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An Enabling Foundation for NASA’s Earth and Space Science Missions 1 Overview of the Science Mission Directorate’s Mission-Enabling Activities NASA’s Science Mission Directorate (SMD) sponsors, develops, and conducts research in and from space in the disciplines of Earth science and applications, heliophysics (i.e., solar and space physics), scientific exploration of the planets and other solar system bodies, and astronomy and astrophysics. NASA’s strategic plan1 provides the following set of strategic objectives for SMD: Study Earth from space to advance scientific understanding and meet societal needs. Understand the Sun and its effects on Earth and the solar system. Advance scientific knowledge of the origin and history of the solar system, the potential for life elsewhere, and the hazards and resources present as humans explore space. Discover the origin, structure, evolution, and destiny of the universe, and search for Earth-like planets. SMD advances these goals by developing and operating spaceflight missions conducted primarily from spacecraft operated in Earth orbit; in interplanetary space; and in orbit around, or on the surfaces of, other solar system bodies. These spacecraft missions are managed within SMD by four science divisions—one for each of the four science discipline areas noted above. Important complementary activities carried out in addition are either mission-enabling or directly address SMD strategic goals in other ways. As emphasized in the NASA Science Plan: “Long-term outcomes are science based, not mission based; thus suborbital and research and analysis (R&A) programs are part of the discussion—it is not simply a matter of weighing a mission in one area against a mission in another.”2 MISSION-ENABLING ACTIVITIES—DEFINITION The Committee on the Role and Scope of Mission-Enabling Activities in NASA’s Space and Earth Science Missions defined mission-enabling activities as including the following: 1 NASA, 2006 NASA Strategic Plan, NP-2006-02-423-HQ, Washington, D.C., 2006. 2 NASA, Summary of the Science Plan for NASA’s Science Mission Directorate 2007-2016, NP-2007-03-462-HQ, Washington, D.C., 2007, p. 13.
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An Enabling Foundation for NASA’s Earth and Space Science Missions Research projects (especially via the R&A grants programs) and special research facilities (including sub-orbital flight payloads and operations, ground-based telescopes and dedicated laboratories, and high-end computer systems and data archives); Development of advanced sensors, research instruments, and spaceflight mission system technologies; General data analysis (including archival data studies and synthesis of new and/or long-term data sets from multiple spaceflight missions); and Earth science applications (including research to apply NASA Earth science results to fields such as agriculture, ecology, and public health and safety). The committee characterizes mission-enabling activities as the ensemble of non-spaceflight-mission-specific programs that create the scientific and technological expertise and associated infrastructure necessary to define, execute, and benefit from the spaceflight missions. In some cases these activities can lead directly to significant scientific accomplishments that advance the strategic goals of NASA without being linked to a spaceflight mission. This infrastructure includes A knowledge base that allows NASA and the scientific community to explore new frontiers in research and to identify, define, and design cost-effective space and Earth science missions required to address the strategic goals of the agency; A wide range of technologies that enable NASA and the scientific community to equip and conduct spaceflight missions to pursue the agency’s scientific goals; and A robust, experienced technical workforce to plan, develop, conduct, and utilize the scientific missions. Other essential elements of SMD’s space and Earth science programs that do not fall within the committee’s definition of “mission-enabling”—and that the committee has not included in its examination of mission-enabling activities—are as follows: Spaceflight mission science team activities, Post-launch spaceflight mission operations and data analysis (both during the prime mission phase and during extended mission operations), Mission-specific technology development, Guest-observer programs and participating scientist programs for spaceflight missions (but depends on discipline-unique approaches), Education and public outreach, and Space and ground communications systems (e.g., Deep Space Network and the Tracking and Data Relay Satellite System, both of which are currently budgeted and managed outside SMD in the Space Operations Mission Directorate). Nearly one-quarter (~$1 billion) of the total SMD budget of $4.5 billion is identified by NASA as mission enabling, as shown in Figure 1.1.3 In briefing the committee, NASA SMD officials explained that the present balance between spaceflight-mission and mission-enabling activities is largely a product of the SMD program’s evolution over its 50-year history rather than of a more systematic planning and implementation process. Although having data to trace historical trends in the relative allocations of funding for spaceflight missions and mission-enabling activities would have benefited the committee’s deliberations, such data were not available. Top-level goals and scientific priorities for all four SMD science divisions are traceable to NRC decadal surveys, which identify the highest-priority scientific directions for a field and present ranked priorities for facilities 3 Slightly more than half of the $4.5 billion total SMD budget is applied to missions in phases A (preliminary analysis) through D (fabrication and launch) and mission operations. The remaining quarter of the SMD budget is allocated to support for specific flight mission science teams and to program-wide communications, data archives, and computing infrastructure.
