Johannes Geiss – författare

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 modelling of comets, the solar nebula, and the collapse of interstellar clouds.

This title results from a workshop at the International Space Science Institute (ISSI) in Bern, Switzerland, where geochemists, geophysicists, and photogeologists have combined their expertise to constrain the timescales and geological processes in the evolution of Mars. In order to achieve this goal, the ages of cratered lunar surfaces, which are dated precisely by the radiometric ages of returned samples, have been taken as a reference for the inner solar system chronology. The derived ages of cratered geological units on Mars indicate ongoing geological activity from about 4.5 Gyr ago till modern geologic time. Ancient surfaces involve primordial crustal material with strong magnetization that has remained from Mars' core formation within the first 20 Myr of the solar system, whereas other surfaces were created during major geological processing at about 3-4.5 Gyr ago, probably associated with a denser atmosphere and more fluvial environment, and also to exposures of volcanism. The youngest surfaces indicate volcanism, weathering, gullying, exhumation, and modest water release all operating within the last few 100~Myr, with the youngest detected flows at less than 10 Myr ago.Neither Earth nor Moon offers such a complete geological record. This picture is consistent with radiometric age data of Martian meteorites which indicate that Mars has not only ancient crustal material, as represented in the ALH84001 meteorite, but at least some geologically young igneous rocks with ages of a few 100 Myr. Remote sensing of the Martian surface identifies two broad groups of igneous rock units, basaltic and andesitic, as is confirmed by in-situ chemical analyses at the Pathfinder landing site. Based on these results, the book contains an update on the overall stratigraphic system and geologic processes of the Martian surface, and a review on the newest models of the Martian interior structure and on the knowledge about the history of the Martian atmosphere and hydrosphere.

This volume, number 16 in the Space Sciences Series of ISSI, reviews the present knowledgeonmanyaspectsofthehistoryofthesolarsystem. Itfocuses onisotopic signatures ofvolatile elements as tracers for the evolutionary processes during the formation of the Sun and the planets from an interstellar molecular cloud and, in tum, illuminates how the isotopic compositions of present-day solar system ob- jects had been established. This integrated collection of articles complements the information provided by previous ISSI volumes such as From Dust to Terrestrial Planets and Chronology and Evolution of Mars, expanding the time scale for the history ofthe solar system. The convenors, Therese Encrenaz, Observatoire de Paris, Meudon; Johannes Geiss, ISSI, Bern; Reinald Kallenbach, ISSI, Bern; Konrad Mauersberger, Max- Planck-Institut fUr Kernphysik, Heidelberg; Tobias Owen, University of Hawaii, Honolulu; and Fran~ois Robert, CNRS-Museum d'Histoire Naturelle, Paris, in- vited experts in planetary science, solar and heliospheric physics, astrophysics, mineralogy, and chemistry to an interdisciplinary workshop in Bern, 14-18 Jan- uary 2002.The resulting review articles are grouped into four sections 'Sun and Protosolar Nebula', 'Outer Solar System', 'Earth, Terrestrial Planets, and Moon', and 'Isotopic FractionationProcesses'.

This book results from a workshop at the International Space Science Institute (ISSI) in Bern, Switzerland, where geochemists, geophysicists, and photogeologists have combined their expertise to constrain the timescales and geological processes in the evolution of Mars. In order to achieve this goal, the ages of cratered lunar surfaces, which are dated precisely by the radiometric ages of returned samples, have been taken as a reference for the inner solar system chronology. The derived ages of cratered geological units on Mars indicate ongoing geological activity from about 4.5 Gyr ago till modern geologic time. Ancient surfaces involve primordial crustal material with strong magnetization that has remained from Mars' core formation within the first 20 Myr of the solar system, whereas other surfaces were created during major geological processing at about 3-4.5 Gyr ago, probably associated with a denser atmosphere and more fluvial environment, and also to exposures of volcanism.The youngest surfaces indicate volcanism, weathering, gullying, exhumation, and modest water release all operating within the last few 100~Myr, with the youngest detected flows at less than 10 Myr ago. Neither Earth nor Moon offers such a complete geological record. This picture is consistent with radiometric age data of Martian meteorites which indicate that Mars has not only ancient crustal material, as represented in the ALH84001 meteorite, but at least some geologically young igneous rocks with ages of a few 100 Myr. Remote sensing of the Martian surface identifies two broad groups of igneous rock units, basaltic and andesitic, as is confirmed by in-situ chemical analyses at the Pathfinder landing site. Based on these results, the book contains an update on the overall stratigraphic system and geologic processes of the Martian surface, and a recent review on the newest models of the Martian interior structure and on the knowledge about the history of the Martian atmosphere and hydrosphere.

One of the most attractive features of the young discipline of Space Science is that many of the original pioneers and key players involved are still available to describe their field. Hence, at this point in history we are in a unique position to gain first-hand insight into the field and its development. To this end, The Century of Space Science, a scholarly, authoritative, reference book presents a chapter-by-chapter retrospective of space science as studied in the 20th century. The level is academic and focuses on key discoveries, how these were arrived at, their scientific consequences and how these discoveries advanced the thoughts of the key players involved. With over 90 world-class contributors, such as James Van Allen, Cornelis de Jager, Eugene Parker, Reimar Lüst, and Ernst Stuhlinger, and with a Foreword by Lodewijk Woltjer (past ESO Director General), this book will be immensely useful to readers in the fields of space science, astronomy, and the history of science. Both academic institutions and researchers will find that this major reference work makes an invaluable addition to their collection.

This volume, number 16 in the Space Sciences Series of ISSI, reviews the present knowledgeonmanyaspectsofthehistoryofthesolarsystem. Itfocuses onisotopic signatures ofvolatile elements as tracers for the evolutionary processes during the formation of the Sun and the planets from an interstellar molecular cloud and, in tum, illuminates how the isotopic compositions of present-day solar system ob- jects had been established. This integrated collection of articles complements the information provided by previous ISSI volumes such as From Dust to Terrestrial Planets and Chronology and Evolution of Mars, expanding the time scale for the history ofthe solar system. The convenors, Therese Encrenaz, Observatoire de Paris, Meudon; Johannes Geiss, ISSI, Bern; Reinald Kallenbach, ISSI, Bern; Konrad Mauersberger, Max- Planck-Institut fUr Kernphysik, Heidelberg; Tobias Owen, University of Hawaii, Honolulu; and Fran~ois Robert, CNRS-Museum d'Histoire Naturelle, Paris, in- vited experts in planetary science, solar and heliospheric physics, astrophysics, mineralogy, and chemistry to an interdisciplinary workshop in Bern, 14-18 Jan- uary 2002.The resulting review articles are grouped into four sections 'Sun and Protosolar Nebula', 'Outer Solar System', 'Earth, Terrestrial Planets, and Moon', and 'Isotopic FractionationProcesses'.