3
Astrophysics Program Plans and Progress

The AANM survey report and the Q2C report together recommended a coordinated program designed to address major astrophysical questions. The program included goals, strategies, and relative priorities, and it emphasized that optimizing scientific return would require, in addition to recommended NASA missions over a range of sizes, a correspondingly balanced program of astrophysical theory, data archiving, and data mining coordinated with continued development of the necessary scientific and technical workforce. The set of recommended missions for space-based science was highly diverse: Some were large, some moderate, and some small; and some required substantially more technology development than others.

In assessing the progress of NASA’s Astrophysics program toward achieving the goals outlined in NRC reports, it is essential to distinguish between accomplishments based on goals and priorities established in decadal reports that preceded the AANM survey, and those based on the more recent goals set in the AANM survey itself.

RECENT ASTROPHYSICS ACHIEVEMENTS

Recent NASA missions have delivered a scientific program in astrophysics that can only be described as spectacular.1 If anything, scientific progress has

1

All of the missions mentioned in this section were recommended in previous NRC decadal surveys of astronomy and astrophysics: the Hubble Space Telescope in Astronomy and Astrophysics for the 1970’s, and the Chandra X-Ray Observatory and Spitzer Space Telescope in Astronomy and Astrophysics for the 1980’s; the rest of the missions discussed are part of the Explorer line. Although not prioritized directly in The Decade of Discovery in Astronomy and Astrophysics (1991), the Small Explorer line was recommended for acceleration in that decadal survey report.



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A Performance Assessment of Nasa’s Astrophysics Program 3 Astrophysics Program Plans and Progress The AANM survey report and the Q2C report together recommended a coordinated program designed to address major astrophysical questions. The program included goals, strategies, and relative priorities, and it emphasized that optimizing scientific return would require, in addition to recommended NASA missions over a range of sizes, a correspondingly balanced program of astrophysical theory, data archiving, and data mining coordinated with continued development of the necessary scientific and technical workforce. The set of recommended missions for space-based science was highly diverse: Some were large, some moderate, and some small; and some required substantially more technology development than others. In assessing the progress of NASA’s Astrophysics program toward achieving the goals outlined in NRC reports, it is essential to distinguish between accomplishments based on goals and priorities established in decadal reports that preceded the AANM survey, and those based on the more recent goals set in the AANM survey itself. RECENT ASTROPHYSICS ACHIEVEMENTS Recent NASA missions have delivered a scientific program in astrophysics that can only be described as spectacular.1 If anything, scientific progress has 1 All of the missions mentioned in this section were recommended in previous NRC decadal surveys of astronomy and astrophysics: the Hubble Space Telescope in Astronomy and Astrophysics for the 1970’s, and the Chandra X-Ray Observatory and Spitzer Space Telescope in Astronomy and Astrophysics for the 1980’s; the rest of the missions discussed are part of the Explorer line. Although not prioritized directly in The Decade of Discovery in Astronomy and Astrophysics (1991), the Small Explorer line was recommended for acceleration in that decadal survey report.