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An Enabling Foundation for NASA’s Earth and Space Science Missions FIGURE 1.1 The approximate distribution of all mission-enabling activities for fiscal year 2008. Funding levels are given in millions. SOURCE: NASA Science Mission Directorate briefing to the committee on January 22, 2009. and missions to pursue the science over the span of a decade. Thus the decadal surveys serve to provide some long-term stability to each division’s scientific goals. Research and technology development projects supported by mission-enabling programs are almost always managed and conducted by principal investigators or principal-investigator-led teams. NASA officials reported to the committee that, based on a sampling of fiscal year (FY) 2007 projects, approximately 60 percent of the total mission-enabling funding goes to universities, 33 percent goes to NASA centers, and 7 percent goes to other non-NASA institutions. Management of SMD research activities is currently driven by several annual administrative cycles. They include the annual budget cycle, during which portfolios are reviewed and overall budget allocations are made; annual proposal solicitations, during which budgets for new awards are set; and proposal selection and award decision making, which is based on scientific merit and programmatic needs. SMD officials indicated that when a need is identified to expand research efforts in a given area it is easier for them to create new programs and redistribute resources among portfolios than to expand portfolios already covering that area. The committee found that there are important differences between the research management practices and level of mission-enabling research funding of the four different SMD science divisions. Those differences include whether the divisions invite open-ended or targeted research topics for proposals, how data analysis activities are treated within and outside flight mission budgets, management of data archives and suborbital programs, roles of interdisciplinary and large-scale modeling efforts, and the roles of other funding agencies. Table 1.1 provides a summary of the relative sizes of the four divisions’ programs.
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An Enabling Foundation for NASA’s Earth and Space Science Missions TABLE 1.1 Comparative Statistical Data for SMD Science Division Mission-Enabling Programs Astrophysics Heliophysics Planetary Science Earth Science SMD Total Total budget ($M, FY 2009) a 1,206 592 1,326 1,380 4,503 Total mission-enabling budget ($M, FY 2009)b 127 77 312 556 1,072 Mission-enabling budget as a percentage of total budget 10 13 24 40 24 Proposals received (for 2008) 824 407 1,115 1,338 4,039c Overall acceptance rate (%, 2008) 36 29 28 31 31 Number of NESSF graduate student awards (2008) 8 4 17 51 79 Number of program officers 11 9 23 31 78 NOTE: Data on proposal volume, acceptance rate, graduate fellowships, and SMD staff are from Research and Analysis Web site. NESSF is the NASA Earth and Space Science Fellowships program. a Totals do not include the one-time 2009 American Recovery and Reinvestment Act supplement of $75 million for astrophysics and $325 million for Earth science. b Total does not include the one-time 2009 American Recovery and Reinvestment Act supplement of $74 million for Earth science research and technology. c SMD total includes 355 proposals for cross-directorate programs. SMD maintains an Internet site, Service and Advice for Research and Analysis,4 that provides a relatively comprehensive listing of mission-enabling research proposal opportunities and deadlines, proposal submission and award statistics, names of NASA points of contact, and other program information. PURPOSES SERVED BY MISSION-ENABLING ACTIVITIES Research and development (R&D) is important to the future of the nation. The NRC report Rising Above the Gathering Storm: Energizing and Employing America for a Brighter Economic Future5 emphasized the importance of research and technological innovation and recommended strengthening science and engineering research “to maintain the flow of new ideas that fuel the economy, provide security, and enhance the quality of life.” In a speech before the National Academy of Sciences on April 27, 2009, President Barack Obama reaffirmed the importance that his administration places on investments in R&D, and he committed to fund the nation’s total R&D effort at 3 percent of the gross domestic product, which in effect would double the national R&D effort. The mission-enabling programs within NASA in general and SMD in particular are an essential, although often overlooked, component of the nation’s R&D endeavors. They serve all of the purposes expected of an investment in R&D: the development of innovative technologies; the creation of new knowledge through basic research in a broad range of disciplines; and technical workforce development. They enable a specific set of program objectives, in this case the mission of SMD, and they help sustain the fundamental underpinning of the technological capabilities on which U.S. economic and national security depend.6 Box 1.1 illustrates the interplay of many of these mission-enabling activities as researchers sought to understand the heating of the Sun’s outer atmosphere to million-degree temperatures. Over the course of its history SMD has demonstrated many mission-enabling successes across all four of its mission disciplines, and it has clearly established the importance of the mission-enabling portion of the program to SMD’s overall success. Communicating these successes in the broader community is very important to NASA’s 4 See http://nasascience.nasa.gov/researchers/sara/. 5 National Academy of Sciences-National Academy of Engineering-National Research Council, Rising Above the Gathering Storm: Energizing and Employing America for a Brighter Economic Future, The National Academies Press, Washington, D.C., 2007, p. 7. 6 Technological, economic, and societal benefits of NASA programs in the broader national context are discussed in the recent NRC report America’s Future in Space: Aligning the Civil Space Program with National Needs, The National Academies Press, Washington, D.C., 2009.
