team should be appointed by NASA Headquarters as soon as possible to provide oversight, guidance, and recommendations as an integral part of the implementation process. The team's responsibilities should include, among other things, devising “decision trees” based on the proposed missions' potential for
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Space Studies Board scientific discoveries, assessing the scientific consequences of various descope options, and determining if proposed landing sites meet program goals. Plans should be formulated for integrating the myriad elements of the Mars exploration architecture. These elements include NASA (e.g., intercenter roles, responsibilities, and interfaces), the scientific community, the public, and international constituents. The process of sample handling (from arrival on Earth to distribution to investigators) and data analysis (from collection to distribution to the scientific community in a usable form) must be defined within the context of well-developed “end-to-end,” science-driven plans. Relevant resources must also be identified for these and related activities, such as sample- and data-analysis programs, and upgrading laboratory facilities. The enabling and enhancing activities, such as the micromissions, the uncommitted payload mass, and operational tests, are fundamental to fulfilling the scientific objectives of the Mars exploration program because they can enhance the data return, enable new or unique measurements, provide flexibility to respond to new discoveries, and permit the optimization of surface operations based on experience from relevant preflight tests. In addition, the micromissions and uncommitted payload mass provide a potential means of addressing scientific goals not currently included in NASA's architecture (e.g., studies of martian climate change). COMPLEX notes that it was not able to comment on those aspects of the Mars exploration architecture relating to preparations for a possible program of human exploration in the next century. The Space Studies Board points out that scientific issues relating to this topic have been and continue to be discussed by its Committee on Human Exploration and Committee on Microgravity Research. In addition, relevant engineering and technical issues are being considered by the NRC's Aeronautics and Space Engineering Board. The Space Studies Board and COMPLEX look forward to following the future development and implementation of NASA's plans for Mars exploration and, in particular, sample-return missions. COMPLEX is particularly interested in hearing an updated presentation at the earliest opportunity, so that the committee can follow the exploration architecture's evolution into an implementation plan. COMPLEX is also interested in receiving responses on the comments contained in the attached assessment. Signed by Claude R. Canizares Chair, Space Studies Board Ronald Greeley Chair, Committee on Planetary and Lunar Exploration COMPLEX's ASSESSMENT OF NASA'S MARS EXPLORATION ARCHITECTURE NASA's Mars exploration “architecture” was reviewed by the National Research Council's (NRC's) Committee on Lunar and Planetary Exploration (COMPLEX) at its September 15-17, 1998, meeting in Washington, D.C. The term “architecture ” is used by NASA to signify the overall technological and scientific framework within which it will conduct a program to understand the potential biological history of Mars and the search for evidence of past or present life. A focus of the architecture is the return of a series of samples and relevant data to Earth. Presentations on the Mars exploration architecture were given by Dr. Charles Elachi (Director of Space and Earth Science Programs at the Jet Propulsion Laboratory [JPL] and chair of the Mars Architecture Definition Team), Dr. Dan McCleese (Chief Scientist of the Mars Exploration Directorate, JPL), and Dr. Frank Jordan (Manager for the Mars Planning and Architecture Office, JPL) on the strategies behind and elements of the architecture. In addition to members of COMPLEX, leading experts on Mars from the scientific community were invited to participate in the discussion of the Mars exploration architecture (see Appendix 1*). After the presentations, four * Note that the two appendixes referred to in the text of this assessment and included in the original letter report are not reprinted in this Annual Report.