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A Performance Assessment of Nasa’s Astrophysics Program been even more rapid than anticipated at the time of the AANM survey. Missions in operation at that time, such as HST, have continued to deliver essential data concerning the nature and origins of planets, stars, galaxies, and the universe. The pace of NASA-led launches from 1999 through 2004 was impressive, including Chandra (1999), FUSE (1999), HETE-2 (2000), WMAP (2001), GALEX (2003), CHIPS (2003), Spitzer (2003), and Swift (2004). These successful missions have given rise to an enormous breadth of scientific discoveries ranging from new information for studies of protoplanetary disks around nearby stars to measurements of supermassive black holes in active galactic nuclei and images of vast reservoirs of hot gas in clusters of galaxies. Gamma-ray bursts continue to be discovered and monitored through synoptic missions like Swift, and results from the WMAP mission have set entirely new standards of precision for the measurement of fundamental cosmological parameters. In all respects, these missions have delivered on their scientific promise in the best traditions of the NASA programs that proposed and executed them. Origin of the Universe: Geometry, Structure, and Contents NASA missions have provided key insights leading to validation or disproof of cosmological models. Understanding the nature of dark energy and dark matter requires conducting a census of basic constituents of the universe: dark energy, dark matter, baryons, heavy elements, stars, and so on, all as functions of cosmological time (Figure 3.1). The history of the universe is revealed in some detail by the density fluctuations traced by WMAP and the measurement of the present expansion rate (the Hubble constant) by HST. Large samples of Type Ia supernovas traced over a significant span of the history of the universe have become an important tool for measuring the properties of dark energy. Studies carried out with HST have been critical for rapid, more detailed observations of the most distant Type Ia supernovas discovered by automated ground-based searches and studied spectroscopically with the largest telescopes from the ground. HST has been essential for the detection and measurement of gravitationally induced cosmic shear, the apparent distortion in the elliptical shapes of galaxies caused by the gravitational bending of light as it travels through space, on small angular scales (Figure 3.2). Groundbreaking spectroscopic observations of deuterium, interstellar molecular hydrogen, and multiply ionized carbon and oxygen have been produced by the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite and by the Space Telescope Imaging Spectrograph (STIS) on HST, and have contributed to understanding of the content, distribution, and physical conditions of baryonic matter throughout the universe. NASA programs have been critical to understanding the

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A Performance Assessment of Nasa’s Astrophysics Program FIGURE 3.1 A composite with an x-ray image that reveals the location of the majority of the baryonic matter in the cluster (pink) and a gravitational lensing (shear) image that shows where the gravitating matter is. The blue color indicates the location of most of the mass. This experiment showed definitively that the gravitating matter is indeed dark, and the results ruled out theories that postulate that gravitating matter is hot and baryonic. SOURCE: X-ray image: NASA/Chandra X-Ray Center/Harvard-Smithsonian Center for Astrophysics/M. Markevitch et al. Optical image: NASA/Space Telescope Science Institute; Magellan/University of Arizona/D. Clowe et al. Lensing map: NASA/Space Telescope Science Institute; European Southern Observatory Wide Field Imager; Magellan/University of Arizona/D. Clowe et al. chemical history of the universe, including the creation of materials essential to the origins of life, through better documentation of the processes of nucleosynthesis inherent in stellar evolution. Origin and Evolution of Galaxies Following the 2002 servicing mission to Hubble, the multiwavelength combination of the Advanced Camera for Surveys (ACS) and Near Infrared Camera and Multi-Object Spectrometer (NICMOS) has delivered views of distant galaxies with unprecedented clarity and depth. These observations have revealed

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A Performance Assessment of Nasa’s Astrophysics Program FIGURE 3.2 The deepest image of the visible universe ever obtained, dubbed the “Hubble Ultra Deep Field,” is a 1 million-second-long exposure obtained by the Hubble Space Telescope. The image is a composite of one made in the optical portion of the spectrum with Hubble’s Advanced Camera for Surveys (ACS) and another obtained in the infrared with its Near Infrared Camera and Multi-Object Spectrometer (NICMOS). About 10,000 galaxies are evident, many of which are too faint to be seen in images obtained with ground-based telescopes. The combined image provides unprecedented detail on galaxies across cosmic time, especially the first generation of galaxies that formed within the first billion years after the big bang. SOURCE: NASA, European Space Agency, S. Beckwith (Space Telescope Science Institute), and the Hubble Ultra Deep Field team.