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An Enabling Foundation for NASA’s Earth and Space Science Missions BOX 1.1 Case Study: Mission-Enabling Activities Advance Study of the Solar Corona Research on why the solar corona is millions of degrees hotter than the Sun’s surface offers a case study of the essential importance that mission-enabling activities play for space science. The story begins with NASA-funded theoretical research in the 1980s. Eugene Parker noted that convective motions at the solar surface displace the footpoints of coronal magnetic field lines in random directions. This causes the field lines to become wrapped and braided in complicated ways, perhaps resembling a bowl of tangled spaghetti. He further surmised that magnetic energy should be explosively released at the interfaces between the misaligned field lines, and, after estimating the size of each event, he coined the term “nanoflare.” The idea was very appealing. However, observations at the time were not sufficient to provide a rigorous test, and so NASA funded new instrument development. Normal-incidence, multilayer optics were developed to replace grazing-incidence telescopes, and the technology has now revolutionized our understanding of coronal structure and dynamics and is now standard on currently operating and upcoming solar missions. Laboratory work is another mission-enabling activity that has contributed to our understanding of coronal heating, including nanoflares. Spectroscopic observations cannot be interpreted quantitatively without the relevant atomic rate coefficients, and there is a long history of measuring (and calculating) these coefficients under NASA support. Finally, ever-improving space and ground-based observations have motivated a new round of theoretical investigations to understand the details of how magnetic field footpoint motions in the photosphere lead to magnetic reconnection and nanoflares in the corona. Meanwhile, numerical simulations are showing that the spatial and temporal dependence of the energy release can have a fundamental influence on the resulting loop dynamics and structure and help explain certain mysteries in the space mission observations. FIGURE 1.1.1 This X-ray image shows loops of magnetic fields extending high above the solar limb into the corona and indicates that energy deposition occurs on very small scales and in a complex pattern. The spectacular images from the Transition Region and Coronal Explorer mission were made possible by the optics developed from earlier rocket experiments funded through the NASA suborbital program. SOURCE: Courtesy of NASA Transition Region and Coronal Explorer (TRACE) team.
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An Enabling Foundation for NASA’s Earth and Space Science Missions future success, especially in an environment of restricted or diminishing fiscal resources. The paragraphs below describe and illustrate the three key areas of intellectual, technical, and human-capital mission-enabling elements in more detail. The committee’s intent is to present a few examples in each area rather than to provide a comprehensive list. Knowledge Base to Enable Spaceflight Missions Science mission spacecraft developed by SMD represent a significant investment of national resources. As such, the science mission teams require the best possible knowledge of mission objectives and their science context if spaceflight missions are to be developed in a cost-effective manner that maximizes the return on investment. As missions become more complex, the knowledge base necessary to support the strategic goals of SMD is constantly growing across all science disciplines and consists of activities that span all modes of basic and applied research. These modes include theoretical investigations and modeling; acquisition and analysis of supporting data from ground-based facilities, laboratories, aircraft, balloons, and sounding rockets; analysis of mission data (separate from the mission-funded analysis); establishment and/or maintenance of computational, curatorial, and other ground-based facilities; and establishment and maintenance of data archive facilities. Theoretical Investigations and Modeling Modeling, usually by numerical simulations, and theoretical research are required to turn measurements and observations into physical understanding. The predictions from modeling and theory also serve as motivation for future missions. For example, Earth system models, constrained by observations, are used to predict changes in the Earth’s environment and design requirements of future sensors by means of Observation System Simulation Experiments. In planetary science, modeling of the dynamical evolution of the early solar system has offered explanations for the Late Heavy Bombardment of the Moon and the capture of the Jovian Trojan population of asteroids, and models of the accretion of the terrestrial planets strongly suggest that material from the outer asteroid belt is the source of the Earth’s ocean water. These models give focus to the analysis of terrestrial, meteorite and returned lunar samples, and the interpretation of crater populations on planetary surfaces. In astrophysics, modeling of nucleosynthesis in supernovae has led to understanding of the abundances of elements in the solar system and in the interstellar medium. Modeling of hydromagnetic shocks around supernova explosions has led to an understanding of the acceleration of cosmic rays. (For a further example, see Box 1.2.) Acquisition and Analysis of Supporting Data from Ground-Based Facilities, Laboratories, Aircraft, Balloons, and Sounding Rockets Many spacecraft missions require supporting observations, from the ground or from suborbital vehicles, to be able to plan their observations and interpret their data. Suborbital missions—balloons, sounding rockets, and aircraft—have a number of essential functions in mission-enabling activities.7 They are a training ground for both the current and the next generation of scientists and engineers and are testing platforms for new instrumentation. In some cases the suborbital program provides the most cost-effective, and quickest, means to accomplish the science, more so than spacecraft observations. (For examples, see Box 1.3.) In other cases near-coincident ground-based telescope observations of a mission target provide information critical to interpreting the mission data. For example, in Earth science ground truth or aircraft flights under the orbital tracks of spacecraft are essential for the calibration, validation, and interpretation of remote-sensing data. The suborbital program also provides measurements with higher spatial and temporal resolution and data for atmospheric species that cannot be observed from space. Satellite and suborbital data are used synergistically to investigate processes controlling atmospheric composition and to evaluate, improve, and constrain Earth system models. In planetary science and astrophysics, 7 For a comprehensive assessment of SMD suborbital programs see the forthcoming report of the NRC Committee on NASA’s Suborbital Research Capabilities.