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Space Studies Board working groups, each led by members of COMPLEX, discussed the scientific elements of the architecture, including exobiology, sample return, surface science, and remote sensing, in the context of recent scientific and technical developments. Results from the working groups were then discussed in open sessions of the full group. Later, in closed session, COMPLEX deliberated on the presentations and the results from the discussions of the working groups, taking into account recommendations contained in relevant NRC reports (e.g., Mars Sample Return: Issues and Recommendations , “Scientific Assessment of NASA's Mars Sample-Return Mission Options” [December 3, 1996], Review of NASA's Planned Mars Program , and The Search for Life's Origins ), and it developed and reached consensus on the conclusions and recommendations presented in this assessment. COMPLEX regards this assessment as an incremental step in an iterative process that has been in progress for many years and will continue with the evolution of NASA's planning for Mars exploration and, in particular, sample-return missions. COMPLEX finds that the general architecture (see Appendix 2) is well thought out and is a rational approach to achieving the goals of the program. The incorporation of plans for the return of multiple samples selected at a variety of diverse sites is a substantial strength of the architecture. As such, the architecture's scientific potential appears to be very high. Given the lack of detailed definition of the Mars missions in the post-2001 era and the lack of specifics in the presentations to COMPLEX (see Appendix 2), an assessment of “the degree to which the revised [Mars Surveyor] program is responsive to the Board's previous scientific advice” must await the completion of an implementation plan based on the architecture. However, based on discussions and deliberations, COMPLEX was able to identify three general issues that need to be addressed if NASA's Mars program is to realize its full scientific potential. These issues include: Architecture design, Architecture implementation, and Budgetary and technology concerns. A fourth potential category is the relationship between the architecture and possible human-exploration missions to Mars in the next century. This issue was not discussed, however, because COMPLEX did not receive any detailed information on this topic. In the sections that follow, COMPLEX discusses pertinent issues in the three areas listed above and presents specific conclusions and recommendations. Architecture Design As a result of its discussions and deliberations, COMPLEX concluded that two areas of the overall architecture require attention, namely: The manner in which the architecture's biologically oriented goals are posed; and Issues relating to the integration of various facets of the architectures. Rephrase the Objectives in the Goal Statement The goal statement for the Mars architecture should be phrased in a fashion that maintains both excitement and scientific integrity. The goal of NASA's Mars exploration program is, according to the presentations received by COMPLEX, “[to] achieve significant advances toward understanding the biological history of Mars and [to] search for evidence of past or present life” (see Appendix 2). Finding convincing evidence of present or past life on Mars would be a discovery of paramount significance to society. However, it is also possible that life has never existed on Mars. NASA, the scientific community, and the public must recognize that the planned program of exploration will provide valuable constraints on where and under what conditions life originates, independent of whether life is found. In searching for evidence of past or present life on Mars, it is important to understand that either answer, positive or negative, is scientifically important and that any evidence, particularly that obtained early in the
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Space Studies Board program, is likely to be somewhat ambiguous.1 Consequently, the larger context of the evidence is key to its proper interpretation. Thus, the scientific goals and objectives of NASA's Mars exploration program must be stated in scientifically valid and reasonable terms. The interpretation of biologically relevant observations can be maximized only if the data are gathered in the context of a broad framework of research aimed at understanding the origin and evolution of the martian environment. Thus, an appropriate focus for NASA's Mars program is the comprehensive goal of understanding Mars as a possible abode of past or present life. To the extent possible, information must be obtained on the global martian environment in order to understand the events in the history of the martian samples and of the planet in general.2 The missions outlined in the Mars exploration architecture will provide some of this information through the course of site selection, in situ surface observations, and analysis of returned samples. One consequence of a biologically oriented program is a heightened awareness of issues related to planetary protection. As a result, maintenance of both the scientific integrity of returned samples and the public's trust demands that the program be conducted within the framework of appropriate safeguards relating to forward and back contamination.3,4 Develop Plans to Integrate the Program Elements One of the greatest strengths of the Mars exploration program is the breadth and depth of its support. The exploration of Mars is a high priority for the scientific community,5 it is a major programmatic goal for NASA,6 and it is a prime policy goal of the Clinton Administration.7 Mars is also of great interest to the public and is the next obvious target for human exploration beyond the Earth-Moon system.8 These collective constituencies support Mars exploration for different reasons, and the exploration architecture will, necessarily, be a compromise reflecting diverse goals and aspirations. Integrating the various rationales for Mars exploration is a challenge for NASA, the nation, and the international community. Internally, NASA must integrate the diverse interests of three primary constituencies: The traditional planetary science community; The human exploration community; and The increasingly important biological and life sciences communities. The roles, relationships, and interfaces among these interests and associated constituencies in various NASA centers must be articulated to avoid confusion and misunderstanding and to ensure that the scientific goals for the exploration of Mars are not compromised by competing goals and objectives.9 At the national level, NASA's Mars exploration architecture must be responsive to other goals. The program must integrate: 1 Space Studies Board, National Research Council, “Scientific Assessment of NASA's Mars Sample-Return Mission Options,” letter report to Jurgen Rahe, NASA, December 3, 1996, page 2. 