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A Performance Assessment of Nasa’s Astrophysics Program galaxies too faint to be seen by ground-based telescopes. Studies of the earliest epochs of star and galaxy formation are critical to an understanding of the era of cosmic reionization, and of the initial growth of cosmic structure on all scales. Studies with the Galaxy Evolution Explorer (GALEX) are revealing details of star formation in the local universe and its coupling to more global phenomena on galactic and intergalactic scales (Figure 3.3). Recent observations have provided critical clues that the growth of the central engines of active galactic nuclei and more normal galaxies are intimately linked. As a consequence, active galactic nuclei are no longer viewed as peripheral oddities but are understood within a more unified picture of galactic evolution. The growth of supermassive black holes in the centers of galaxies has been found to be tightly correlated with the masses of the stellar spheroids in which they are found, raising the question, Which came first, the galaxy or the supermassive black hole? Understanding the evolutionary relationship between supermassive black holes and their host galaxies, and characterizing the conditions under which galactic nuclei are active, are fundamental objectives discussed in both the AANM survey and the Q2C report. Exploring these related questions requires diverse information gleaned from both ground- and space-based observations, FIGURE 3.3 The “grand design” spiral galaxy pair NGC 5194 and NGC 5195, also known as M51, viewed in ultraviolet light by the Galaxy Evolution Explorer (GALEX) (left), in optical light from the Palomar Digitized Sky Survey (center), and in infrared light by the Two Micron All Sky Survey (right). The regularity and prominence of the spiral structure in the bigger galaxy NGC 5194 are believed to result from the gravitational effects of the passage of the smaller one NGC 5195 seen at the tip of its northern spiral arm. The ultraviolet image illustrates sites of ongoing high-mass star formation. In contrast, the long wavelengths trace the older long-lived stellar populations. Note that the small perturbing companion NGC 5195 is devoid of the hot, young, massive stars highlighted by GALEX. SOURCES: NASA/California Institute of Technology (left); Digitized Sky Survey (center); University of Massachusetts/Infrared Processing and Analysis Center/ California Institute of Technology/NASA/NSF (right).

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A Performance Assessment of Nasa’s Astrophysics Program as well as theory and simulations. There is now a much better census of active galactic nuclei, and Chandra observations have resolved the x-ray background into a set of sources that nearly all correspond to active galactic nuclei at the center of normal galaxies. In the cores of galaxy clusters the echoes of multiple and powerful active galactic nuclei outbursts can be observed, and their effect on the formation of other galaxies can be explored. Observations with the Spitzer Space Telescope reveal distant, massive clusters containing some of the most massive galaxies in the universe, seen as they are still in early stages of formation. Origins of Black Holes and the Gamma-Ray Burst Mystery Great progress has been made in solving the mystery of gamma-ray bursts (GRBs), now thought to be the birthing signals of stellar-mass black holes. HST and the largest ground-based telescopes have captured such events as they occurred, observations that have helped to characterize the host galaxies. From this work long-duration GRBs were discovered to be associated with distant galaxies, and a few have been clearly associated with supernovas. Swift is now providing large statistical samples of GRBs, and the short-duration GRBs have been localized using the capabilities of HETE-2. The synergistic observations possible with three Great Observatories and large ground-based telescopes have provided unprecedented opportunities to explore multiwavelength, time-varying phenomena to obtain a more complete picture of the physical processes in pulsars and neutron stars, star-formation regions, active galactic nuclei, and the most distant and youngest galaxies known (Figure 3.4 and 3.5). Origins of Stars and Planets With its unprecedented capability to examine dusty clouds that are opaque at optical wavelengths, the Spitzer Space telescope has delivered exquisite images of disks around forming stars: the birthplaces of planets. Complementary to studies of the coldest, darkest clouds at millimeter and submillimeter wavelengths, Spitzer observations at mid- and far-infrared wavelengths provide unique and vital probes of clouds at somewhat warmer temperatures. Spitzer detections of debris and transition disks enable studies of the mechanisms by which planetary systems might form, while Spitzer and HST both provide insight into the physical conditions characteristic of extrasolar planets. For the first time, Spitzer has detected the warm infrared glow of two previously detected “hot Jupiter” planets, massive gaseous extrasolar planets that orbit very close to and rapidly around their parent stars. Spectral observations with HST yield clues to the chemical composition of the extrasolar planetary atmospheres and may even reveal how hot Jupiters, because of their proximity to the central star, may lose a substantial fraction of their atmospheres, leaving behind planets with hydrogen deficiencies or no atmospheres at all.

