Astronomy and Astrophysics for the 1970s: Volume 1: Report of the Astronomy Survey Committee (1972)

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~ aa {,/ ./t3 'f NOTICE: ,.~ :uudy ~pontd htnin · ·as UDd4!nak:l"n Undn' '"~ ttjk or tM Nacioftal /172 Academy or S<kMO Wlth the aprc:ss apprO'I'I..I or tht Council of the" Auckmy. Such ap- v. I prcwal ind""ated th:at tht- Coundl considered that 1~ prob~m b o( r:'ltlonalslpifinn«. that d\ol(~tion of tht probtftft rtquirtd scit:nti&r or tttllin.K"al comprccncc. and that the c.:u fftOU«'ft of I"'AS •-en JM"-ialtarly witabk to tbc C'OIIduct o( the projcc«. 1'hc inuitutiooftal rnpcxuibilldcs olahe Ac.tcmy •r'ff thrn disdu.'lf'd in tht rolloa-lna ma.nnn-: Tht mtmben of the study rommin« ..-c:rt: sdcatd for 1~ indMdual ~eholarty com· pctacc and ,;.da:meru • .,,.it.h clue consideration SOl- the ba••n« and bftadth of dkriplincs. Rc•ponlibllhy lOr all uperu. of this repon ruts • •ith the study ('Onlmiuee. to •·hom sinct"re •PI,..C'It'itlion il hereby clfpmscd. AhhOU.jth the reporu of our study eommiH~ art not 'ubmlltcd for approval to tlw: Academy membership nor to the Council. CllC'h report is n:vie•·cd b)' • K¢ond group of 'PI'roprh•tcly q11nlilied indiv1duah a~ ing 10 pnX'\.'ttUttll ~nb4l'ihed 11nd monitomt b)' the Academy'J Rtpon R~~-· Commiuce. Such reviews are intclldl'<l to determine, i ntf'ruliu, "'hc:ther the mnjor qu e~1ions 11100 n:lt:''J,nt points of vie'<' tu•,•e ~en nddren«< and whether the: rc-j>tlf1Cd lindlng$, ~n clusions. 3nd recomme•kt:uionll arO!iC from t he avalluble data nnd intOnnatlo". Oiscribution ofthe ft port is appnm:d. by t he Prcsidc:nl. only a fter S:ttisfactory compktkm of th~ review p«ess. Printina and Publishine Oflic:.'t- N•douJ AC'Jdtmy of SC"ient"G 2101 COtlllitudon Annut Wat.hington. D.C. 10418 1$81'1 ().~2029·8 Ubr•ry of Congms Ca1alog Card Number 72· 79131 Printed l.n the Unhed St11tes of America Order !rem l!":iorul Technical ln!cr7~lion Service. S;rir.~~;"ld, Va. 22151 O !lo. ;dar Titk h#: Spiral plaxr tho-Mn& stan and &JOUpt of stars ., t hellmh or re:soh.uion or the 2001n. tctucope Ulln& direct photop-&phy. (,Photo courttry oflltlle Obunvuori~l.) 

April 1972 Dear Or. Hondler: I take pleasure in transmilling to you herewilh lhe final report of the Astronomy Survey Commiuee chaired by Dr. Jesse Greenstein. This repor1 wasreviewed by COS PUP at its October 197 1 meeting and has been slightly revised in the light of the comments made to Dr. Greenstein on that occasion or subsequently in writing by individual members of the committee. In the opinio n of COS PUP , thisreport breaks new ground in a number of respects. It makes a serious attempt to identify priority programs over a very broad range of science, which embraces all of ground-based astronomy and trutt part of the space program that direelly contributes to lhe resolution of primarily astronomical questions. excluding planetary exploration and manned space fli&ht. All techniques of observation and calculation are treated within a common priority framework, and the priorities are oriented to scientifoc: que• lions to be attacked by several observational techniques in parallel. Thus, for example, in connecdon with HEAO, the importance or associa1ed expan-- sion of ground-based optical and infrared facilities to identify x-ray sowces observed from space is emphasized, and a.n intennediate optical tele- scope for lhis purpose is assigned to the same priority category as the H £AO itself. In integrating a large part of space science into its priority scheme, this report goes well beyo nd Gro•md-Based Astronomy: A Ten· Year Program (the Whitford report) and should be part icularly useful for plonnlng purposts of the government at a time when a stronger attempt is being made to inte- grate NAS A planning into the general national scientific effort. The rcpon brings out very clearly the interrelationships of the several observational techniques and instruments and provides a good sense of the unity of astron-- omy and its increuinJly close relationship to virtu.tlly every subf~tld of physics and, increasinJ)y, to chemistry.lt points out that many of the newer areas of astronomy are pursued by very young scientisu having tht:ir original trainins in physics. The report aloo brings out the remarkable vitality of the field, u evidenced both by the discoveries of the last five years and by the influx of new young and very talented research workers. This Oowering has occurred despite a virtual moratorium on funding of major new equipment since the publica- tion of the Whitford report, especially in the field of radio astronomy. Noth- v 

