NASA-CP-2223-VOL-1 _i\; 19820017167 . NASA Conference Publication 2223 Vi brational-Rotational Spectroscopy for Planetary Atmospheres Volume! Proceedings ofa workshop held at Annapolis, Maryland March 17-19,1980 NI\S/\ NASA Conference Publication 2223 VibrationaI-Rotational Spectroscopyfor PlanetaryAtmospheres Volume I Edited by Michael J. Mumma Goddard Space Flight Center Kenneth Fox University of Tennessee John Hornstein Computer Sciences Corporation Proceedings of a workshop held at Annapolis, Maryland March 17-19, 1980 N/_A NationalAeronautics and SpaceAdministration ScientificandTechnical InformationBranch 1982 PREFACE In the last part of the 1970's we experienced a dramatic and exciting explosion of our knowledge about the other planets in our Solar System as NASA's Pioneer, Voyager and Viking spacecraft swept past Jupiter and Saturn, orbited Venus and Mars, and entered the atmospheres of Venus and Mars. For the first time we obtained comprehensive information on the composition and dynamics of these varied atmospheres. New observations resulted in new demands for supporting laboratory studies. Data were needed for a variety of molecular species to better understand the spectra observed from the spacecraft, to interpret atmospheric structure measurements, to aid in greenhouse and cloud physics calculations, and to plan the next generation of experiments which would build upon the findings of this generation of exploration. It was in this exciting and hopeful atmosphere that some 75 physicists, chemists and planetary astronomers gathered in Annapolis to exchange their current findings and identify their needs as individuals and as a group. The interaction was fruitful. New ideas were spawned and our knowledge of the structure of things large and small, of planets and of molecules, was expanded. As this volume goes to press, the original purpose is clouded by an uncertain future. The next generation of spacecraft experiments now appears to belong to the next generation. It is our hope that it will not be so for long. But if it is, then here is a piece of our wisdom...for the next generation. Robert E. Murphy Discipline Scientist Planetary Atmospheres ,,t m Volume I CONTENTS Page PREFACE iii INTRODUCTION ......................................................... 1 EXECUTIVE SUMMARY ................................................... 3 PARTICIPANTS .......................................................... 7 A ROUND TABLE DISCUSSION ON PROSPECTS FOR OBSERVATIONS IN THE NEXT DECADE (1980-1990) .................................... 13 The Space Telescope - John Caldwell ....................................... 14 The Future of Ground-Based Near-IR Observations - Uwe Fink .................. 17 The Next Decade in Space-Based Observations - Rudi Hanel .................... 19 Next Generation Infrared Spectroscopy of the Planets - Michael Mumma .......... 20 The 10 _m Region - Alan Tokunaga 23 INTRODUCTION TO PLANETARY SPECTROSCOPY ............................ 27 Molecular Spectroscopy and Planetary Exploration from Space - Rudolph A. Hanel.. 29 Radiative Transfer and Remote Sensing - Barney J. Conrath .................... 47 Rayleigh, Raman and Particulate Scattering - William D. Cochran 63 REVIEW OF THEORETICAL AND EXPERIMENTAL SPECTROSCOPIC METHODS ... 87 Prediction of Molecular Infrared Band and Line Intensities - WillisB. Person ....... 89 New Theoretical and Experimental Methods for Pressure-Broadened Linewidths and Their Interpretation - Jack J. Gelfand 125 Laboratory Molecular Spectroscopy - Jack Margolis .... 149 Microwave Rotational Spectroscopy - H. Pickett ........ • • •..... .... ..... .... 171 SPECTROSCOPIC DATA COMPILATIONS ..................................... 189 The JPL Millimeter, Sub-Millimeter, and Microwave Line Catalog - Herbert Pickett •L.,........................................... 191 The AFGL Molecular Line Atlases - Laurence Rothrnan ........................ 195 *Volume I of II v CONTENTS (Continued) Page THE TERRESTRIAL PLANETS - CURRENT KNOWLEDGE ............. ......... 209 Thermal Balance of Venus - Martin Tomasko ................................ 211 Neutral Species in the Atmosphere of Venus - Andrew Young ................... 229 Transient Species on Mars and Venus - Yuk L. Yung .......................... 243 SPECTROSCOPY PERTINENT TO THE INNER PLANETS ....................... 253 Gaseous Infrared Absorption in the Lower At-mosPhere of Venus - C.Chackerian, Jr. and R. W. Boese ............................. 255 The Spectroscopy of Venus - Reinhard Beer ................................. 271 Spectroscopic Measurements of Mars and Venus with Heterodyne Techniques - Albert Betz ........ ........................... 277 Infrared Absorption by OH-Containing Compounds - John J. Hillman ............. 