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A Performance Assessment of Nasa’s Astrophysics Program FIGURE 3.4 The giant elliptical galaxy M87. The top image is a composite showing x-ray (red) and optical (blue) emission from M87 at the heart of the Virgo cluster. The optical light arises from stars in the galaxy, and the x-rays trace hot gas, fed by the supermassive black hole at the galaxy’s center. The hot gas outlined by the x-rays shows a series of loops and bubbles that can be traced to outbursts emanating from close to the black hole. The bottom image shows a close-up of high-energy x-rays in the very hot central region, showing the ring-like signature of an outward propagating shock wave (rather like a sonic boom) as expected from an outburst near the black hole. Such images allow researchers to understand the nature and behavior of supermassive black holes in galaxies. SOURCE: X-ray image: NASA/Chandra X-Ray Center/Harvard-Smithsonian Center for Astrophysics/W. Forman et al. Optical image: Digitized Sky Survey.

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A Performance Assessment of Nasa’s Astrophysics Program FIGURE 3.5 Composite image of the optical (red) and x-ray (blue) emission from the Crab Nebula, the remnant of an exploding supernova event that could be seen from Earth with the naked eye in 1054 A.D. The core of the star remains today as a rapidly rotating neutron star and is observed as a radio and x-ray pulsar; the star rotates 33 times per second. The star’s outer layers, still expanding away from the core, make up the extended glowing nebula seen in this image. The extent of the x-ray emission is smaller than that of the optical light because the higher-energy x-ray-emitting electrons radiate energy more rapidly as they move than do the electrons associated with the optical emission. SOURCE: Optical image: HST (NASA/HST/Arizona State University/J. Hester et al.). X-ray image: Chandra X-ray Observatory (NASA/HST/Arizona State University/J. Hester et al.).

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A Performance Assessment of Nasa’s Astrophysics Program PLANS AND PROGRESS TOWARD RECOMMENDED GOALS Nearly all of the exciting scientific progress summarized above was accomplished with instruments planned and developed in the 1990s or earlier. In this section the committee focuses on NASA’s planning and implementation for the achievement of goals recommended for astrophysics for the remainder of the present decade and beyond. Decadal surveys articulate and prioritize the science goals identified by the community for the upcoming decade and recommend ground- and space-based projects and missions for achieving those goals. Implementation is guided by the roadmaps that NASA generates every 3 years. As laid out in the 2003 roadmaps, the 2003 program plan for the Astrophysics Division provided a logical progression of missions to properly address the recommendations of both the AANM survey and the Q2C report,2 including recommendations for science priorities as well as those for program balance in terms of mission goals, types, and sizes; technology development; infrastructure support; and other non-mission-related activities. In 2003, what is now the Astrophysics Division was made up of two program units: Structure and Evolution of the Universe (SEU), and Origins. Each developed its own roadmap. The Origins roadmap3 covered primarily those missions designed to observe in the optical and infrared portions of the spectrum, in order to address questions about the formation of galaxies, stars, and planets. The SEU roadmap,4 a plan for the implementation of several missions in high-energy astrophysics and cosmology, was able to integrate the AANM survey’s astrophysical goals with the scientific opportunities identified in the Q2C report, creating a coherent program now called the Beyond Einstein program. The Beyond Einstein program was also an integral component of the interagency plan led by the Office of Science and Technology Policy for responding to the science opportunities identified in the Q2C report.5 In the 2006 draft science plan produced by NASA’s Science Mission Directorate6 and reviewed by the NRC,7 the outlook for astrophysics missions differs 2 The Solar Dynamics Observatory mission recommended in the AANM survey is part of NASA’s Heliophysics Division and therefore not discussed in the present report. 3 National Aeronautics and Space Administration, Origins Roadmap, Washington, D.C., January 2003. 4 National Aeronautics and Space Administration, Beyond Einstein: From the Big Bang to Black Holes, Washington, D.C., January 2003. 5 National Science and Technology Council Committee on Science, A 21st Century Frontier for Discovery, The Physics of the Universe: A Strategic Plan for Federal Research at the Intersection of Physics and Astronomy, Office of Science and Technology Policy, Washington, D.C., February 2004. 6 National Aeronautics and Space Administration, NASA Science Plan, Draft 3.0, Washington, D.C., June 23, 2006. 7 National Research Council, “Review of NASA’s 2006 Draft Science Plan,” letter report, The National Academies Press, Washington, D.C., 2006.