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An Enabling Foundation for NASA’s Earth and Space Science Missions BOX 1.2 Theory Links Old Measurements to New Missions One of the most interesting discoveries of the Ulysses heliophysics mission was that low-energy charged particles, known to be accelerated in the solar wind at low heliographic latitudes, are seen at the highest heliographic latitudes. The magnetic field in the heliosphere was thought to lie, on average, along cones of constant latitude, and particles, particularly low-energy ones, follow the magnetic field. It was therefore a puzzle as to how the particles seen at high latitudes were able to propagate there, from their acceleration site. When a new and interesting discovery such as this is made, theorists, supported through the mission-enabling program, attempt to explain it. Thus, a model was developed that challenged the concept that the heliospheric magnetic field lies on cones of constant latitudes, and rather suggested that global motions of the heliospheric field near the Sun would introduce pathways in latitude for the accelerated particles in the heliosphere, accounting for their observations at high latitudes. The revised theory for the heliospheric magnetic field has many implications for better understanding our star, the Sun. When the global motions of the heliospheric field at the Sun were considered in more detail, researchers realized that the motions offer an explanation for such diverse observations as the origin of the solar wind, the differences in the composition of the fast and slow solar wind, and even the reversal in the magnetic field of the Sun during the solar cycle. The original Ulysses observation stimulated many new theories, which in turn stimulated the need for new observations, which will be carried out on upcoming missions such as Solar Dynamics Observatory or the planned Solar Orbiter mission. FIGURE 1.2.1 The component of the Sun’s magnetic field that forms the heliospheric magnetic field (green lines) moves through the outer corona as shown by the red arrows. SOURCE: After L.A. Fisk, Motion of the footpoints of heliospheric magnetic field lines at the Sun: Implications for recurrent energetic particle events at high heliographic latitudes, Journal of Geophysical Research 101:15547-15553, 1996. Copyright 1996 American Geophysical Union.
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An Enabling Foundation for NASA’s Earth and Space Science Missions BOX 1.3 Suborbital Measurements Enhance Atmospheric Science and Astrophysics NASA’s atmospheric chemistry program used balloon-borne instruments to provide the initial observations of key stratospheric species necessary to understand the processes, both human and natural, that impact the abundance of stratospheric ozone. Balloon-borne observations in the 1970s showed the destruction of chlorofluorocarbons (CFCs) and production of chlorine monoxide (ClO). Measurements made on the ER-2 aircraft during the Antarctic Airborne Ozone Expedition in 1987 first showed a negative correlation between ClO and ozone. These measurements were cited in Congressional hearings as the “smoking gun” linking CFC-derived chlorine to the ozone hole. Within a few months of the February 24, 1987, optical discovery of a supernova explosion (SN1987a) in the nearby Large Magellanic Cloud galaxy, a balloon-borne instrument detected gamma rays from the ejecta of a supernova for the first time. Over the next 2 years, a series of payloads flown from Australia measured gamma-ray lines from freshly produced radioactive nuclei and confirmed the basic theory of supernovae. According to this theory, after a massive star has spent its nuclear fuel, the core collapses in a massive explosion causing a burst of radiation that creates the heavy elements essential to the formation of stars, planets, living things, and most structure in the universe, and leaving behind a neutron star or a black hole. Such a short lead-time from discovery of a new event to making direct observations in wavelengths only observable above the atmosphere was possible within the balloon program. If observations had waited for the typical several-year lead-time for a spacecraft mission, the rapidly fading gamma-ray emission would have been undetectable. FIGURE 1.3.1 Left: ER-2 research aircraft. SOURCE: Courtesy of Jim Ross, NASA Dryden Flight Research Center. Right: Supernova SN1987a as observed with the Hubble Space telescope. SOURCE: Courtesy of Dr. Christopher Burrows, ESA/STScI, and NASA.
