Comet nuclei are the most primitive bodies in the solar system. They have been created far away from the early Sun and their material properties have been altered the least since their formation. Thus, the composition and structure of comet nuclei provide the best information about the chemical and thermodynamic conditions in the nebula from which our solar system formed.
In this volume, cometary experts review a broad spectrum of ideas and conclusions based on in situ measurement of Comet Halley and remote sensing observations of the recent bright Comets Hale-Bopp and Hyakutake. The chemical character of comet nuclei suggests many close similarities with the composition of interstellar clouds. It also suggests material mixing from the inner solar nebula and challenges the importance of the accretion shock in the outer nebula. The book is intended to serve as a guide for researchers and graduate students working in the field of planetology and solar system exploration. Several special indexes focus the reader's attention to detailed results and discussions. It concludes with recommendations for laboratory investigations and for advanced modeling of comets, the solar nebula, and the collapse of interstellar clouds.

Zusammenfassung
Proceedings of an ISSI Workshop, 14-18 September 1998, Bern, Switzerland

Inhalt
I: Gases and Grains in the Coma.- Composition of the Volatile Material in Halley's Coma from In Situ Measurements.- Remote Observations of the Composition of Cometary Volatiles.- Cometary Deuterium.- Comet Halley's Gas Composition and Extended Sources: Results from the Neutral Mass Spectrometer on Giotto.- On the Existence of Distributed Sources in Comet Comae.- The Distributed CO in Comet Halley.- H2O Activity of Comet Hale-Bopp.- Hale-Bopp and Its Sodium Tails.- Rocky Cometary Particulates: Their Elemental, Isotopic and Mineralogical Ingredients.- The Silicate Material in Comets.- On the Organic Refractory Component of Cometary Dust.- II: From Coma Abundances To Nucleus Composition.- From Coma Abundances to Nucleus Composition.- On the Prediction of CO Outgassing from Comets Hale-Bopp and Wirtanen.- On the Flux of Water and Minor Volatiles from the Surface of Comet Nuclei.- Morphological Structure and Chemical Composition of Cometary Nuclei and Dust.- Polarization of Light Scattered by Cometary Dust Particles: Observations and Tentative Interpretations.- Changes in the Structure of Comet Nuclei due to Radioactive Heating.- III: Origin of Cometary Materials.- pectroscopy Between the Stars.- The Composition of Interstellar Molecular Clouds.- Evolution of Interstellar Ices.- An ISO View on Interstellar and Cometary Ice Chemistry.- Chemical and Physical Processing of Presolar Materials in the Solar Nebula and the Implications for Preservation of Presolar Materials in Comets.- Rare Atoms, Molecules and Radicals in the Coma of P/Halley.- Ion Irradiation and the Origin of Cometary Materials 269.- Formation and Processing of Organics in the Early Solar System.- Perspectives on the Comet-Asteroid-Meteorite Link.- IV: Critical Measurements For The Future.- Diversity ofComets: Formation Zones and Dynamical Paths.- Rosetta Goes to Comet Wirtanen.- Coma Composition and Evolution of Rosetta Target Comet 46P/Wirtanen.- Missions to Comets and Asteroids.- Characterization of Cosmic Materials in the Laboratory.- Studies of Comets in the Ultraviolet: The Past and the Future.- Critical Questions and Future Measurements Collated Views of the Workshop Participants.- V: Summary And Indexes.- Cometary Materials: Progress Toward Understanding the Composition in the Outer Solar Nebula.- Comet Index.- Molecule Indexes.- Abbreviations.- Author Index.- List of Participants.