m II II -- -'ZR__ -_'-"-"-"-"-"_--Z__ _. 17£ -- -. -- 'r ' --_ZI__Z _ --_ _%H, _ " - Z r _ m m-- _ .... •_ ;/_x_ _ _-- .... .IZ • __ L NASA Conference Publication 3061 Carbon in the Galaxy: Studies From Earth and Space Edited by Jill C. Tarter SETI Institute Mountain View, California Sherwood Chang Ames Research Center Moffett Field, California Doug J. DeFrees Molecular Research Institute Palo Alto, California Invited papers from a meeting sponsored by the Life Science Division, National Aeronautics and Space Administration, Washington, D.C., and held at Ames Research Center Moffett Field, California November 5-6, 1987 IW_A National Aeronautics and Space Administration Office of Management Scientific and Technical Information Division 1990 TABLE OF CONTENTS Page PROLOGUE ........................................................................................................................................ vii ACKNOWLEDGMENTS .................................................................................................................. xiii MEETING PARTICIPANTS .............................................................................................................. xv STUDIES OF CARBON IN PRIMITIVE BODIES Carbon in Primitive Meteorites ....................................................................................................... 3 John F. Kerridge Carbon in Comet Dust .................................................................................................................... 21 D. E. Brownlee Carbon-rich Particles in Comet Halley ......................................................................................... 27 Benton C. Clark STUDIES OF CARBON IN INTERSTELLAR SPACE Astronomical Observations of Solid Phase Carbon ....................................................................... 39 M. Jura Survival of Carbon Grains in Shocks ............................................................................................ 47 C. Gregory Seab Carbon Stardust: From Soot to Diamonds .................................................................................... 59 A. G. G. M. Tielens Interstellar Grain Chemistry and Organic Molecules .................................................................. 113 L. J. Allamandola and S. A. Sandford Carbon Chemistry of Circumstellar Envelopes ........................................................................... 147 John H. Bieging Carbon Chemistry in Dense Molecular Clouds: Theory and Observational Constraints ............ 159 Geoffrey A. Blake CI, CII, and CO as Tracers of Gas Phase Carbon ....................................................................... 181 Jocelyn Keene iii PRECEDING PAGE BLANK NOT FILMED LABORATORY STUDIES OF CARBON Down-to-Earth Studies of Carbon Clusters ................................................................................. 199 R. E. Smalley Electronic and Molecular Structure of Carbon Grains ................................................................. 245 Jan AlmliSf and Hans-Peter Liithi A Unifying Picture of Gas-Phase Formation and Growth of PAH, Soot, Diamond and Graphite ....................................................................................................................................... 259 Michael Frenklach The Formation and Structure of Circumstellar and Interstellar Dust ........................................... 275 H. W. Kroto STUDIES OF CARBON FROM SPACE SIRTF: Probing the Dark Comers of the Galaxy ........................................................................ 287 Michael W. Werner and Dora S. Willoughby Research Opportunities on the Space Station .............................................................................. 303 Guy Fogleman SUMMARY AND CONCLUDING REMARKS What Have We Learned; Where Do We Go From Here? ............................................................ 311 J. Mayo Greenberg ABSTRACTS FROM CONTRIBUTED POSTER PAPERS The Possible Presence of Interstellar PAHs in Meteorites and Interplanetary Dust Particles ..... 319 L. J. Alltur_ndola, S. A. Sandford, and B. Wopenka Laboratory Simulation of Interstellar Grain Chemistry and the Production of Complex Organic Molecules ...................................................................................................................... 321 L. J. Allamandola, S. A. Sandford, and G. J. Valero Nature and Origin of Interstellar Diamond from the Allende CV3 Meteorite ............................. 323 David Blake, Friedemann Freund, Ted Bunch, Kannan Krishnan, Alexander Tielens, Mitch Stampfer, and Sherwood Chang An Ionic Mechanism of Carbon Formation in Flames ................................................................ 