THE DECADE OF DISCOVERY IN ASTRONOMY AND ASTROPHYSICS Astronomy and Astrophysics Survey Committee Board on Physics and Astronomy Commission on Physical Sciences, Mathematics, and Applications National Research Council NATIONAL ACADEMY PRESS Washington, D.C. 1991 NATIONAL ACADEMY PRESS • 2101 Constitution Avenue, NW • Washington, DC 20418 NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special compe_nces and with regard for appropriate balance. This report has been reviewed by a group other than the authors according to procedures approved by a Report Review Committee consisting of members of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. This project was supported by the Department of Energy under Grant No. DE-FGO5- 89ER40421, the National Aeronautics and Space Administration and the National Science Foundation under Grant No. AST-8901685, the Naval Research Laboratory under Contract No. N00173-90-M-9744, and the Smithsonian Institution under Purchase Order No. SF0022430000. Additional support was provided by the Maurice Ewing Earth and Planetary Sciences Fund of the National Academy of Sciences created through a gift from the Palisades Geophysical Institute, Inc., and an anonymous donor. Library of Congress Cataloging-in-Publication Data National Research Council (U.S.). Astronomy and Astrophysics Survey Committee. The decade of discovery in astronomy and astrophysics / Astronomy and Astrophysics Survey Committee, Board on Physics and Astronomy, Commission on Physical Sciences, Mathematics, and Applications, National Research Council. p. cm. Includes bibliographical references and index. ISBN 0-309-04381-6 1. Astronomy--Research. 2. Astrophysics---Research. I. Title. QB61.N38 1991 5201.72---dc20 90-21659 C_ Cover: A view of the Milky Way Galaxy obtained by NASA's Cosmic Background Explorer (COBE). The central parts of the Milky Way, the galaxy in which our sun and solar system are located, are normally obscured by intervening gas and dust. Observations in the near-infrared reveal a thin disk and a central bulge of stars at the center of the galaxy, located some 28,000 light-years away. Courtesy of the COBE Science Working Group and NASA's Goddard Space Flight Center. Copyright C) 1991 by the National Academy of Sciences No part of this book may be reproduced by any mechanical, photographic, or electronic process, or in the form of a phonographic recording, nor may it be stored in a retrieval system, transmitted, or otherwise copied for public or private use, without written permission from the publisher, except for the purposes of the official use of the U.S. government. Printed in the United States of America NATIONAL RESEARCH COUNCIL This report on astronomy and astrophysics, The Decade of Discovery, is both timely and unique. During a period when the federal government recognizes the need for, and the difficulty of, fiscal restraint, the report sets clear priorities for funding. The report is unusual in the widespread sponsorship by governmental agencies seeking advice on the research they sponsor in this field and in the breadth of participation by the relevant professional community• The report describes a prioritized set of research initiatives that excite the intellect and stir a sense of adventure, ranging from understanding the large-scale distribution of matter in the universe to searching for planetary systems around nearby stars. In recent years, remarkable discoveries about the universe have attracted professional scientists trained in other fields to astrophysics and have stimulated many young people to study scientific or technical subjects. This study documents the amazing improvements in our ability to investigate the heavens made possible by recent advances in telescopes, detectors, and computers. At the same time, it makes clear the urgent need to maintain and improve the naLion's infrastructure for research in astronomy. In the organizational stages of the committee's work, the survey's chair visited, together with the chair of the National Research Council or with an NRC staff representative, leaders of the sponsoring agencies, members of Congress and their staffs, and relevant individuals in tile Office of Management and Budget. These visits helped astronomers direct their efforts to questions pertinent to govermnental needs, while preserving the ability of the committee to make independent judgments based on scientific expertise• Parts of this report address questions raised in those early consultations, including chapters on the potential of astronomy from tile moon; on education, science management, and