m^f. THE NEXT GENERATION SPACE TELESCOPE I Mr Simulated images Cover: Two simulated images by James Gunn illustrate the improvements in resolution and sensitivity that the NGST would give when compared to the Hubble Space Telescope. TELESCOPE iVJASA SCIENCE National Aeronautics and INSmUTE Space Administration THE NEXT GENERATION SPACE TELESCOPE Proceedings of a Workshop jointly sponsored by the National Aeronautics and Space Admnistration and the Space Telescope Science Institute and held at the Space Telescope Science Institute Baltimore, Maryland, 13-15 September 1989 Editors: Pierre-Yves Bely and Christopher J. Burrows Space Telescope Science Institute Garth D. Illingworth University of California, Santa Cruz Published and distributed by the Space Telescope Science Institute 3700 San Martin Drive, Baltimore, MD, 21218 CTK^ ' r-t J Scientific Organisation Committee: Garth D. Illingworth (Chair), University of California James Roger Angel, University of Arizona Jacques M. Beckers, European Southern Observatory James E. Gunn, Princeton University Donald N.B. Hall, University of Hawaii Malcolm Longair, Royal Observatory, Edinburgh Hervey S. (Peter) Stockman, Space Telescope Science Institute Edward J. Weiler, NASA Headquarters Local Organisation Committee: /4^r[^TrAav>^^i Lc\o^<^<' "^ Pierre Y. Bely (Chair) ^ 6?6 Burrows Christopher ^.g J ^^^^ _ ^ Barbara EUer . / Hervey S. (Peter) Stockman ' " 1 TABLE OF CONTENTS Foreword 1 Conclusions of the Workshop 5 Sage Advice 7 SESSION 1. INTRODUCTION AND PLANS Sumnciary of Space Science Board 1995-2015 Study, G. Field, CFA 11 Status and Future of NASA Astrophysics, E. Weiler, NASA Headquarters . 16 ESA Long Term Plans and Status, F. Macchetto, STScI 27 The Next Generation UV-Visible-IR Space Telescope G. Illingworth, UCSC . 31 SESSION 2. SCIENTIFIC POTENTIAL NGST and Distant Galaxies, J. Gunn, Princeton 39 Planetary Astronomy with a Large Space Telescope, R. Brown, STScI ... 44 Star Formation Studies with a Large Space Telescope, L. Blitz, U of Maryland 49 Quasi-stellar Objects and Active Galactic Nuclei: Prospects for a 10 meter Space Telescope, J. Miller, Lick Obs 54 Stellar Populations in Galaxies: the Scientific Potential for a 10-16 m Space Telescope, J. Gallagher, AURA 61 Quasar Absorption-line Studies with HST Successor, R. Green, NOAO ... 72 Use of 16m Telescope to Detect Earthlike Planets, R. Angel, Steward Obs. 81 SESSION 3. LARGE OPTICS: GROUND-BASED DEVELOPMENTS The Keck Telescope Project, J. Nelson, Lawrence Berkeley Lab., UCB ... 99 Stressed-lap Polishing, H.M. Martin and J.R.P Angel, Steward Obs. 101 Large Telescope 0-IR Astronomy from the Ground, N. Woolf, Steward Obs 110 SESSION 4. CURRENT PROPOSALS AND STUDIES Considerations for a Next Generation UV-Optical Space Telescope, M. Nein and S. H. Morgan, NASA MSFC 117 IBIS: An Interferometer-Based Imaging System for Detecting Extrasolar Planets with a Next Generation Space Telescope, D. Diner, JPL 133 The Large Deployable Reflector, P. Swanson, JPL 142 PAMELA: High Density Segmentation for Large, Ultra-light, High Performance Mirrors, J. Rather et al, Kaman Aerospace Corp. 147 Optical Interferometry from Space, R. Stachnik, NASA Headquarters .... 157 Direct IR Interferometric Detection of Extrasolar Planets, M. Shao, JPL . 160 SESSION 5. TECHNOLOGIES FOR lARGE, HIGH THROUGHPUT WIDEBAND OPTICAL SYSTEMS IN SPACE Design Concepts for Very Large Aperture, High-performance Telescopes, D. Korsch, Korsch Optics 171 The Lunar Configurable Array Telescope (LCAT), A. Meinel/M. Meinel, JPL 177 Large Optical Fabrication Considerations and Speculation about the Overall NGST Configuration, M. Krim, Perkin Elmer 182 Large Segmented Optics Fabrication and Wavefront Control, R. Vyce, Itek . 198 Fabrication of Large and Fast Mirrors with Extroardinary Smooth Surfaces, D. Knohl, Carl Zeiss 209 Economical Production of Large Optics, D. Pileri and W. Prensky, Kodak . 217 Super Smooth Optics for Extrasolar Planet Detection, R.J. Terrile, JPL, and C. Ftaclas, Hughes 225 Sensing and Control for Large Opticcd Systems, A. Wissinger, Perkin Elmer . 232 Requirements for Diffraction Limited Optics, C. Burrows, STScI 241 Precision Segmented Reflectors (PSR), R. Lin, JPL 252 ASCIE: An Integrated Experiment to Study Control Structure Interaction in Large Segmented Optical Systems, J-N Aubrun and K. LoreU, LMSC . 256 Control Structure Interaction (CSI) Technology, W. Layman, JPL 263 Pointing Control System for a 10 meter Space Telescope, D. TenereUi, LMSC 270 Moving Target Tracking for a Next Generation Space Telescope, D. SkiUman, NASA GSFC 274 Passive Cooling of a 10 meter Space Telescope, P. Tulkoff, Swales 279 Cryogenics for Space Observatories: Technology, Requirements, Issues, H. Schember , JPL 285 Visible and UV Detectors for High Earth Orbit and Lunar Observatories, B. Woodgate, NASA GSFC 296 Infrared Detectors for a 10 m Space or Lunar Telescope, R. Thompson, Steward Obs 310 SESSION 6. SPACE LOGISTICS Advantages of High vs. Low Earth Orbit for SIRTF, P. Eisenhardt and M. Werner, NASA Ames 321 Orbital Sites Tradeoff Study, D. Neill, P. Bely, G. MiUer, and A. Spigler, STScI 333 The Moon as a Site for Astronomical Observatories, J. Burns, New Mexico State U 341 Required Technologies for a 10-16 m UV-Visible-IR Telescope on the Moon, S. Johnson and J. Wetzel, BDM Corp 348 Space Logistics: Launching Capabilities, R. Furnas, NASA Headquarters . 