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A Performance Assessment of Nasa’s Astrophysics Program considerably from that in the 2003 plan. As Table 3.1 shows, the 2006 plan forecasts delays in the 2003 plan’s projections—changes that will delay progress toward the achievement of established scientific goals. Obviously many constraints within and outside NASA can lead to program delays and deferrals, and NASA must formulate plans for its Astrophysics program, together with its many other programs, within the framework of the agency’s overall budget and mission. But the fact that GLAST (2007) and JWST (2013) are the only NASA-led moderate or major new space astrophysics missions slated for completion or even for substantial progress in the 2000-2010 decade is disappointing. Nevertheless, the committee believes that NASA has generally done well in crafting program plans that are responsive to the science goals and opportunities outlined in the AANM survey and the Q2C report. Providing Missions for New Science Although NASA’s Astrophysics program plans address the NRC’s recommendations, progress toward achieving the recommended missions has not matched the anticipated pace.8 As mentioned above, NASA’s currently operating missions have begun to address the scientific goals of the AANM survey report, but to continue to make progress (as well as to address the scientific opportunities identified in the Q2C report), new missions are necessary. JWST The top-priority major space mission for implementation in the present decade is the James Webb Space Telescope. NASA has taken its high priority seriously. The technology development effort has been substantial and successful, leading to significant risk reduction, particularly in the areas of detectors, scientific instruments, and flight mirror blanks. The flight system design, currently in Phase B, is occurring on the baseline schedule with the preliminary design review and subsequent transition to Phase C/D expected in 2008. Launch is planned in the 2013 timeframe. The development of JWST has not been without problems. The estimated cost for design and development of the mission, including the launch vehicle, is $3.3 billion, roughly $2 billion (in FY 2006 dollars) more than the AANM decadal survey anticipated. This cost increase can be traced to a number of factors. The cost estimate provided by NASA to the AANM decadal survey committee was unrealistically low. The agency rebaselined the project in 2004, providing a more realistic cost estimate of $2.5 billion through to launch. Since that baseline was established, the cost of the project has increased by nearly another billion dollars. 8 This section does not discuss the ARISE mission, which has not been funded and does not appear in any NASA roadmap.

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A Performance Assessment of Nasa’s Astrophysics Program TABLE 3.1 Summary of NASA Plans for Recommended Largeand Moderate Astrophysics Missions   Launch Dateb Mission Recommended bya 2003 Plan 2006 Plan Hubble Space Telescope Servicing Mission-4 AA1980, DDAA, AANM 2004 2008 Space Infrared Telescope Facility (SIRTF) AA1980, DDAA 2003 Launched August 2003 Stratospheric Observatory for Infrared Astronomy DDAA, AANM 2005 Canceledc Space Interferometry Mission AA1980, DDAA, AANM 2005-2010 NET 2015 Keck Telescope Outriggers   2003 Canceled Herschel/Planck ESA 2007 2008 Gamma-ray Large Area Space Telescope AANM 2007 2007 Kepler (Discovery) AANMd 2007 2008 James Webb Space Telescope AANM 2005-2010 2013 Constellation-Xe AANM, Q2C NET 2011 NET 2016 Terrestrial Planet Finder AANM (td) 2010-2015 NET 2018 Laser Interferometer Space Antennae AANM, Q2C NET 2011 NET 2016 Black Hole Finder Probee AANM NET 2012 Deferred Single Aperture Far Infra-Red Observatory AANM (td) Deferred Deferred Inflation Probee Q2C NET 2012 Deferred Joint Dark Energy Missione Q2C NET 2012 Deferred LBTI (Large Binocular Telescope Interferometer) AANM 2005 2009 aAA1980, Astronomy and Astrophysics for the 1980’s (1982); DDAA, The Decadeof Discovery in Astronomyand Astrophysics(1991); ESA, European Space Agency; AANM, Astronomy and Astrophysics in the New Millennium(2001); Q2C, Connecting Quarkswith the Cosmos: ElevenScience Questions for the New Century (2003); (td), missions recommended for technology developmentin this decade. bNET, no earlier than. cSOFIA has since been reinstated by NASA, with a goal of beginningscience operations in 2012. dAANM recommended a diverse range of NASA mission sizes, but didnot identify particular Discovery- or Explorer-class missions. eDenotes a Beyond Einstein program mission.

