(NASA-CR-198818) THE FUTURE OF N95-31364 SPACE IMAGING. REPORT OF A COMMUNITY-BASED STUDY OF AN ADVANCED CAMERA FOR THE HUBBLE Unclas SPACE TELESCOPE Final Technical Report (Space Telescope Science Inst.) 150 p G3/89 0055789 TheFuture of SpaceImaging hen Lyman Spitzer first proposed a great, earth-orbiting telescope in I946, the nudear energy source of stars had been known for just six years. Knowledge of galaxies beyond our own and the understanding that our universe is expanding were only about twenty years of age in the human consciousness. The planet Pluto was seventeen. Quasars, black holes, gravitational lenses, and detection of the Big Bang were still in the future--together with much of what constitutes our current un- derstanding of the solar system and the cosmos beyond it. In I993, forty- seven years after it was conceived in a forgotten milieu of thought, the Hubble Space Telescope is a reality. Today, the science of the Hubble attests to the forward momentum of astronomical exploration from ancient times. The qualities of motion and drive for knowledge it exemplifies are not fixed in an epoch or a generation: most of the astronomers using Hubble today were not born when the idea of it was first advanced, and many were in the early stages of their education when the glass for its mirror was cast, The commitments we make today to the future of the Hubble observatory will equip a new genera- tion of young men and women to explore the astro- nomical frontier at the start of the 2I st century. / The Future of SpaceImaging Report of a Community-Based Study of_n Advanced Camera forthe Hubble Space Telescope Edited by Robert A. Brown Space Te[escope Science bmitute 3700 5hn Martin Ddve Ba[timore, Ma_[a,ld 21218 October J9_ II! Authorship This report is the product of the Future of Space hnaging study' and of the subsequent preparation of the proposal of the Advanced Camera to the ESA M3 competition 2, in which the following people participated or to which they contributed. It was our privilege to conduct this study and author this report on behalf of the international community of as- tronomers. We express our particular gratitude to our many colleagues who responded to the community survey. James Beletic' Georgia Institute of Technology Pierre Bely' Space Telescope Science Institute, ESA J. Chris Blades _ Space Telescope Science Institute Robert Brown I'2 Space Telescope Science Institute Christopher Burrows' Space Telescope Science Institute, ESA Mark Clampin ''2 Space Telescope Science Institute France Cordova 2 Pennsylvania State University Edward Cheng _ Goddard Space Flight Center James Crocker t'z Space Telescope Science Institute Greg Davidson National Aeronautics and Space Administration Jean Michel Deharveng 2 Laboratoire d'Astronomie Spatiale, Marseille Robert Fosbury _'2 ST-European Coordinating Facility, ESA John Hoessel _ University of Wisconsin John Huchra ''2 Center for Astrophysics Garth lllingworth z Lick Observatory Roll-Peter Kudritzki z University of Munich Tod Lauer' National Optical Astronomy Observatories Michael Lesser ''_ Steward Observatory Edwin Lob _ Michigan State University Duccio Macchetto 2 Space Telescope Science Institute, ESA Aden & Marjorie Meinel' Jet Propulsion Laboratory George Miley 2 Leiden Observatory PRECEDING PAGE BLANK NOT FI,LMEFPAC__.iL__ ii': f_£,_l!C:,_!_[_i.f_Ai:K Jv FOSI: Frontiers of Space Imaging Wal-rcll moos 1 Johns Hopkins University Jeremy Mould' California Institute of Technology Susan Ne_ Goddard Space Flight Center Francesco Paresce z Space Telescope Science Institute, Torino, ESA Ronald Polidan _ Goddard Space Flight Center Michel Sffisse z Laboraroire d'Astronomie Spatiale, Marseille Francois Schweizer' Carnegie Institution of Washington Donald York _ University of Chicago Preface In March I99Z, the National Aeronautics and Space Administration (NASA) Program Scientist for Hubble Space Telescope (HST) invited the Space Telescope Science Institute (ST Scl) to conduct a commu- ni[y-based study of an Advanced Camera (AC), which would be in- stalled on a scheduled HST servicing mission in [999. The study had three phases: a broad community survey of vicws ola the candidate sci- ence program and required performance of the AC, an analysis of tech- nical issues relating to its implementation, and a panel of experts to for- mulate conclusions and prioritize recommendations. An oral report was delivered in December r99z, at which time NASA made a second re- quest to ST ScI, to assist in preparing a proposed for the AC on behalf'of the astronomical community to the European Space Agent T (ESA) (.'