The return of Halley's Cornet in 1986 has generated much ex citement in the scientific community with preparations already afoot for an International Cornet Watch and a cornet launch by the European Space Community, the Japanese and Soviet Space Scientists. The meet ing held at the University of Maryland in October 1980 was primarily stimulated by the preparations for further study of this cornet and by one of the most important unanswered questions related to comets, name ly, whether they may have made a eontribution to the origin of life on earth. Our un"derstanding of the role of comets in the origin of life must necessarily come from our studies of the astronomy and the chem istry of comets. Some clues to the processes which led to the for mation of organic molecules and eventually to the appearance of life have come from these studies of comets, perhaps the most ancient of all objects in our solar system. Whether there is, however, a biology of comets still remains to be seen, although some claims have been made that perhaps comets might themselves provide an environment for even the beginnings of life. Scientists with the latest available information on comets and differing opinions as to the role of comets in the origin of life attended this symposium. The formal papers presented are now being made available to the students of chemical evolution within the pages of this volume.

The idea that comets may be connected with the origin of life on Earth was considered heresy a few decades ago, with scientists shying away from this possibility as if from a medieval superstition. However the case that comets may have contributed at least the complex organic building blocks of life has become very strong, and mechanisms have now been identified whereby comets may incubate and transfer microbial life from one cosmic habitat to another in the Galaxy. The latter process cometary panspermia was pioneered by the late Sir Fred Hoyle and one of the present authors in the early 1980's. A theory that was once controversial is slowly gaining scientific respectability and support.The recent surge of interest in astrobiology has led to a spate of books in astrobiology — combining astronomy and biology — but in most of these, cometary panspermia is dealt with only cursorily. The present book sets out the case for cometary panspermia in a cogent way, combining evidence from space science, celestial mechanics, geology and microbiology. It should be an essential part of any university course on astrobiology, and also serve as a reference textbook for researchers in the field.

This volume considers the role comets may have played in the origins and evolution of life. This is the only book dealing in depth with this subject. It is particularly relevant in light of recent investigations of Halley's comet, of new insights into organic synthesis in meteorites and comets, and of new results of numerical simulations of cometary orbits and impacts on Earth. The book is intended as a comprehensive review of current research.

The field of planetary biology and chemical evolution draws together experts in astronomy, paleobiology, biochemistry, and space science who work together to understand the evolution of living systems. This field has made exciting discoveries that shed light on how organic compounds came together to form self-replicating molecules-the origin of life. This volume updates that progress and offers recommendations on research programs-including an ambitious effort centered on Mars-to advance the field over the next 10 to 15 years. The book presents a wide range of data and research results on these and other issues: The biogenic elements and their interaction in the interstellar clouds and in solar nebulae. Early planetary environments and the conditions that lead to the origin of life. The evolution of cellular and multicellular life. The search for life outside the solar system. This volume will become required reading for anyone involved in the search for life's beginnings-including exobiologists, geoscientists, planetary scientists, and U.S. space and science policymakers.

Ultraviolet Astronomy and the Quest for the Origin of Life addresses the use of astronomical observations in the ultraviolet range to better understand the generation of complex, life-precursor molecules. The origin of RNA is still under debate but seems to be related to the generation of pools of complex organic molecules submitted to heavy cycles of solution in water and drying. This book investigates whether these cycles require a planetary surface or may occur in space by examining both the theoretical and observational aspects of the role of UV radiation in the origin of life. This book offers the latest advances in these studies for astronomers, astrobiologists and planetary scientists. - Addresses both the theoretical and observational aspects of the role of Ultraviolet (UV) radiation in the origin of life - Builds on the requirements to produce prebiotic molecules in space and the implications for the origin of RNA - Investigates the use of ultraviolet observations related to planetary system formation, the evolution of young planetary disks, and the interaction of stars with planetary atmospheres

Origins of the Earth, Moon, and Life: An Interdisciplinary Approach presents state-of-the-art knowledge that is based on theories, experiments, observations, calculations, and analytical data from five astro-sciences, astronomy, astrobiology, astrogeology, astrophysics, and cosmochemistry. Beginning with the origin of elements, and moving on to cover the formation of the early Solar System, the giant impact model of the Earth and Moon, the oldest records of life, and the possibility of life on other planets in the Solar System, this interdisciplinary reference provides a complex understanding of the planets and the formation of life. Synthesizing concepts from all branches of astro-sciences into one, the book is a valuable reference for researchers in astrogeology, astrophysics, cosmochemistry, astrobiology, astronomy, and other space science fields, helping users better understand the intersection of these sciences. - Includes extensive figures and tables to enhance key concepts - Uses callout boxes throughout to provide context and deeper explanations - Presents up-to-date information on the universe, stars, planets, moons, and life in the solar system - Combines knowledge from the fields of astrogeology, astrophysics, cosmochemistry, astrobiology, and astronomy, helping readers understand the origins of the Earth, the moon, and life in our solar system

Living material contains about twenty different sorts of atom combined into a set of relatively simple molecules. Astrobiologists tend to believe that abiotic mater ial will give rise to life in any place where these molecules exist in appreciable abundances and where physical conditions approximate to those occurring here on Earth. We think this popular view is wrong, for it is not the existence of the building blocks of life that is crucial but the exceedingly complicated structures in which they are arranged in living forms. The probability of arriving at biologically significant arrangements is so very small that only by calling on the resources of the whole universe does there seem to be any possibility of life originating, a conclusion that requires life on the Earth to be a minute component of a universal system. Some think that the hugely improbable transition from non-living to living mat ter can be achieved by dividing the transition into many small steps, calling on a so-called 'evolutionary' process to bridge the small steps one by one. This claim turns on semantic arguments which seek to replace the probability for the whole chain by the sum of the individual probabilities of the many steps, instead of by their product. This is an error well known to those bookies who are accustomed to taking bets on the stacking of horse races. But we did not begin our investigation from this point of view.