325 H. F. Calcote iv On Planetary Nebulae as Sources of Carbon Dust: Infrared Emission from Planetary Nebulae of the Galactic Halo ...................................................................................................... 327 Harriet L. Dinerstein and Daniel F. Lester Impact Fracture Experiments Simulating Interstellar Grain-Grain Collisions ............................ 328 Friedemann Freund, Sherwood Chang, and J. Thomas Dickinson Diamonds in Detonation Soot ..................................................................................................... 330 N. Roy Greiner, Dave Phillips, J. D. Johnson, and Fred Volk Probing the Possibility of a 12C4t13C Galactic Abundance Gradient ........................................... 331 Isabel Hawkins New Observations of Interstellar Organic Molecules ................................................................. 333 W. M. Irvine, P. Friberg, H. E. Matthews, Y. C. Minh, and L. M. Ziurys 335 Search for Interstellar Methane ................................................................................................... R. F. Knacke, Y. H. Kim, K. S. Noll, and T. R. Geballe Raman Spectroscopic Studies of Carbon in Extra-Terrestrial Materials .................................... 336 John Macklin, Donald Brownlee, Sherwood Chang, and Ted Bunch Can the Chirality of the ISM Be Measured? ............................................................................... 337 Y. Pendleton, S. Sandford, M. Werner, J. Lauer, and S. Chang On Diamond, Graphitic and Amorphous Carbons in Primitive Extraterrestrial Solar 339 System Materials ......................................................................................................................... Frans J. M. Rietmeijer FT-IR Spectroscopic Studies of Polycyclic Aromatic Hydrocarbons ......................................... 341 D. W. Salisbury, J. E. Allen, Jr., B. Donn, W. J. Moore, and R. K. Khanna Carbon in the Outer Solar System ................................................................................................ 342 D. P. Simonelli, J. B. Pollack, and C. P. McKay Carbon in the Galaxy: Studies from Earth and Space ORIGINAL PAGE BLACK AND WHITE PHOTOGRAPkt PROLOGUE On November 5 and 6, 1987, the Planetary Biology Branch at Ames Research Center, with support from the Exobiolo .gy Program of the Life Sciences Division at NASA Headquarters, conducted a meeting on "Carbon in the Galaxy: Studies from Earth and Space." The meeting brought together over 50 scientists from diverse disciplines who had in common a keen interest in the various forms of carbon that are found throughout the galaxy and on Earth. The papers and abstracts of posters presented at that meeting (as reproduced in this Conference Publication) give some of the flavor of the exciting interchange that took place when the scientists began to consider areas of carbon research that had previously seemed unrelated to their own work. Carbon is one of the chemical elements characteristic of life on the Earth. Indeed, the chemistry of carbon is predominantly organic chemistry - the Chemistry of material usually associated with living organisms. The purpose of the Exobiology Program is to determine the origin and distribution of life and life-related molecules throughout the universe. Thus, the recent discoveries of carbon in its various forms and in various cosmic environments has been the cause of much interest and excitement for exobiologists. The Ames meeting was designed to bring scientists from various disciplines together and focus on aspects of the study of carbon that are related to the origins of life and of life-related compounds in the galaxy. Many forms of carbon were available on the nascent Earth and some must have played an important role in the processes leading to the evolution of life. Likewise, these forms of carbon are available on other bodies in the Solar System and in other planetary systems that may have formed throughout the galaxy. By bri.nging these scientists together, the sponsors of the meeting hoped to identify the major open questions about the nature, origin and distribution of carbon in the galaxy, as well as the most fruitful observational, theoretical and/or experimental approaches to answering those questions with ground- and space-based activities. This meeting provided a new perspective on the statt, s of research into the nature and origin of the various forms of carbon and its potential relationship to the origin of life. As expected, the interactions among the scientists attending the meeting led to new suggestions of observations and experiments; new ways of trying to answer old questions. Overall, the conference had the desired result of providing an overview and establishing a sound basis for continued ground-and space-based research on carbon in the