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An Enabling Foundation for NASA’s Earth and Space Science Missions laboratory studies of chemical reactions—under pressures and temperatures of different solar system and cosmic conditions, absorption coefficients and spectral line properties, and atomic and molecular transitions—are often essential to the planning and interpretation of data from spaceflight missions. They feed into instrument design, identifying wavelength regimes and required resolution to study specific processes. Supporting ground-based telescopic observations have supported planetary and comet fly-by and entry missions, discovered a new class of comets in the asteroid belt (see Box 1.4), and mapped seasonal methane in the Martian atmosphere to indicate regions of the surface beneath which liquid water may exist today, possibly indicating life, thereby targeting future surface mission investigations on the planet. In astrophysics, a NASA-funded ground-based survey of the sky in the near-infrared (the Two-Micron All Sky Survey, or 2MASS) provided a highly sensitive sky census for use in planning the next generation of infrared astronomy space missions. Analysis of Mission Data NASA science missions are often of limited duration. The spacecraft, however, will almost always return data for many years beyond the prime mission phase, the continued analysis of which generates important scientific results and directly contributes to the knowledge base on which new missions are designed. For example, combined Mars data sets from missions extending back to Viking in the 1970s have built up the story of the evolution of water on the Martian surface, constraining optimum landing sites for Mars Science Laboratory. Survey data from the 1983 Infrared Astronomical Satellite mission provided maps of background sky brightness as well as interstellar cirrus structures integrated in observation planning tools for Spitzer Space Telescope, which was launched in 2003. The Heliophysics Great Observatory is a constellation of more than 15 spacecraft, strategically located throughout geospace and the heliosphere, which enables an unprecedented, coordinated study of the Sun and its influence on the heliosphere and Earth. These coordinated data analysis activities are conducted as a mission-enabling activity through a guest investigator program. Establishment and/or Maintenance of Computational, Curatorial, and Other Ground-Based Facilities NASA science missions often require specialized and/or dedicated facilities to support analysis of their returned data and samples or to conduct studies to interpret data or run simulations. For example, the astromaterials curation facility at Johnson Space Center manages returned samples from Apollo, interplanetary dust collection experiments from aircraft, cometary samples returned from Stardust, and more. (See Box 1.5.) It is critical for current and future use that these materials be kept in controlled environments and that all handling is tracked. A specialized laboratory for obtaining reflectance spectroscopy of wide ranges of terrestrial and extraterrestrial materials at Brown University is used to explore the effects of parameters such as particle size and illumination and existence angles in order to properly interpret spectra of planetary and asteroidal surfaces returned from spacecraft. NASA maintains high-end computer systems and services at the Ames Research Center and the Goddard Space Flight Center (GSFC) that are used for data analysis and modeling in all four SMD science discipline areas.8 For example, in 2008 these supercomputer systems supported over 130 principal-investigator-led projects in Earth sciences such as developing advanced data assimilation and visualization tools and modeling how interactions of Earth’s oceans and atmosphere affect climate change. Predictions of space weather and how it will affect terrestrial systems depend on advances in models of the various phenomena that control the impact of the Sun on Earth. The Community Coordinated Modeling Center at GSFC provides a readily accessible, community-developed model, as well as visualization and analysis tools and validation and metrics information. Establishment and Maintenance of Data Archive Facilities In the early years of NASA, the amount of data returned from missions was limited and generally thoroughly analyzed and made available through mission-related publications. Over time, data volumes have increased and 8 See http://www.hec.nasa.gov/news/reports/HEC_2007-2008_web.pdf.
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An Enabling Foundation for NASA’s Earth and Space Science Missions BOX 1.4 Planetary Astronomy Program Discovers Main Belt Comets In work using ground-based optical telescopes funded by the NASA planetary astronomy program, astronomers discovered comets orbiting in the main asteroid belt, a previously unknown class of solar system body. These bodies, referred to as “main-belt comets” (MBC), have caused a rethinking of the textbook categorization of comets and asteroids. The MBC are active (i.e., they eject substantial amounts of dust and gas) and have retained ice for the age of the solar system. At a distance of only 3 AU from the Sun they are exciting targets for future comet missions. Their orbits and low level of activity benefit mission design, and the presence of ice implies that they are well preserved early solar bodies, unaltered by the internal heating experienced by many asteroids and all of the meteorite parent bodies. NASA-funded R&A programs have also supported work at ground-based telescopes that has led to the discovery of other new classes of solar system bodies that will be targets for future missions. These include Kuiper Belt objects beyond the orbit of Neptune and Trojan “asteroids” in 1:1 orbital resonance with Neptune. FIGURE 1.4.1 The family of main-belt comets (red orbits) shares the region of the solar system occupied by main-belt asteroids (orange orbits). The black ovals show the orbits of Mercury, Venus, Earth, Mars, and Jupiter. SOURCE: Courtesy of Pedro Lacerda, Queen’s University Belfast.
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An Enabling Foundation for NASA’s Earth and Space Science Missions BOX 1.5 Curation of Meteorites from Mars and the Moon NASA’s support for the laboratory analyses of meteorites led to the discovery of meteorites from Mars and also from the Moon. A very rare class of meteorites had elemental and mineralogical compositions suggestive of origin in a differentiated body of planetary size. Analysis of noble gases trapped in the meteorites matched Viking’s in situ analysis of the Martian atmosphere showing that these meteorites are liberated rocks from Mars. The growing collection of now 34 meteorites provides a unique sample-based information source on the geological chronology of Mars. The samples from various locales on Mars provide a wealth of information for planning future Mars missions and provide a broad base of sample information useful for analysis of data from missions. Similar studies have also identified 63 lunar meteorites, and these also play a major role in understanding the geology and history of the Moon as well as planning future missions. FIGURE 1.5.1 Left: The Martian meteorite, EETA79001, was collected in 1979 in the Elephant Moraine area of Antarctica. Right: The lunar meteorite, MAC88105, was collected in 1988 from the MacAlpine Hills area of Antarctica. SOURCE: NASA Astromaterials Acquisition and Curation Office.