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A Performance Assessment of Nasa’s Astrophysics Program NASA had attributed half of that increase ($530 million) to a 22-month slip in the projected launch date, a slip that the program traces to a limitation of funds for the project in FY 2005 and FY 2006 and a delay in receiving approval to use a foreign launch vehicle.9 Another third of the increase ($386 million) is due to growth in the cost of the mission. The remaining increase ($125 million) is attributable to additional contingency budget reserves being added to the project.10 The JWST project has had two descopes to date, including a change from an 8-m-class to a 6-m-class mirror and a reduction of short-wavelength capability. Nevertheless, this large and challenging program appears to be healthy and on a path to being capable of accomplishing most of its stated scientific requirements. It has met all its cost, schedule, and technical milestones since being replanned in September 2005. At the same time, its past cost growth and schedule slippage cause the committee to be concerned about its continued success in meeting technical milestones and cost estimates. As the highest-priority large mission, JWST remains critical to realization of the goals set forth in the AANM survey report. GLAST The AANM survey’s highest-priority recommendation in the moderate space mission category was the Gamma-ray Large Area Space Telescope (GLAST), on which NASA and DOE have worked together as the developing agencies. The GLAST team and NASA officials told the committee that GLAST was a model for interagency cooperation, and that although there were problems (such as a cost overrun on the Large Area Telescope, the primary instrument on the spacecraft), the agencies were able to resolve them successfully. The mission is planned for launch in 2007. TPF The AANM decadal survey committee broke new ground by recommending that NASA invest in technology for missions that would not be ready to begin development until the decade beyond that addressed by the report. One of these recommendations was that NASA commit $200 million for technology development for an interferometric Terrestrial Planet Finder (TPF) mission. Following rapid advances in coronagraph technology, NASA chose in 2003 to divide the project into two missions, an interferometer (TPF-I) and a coronagraph (TPF- 9 The magnitude of the impact of the delayed Ariane launch decision is unclear; it is possible that the delay caused by the decision gave the project time to make progress in areas that potentially would have caused a similar slip. 10 Presentation from Phil Sabelhaus, JWST project manager, at the June 2006 meeting of the Space Studies Board.