ing could provide more cogent evideMe of the ripeness of the field for major advances. Despite funding limitations, the United States stUI holds a command- ing po>ition, especially in the newer experimental areas of research, such as infrared and millimeter-wave astronomy, long-baseline interferometry, and high-energy astronomy. Moreo.-er, because of the technological support pro- grams, which ha.-e already greatly incrused the efficiency of existing optical and radio telescopes, this country is in a superior position to exploit the new scientifoc opportunities opened up by recent discoveries made with relatively modest instrumentation. One of the most sttilcing conclusions of the report is the high probability it assigns to the existence of intelligent life elsewhere in the universe. This concluoon, so different from any that would have been reached only a few years ago, is largely a consequence of the entirely new picture of the origin of the stars and their attendant planetary systems. This picture has emerged from discoveries or" the existeMe and properties of complex interstellar molecules and the prevalence of solid particlu in regions of star formation, leading to the realization that planetary systems probably often accompany star formation. In this and other respects, astronomy ranks with molecular biology in its potential impact on man's philosophical conception of himself and his place in the universe. In evaluating the report, COSPU P felt that the Astronomy Survey Com- mittee had p resented an extremely persuasive case for the scientiJk opportun- iliu in the field and for the validity of the diffocult priority choices it had made. The present rate of PhD production will supply enough new astronomers for the recommended expansion of effort, especially >ince there is much trans- fer from physics. The reporl does not predict where these PhD's will eventually find a place in the existing national programs. The future of the very large popu- lation of talented astronomers in the middle or late twenties is dubious without an expansion of federal support. For reasons that are readily understandable. in view of the present enor- mous promise of the field, the reporl has given, perhaps, inadequate attention to the probable scientifiC consequences of more constricted fiSCal support than is implied by even its farst four priorities or to how the national program would be reoriented to minimize the damage from such austerity. Other COS PUP sur- veys under way have gone into considerably more detail on the consequences of limited budgets, and such an analysis may be needed to provide a fair compari- son with other fields of science. I should also lllce to call attention to some overlap bet ween the astronomy and the physics surveys. In fact, there was a panel on astrophysics and relativity chaired by Professo r George Field that reported to both survey committees. Physics and astronomy intersect in this domain, which is one of the most ex- citing and dynamic ones in both disciplines. The recommendations of the survey vi 

c:ommiuees are reasonably eonsiuent with each o ther in their areas of intersection. COS PUP hu not attempted and cannot atternpl , al lhis srage, to compare the priorities with those in othe11 fields of science. Our endorsem<nt of the report, therefore, should not be laken as unqualified endorscment of each element of the recommended prosram in competition with elemenls in orher scienlilic f~elds. AJtronomy has scrved as an ultimate testing ground of technolosr at very low light and si811allevels. By most of the tests we consider relevant- scien- tific opportunity, ripeness for exploitation, availability of supporting technoi- OSY. ability a nd recent accomplishments of the people in the field, philosophi- cal and cultural impact- this program rates 3 high relative priority. Qf COUI1e, its possible impact o n technology or on the resolution of current societal prob- lems cannot now be foreseen , but we believe that this fact is mo re than out- weighed by its extraordinary scientific promise, which we consider the more pertinent consideration for this particular field. Sincerely yours. H"""y Brooks for the C OMMITTEE ON SCI EN C£ AND PU BLIC POLtCY vii 

This comprehensive repon of the Astronomy Survey Committee, like its predecessor report on ground-based astronomy, conveys the excitement and challenge inherent in the deepening understanding of the universe offered by modern astronomy. While making an impressive case for the values of astron- omy itself, it also convinces us once more of the powerful connections among astronomy, the other natural sciences. and ph ilosophy. Today, more than ever. ;.Astronomy is everyone's second science.'' In recounting in so thorough and scholarly a way the promise of astronomy. the distinguished membership of the Astronomy Survey Committee has also revealed again the continuing promise of all science. For lhis we are most grateful. PHILIP HANDLER Pres;delll_ , National Academy of Sciences Washington, D.C. April 1972 IX 