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An Enabling Foundation for NASA’s Earth and Space Science Missions continue to increase dramatically. Many missions today rely on years of post-mission analysis to extract most of the value from the data obtained. Also, as knowledge of the universe evolves, data can be reanalyzed and new information extracted from it. One example of this was reanalysis of Pioneer 10 and 11 dust impact data from the outer solar system, decades after its acquisition, showing evidence of dust spiraling in towards the sun from collisional production in the Kuiper Belt. At the time of the Pioneer mission, the Kuiper Belt had not been discovered. The primary product of all NASA missions is data. Their archiving, curation, and availability to the science community are critical to the derivation of value from those missions and hence are fundamental to the justification of continued data acquisition. The NASA Planetary Data System (PDS) is the repository of all planetary digital data. All data in the PDS are peer-reviewed, curated at science discipline nodes, and accessible via the Internet. The challenge of the PDS is the extreme diversity of the nature and formats of its holdings, including mission data having different types of imaging systems and other remote sensing and in situ measurement instruments, as well as ground-based telescopic data, laboratory data, and derived data. The Earth Observing System Data and Information System manages and distributes data products through the Distributed Active Archive Centers. The centers process, archive, document, and distribute data from past and current research satellites and field programs. (See Box 1.6.) In heliophysics, the Virtual Solar Observatory provides access to space- and ground-based observations of the Sun, providing access to solar data through a variety of search engines. NASA-supported archives have become fundamental to the infrastructure in astrophysics. The High Energy Astrophysics Science Archive Research Center, Multi-mission Archive at the Space Telescope Science Institute, and Infrared Processing and Analysis Center service thousands of requests per day from the community. NASA’s shared support is also critical to other very large astrophysics archives such as the Set of Identifications, Measurements, and Bibliography for Astronomical Data (SIMBAD) and the Sloan Digital Sky Survey. Although not precisely a data archive, the journal access and bibliographical facilities of the Astrophysics Data System are used by most astronomers every day. NASA’s shared support (with NSF) of the newly founded National Virtual Observatory promises to tie most astrophysics databases together with 21st-century technology. Technology Development for Spaceflight Missions Advances in technology facilitate advances in science. SMD missions operate in many different operating and radiation environments, such as Earth orbit, deep space, and planetary surfaces. Spacecraft systems and associated instrumentation must be designed and optimized to operate properly and make specific observations to address the intended mission science objectives. Past developments and adaptations in these areas have made the current SMD’s missions possible just as ongoing investments and development efforts will enable future missions. For example, many instruments flown on NASA planetary science missions can trace their heritage to the Planetary Instrument Design and Development Program (PIDDP) and its counterparts dedicated to technologies for Mars missions and astrobiology. These technology development projects have impacted all mission-size classes ranging from small and moderate-class Discovery missions to major flagship-class missions. In addition to contributions to instruments used for Mars missions, PIDDP has supported development of instruments or advanced instrument technologies that were subsequently used on the NASA-European Space Agency (ESA) Cassini mission to Saturn, Hubble Space Telescope, Messenger mission to Mercury, Near Earth Asteroid Rendezvous mission, ESA Rosetta comet mission, and ESA Beppi Colombo mission to Mercury, among others. Suborbital programs provide a risk-tolerant pathway to support new instrument development, evaluation of innovative technologies, and flight operations experience while also carrying out important and often ground-breaking scientific research. (See Box 1.7.) These programs can be mounted quickly and inexpensively, and they bridge the gap between laboratory development of new technologies and flight-tested maturity. For example, balloon missions provided development and test opportunities for the large silicon strip detector arrays now in orbit on the Fermi Gamma-ray Space Telescope. Spiderweb bolometers developed for balloon-borne measurements of the cosmic microwave background are now in space on the ESA Plank and Herschel missions. In briefing the committee, the chair of NASA’s Astrophysics Sounding Rocket Assessment Team reported that over its five-decade history the astrophysics sounding rocket program had contributed to development of dozens of new
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An Enabling Foundation for NASA’s Earth and Space Science Missions BOX 1.6 Case Study: Ocean Color Science Advances via Mission-Enabling Activities Satellite remote sensing of ocean color has progressed significantly in the last three decades through a combination of new missions, mission-enabling data analysis, and technology development activities. For example, researchers have documented a significant decrease in ocean productivity through analysis of the multiple-satellite time series of ocean color measurements. Moreover, the technical capabilities of each mission have improved, which in turn have enabled more precise as well as more accurate measurements of the optical properties of the upper ocean. With the growing impacts of climate change on ocean ecosystems, the science issues have also evolved to include considerations of ecosystem function (e.g., nutrient cycles, organism resource production and consumption rates, and organism-environment feedback processes) and ecosystem structure (e.g., the numerical and physical distributions of species, nutrients, and natural resources in ecosystems and the configuration of these ecosystems’ food webs). Of particular interest are studies of how climate-driven ocean acidification has led to decreased reef-building rates and declining populations of larval marine species like commercial fish and shellfish. To address these questions, mission-enabling activities have directly led to new technical requirements for future ocean color missions that rely on hyperspectral spectrometers rather than multiband spectroradiometers, which have been flown for the past 30 years. Technical investments in airborne hyperspectral sensors have demonstrated that such sensors can be developed and flown with sufficient performance to meet the science requirements and at a cost to fit within an achievable budget profile. The plots below, from satellite measurements of ocean color, show that global changes in annual average sea surface temperature (a) and net phytoplankton productivity (b) for the 1999 to 2004 warming period were inversely related (c). FIGURE 1.6.1 Reprinted by permission from Macmillan Publishers Ltd.: Nature, M.J. Behrenfeld, R.T. O’Malley, D.A. Siegel, C.R. McClain, J.L. Sarmiento, G.C. Feldman, A.J. Milligan, P.G. Falkowski, R.M. Letelier, and E.S. Boss, Climate-driven trends in contemporary ocean productivity, Nature 444:752-696, Copyright 2006.