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A Performance Assessment of Nasa’s Astrophysics Program C) version, and began to invest in technology for both missions with a goal of launching TPF-C near the end of the decade. This change in strategy was assessed in an NRC letter report that made the interim recommendation that NASA return TPF to the originally recommended spending level, in part to preserve balance with other projects.11 Since that time, TPF funding has been reduced such that the projected launch date for either version is now no earlier than 2018. Einstein Great Observatories NASA’s 2003 Beyond Einstein roadmap identified the Constellation X-ray Observatory (Con-X) and the Laser Interferometer Space Antenna (LISA) as Einstein Great Observatories. Con-X was the second-priority large-category mission recommended by the AANM survey, and LISA was the second-priority moderate mission. Both missions were also recommended in the Q2C report. Since the release of the AANM survey report, cost estimates for both Con-X and LISA have grown, and as a result LISA is now also classified as a flagship mission—an Einstein Great Observatory. To this point both missions have received technology development support from NASA, but the investment has been unsteady and far less than that envisioned in the AANM decadal survey ($1,050 million combined). LISA is a collaboration with the European Space Agency (ESA), and both ESA and NASA have funded the Space Technology-7 (ST-7) technology demonstration mission, which will validate a number of technologies critical to the project. ST-7 is planned for launch in 2010 or 2011. Einstein Probes NASA’s Beyond Einstein roadmap highlighted three missions recommended by the NRC as Einstein Probes, and it recommended that NASA conduct these missions as competitively selected principal-investigator-led missions with a cost cap of $600 million. Although a number of mission concept studies have been supported, no Announcement of Opportunity is expected for these missions until at least 2009. The Q2C report recommended that NASA collaborate with the Department of Energy on the Joint Dark Energy Mission, a wide-field telescope in space that would explore the acceleration of the expansion of the universe. NASA has competitively selected three proposals for mission concept studies, and the results of those studies are due in 2008. Also explicitly recommended in the Q2C report was the Inflation Probe, which would aim to detect the signature of inflation in the infant universe by measuring the polarization of the cosmic microwave background (CMB). NASA 11 National Research Council, “Review of Science Requirements for the Terrestrial Planet Finder: Letter Report,” letter report, The National Academies Press, Washington, D.C., 2004.

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A Performance Assessment of Nasa’s Astrophysics Program has funded a number of mission concept studies designed to address the goals of this mission and has cooperated with NSF and DOE to support the CMB roadmap activity called for in the Physics of the Universe12 report. The Black Hole Finder Probe is the roadmap’s response to the AANM survey’s third-priority moderate mission, the Energetic X-ray Imaging Survey Telescope (EXIST). The Black Hole Finder Probe would conduct a census of accreting black holes, from supermassive black holes in the nuclei of galaxies, to intermediate-mass (about 100 to 1000 solar-mass) holes produced by the very first stars, to stellar-mass holes in the Milky Way Galaxy. In August 2006, NASA requested that the NRC conduct a study to identify which of the five Beyond Einstein mission concepts (the two Einstein Great Observatories and the three Einstein Probes) should be started first, based on both scientific priority and technology readiness. The report is due in September 2007, to help the agencies prepare for a FY 2009 start. Unprioritized Recommended Missions The AANM survey report recommended that NASA implement or participate in a number of missions that were not included in the report’s priority list. These missions were either missions recommended in previous NRC decadal surveys (HST, SOFIA, SIM) or missions led by foreign partners (such as the Herschel/ Planck mission). HST continues to produce exceptional science despite the effects of aging and the loss of the Space Telescope Imaging Spectrograph (STIS). NASA’s long-delayed SM-4 servicing mission, recommended by the AANM survey, will install the Wide Field Camera 3 and Cosmic Origins Spectrograph instruments, recover the STIS capability, and install replacement components that will prolong its life-time for 5 years or more. However, the delay in the servicing mission (discussed in Chapter 4) has cost the Astrophysics Division more than $600 million. The Stratospheric Observatory for Infrared Astronomy (SOFIA) is a general-purpose suborbital observatory designed to operate in the lower stratosphere above 99.8 percent of the obscuring atmospheric water vapor. The mission’s scientific goals have not changed since the mission was recommended in the NRC’s 1991 decadal survey,13 and the AANM survey recommended that NASA complete the project. The first flights for SOFIA are planned for 2009, and the observatory is expected to move to operational status in 2012. The Space Interferometry Mission (SIM; now SIM PlanetQuest) was origi- 12 National Science and Technology Council Committee on Science, A 21st Century Frontier for Discovery, The Physics of the Universe: A Strategic Plan for Federal Research at the Intersection of Physics and Astronomy, Office of Science and Technology Policy, Washington, D.C., February 2004. 13 National Research Council, The Decade of Discovery in Astronomy and Astrophysics, National Academy Press, Washington, D.C., 1991.