360 On-orbit Assembly and Maintenance, D. Soderblom, STScI 365 Technological Spinoff from the Next Generation, V. Trimble, UMD/UCI . 367 List of Participants 369 FOREWORD In Space Science in the Twenty-First Century, the Space Science Board of the Na- tional Research Council identified high-resolution interferometry and high-throughput instruments as the imperative new initiatives for NASA in astronomy for the two decades spanning 1995 to 2015. In the optical range, the study recommended an 8 to 16-meter space telescope, destined to be the successor of the Hubble Space Telescope (HST), and to complement the ground-based 8 to 10-meter-class telescopes presently under construction. It might seem too early to start planning for a successor to HST. In fact, we are late. The lead time for such major missions is typically 25 years, and HST has been in the making even longer with its inception dating back to the early 1960s. The maturity of space technology and a more substantial technological base may lead to a shorter time scale for the development of the Next Generation Space Telescope (NGST). Optimistically, one could therefore anticipate that NGST be flown as early as 2010. On the other hand, the planned lifetime of HST is 15 years. So, even under the best circumstances, there will be a five year gap between the end of HST and the start of NGST. The purpose of this first workshop dedicated to NGST was to survey its scientific po- tential and technical challenges. The three-day meeting brought together 130 astronomers and engineers from government, industry and universities. Participants explored the tech- nologies needed for building and operating the observatory, reviewed the current status and future prospects for astronomical instrumentation, and discussed the launch and space support capabihties likely to be available in the next decade. To focus discussion, the invited speakers were asked to base their presentations on two nominal concepts, a 10-meter telescope in space in high earth orbit, and a 16-meter telescope on the moon. Artist's view of these two concepts are shown in Figures 1 and 2, and their specifications are summarized in Table 1. The workshop closed with a panel discussion focused mainly on the scientific case, siting, and the programmatic approach needed to bring NGST into being. The essential points of this panel discussion have been incorporated into a series of recommendations that represent the conclusions of the workshop. Speakers were asked to provide manuscripts of their presentation. Those received were reproduced here with only minor editorial changes. The few missing papers have been replaced by the presentation viewgraphs. The discussion that follows each speaker's paper was derived from the question and answer sheets, or if unavailable, from the tapes of the meeting. In the latter case, the editors have made every eflFort to faithfully represent the discussion. We are most thankful to all the speakers for their very thoughtful and valuable con- tributions. Their vast experience in science and engineering wiU be essential for the successful completion of a project of this scale. Thanks are due to Roger Angel, Jack Burns, Don Hall, Duccio Macchetto, Joe Miller, Jean OHvier, Peter Stockman, Dominick TenereUi, and Rodger Thompson for chairing the various sessions or for their participation in the panel. We would also Uke to thank John Bahcall who introduced the workshop by sharing some of his experiences with the HST project. His pertinent remarks about the dedication of those involved in the development of HST emphasized the deep and widespread commitment needed to bring about its successor. We would particularly Hke to thank Riccardo Giacconi for his keen interest and sup- port of the workshop. He had urged us for some time to think of the long-term needs of the astrophysics community and to explore the scientific potential and technical challenges of a successor to HST. We also greatly appreciate the support given by Peter Stockman. He contributed invaluable advice and assistance throughout, ensured that the appropriate Institute resources were available, and gave an excellent summary of the meeting. We would also Hke to extend our gratitude to Charles Pellerin for personally support- ing the meeting and providing NASA funding for the publication of these proceedings. This workshop is but an early step on the long journey to the completion of NGST. As evidenced by these proceedings, however, the spectacular views of the heavens to be provided by this telescope and a deeper understanding of our universe and its origin are a worthy destination for this complex and challenging journey. The Editors Table 1. Nominal Next Generation Space Telescope (NGST) orbit.