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An Enabling Foundation for NASA’s Earth and Space Science Missions BOX 1.7 Sounding Rocket Technology and Exploration Unveiled the X-ray Universe In 1963 an Aerobee rocket was launched from White Sands, NM, to detect X-rays from the Moon. With a flight to only 225 km altitude, onboard Geiger counters discovered Scorpio X-1, the first astronomical X-ray source other than the Sun, and detected the cosmic diffuse X-ray background radiation. This unexpected discovery on a single rocket flight opened up an entirely new field of science and a highly productive window on the universe. The mission-enabling discovery led to more rocket and balloon projects, and just 7 years later UHURU became the first Earth-orbiting mission dedicated entirely to celestial X-ray astronomy. This early sounding rocket work also was a factor leading to recognition of astrophysicist Riccardo Giacconi with the 2002 Nobel Prize in Physics. According to briefings to the committee, sounding rocket projects have contributed to new technologies for X-ray Geiger counters and proportional counters, modulation collimators, multi-anode detectors, polarimeters, grazing incidence mirrors, and quantum calorimeters, and those flight technology developments were subsequently used on nearly a dozen spaceflight missions. FIGURE 1.7.1 Artist’s depictions of the UHURU (left) and Chandra (right) X-ray astronomy observatories. SOURCES: Courtesy of the Smithsonian Astrophysical Observatory (SAO) (left) and NASA Marshall Space Flight Center (right).
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An Enabling Foundation for NASA’s Earth and Space Science Missions astronomical instrument technologies (e.g., aberration-corrected holographic gratings, far-ultraviolet optical coatings, and X-ray calorimeters) that subsequently played an enabling role on more than 20 different space astronomy missions. Similarly, balloon flights have provided development and test opportunities for prototype X-ray and gamma ray optics and detectors, cosmic microwave background bolometers, cosmic ray isotope spectrometers, Earth-atmosphere limb sounders, and many other instruments. These technologies have been incorporated into many past, currently operating, and planned future spaceflight missions. Science and Engineering Workforce Each of the four science disciplines within SMD requires a workforce of scientists, engineers, and other technical specialists to successfully accomplish its mission and associated research objectives. Because of the specialized state-of-the-art nature of the work undertaken by SMD, workforce maintenance is not only mission enabling but also mission essential. The engineering workforce is maintained primarily at NASA centers and industry plus university and nonuniversity laboratories. The science workforce is maintained and developed primarily through a system of competitive grant programs that are subject specific.9 Workforce stability, especially at universities and other nongovernment laboratories, is very sensitive to the stability of funding available through these programs and quickly responds negatively to sudden cuts. It is inelastic because workforce that is lost one year due to funding shortfalls will not be available when monies suddenly return. Specialists often depart for other career opportunities, and it takes a decade to train replacement scientists (including graduate school and postdoctoral experience). Some workforce specialties, such as astronomy, have significant sources of funding through other agencies (e.g., NSF) and private institutions. Other areas, such as planetary science, are largely creations of SMD and its progenitors and have little support beyond that provided via SMD-funded research activities. While research programs in general are not designed or contemplated with workforce maintenance in mind, they are the core of that maintenance and also the principal means by which training graduate students, post-docs, and early-career specialists in the discipline occurs. SMD also supports focused programs targeting students and younger researchers. The skills needed both inside and outside NASA in managing a scientific research project develop through years of experience. SMD-sponsored programs in advanced technology development and suborbital flight projects are especially relevant for providing hands-on hardware experience in engineering disciplines. Thus there is an important distinction between training in specialized skills, which is where mission-enabling activities have an important role, and education, which is the responsibility of the universities. Examples of SMD training programs include the following: The NASA Earth and Space Science Fellowship program made awards to 87 graduate students in 2007 and 79 graduate students in 2008 across all four science discipline areas. (See Table 1.1 for discipline details.) The Earth Sciences division supports a New Investigator Program for junior scientists within 5 years of having received a terminal degree and is currently undertaking a new initiative to address the need for more young researchers having experience in building instruments within that community. The Planetary Sciences division supports a competitive Fellowship for Early Career Researchers Program providing additional salary and funding for equipment to researchers within 7 years of having received their Ph.D.10 Research grants to researchers at universities often include support for students who participate in research projects under the direction of a university faculty or research staff supervisor, and SMD-supported research projects frequently comprise the subjects of student dissertations. The sounding rocket, balloon, and aircraft programs are important training venues, not only for scientists but also for engineers and engineering managers, in designing, building, and operating flight instrumentation and 9 In briefing the committee, NASA officials reported that approximately 60 percent of SMD research grant funds goes to universities and other nongovernment laboratories, with about 33 percent going to NASA center researchers and the remainder going to other federal agencies. 10 For more information on SMD student and postdoctoral opportunities see the SARA Web site at http://nasascience.nasa.gov/researchers/sara/student-programs.