2 Space Studies Board, National Research Council, “Scientific Assessment of NASA's Mars Sample-Return Mission Options,” letter report to Jurgen Rahe, NASA, December 3, 1996, page 4. 3 Space Studies Board, National Research Council, Biological Contamination of Mars: Issues and Recommendations, National Academy Press, Washington, D.C., 1992, pages 9-11. 4 Space Studies Board, National Research Council, Mars Sample Return: Issues and Recommendations, National Academy Press, 1997, pages 3-5, 27-29, and 36. 5 Space Studies Board, National Research Council, An Integrated Strategy for the Planetary Sciences: 1995-2010, National Academy Press, Washington, D.C., 1994, page 8. 6 Office of Space Science, NASA, The Space Science Enterprise Strategic Plan: Origins, Evolution, and Destiny of the Cosmos and Life, NASA, Washington, D.C., 1997, pages 21-22. 7 National Science and Technology Council, Executive Office of the President, National Space Policy, The White House, Washington, D.C., 1996, page 2; available online at < www.whitehouse.gov/WH/EOP/OSTP/NSTC/html/fs/fs-5.html >. 8 Advisory Committee on the Future of the U.S. Space Program, Report of the Advisory Committee on the Future of the U.S. Space Program, U.S. Government Printing Office, Washington, D.C., 1990, page 6. 9 Space Studies Board, National Research Council, Science Management in the Human Exploration of Space, National Academy Press, Washington, D.C., 1997, pages 2 and 27.
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Space Studies Board The public's profound interest in exploration; The desire of the scientific community to generate new knowledge; The interest of engineers and technologists in advancing their arts; and Policy stakeholders' interest in using the program to advance educational goals, promote industry, and enhance national prestige. The incorporation of a significant degree of international cooperation in the Mars exploration program raises new integration issues. International partnerships significantly enhance the program elements that can be undertaken, leverage scarce resources, optimize the limited launch opportunities, and promote the vitality of the worldwide scientific and engineering communities. International cooperation, however, exposes the program to uncertainties related to the domestic forces driving the space programs of the participating nations. If insufficient care is taken to define the roles and responsibilities of the various participants, any ensuing problems will threaten the benefits of the collaboration and have a chilling effect on future cooperation. 10,11 International participation makes a given project much more difficult. The advantages can, however, certainly justify the added difficulty, but they need to be carefully analyzed to ensure that the justifications are valid. Plans should be formulated for integrating the myriad elements of the Mars exploration architecture. These elements include NASA (e.g., intercenter roles, responsibilities, and interfaces), the scientific community, the public, and international constituents. Architecture Implementation As planning for the implementation phase of the Mars exploration program begins, several key issues must be taken into account. These include: Contingencies, discoveries, and descope options; The role of a Science Definition Team; Ensuring valid sample and science return; Accessing high-priority landing sites; Promoting enabling and enhancing activities; Planning for activities related to sample return and data analysis; and Integrating public outreach and educational activities. Consider Contingencies, Discoveries, Descopes, and the Role of a Science Definition Team Two elements of planning need to be incorporated in the implementation plan deriving from the proposed Mars exploration architecture. These are its potential for scientific discoveries and the impact of possible descope options (i.e., reductions in capabilities required as a result of unforeseen problems in the implementation of the program). The scientific potential of the missions outlined by the Mars Architecture Definition Team is very high, and a wealth of scientific discoveries can be expected. The Mars exploration program should capitalize on this potential and retain sufficient flexibility to respond to discoveries. NASA's sample-return strategy is, for example, centered on the exploration of various manifestations of past or present aqueous environments. 12 But if the first site selected for sample return fails to yield evidence of aqueous environments or, alternatively, presents convincing evidence of extinct or extant life, does the basic strategy (including subsequent site selections and instrumentation) remain the same, or does it change? If so, how would the strategy be revised? Because the time between missions and the time for analysis of results are limited, the potential 10 Space Studies Board, National Research Council, An Integrated Strategy for the Planetary Sciences: 1995-2010, National Academy Press, Washington, D.C., 1994, pages 32-33. 11 Space Studies Board, National Research Council, and European Space Science Committee, European Science Foundation, U.S.-European Collaboration in Space Science, National Academy Press, Washington, D.C., 1998, pages 39-41. 12 Mars Expeditions Strategy Group, NASA, The Search for Evidence of Life on Mars, Jet Propulsion Laboratory, Pasadena, California, 1996, page 2.