international collaborations; and on the importance of astronomy to broad societal goals• The committee considered many more equipment initiatives than it could recommend with fiscal responsibility. Thus the committee prioritized initiatives on the basis of their scientific importance, timeliness, and cost-effectiveness. The widely inclusive nature of the committee's deliberations ensures that this prioritization will have the support of the great majority of the nation's astronomers. The underlying strength of this report is the excitement of the recent discoveries that are surveyed and the clear path to even more extraordinary revelations that is set forth in the new initiatives• Page 2 The arguments presented in favor of these initiatives include the universal appeal of astronomy to the curious of all ages, the stimulating educational effects of astronomical programs, the strong linkage with other physical sciences, and the remarkable but unforeseen applications of astronomical techniques to more practical endeavors. I would llke to thank the Astronomy and Astrophysics Survey Committee and the panel members for the large investment of time and energy represented in this report. The fortunes of astronomy in any nation are symbolic of the treatment of all of basic science. John Bahcall understood this, and he has earned the gratitude of the scientific community as a whole and astronomers in particular for his inspired leadership and vision in developing an extraordinary consultative process and bringing this survey to a responsible conclusion. Chair National Research Council iv ASTRONOMY AND ASTROPHYSICS SURVEY COMMITTEE JOHN N. BAHCALL, Institute for Advanced Study, Chair CHARLES A. BEICHMAN, Institute for Advanced Study, Executive Secretary CLAUDE CANIZARES, Massachusetts Institute of Technology JAMES CRONIN, University of Chicago DAVID HEESCHEN, National Radio Astronomy Observatory JAMES HOUCK, Cornell University DONALD HUNTEN, University of Arizona CHRISTOPHER E McKEE, University of California, Berkeley ROBERT NOYES, Harvard-Smithsonian Center for Astrophysics JEREMIAH P. OSTRIKER, Princeton University Observatory WILLIAM PRESS, Harvard-Smithsonian Center for Astrophysics WALLACE L.W. SARGENT, California Institute of Technology BLAIR SAVAGE, University of Wisconsin ROBERT W. WILSON, AT&T Bell Laboratories SIDNEY WOLFF, National Optical Astronomy Observatories National Research Council Staff Robert L. Riemer, Senior Program Officer Susan M. Wyatt, Administrative Associate Board on Physics and Astronomy William Spindel, Principal Staff Officer (1989) Sandra Nolte, Administrative Assistant (1989-1990) Phoebe Wechsler, Administrative Assistant (1989-1990) Institute for Advanced Study BOARD ON PHYSICS AND ASTRONOMY FRANK D. DRAKE, University of California, Santa Cruz, Chair LLOYD ARMSTRONG, Johns Hopkins University W. DAVID ARNETT, University of Arizona HOWARD C. BERG, Harvard University RICHARD S. BERRY, University of Chicago WILLIAM E BRINKMAN, AT&T Bell Laboratories GEORGE W. CLARK, Massachusetts Institute of Technology HAROLD P. FURTH, Princeton University MARTHA P. HAYNES, Cornell University CHARLES F. KENNEL, University of California, Los Angeles WALTER KOHN, University of California, San Diego STEVEN E. KOONIN, California Institute of Technology LEON LEDERMAN, Fermi National Accelerator Laboratory VERA RUBIN, Carnegie Institution of Washington DAVID N. SCHRAMM, University of Chicago DANIEL TSUI, Princeton University STEVEN WEINBERG, University of Texas Donald C. Shapero, Staff Director Robert L. Riemer, Associate Staff Director Ronald D. Taylor, Program Officer Susan M. Wyatt, Administrative Associate Mary Riendeau, Senior Secretary Anne K. Simmons, Secretary vi COMMISSION ON PHYSICAL SCIENCES, MATHEMATICS, AND APPLICATIONS* NORMAN HACKERMAN, Robert A. Welch Foundation, Chairman PETER J. BICKEL, University of California, Berkeley GEORGE E CARRIER, Harvard University HERBERT D. DOAN, The Dow Chemical Company (retired) DEAN E. EASTMAN, IBM T.J. Watson Research Center MARYE ANNE FOX, University of Texas PHILLIP A. GRIFF1THS, Duke University NEAL E LANE, Rice University ROBERT W. LUCKY, AT&T Bell Laboratories CHRISTOPHER F. McKEE, University of California, Berkeley RICHARD S. NICHOLSON, American Association for the Advancement of Science JEREMIAH P. OSTRIKER, Princeton University Observatory ALAN SCHRIESHEIM, Argonne National Laboratory ROY F. SCHWITTERS, Superconducting Super Collider Laboratory KENNETH G. WILSON, Ohio State University NORMAN METZGER, Executive Director *The project that is the subject of this report was initiated by the