295 Infrared Absorption of Sulfur-Bearing Compounds ............................ 311 THE OUTER PLANETS - CURRENT KNOWLEDGE ............................ 331 Thermal Structure of Jupiter and Saturn - Glen Orton ......................... 333 Composition of Jupiter - Ronald Prinn ........ ......... .... ...... .......... 363 Voyager IRIS Measurements of the Jovian Atmosphere - Virgil G. Kunde ....... ... 387 Jupiter and Saturn from 2 to 6 lain - Harold P. Larson _........................ 407 vi Volume II CONTENTS Page LABORATORY SPECTROSCOPY PERTINENT TO THE OUTER PLANETS ......... 429 H2 and HD Spectroscopic Status - Jack Margolis ............................. 431 Collision-Induced Sharp Features in the Infrared Spectrum of HD - R. M. Herman ............................................... 439 Far Infrared Spectra of H2 and Mixtures of H2-CH4 and H2-He* - George Birnbaum ........................................... 449 A Review of Acetylene, Ethylene and Ethane Molecular Spectroscopy for Planetary Applications - W. C. Maguire .... "........................... 473 Current Studies of CH4 from 2.5 to 7 pm - Linda Brown ....................... 503 Line Intensities from Band and Diode Laser Measurements: u4 of CH 4 - Kenneth Fox ............................................. 529 Random Walks with the 6420- and 6825-A Features of Methane: Lost in the Wilderness - Barry Lutz ....................................... 549 Current Band Model Studies of CH4 at Wavelengths Less than 2.5 Microns - Uwe Fink .......................................... 559 Long-Pathlength Absorption Spectroscopy of CH4 - Peter Silvaggio............... 585 Current Studies of CH3D: Ye Olde Line Drive - Barry Lutz .................... 599 Spectra of Ammonia - K. Narahari Rao .................................... 611 Current Studies of PH3 - A. Goldman ...................................... 635 SPECTROSCOPY OF MINOR BODIES ........................................ 655 Gaseous SO2 on Io - John Pearl .......................................... 657 Titan on the Eve of Voyager Encounter - John Caldwell ....................... 673 Organic Chemistry in Titan's Atmosphere - Thomas Scattergood ................. 679 Spectroscopy of Triton and Pluto: Status and Prospects - Dale Cruikshank ......... 699 Comments on Pluto's Atmosphere - L. Trafton .............................. 709 Speculations on the Infrared Molecular Spectra of Comets - Michael J. Mumma ..... 717 SUMMARY OF THE WORKING SESSION ..................................... 745 *Volume II of II vii INTRODUCTION This workshop was sponsored by Dr. Robert Murphy, Head of the Planetary Atmospheres Program at NASAHeadquarters, who recognized the need for an intensive inter-disciplinary scientific meeting devoted to assessing the current status of, and present and future needs for spectroscopy supporting the study of planetary atmospheres. Initial discussions between Dr. L. Wallace and Dr. M.J. Mumma,co-chairmen, and Dr. _urphy produced a concensus for a workshop of limited size and scope. The size was restricted to forty participants with a goal of providing several experts in each sub-discipline needed to adequately address the topic. The scope was restricted to vibrational-rotational spectroscopy in order to keep the length of the workshop manageable. The important topic of electronic molecular spectroscopy, corresponding roughly to the visual through extreme ultraviolet wavelength range, deserved thorough treatment but was beyond the scope of this workshop. In contrast to ultraviolet spectroscopy, infrared studies of the planets generally probe lower altitudes where the chemistry and compositions are often very different. Furthermore, the infrared spectroscopic and theoretical communities are essentially independent of their counterparts working on electronic-transitions, and adequate representation of both communities would have dictated a much larger group, hence a less favorable environment for in-depth discussion and free exchange of ideas. The organizing committee (M.J. Mumma,L. Wallace, K. Fox, V. Kunde) chose a three-day format for the workshop, with approximately one-half of the available time allocated to formal talks and one-half to discussion. Because the participants' backgrounds and fields varied greatly, we decided to devote the first session to general reviews of current knowledge and problems in areas directly related to planeta_, spectroscopy, such as radiative transfer and remote sensing, theoretical molecular spectroscopy, laboratory molecular spectroscopy, and observational capabilities from spacecraft and from the ground. Subsequent sessions were usually keyed to a specific planet and typically began with an invited review on current understanding and problems relating to that atmosphere, followed