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Space Studies Board changes in strategy must be considered and debated by the scientific community in advance as a part of the decision-making process. The proposed architecture is, however, very complex, involving multiple mission elements, many of which have not flown previously in planetary projects. Because of the inherent risks in these elements and limitations in funds and schedule, it is essential that various descope options and contingencies be defined for each major element of the program and that the scientific consequences of the descopes be clearly identified. The Space Studies Board has consistently maintained that scientists should be involved in flight programs from the earliest possible opportunity.13 Thus, a Science Definition Team should be appointed by NASA Headquarters as soon as possible to provide oversight, guidance, and recommendations as an integral part of the implementation process. The team's responsibilities should include, among other things, devising “decision trees” based on the proposed missions' potential for scientific discoveries, assessing the scientific consequences of various descope options, and determining if proposed landing sites meet program goals. Members of this team should include scientists who have direct experience in handling extraterrestrial samples. Ensure Valid Sample and Science Return The focus of each Mars lander scheduled for launch between 2003 and 2013 is, according to the architecture, the collection and return to Earth of diverse materials from sites for which basic geomorphic, mineralogic, petrologic, and chemical information has been gathered. Detailed study of the materials and the accompanying information will be conducted in terrestrial laboratories. As outlined, these missions are responsive to the scientific rationale for Mars sample-return missions established by COMPLEX and other groups.14-18 Each lander is equipped with a rover significantly more capable than that carried by Mars Pathfinder. Together, the rover and lander must deliver the maximum allowable mass of rock and soil to the sample-return container. Although the landers may be capable of collecting their own samples (with the aid of an arm and, perhaps, a drill) and conducting geological observations, the rover's mobility is the key to ensuring that the samples selected at each landing site represent the full diversity of materials present.19-24 Each rover must, therefore, carry instruments that can characterize the rocks as well as the environments within which the rocks are found. To meet the goals of in situ determination of geomorphology, mineralogy, petrology, and chemistry for each landing site, the standard rover instrument complement for these missions should provide images of the terrain at scales ranging from panoramic to microscopic; mineralogical analysis for accurate determination of rock types; 13 Space Studies Board, National Research Council, Managing the Space Sciences, National Academy Press, Washington, D.C., 1995, pages 74-75. 14 Space Studies Board, National Research Council, “Scientific Assessment of NASA's Mars Sample-Return Mission Options,” letter report to Jurgen Rahe, NASA December 3, 1996. 15 Space Studies Board, National Research Council, Review of NASA's Planned Mars Program, National Academy Press, Washington D.C., 1996, pages 10-11. 16 Space Studies Board, National Research Council, An Integrated Strtegy for the Planetary Sciences: 1995-2010, National Academy Press, Washington, D.C., 1994, page 104. 17 Space Studies Board, National Research Council, 1990 Update to Strategy for Exploration of the Inner Planets, National Academy Press, Washington, D.C., 1990, page 5. 18 Space Science Board, National Research Council, Space Science in the Twenty-First Century: Imperatives for the Decades 1995 to 2015— Planetary and Lunar Exploration, National Academy Press, Washington, D.C., 1988, pages 8-9 and 17. 19 Space Studies Board, National Research Council, “Scientific Assessment of NASA's Mars Sample-Return Mission Options,” letter report to Jurgen Rahe, NASA December 3, 1996, pages 3-4. 20 Space Studies Board, National Research Council, Review of NASA's Planned Mars Program, National Academy Press, Washington, D.C., 1996, page 23. 21 Space Studies Board, National Research Council, An Integrated Strategy for the Planetary Sciences: 1995-2010, National Academy Press, Washington, D.C., 1994 page 104. 22 Space Studies Board, National Research Council, Space Science in the Twenty-First Century: Imperatives for the Decades 1995 to 2015—Planetary and Lunar Exploration, National Academy Press, Washington, D.C., 1988, page 93. 23 Space Studies Board, National Research Council, Strategy for Exploration of the Inner Planets: 1977-1987, National Academy of Sciences, Washington, D.C., 1978, page 44. 24 Space Science Board, National Research Council, Post-Viking Biological Investigations of Mars, National Academy of Sciences, Washington, D.C., 1977, pages 14 and 23.