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An Enabling Foundation for NASA’s Earth and Space Science Missions payloads. All three types of vehicles support university-based research teams, and the typical project durations of a few years or less are good matches to the duration of a graduate student thesis project. They are equally important for students, early-career technical professionals, and junior NASA engineers and managers as unique opportunities to gain hands-on experience and insight into the disciplines of systems engineering and operations. (See Figure 1.2.) DIFFERENCES IN MISSION-ENABLING ACTIVITIES ACROSS SMD DISCIPLINE DIVISIONS The elements of the mission-enabling programs in each of the SMD science divisions—astrophysics, heliophysics, planetary science, and Earth science—are very similar. Each division provides some support for technology development, data analysis and interpretation, theory and modeling, workforce development, and so on. However, for each division, the balance among these various elements can differ depending how the science of the division is conducted, the extent to which other agencies support programs that complement or depend on NASA, and many other factors. To highlight some of the differences, the committee considered how the SMD divisions’ programs interact with the research programs of other agencies. In the case of planetary science, NASA is by far the principal sponsor of research, and thus programs supported by other agencies are not a major factor. In the case of astrophysics, the NSF, DOE, DOD, and even private foundations provide support for ground-based astronomical observations, and DOE also supports some spaceflight studies. In heliophysics, development of an operational capability in space weather modeling and forecasting is an important concern of DOD and NOAA; consequently both of those agencies and NSF provide complementary support for space weather research.11 Earth science has the most extensive interagency relationships because issues such as climate change and environmental monitoring are the concern of multiple agencies. Coordination of government climate change research receives particular attention from the White House, and global Earth observing systems are also an area of major international collaboration and coordination. There are also differences among the SMD divisions in the importance of numerical modeling. Researchers connected to all divisions make use of numerical modeling because this is the means by which data are interpreted, theoretical calculations are grounded, and complex physical processes are simulated and understood. In divisions where there is a current or ultimate end user who will depend on the predictive capability the models will provide, the modeling activity gets particular emphasis. In heliophysics, models of the Sun-Earth system ultimately need to provide the capability to predict space weather hazards and effects. In Earth science, advances in modeling the global Earth system—i.e., the biosphere, atmosphere, oceans, land surface, and cryosphere—will improve weather forecasting and predictions of climate change that will serve as the basis for major environmental policy decisions. Data analysis programs are often mission specific, and in such cases they are not treated in this report as a broader mission-enabling activity. The part of data analysis programs that is considered to be mission enabling is the analysis of data from past missions and programs that facilitates the synthesis and analysis of data from multiple missions. The level of emphasis on this mission-enabling activity depends on the suite of missions that is available in a particular field and the character of the scientific problems to be addressed. In heliophysics, many scientific problems require analysis of data from a suite of spacecraft, known collectively as the Heliospheric Great Observatory, launched during the last several decades. Analysis of current missions in astrophysics and planetary exploration are often done in the context of results from past missions. Earth science, which addresses the Earth as an integrated system, depends on the observations from multiple spacecraft and instruments, which need coordinated analysis and interpretation. The importance of ground-based and suborbital observations also varies among the divisions. Earth science is heavily dependent on aircraft and ground-based observations for ground-truth and for calibration and validation of spaceflight data. Significant scientific observations in astrophysics can be conducted from high-altitude balloons and aircraft. Sounding rockets have a important role in technology development, workforce development, and 11 NASA also has its own internal needs for operational space weather capabilities to understand and mediate space radiation risks to human spaceflight beyond low Earth orbit.
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An Enabling Foundation for NASA’s Earth and Space Science Missions FIGURE 1.2 Participation in sounding rocket flight investigations gives science and engineering students soup-to-nuts, systems-wide exposure to the process of designing, building, integrating, testing, and flying a space research mission, all on a relatively short timescale, low cost, and high risk tolerance. SOURCES: Top: Courtesy of Stephan McCandliss, Johns Hopkins University. Bottom: Shown is Pennsylvania State University (PSU) graduate student Ann Hornschemeier; courtesy of David N. Burrows, PSU.
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An Enabling Foundation for NASA’s Earth and Space Science Missions science in both heliophysics and astrophysics. Missions in planetary science require ground-based observations, especially for mission planning and often also to provide data to complement the spacecraft data. Technology development is a common need across the divisions, yet here too there are differences. In divisions that rely more on facility-class instruments, the technology advances need to feed into the major engineering organizations, especially NASA centers and industry, that will be responsible for the design and development of the facility instruments. When the instruments are developed by principal investigator-led teams, the technology advances may need to be available to university researchers. Theoretical research is also a common activity among the divisions, but there can be differences in who depends most on the research results. In divisions with a strong numerical modeling emphasis—i.e., heliophysics and Earth science—advances in theoretical research need to be strongly coupled with and feed into the modeling effort. As a consequence of the different roles mission-enabling activities have within each division, the committee believes that it is entirely appropriate for mission-enabling activities to be managed separately in each of the divisions and not consolidated in a single SMD mission-enabling program organization. The balance among different kinds of mission-enabling activities will surely differ substantially among the divisions, but it is to be expected that each division should include some level of support for each of the elements described previously in this chapter.