Astronomy Survey Committee JESSE L GREENSTEU<.California Institute of Technology. Chairman HELMUT A. AlT. KittPeak National Observatory JACQUES I£CKERS. Sacramento Park Observatory GEOFFUY BURII OCE. Univemty of California, San Diego BERNARD F. lURK£. Massacbusens Institute of Technology ALASTAIR G. W, CAMERON. Yeshiva University FRANK o. CorneU University DRAKE. RAY L. DUNCOMBE. U.S. Naval Observatory GEORG£ FIELD. University of California, Berkeley HERBERT FRIEDMAN. Naval Research Laboratory JOHN e. GAUSTAD. University of California. Berkeley LEO GoLDBERG. Kitt Peak National Observatory DAVID HEESCH EN. National Radio Astronomy Observatory GEOFFREY KELLBR. Ohio State University ROBERT P. KRAFT. University of California, Santa Cruz ROBERT 8. LEIGHTON. California Institute of Technology DONALD C. MORTON. Princeton University Observatory ROBERT MOYES. Smithsonian Astrophysical Observatory CHARLES R. O' DELL. Yerkes Observatory JEREMIAH r. OSTitiKER. Princeton University Ob~rvat.ory IRUNO 8. ROSSI. Massachusetts Institute of Technology HARLAN J. SMITH. Univenity of Texas LYMAN SPITlER. Princeton University Observatory BRUCE If . OREOORY, Executive Secretary xi 

Preface The Astronomy Survey Committee was established in mid-1969. at there· quest of the Committee on Science and Public Policy of the National Academy of Sciences in response to requests &om several federal agencies. Its goal was to outline the present state of astronomy. to identiry the most exciting problem areas in that field, and to recommend a program for the United States for the next ten years, inc.l uding both major new ground· based facilities and major space-science programs. From the beginning, the Survey Committee was also faced with the problem of assessment of priorities within the framework of recent federal funding. In the two years of the Survey, a large number of surprising and important discoveries oc· curred in astronomy. while growth in support was slowing down and major groups faced retrenchment or loss of funding: for the years from 1968 to 1971 the National Science Foundation funds for basic research grants in astronomy remained unchanged at about S6 million per year, while 400 new PhD's graduated and sought research support. In 1964. the National Ac.a demy of Sciences published a report entitled Ground·BtU~ Astronomy: A Ten· Year Progrum. prepared by a panel headed by A. E. Whitford. The present Survey has a dllferent emphasis. It reviews the present state and future need for facilities. Oight programs, and ongoing suppon of all astronomy, including space science and solar physics; one of its main themes is the rapid progress of the field since the Whitford report. The effectiveness of ground-based facilities has increased extraordinarily as the result of new applications of sophisticated electron· ics, which have greatly enhanced the effectiveness of existing telescopes xiii 

xiv Prt:f'act• and extended their use far into new wavelength regions. The capability provided by the space·astronomy program resulted in observations at es· sentially all wavelengths unobservable from the ground. These advances led to the discovery of many new objects and phenomena and made it dear that the astronomical unh·erse was in many ways still laraely unexplored. New facilities are needed on the ground and in eanh orbit to exploit fully the promising opponunities opened by ad'·anccd te<hnologies. Funher· more. the new discm•tries brought new questions concerning total energy output. high-density maner, and general relativity that touched on central unsolved problems of both physics and cosmology. The charge lo the Astronomy Survey Commillee was to consider the broad rnnge of aslronomy, excluding lunar and planetary exploration. We do not discuss the moon and meteorites, for example, not because we do not consider them to be important; quite to t he contrnry, they provide information essential for our understanding or the f'ormntion of the sun and the earth. The impressive results of the geological exploration of the moon, the dating of lunar rocks, and the initial heat-now determinations are major contr1butions to our picture of the formation or the solar system. The moon and planets. the earth's atmosphere and exosphere, geophysics, and earth resources have not gone unstudied; they have been the topic of extensive reports prepared by the National Academy of S.:ienC<Os as well as by other groups working directly with concaned government agencies. Following discussions begun in 1968. a 2J-member Suf\·ey Comminee was appointed in July 1969. Special panels were created. each with a Sur· vey Committee member as chairman; later. several working groups and special study committees were created to fill gaps in coverage of subject matter and te<hnique. One thing that became apparent with the forma· tion of these panels was the youth of the astrophysics community-the median age is less lhan 34. It also became apparent lhat the road to a career in astronomy is no! only through graduate schools of astrophysics: whereas in J 966 only 26 percent of those now calling themselves aslrono· mers received their Ph D's in physics, t his had grown to above 40 pereent by 1970. We are deeply grateful to the nearly 100 panel members who did much of the technical work and, particularly, to Richard Berendten. Roben Doyle, Gerald H. Newson, and Terry P. Roark. who gathered and ana- lyud the statistical material that formed the basis of our study. Each panel repon was critically revi.,.ed by the entire Survey Comminee. altered or returned for desired changes. with e.xten.sh-e disc:ussions be~ tto·een the Committee and the panel chairmen. We felt that a frank and even corrosive review by scientists representing all fields o f astronomy was the best method for sharpening the vision and reducing the priority list 