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Space Studies Board major-element chemical analyses of selected samples; and detection of organic or reduced inorganic carbon if either is common and abundant (>1%) in the rocks at the site.25-28 Proper geological characterization of each site is required not only to provide local context for collected samples, but also to obtain new information about the surface of Mars independent of the sampling activity. This latter purpose must always be fulfilled so that each mission will be scientifically successful even if unforeseen circumstances prohibit samples from being collected or returned to Earth. These basic goals should be met by each mission within the 2003 to 2013 suite; other goals may be accommodated but should not interfere with the core activities of any mission or jeopardize future missions. Maintain Flexibility for Accessing High-Priority Landing Sites Several issues related to landing-site selection and implementation directly affect the ability to search for evidence of martian life. Current engineering constraints appear to rule out many sites of exobiological interest, based either on their latitude (which must be between 5 degrees, north, and 10 degrees, south,) or their elevation (which must be below an altitude of 2.5 km). It is important that decisions not be made that would unnecessarily constrain the ability to land in a given location. Moreover, because the size of currently achievable landing-error ellipses is far greater than the distances that current rovers can be expected to traverse, there is no certainty that some discrete sites of high scientific interest can actually be reached. Information necessary to identify sites of particular interest will be obtained on early missions, particularly Mars Global Surveyor and Mars Geochemical Mapper (scheduled for launch in 2001). In this regard, participants in COMPLEX's discussions were concerned over two issues: first, the plan to reduce the operational life of the Mars Geochemical Mapper from 1 martian year to 1 year, and second, the absence of scientific instruments on subsequent U.S. orbiters. These decisions mean that the imaging and other remote-sensing data from the European Space Agency's Mars Express (scheduled for launch in 2003) are critical for site selection and general science. This is true not only for the increased coverage provided by Mars Express, but also for the near-infrared mapping data that would not otherwise be obtained. Promote Associated Enabling and Enhancing Activities The Mars exploration architecture outlines a framework within which it should be possible to conduct a highly focused program of martian exploration. COMPLEX notes that it should be possible to enhance various aspects of the scientific activities that can be conducted within this framework. COMPLEX focuses on three areas: the proposed micromissions, the 100-kg uncommitted payload mass on the landers, and operational tests associated with surface science. Micromissions Micromissions can contribute directly to the science goals of the Mars exploration program in a variety of ways. For example, the network of communication satellites, described as one option, not only would enhance the return of science data to Earth and enable more robust rover operations,29 but also has the potential to act as a navigational aid to enable very precise landings at targets of high scientific interest. Micromissions are also recognized as enabling the flight of various low-altitude aerial platforms, such as aerobots, aircraft, and gliders. Such platforms could provide imaging data with resolutions of 10 cm, bridging the 25 Space Studies Board, National Research Council, “Scientific Assessment of NASA's Mars Sample-Return Mission Options,” letter report to Jurgen Rahe, NASA, December 3, 1996, page 4. 26 Space Studies Board, National Research Council, Review of NASA's Planned Mars Program, National Academy Press, Washington, D.C., 1996, pages 22 and 25. 27 Space Studies Board, National Research Council, An Integrated Strategy for the Planetary Sciences: 1995-2010, National Academy Press, Washington, D.C., 1994, page 104. 28 Space Studies Board, National Research Council, Space Science in the Twenty-First Century: Imperative for the Decades 1995 to 2015—Planetary and Lunar Exploration, National Academy Press, Washington, D.C., 1988, page 93. 29 Space Science Board, National Research Council, A Scientific Rationale for Mobility in Planetary Environments, National Academy Press, Washington, D.C., 1998, in preparation.
