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A Performance Assessment of Nasa’s Astrophysics Program 2 Summary of AANM Survey and Q2C Report Recommendations Following a tradition extending back to the 1960s, Astronomy and Astrophysics in the New Millennium (AANM; National Academy Press, Washington, D.C., 2001) surveyed recent progress in astronomy and astrophysics and made recommendations for the most important new initiatives in the decade 2000-2010. The survey process overlapped with a period of remarkably rapid advances in the field. Planets orbiting stars other than the Sun were being discovered; observations revealed density variations in the very early universe, a few hundred thousand years after the big bang, and clearly identified them as the seeds of galaxy formation; new objects were discovered in the outer part of the solar system, beyond the orbits of Neptune and Pluto; extremely distant galaxies were found near the edge of the observable universe; massive black holes were discovered in the centers of many galaxies; and, near the end of the 1990s, the existence of a new form of energy that pervades the entire universe and has repulsive gravity—called dark energy—was inferred from the discovery that the expansion of the universe is speeding up, not slowing down. Building on these and other advances, the AANM survey committee looked forward to identify several key problems as particularly ripe for progress in the years 2000-2010, including further elucidation and detailed measurements to better characterize the large-scale properties of the universe, including matter, energy, age, and expansion history; the dawn of the modern era of the universe, when the first stars and galaxies formed; the formation and evolution of black holes of all sizes; the formation of stars and planetary systems, including both giant and terrestrial-type planets; and the relationship of Earth to its astronomical environment.
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A Performance Assessment of Nasa’s Astrophysics Program The survey committee went on to lay out a plan under which the most exciting problems could be addressed, setting explicit priorities to guide NASA and the NSF in their allocation of available resources to optimize the return on the nation’s investment in astrophysics. The opening pages of the AANM survey emphasized the importance of balancing new initiatives with research efforts already underway, and ensuring adequate funding for unrestricted grants providing broad support for research— especially research programs involving students and young scientists just entering the field. These priorities were described as prerequisites for a vigorous scientific program extending over the next decade and beyond. The survey committee emphasized the critical need for NASA to maintain a diverse range of mission sizes including major, moderate, and small missions, in order to ensure the most cost-effective returns from space astrophysics. In addition, recognizing the important synergies between experimentation and theory, the survey committee spelled out the essential importance of integrating targeted theoretical efforts into plans for moderate and major new initiatives. The survey committee also emphasized the need for long-term investment in technology development to enable future advances not directly related to ongoing missions. The AANM survey prioritized recommendations for new initiatives into three categories—the major, moderate, and small classes mentioned above—on the basis of projected costs, including costs for the first 5 years of operation. The dividing lines between categories for space-based missions were set at $140 million and $500 million.1 In the major category, the clear top priority was a follow-on to the Hubble Space Telescope, the Next Generation Space Telescope (now known as the James Webb Space Telescope, or JWST). This proposed facility was to be an 8-meterclass infrared telescope with 100 times the sensitivity and 10 times the image sharpness of HST, and would involve cooperative participation by the European and Canadian space agencies. The cost to the U.S. government was estimated by NASA at $1,000 million, excluding some necessary technology development funded in a separate line. The second highly recommended major spaced-based initiative for the decade was Constellation X (Con-X), a suite of four powerful x-ray telescopes designed to study the formation and evolution of black holes. NASA’s estimated cost for Con-X was $800 million. In addition, the AANM survey strongly recommended NASA funding for the technology development required to develop the Terrestrial Planet Finder (TPF) and Single-Aperture Far Infrared Observatory (SAFIR). It was estimated that with suitable planning and development, these missions could be started in earnest near the end of the 2000-2010 decade. Top priority for space-based missions in the moderate category was assigned to the Gamma-ray Large Area Space Telescope (GLAST), with a NASA-estimated 1 Costs were provided in FY 2000 dollars.
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A Performance Assessment of Nasa’s Astrophysics Program cost of $300 million. GLAST was to be a joint NASA and DOE mission; it would provide observations of gamma rays from 10 MeV to 300 GeV with six times the effective area, six times the instantaneous field of view, and much better angular resolution than the Energetic Gamma Ray Experiment on NASA’s CGRO. Next in the ranking was the Laser Interferometer Space Antenna (LISA), designed to detect gravitational waves from merging supermassive black holes anywhere in the universe and from binary stars throughout the galaxy. International cooperation was assumed for each of these projects; NASA’s estimated U.S. cost for LISA was $250 million. Three additional space missions were also ranked: the Solar Dynamics Observer (SDO), designed to study the Sun’s outer convective zone and corona; the Energetic X-ray Imaging Survey Telescope (EXIST), which was to be attached to the International Space Station; and a facility known as Advanced Radio Interferometry between Space and Earth (ARISE), which would extend ground-based radio interferometry so as to provide a 10-fold increase in resolution for the study of regions near supermassive black holes and active galactic nuclei. In the small-mission category, the top NASA-related priority was funding to help create a National Virtual Observatory—a Web-based data-mining facility that would provide wide access to the huge digital collections of astronomical data then being acquired from many sources, and the even larger ones being proposed for the future. Augmentation of NASA’s Astrophysics Theory Program was deemed essential to help restore balance between the acquisition of data and the theoretical research needed to interpret it. Ultralong-duration balloon flights were identified as an important and cost-effective way of carrying out small near-space experiments at a fraction of the cost of satellites, and an Advanced Cosmic-ray Composition Experiment on the International Space Station was identified as a high priority. In late 1999, as the AANM decadal survey was nearing completion, the NRC’s Board on Physics and Astronomy hosted a science meeting on the frontiers of research at the intersection of physics and astronomy. Then-Administrator of NASA Daniel Goldin attended the meeting and at its conclusion asked the NRC to assess the science opportunities in this frontier area of interdisciplinary science and devise a plan for realizing those opportunities. NSF’s Assistant Director for Mathematical and Physical Sciences Robert Eisenstein and DOE’s Associate Director for High-energy and Nuclear Physics S. Peter Rosen joined Administrator Goldin in calling for such a study. The Committee on the Physics of the Universe (CPU) established as a result of the request issued an interim report in January 2001 and released its full report, Connecting Quarks with the Cosmos: Eleven Science Questions for the New Century (Q2C; The National Academies Press, Washington, D.C., 2003), in 2002. Motivations for the Q2C report included a rapidly expanding level of scientific activity at the interface of physics and astronomy, coupled with a concern that this research near the boundary between the disciplines of physics and
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A Performance Assessment of Nasa’s Astrophysics Program astronomy might somehow be overlooked in agency planning processes due to its interagency nature.2 The relevant science includes some of the most exciting areas of recent times: dark matter, dark energy and cosmic acceleration, inflationary cosmology, ultrahigh-energy cosmic rays, solar neutrinos and neutrino astronomy, the cosmic microwave background, and gravitational waves. To ensure that any overlap between recommendations in the Q2C report and the AANM survey would be constructive, the CPU was directed to focus on the science at the intersection of astrophysics and elementary particle physics and not to reprioritize the projects in the AANM survey report. Although it was unusual that two NRC reports touching on scientific opportunities in astronomy and astrophysics were issued in little more than 2 years, the two studies appear to have meshed very constructively3 and have helped build cooperative relationships between NASA, NSF, and DOE in supporting research in an important and rapidly moving field. The Q2C report identified 11 compelling science questions at the intersection of astronomy and physics: What is dark matter? What is the nature of dark energy? How did the universe begin? Did Einstein have the last word on gravity? What are the masses of the neutrinos, and how have neutrinos shaped the evolution of the universe? How do cosmic accelerators work and what are they accelerating? Are protons unstable? What are the new states of matter and energy at exceedingly high density and temperature? Are there additional space-time dimensions? How were the elements from iron to uranium made? Is a new theory of matter and light needed at the highest energies? The report made seven unranked recommendations for addressing these scientific questions, calling particular attention to the desirability of interagency cooperation in responding to them. In particular, the Q2C report recommended measuring the polarization of the cosmic microwave background (CMB), determining the properties of dark energy and other physical elements such as protons and neutrinos, and taking other steps pertaining to an increased understanding 2 Although the charge directed CPU to assess the intersection of physics and astronomy, NASA’s Astrophysics program focuses primarily on the intersection of the subfields of astrophysics and elementary particle physics, and the present report thus uses these more specific terms throughout. 3 For example, the two reports led to the development of NASA’s Beyond Einstein program, which provides a framework for investigating the physics of the universe.
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A Performance Assessment of Nasa’s Astrophysics Program of the astrophysical universe. In addition to these efforts in specified science areas, the Q2C report recommended that to realize the scientific opportunities at the intersection of physics and astronomy, the government should establish an interagency initiative on the physics of the universe, with the participation of DOE, NASA, and NSF, providing structures for joint planning and mechanisms for joint implementation of cross-agency projects. Two of the Q2C report’s recommendations provided additional support for three of the projects and missions recommended by the AANM survey: Con-X, LISA, and the ground-based Large-aperture Synoptic Survey Telescope (LSST). The support was based on the ability of these planned facilities to do science beyond that envisioned in the AANM survey that would be especially relevant to questions at the intersection of astrophysics and elementary particle physics. The Q2C report’s other recommendations did not overlap with those of the AANM decadal survey, and at least some did involve new projects for NASA, including a wide-field space telescope to probe dark energy (now called the Joint Dark Energy Mission, or JDEM) and a mission dedicated to searching for the polarization signature of inflation in the cosmic microwave background.
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