Preface xv propared by the specialists in each technique or field of study. We needed to achieve both a balanced program and an over-all priority assessment. 0\'er an tnormous range of techniques. While the final choke of items of the highest priority was made by the Survey Committee. it Is weighted heavily by recommendations of panelists in each s pecial technique or subject. This over·all priority assessment has not been reviewed by individual panel members and is the rosponsibility of the Survey Committee. It reprosents our best attainable consensus and provides a short list of major research and facilities goals that should be implemented for a well·rounded pursuit of current opportunities in astro· physics and astronomy. In the individual panel reports we give detailed lists of items of high priority as chosen by the individual panels. Clearly, as techniques improve and discoveries are made, these technical panel re- ports will provide Important guidance. As the science develops. we may also ••peel changes of emphasis and new fields to appear. Astronomy has become a fruitful aroa of modern experimental physics. The unh·erse has provided a laboratory with extreme conditions of tem- peraturo and density to test (if not to strain) the laws of physics under most unusual cii"C'umstances. The discoveries in this strange universe remain, at least in part. com· municable to the educated, oootecbnical public. Some 52,000 undergrad· uate studenu take an astronomy course each year. This is often the only science course they will take. so that astronomy remains basic to the rom- munication of seience to its ultimate audienco-the public:. We hope that for them. as for us, this Survey will provide an excitina insiaht into the larger and beautiful world in which we live. The Survey was supported by the National Aeronautics and Space Ad· miniscratlon and the National Science Foundation. The work was admin ~ istered by the Division of Physical Sciences of the National Research Council. We ore grateful for the government liaison officers to the Su.rvey, t.o senior members ofthe staffs of NASA and NSF, who gave us advl~ in the early stages. and to stalf members of rongrossional committees and the Office of Management and Budget for their assistance. We are also grate· ful to the entire community of astronomers and astrophysicists who pro· vided the needed information for the statistical survey, who made special studies, and who gave us ex1.ensive advice. JESSE L C REENSTf:Uf, Cllairman 

Contents I. INTRODUCTION I 2. RECOMMENDATIONS FOR A MAJOR NEW PROCRAM IN THE NEXT DECADE 7 3. ASTROPHYSICAL FRONTIERS 12 Cosmology 12 The Sun 19 Stellar Evolution 24 The Death of Stars and the Birth of Nuclei 29 Exploding Cores of Galaxies 35 Molecules. Dust. and ufe 39 The Solar System 44 Astronomy and Exobiology 49 4. TliE DIMENSIONS OF AMERICAN ASTRONOMY AND ASTROPHYSICS IN THE 1970's 53 Introduction 53 Trained Manpower 55 Financial Support 61 Capital Equipment 67 Ground ·Based Optical TeiHCOpes. 67; Ground·Based Radio Telescopes, 70; Space·Based Telescopes, 70 5. THE HIGH·PRIORITY PROCRAM 76 Very Large Array 76 Optical Astronomy-Electronic Technology and Light· Gathering Power 80 xvi 

Infrared Astronomy 83 High -Energy Astronomical Program 85 Millimeter· Wave Antenna 88 Aircraft. Balloons. and Rockets 90 Solar Program 92 Theoretical Astrophysics and Computing Requirements 94 Optical Spaee Astronomy-Leading to the Large Spaee Telesrope 96 Large Centimeter-Wave Paraboloid 101 Astrometry I02 Beyond the Recommendations 104 Larae Space Te~ope. 105: Optical· and Radio-Aumnonly Instruments, 106: Vcry · Lon~J·Bascline lntcrfcmmflry, 107: Jnrra~ Astronomy. 109: Solar Physics. 11 Theoretical 0; Astrophyslcs. 110 6. IMPLEMENTATION OF THE RECOMMENDATIONS 11 2 Thoughts on Planning 11 2 Introduction, 112: A Leuon ohhe Decade-The Need for Balanrc. IIJ: Planning a Balanced Program for the 1970's., li S PhilosophyofPriorities 118 Space, 119: Radio. 119; Optical. lnfn.red. Sola.r, and l"heoftciell. 120: Priorities and Altcmati.-cs. 120 APPENDIX: PANEL MEMBERS AND OTHER CONTRIBUTORS 125 INDEX 131 xvli