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Space Studies Board gap between data obtained from orbit and the surface. These data not only would provide the potential for new science, but also would enable and enhance planning for surface operations such as rover traverses, as well as avoidance of hazards. Moreover, the data could provide unique information to meet program objectives. For example, the low altitudes at which micromissions could be flown would enable searches for water on scales of a kilometer (using neutron spectroscopy); such observations cannot be performed by orbiters. Moreover, they could survey much larger areas than is possible with surface experiments. Uncommitted Payload Mass As a means to accommodate additional instruments designed to address unanticipated results and discoveries, the uncommitted lander-payload mass provides flexibility to the Mars exploration program. Currently, there are no funds for additional instruments, but potential international pay loads and contributions from NASA's human-exploration program could be added to address the scientific goals of the Mars program not directly addressed in NASA's program (e.g., studies related to martian climate change), while simultaneously maintaining flexibility. Operational Tests Many elements of the architecture include new, untested technologies. It is imperative that the current plans for scientific testing of these elements and for gaining associated operational experience (such as field testing of rovers) be fully supported and documented. 30 This approach will ameliorate potential operational problems on Mars and enhance the potential return of scientific data. Enhancements and Descope Options There is the danger that enabling and enhancing activities such as the micromissions, the uncommitted payload mass, and operational tests might be viewed as “reserves.” COMPLEX views these elements as fundamental in fulfilling the scientific objectives of the Mars exploration program because they can enhance the data return, enable new or unique measurements, provide flexibility to respond to new discoveries, and permit the optimization of surface operations based on experience from relevant preflight tests. In addition, the micromissions and uncommitted payload mass provide a potential means of addressing scientific goals not currently included in NASA's architecture (e.g., studies of martian climate change). The position of these enhancing and enabling activities in a hierarchy of potential descope options cannot be determined until the post-2001 Mars program is more clearly defined and the scientific consequences of their retention or deletion can be assessed more easily. Plan for Activities Related to Sample Return and Data Analysis The returned samples are the most important product of the program, but the value of the science to be derived from them depends critically on how well the record that they contain is preserved in its pristine condition. The presentations given to COMPLEX explained that significant resources will be made available for planetary-protection activities. Planning for what happens to the samples after they reach Earth appears much less clear. Using the lunar sample curation activities as a model, sample handling must include the safe transportation of the samples to an appropriate facility or facilities for testing for biohazards, curation, storage under pristine conditions, preliminary characterization sufficient to permit scientists to request samples and to plan for their analysis, and the distribution of samples to the scientific community. Similar arguments apply to in situ and remote-sensing data collected during Mars missions. These data must be calibrated and archived in such a way that they are readily available to, and usable by, the scientific community. Thus, the process of sample handling (from arrival on Earth to distribution to investigators) and data analysis (from collection to distribution to the scientific community in a usable form) must be defined within the context of well-developed “end-to-end” science-driven plans. Relevant resources must also be identified for these and related activities, such as sample- and data-analysis programs, and upgrading laboratory facilities. 30 Space Science Board, National Research Council, A Scientific Rationale for Mobility in Planetary Environments, National Academy Press, Washington, D.C., 1998, in preparation.
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Space Studies Board Integrate Public Outreach and Science Activities Mars has long been a topic of fascination to the public. The extraordinary interest and response demonstrated during the Pathfinder Mission in 1997 argue that significant educational and outreach activities should be an integral part of the Mars exploration program. The complexity of defining and then conducting rigorous scientific investigations of possible past or present life on another world needs to be explained to the public carefully, thoroughly, and in an engaging manner. The Mars Pathfinder experience demonstrates that the optimum use of Internet capabilities on a near-real-time basis is crucial to this task. Yet, the extremes of either trivial involvement or interference with scientific activities need to be addressed early in the planning in order to avoid potentially harmful complexities or unrealistic expectations by the public, educators, or the media. The planetary-science community should be actively involved in educational and public-outreach activities associated with the Mars exploration program. Such outreach and educational activities might be funded through NASA's current education grants. A relatively few dollars, wisely spent, could yield enormous benefits to the nation's educational system.31 Budgetary and Technology Concerns Better Definition of Program Costs Overall, COMPLEX viewed the architecture as an aggressive plan that, according to the Mars Architecture Definition Team, was consistent with available resources, but COMPLEX'S level of confidence in the estimated costs for program development and implementation was low. Given the constrained funding for the program, COMPLEX believes that the estimated costs for the program need to be much better defined if NASA is to accomplish its stated science objectives.32,33 Furthermore, mechanisms to accommodate identified, but uncosted, components