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A Performance Assessment of Nasa’s Astrophysics Program nally designed to measure the distances to stars throughout the Milky Way Galaxy with significantly more accuracy than is currently possible. The prospect now of the mission’s capability to detect planets around nearby stars has enhanced its scientific value. The AANM survey endorsed this expanded science case and recommended that the mission be completed. SIM PlanetQuest’s technology development has been completed successfully, but the mission is being held in the formulation phase due to budgetary constraints. The long tradition of NASA cooperation on foreign astrophysics missions continues with Herschel/Planck. These missions are being successfully implemented with a substantial science return relative to the money invested. Herschel will make observations in the full far-infrared and submillimeter waveband and will study dust-obscured and cold objects, such as clouds of gas and dust in areas of new star formation, planetary disks, and the first galaxies. Planck will map the cosmic microwave background anisotropies with improved sensitivity and angular resolution, testing inflationary models of the early universe, among other investigations. Explorers The Explorer program specializes in the development of small (SMEX) to medium-class (MIDEX) missions using available technology to provide a low-cost quick response to targeted opportunities for scientific discoveries. For example, when gamma-ray bursts were discovered, the Swift mission was quickly conceived, proposed, built, and launched to address the mystery. When the COBE mission discovered anisotropy in the cosmic microwave background radiation from the infant universe, it was possible to deploy the WMAP mission quickly to exploit the discovery. As noted above, small-scale missions in the current decade have been very productive, with HETE-2, WMAP, RHESSI, CHIPS, GALEX, and Swift launched in the years 2000 to 2004. Despite unstable funding, WISE is now in Phase C/D and scheduled for launch in late 2009. NASA had also selected the NuSTAR SMEX proposal for detailed study, but lack of funds resulted in termination just before the project’s confirmation review. According to NASA’s 2006 Astrophysics program plan, the next competition is scheduled for 2008, which would lead to a 2013 launch. Mission Support Activities NASA’s agency culture is centered on flight missions, but supporting activities such as general technology development and grant support for research, data analysis, and theory are necessary to make NASA’s astrophysics missions successful. Technology development is clearly identified in the AANM survey report

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A Performance Assessment of Nasa’s Astrophysics Program as essential to efficient and cost-effective preparation for future missions not yet slated for development, such as SAFIR. Traditionally development funds were provided by both the Astrophysics Division and the Office of Aerospace Technology (OAT). Before its elimination, OAT provided roughly $40 million per year in technology development that was applicable to astrophysics missions (some of those funds were captured by the Astrophysics Division when OAT was eliminated). The AANM survey report also recommended that NASA tie support for theory research to flight missions, particularly in the form of theory challenges, in order to encourage theorists to contribute to the planning of missions and to the interpretation and understanding of the scientific results. The support for theory connected to operating missions, particularly the Great Observatories, has been adequate but tends not to support the kind of open-ended thinking that is essential to generating ideas that can drive next-generation missions. NASA included support for theory in the TPF and Beyond Einstein Foundation Science programs (although there has been a virtual elimination of the TPF Foundation Science line in FY 2006). The Astrophysics Division attempted to add a Theory Challenge line to the JWST program in the early part of the current decade, but that line was eliminated in the administration’s budget formulation process, and the division has not attempted to recreate it or to provide a Theory Challenge for the GLAST mission. Ensuring the Diversity of NASA Missions The AANM survey report stated that both flagship and Explorer missions are important, noting that, at the time the report was written, opportunities for moderate-scale missions were less readily available. The AANM report recommended that NASA encourage a diverse range of mission sizes in order to produce the most effective science return from the program. Although six astrophysics Explorer missions have been launched in the current decade, those launches are the result of development work performed mostly in the 1990s. Now it appears that only one Explorer mission will be developed and launched in this decade, and at most one Explorer will begin development in this decade for launch in the next. The comparison between this decade and the previous is stark, leading the committee to conclude that NASA has chosen to concentrate its resources on the highest-priority large and moderate missions, to the detriment of the Explorer line and other small initiatives. In so doing, the Astrophysics Division has failed to adequately respond to the AANM survey report’s recommendation that NASA maintain a diverse mission portfolio.