_all Jbr Missio,z Ideas oF26 November i992 ("M3 competition.") A joint US- ESA science team was formed fbr this purpose, and the proposal was submitted in May i993. This report--- The l_)alo'e of Space [magip_-is a compilation of the results of'both the study and ESA proposal. VII Introduction The Hubble Space Telescope (HST) is a cooperative program of the European Space Agency (ESA) and the U.S. National Aeronautics and Space Administration (NASA) to operate a long-lived observatory, in space for the benefit of the international astronomical community. The three years since the launch of liST in 199o have been momentous, with the discovery of spherical aberration and the search for a practical solu- tion. HST was designed for servicing in orbit by the Space Shuttle. NASA and ESA are now preparing intensively for the first shuttle repair mission scheduled for December 1993, which should obviate the effects of spherical aberration and restore the functionality expected for HST at launch. Despite spherical aberration, hundreds of astronomers around the world are analyzing HST data and reporting their discoveries. The earl), results of HST are outstanding, as is illustrated by the recently published proceedings of an international conference, Science with the Hubble Space Telescope.' The HST program of astronomical research is un- matched by any ground-based telescope, and it refreshes the original vi- sion of what could be achieved by a great telescope unlettered by the Earth's atmosphere--a vision postponed briefly but not foreclosed by spherical aberration. HST is now at a crossroads with respect to the second half of its de- sign lifetimeIthe period after I997, when an advanced spectrograph and a near infrared camera will be installed on the second servicing mis- sion. In 1999, a third servicing mission will be required to restore the spacecraft orbit, which decays due to atmospheric drag. Owing to the long development time for space-qualified instruments, now is the time to make critical decisions with respect to what scientific instrument can or should be installed during the 1999 servicing mission. This instrument must be started now to be ready on time in I999. Over the past year and a half, in consultation with the international PRECEDING PAGE BLANK NOT FW..MEJ_ GE V_ INTENTIONALLYBLA/VK VIII FOSI: Frontiers of Space hnaging astronomical community, we have studied the issue of what best can be done with the I999 instrument opportunity. We have asked if there is still a role for HST at the turn of the century. The answer is clearly: Yes/ We are convinced that HST, properly instrumented, will make unique and important astronomical discoveries into the 2I_t century. This is be- cause no ground-based telescope, no matter how large nor how well equipped with adaptive optics, will match HST in terms of wavelength coverage and image quality over a wide field. We have asked what type of instrument will provide the greatest sci- entific benefit to astronomers. We are convinced that it should be a cam- era because otherwise an adequate optical and ultraviolet imaging capa- bility will not be assured in 1999. Furthermore, it should be advanced because detector and computer technology is now capable of deriving full value from a 2.4 m diffraction-limited telescope in space. What combination of scientific programs should define the priorities for the technical performance of the Advanced Camera (AC)? The breadth and depth of the highly competitive HST imaging science program. We have assessed the imaging tasks astronomers have proposed for or desired from HST, and we believe the most valuable 1999 instrument would be a camera with both near ultraviolet/optical (NUVO) and far ultraviolet (FUV) sensitivity, and with both wide field and high resolu- tion options. This report puts forth the scientific case and the technical basis for an AC. It lays the groundwork for a Phase A study to assure feasibility, de- termine cost and schedule considerations, and inform an Announce- ment of Opportunity for the astronomical community to participate in the development of the AC. 1. ST-ECF/STScl Workshop: Science with the Hubble Space Telescope, Pro- ceedings, eds. P. Benvenuti and E. Schreier, (Munich: European South- ern Observatory, i992.) Contents [. AD\:AN(Zlil) CAME1L,X SCIt,,NCE ................................................................................... 1 z. IN,_Tt',UMEN'r S']'ATU_; ................................................................................................ Z 7 3. Ol"l'l(:al, TH jsS(:OPr ASS_:.Mt_I Y. ............................................................................ 37 4- POINIIN(; PH_,FOI_,MANCE ........................................................................................ 43 5. AI)APTIVI", OIrI'ICS & HST 'UNIQUENF, SS SI'A(IF,'. .......................................... 59 6. Axial vs. RADiAl. BAY..............................................................................................77