of the architecture to be supplied by, for example, NASA 's human-exploration program will require careful attention to minimize potential impacts on the science objectives.34 Reduce Risk in the Sample-Return Process The proposed strategy to return martian samples to Earth involves a chain of new and, apparently, untried technologies and operational procedures; failure of a single link in the chain could lead to a failure to return the samples and thus compromise the goal of sample return. The proposed elements that COMPLEX views as high risk include the transfer of the sample cache from the rover to the Mars Ascent Vehicle, the ascent and orbital insertion of the sample pay load, capture of the pay load in orbit by the transfer vehicle, return of the transfer vehicle to Earth, and delivery of the samples to the surface via high-speed (12-km/s) reentry through Earth's atmosphere. Although the redundancy of having two sample caches in orbit available for capture reduces some of the risk, there remain significant concerns for technology development and the impact of development delays on schedule and cost. Ensure That the Program Is Driven by Science The amount budgeted to reduce the data to a form usable for mission planning and usable by the scientific community may be inadequate to support the goals of the Mars program. The aggressive schedule will require rapid reduction and release of data for science analysis and mission planning. The tight requirements for technology development over the course of the program may put additional pressure on the resources budgeted for data analysis. In addition, the resources required for the preliminary characterization of the returned samples and their 31 Space Studies Board, National Research Council, The Role of Small Missions in Planetary and Lunar Exploration, National Academy Press, Washington, D.C., 1995, page 21. 32 Space Studies Board, National Research Council, Managing the Space Sciences, National Academy Press, Washington, D.C., 1995, page 63. 33 Space Studies Board and Aeronautics and Space Engineering Board, National Research Council, Reducing the Cost of Space Science Research Missions, National Academy Press, Washington, D.C., 1997, pages 4-5 and 10-14. 34 Space Studies Board, National Research Council, Science Management in the Human Exploration of Space, National Academy Press, Washington, D.C., 1997, pages 30-32.
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Space Studies Board delivery to the appropriate curatorial facilities are specifically excluded from the Mars program. Also excluded are funds necessary to upgrade laboratories to prepare them for the analysis of martian samples. It is imperative that these essential functions be accommodated and that these and other requirements of the Mars program (e.g., sample- and data-analysis programs) not put additional pressure on NASA's Research and Analysis programs.35,36 A full discussion of all the relevant issues will require a separate study. Conclusions and Recommendations As a result of its assessment, COMPLEX concluded that the architecture is a well-thought-out and rational approach to achieving NASA's programmatic goals for Mars exploration. Nevertheless, although the scientific potential is high, COMPLEX has some concerns about possible impacts on the Mars program's scientific return. These concerns, as outlined above, led COMPLEX to offer the following conclusions and recommendations: The scientific goals and objectives of NASA's Mars exploration program must be stated in scientifically valid and reasonable terms. That is, the interpretation of biologically relevant observations can be maximized only if the data are gathered in the context of a broad framework of research aimed at understanding the origin and evolution of the martian environment. Thus, an appropriate focus for NASA's Mars program is the comprehensive goal of understanding Mars as a possible abode of past or present life. Moreover, a biologically oriented program must be conducted within the framework of appropriate safeguards against forward and back contamination to maintain scientific integrity and public trust. A Science Definition Team should be appointed by NASA Headquarters as soon as possible to provide oversight, guidance, and recommendations as an integral part of the implementation process. The team's responsibilities should include, among other things, devising “decision trees” based on the proposed missions' potential for scientific discoveries, assessing the scientific consequences of various descope options, and determining if proposed landing sites meet program goals. Plans should be formulated for integrating the myriad elements of the Mars exploration architecture. These elements include NASA (e.g., intercenter roles, responsibilities, and interfaces), the scientific community, the public, and international constituents. The process of sample handling (from arrival on Earth to distribution to investigators) and data analysis (from collection to distribution to the scientific community in a usable form) must be defined within the context of well-developed “end-to-end,” science-driven plans. Relevant resources must also be identified for these and related activities, such as sample- and data-analysis programs, and upgrading laboratory facilities. The enabling and enhancing activities, such as the micromissions, the uncommitted payload mass, and operational tests, are fundamental to fulfilling the scientific objectives of the Mars exploration program because they can enhance the data return, enable new or unique measurements, provide flexibility to respond to new discoveries, and permit the optimization of surface operations based on experience from relevant preflight tests. In addition, the micromissions and uncommitted payload mass provide a potential means of addressing scientific goals not currently included in NASA's architecture (e.g., studies of martian climate change). 35 Space Studies Board, National Research Council, Supporting Research and Data Analysis in NASA's Science Programs: Engines for Innovation and Synthesis, National Academy Press, Washington, D.C., 1998, page 9. 36 Space Studies Board, National Research Council, An Integrated Strategy for the Planetary Sciences: 1995-2010, National Academy Press, Washington, D.C., 1994, pages 29-30.
Representative terms from entire chapter: