Water in the Universe Astrophysics and Space Science Library EDITORIAL BOARD Chairman W.B. BURTON, National Radio Astronomy Observatory, Charlottesville, VA, USA [email protected] University of Leiden, Leiden, The Netherlands [email protected] F. BERTOLA, University of Padua, Padua, Italy J.P. CASSINELLI, University of Wisconsin, Madison, USA C.J. CESARSKY, Commission for Atomic Energy, Saclay, France P. EHRENFREUND, University of Leiden, Leiden, The Netherlands O. ENGVOLD, University of Oslo, Oslo, Norway A. HECK, Strasbourg Astronomical Observatory, Strasbourg, France E.P.J. VAN DEN HEUVEL, University of Amsterdam, Amsterdam, The Netherlands V.M. KASPI, McGill University, Montreal, Canada J.M.E. KUIJPERS, University of Nijmegen, Nijmegen, The Netherlands H. VAN DER LAAN, University of Utrecht, Utrecht, The Netherlands P.G. MURDIN, Institute of Astronomy, Cambridge, UK F. PACINI, Istituto Astronomia Arcetri, Firenze, Italy V. RADHAKRISHNAN, Raman Research Institute, Bangalore, India B.V. SOMOV, Astronomical Institute, Moscow State University, Moscow, Russia R.A. SUNYAEV, Space Research Institute, Moscow, Russia For other titles published in this series, go to www.springer.com/series/5664 Arnold Hanslmeier Water in the Universe Prof. Dr. Arnold Hanslmeier Institut für Geophysik, Astrophysik und Meteorologie Universität Graz Universitätsplatz 5 8010 Graz Austria [email protected] ISSN 0067-0057 ISBN 978-90-481-9983-9 e-ISBN 978-90-481-9984-6 DOI 10.1007/978-90-481-9984-6 Springer Dordrecht Heidelberg London New York Library of Congress Control Number: 2010937475 © Springer Science+Business Media B.V. 2011 No part of this work may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recording or otherwise, without written permission from the Publisher, with the exception of any material supplied specifically for the purpose of being entered and executed on a computer system, for exclusive use by the purchaser of the work. Cover illustration: Water Claimed in Evaporating Planet HD 209458b. Illustration Credit: European Space Agency, Alfred Vidal-Madjar (Institut d’Astrophysique de Paris, CNRS), NASA Cover design: eStudio Calamar S.L. Printed on acid-free paper Springer is part of Springer Science+Business Media (www.springer.com) Preface Water is one of the basic elements for life. It is even assumed that the evolution of life is only possible if there is liquid water present. A water molecule has some remarkable properties that make it quite unique in the universe. In the first chapter of this book we will review these basic properties of water and the role of water on Earth. All ancient civilizations realized the importance of water and their cities were constructed near great reservoirs of water. But is water unique on Earth? Do we find water elsewhere in the solar system, on extrasolar planetary systems or in distant galaxies? We will start the search for the presence of extraterrestrial water in our solar system. Surprisingly enough it seems that water in some form and sometimes in only minute quantities is found on any object in the solar system. Even on the planet nearest to the Sun, Mercury, there may be some water in the form of ice near its poles where never the light of Sun heats the surface. And there are objects in the solar system that are made up of a large quantity of water in terms of their mass, like comets and several satellites of the giant planets. If life depends on the presence of liquid water, there are also places besides Earth where liquid water may be found: beneath the ice crust of several satellites of Jupiter and Saturn there might be hidden a liquid ocean. Such an ice crust provides a shield- ing against high energetic radiation. Now, since the first extrasolar planetary systems have been detected, the search for water on such objects has just started. Because from observations it is very dif- ficult to measure the spectroscopic signatures of the atmospheres of such planets, we have to wait for the newly planned observational facilities (both in space and on ground); some of them will be in operation very soon. Water has been detected almost everywhere on extreme and exotic places in the universe: in 5000 K hot sunspots as well as in cold molecular interstellar clouds. Extreme bright sources can be explained by a MASER mechanism that is based on water molecules. They indicate regions where stars are formed and they can be even detected in galaxies that are at a distance of several 100 million light years. Water, which consists of hydrogen and oxygen, was formed after the first gener- ation of luminous stars exploded, so it was not present during the first several 100 million years of the history of our universe. This will be reviewed in the last chapter. v vi Preface The book is intended for the reader interested in astrophysics, astrobiology and science in general. It provides an overview but since more than 350 papers are cited, the reader who wants to go deeper can use these references. It can also be used as a textbook on several topics related to astrobiology. I want to thank Mr. Ramon Khanna and Mr. Donatas Akmanaviciusˇ from Springer for their excellent cooperation. The NASA ADS provides a wonderful tool for searching literature and some introductory remarks are based on information found in the WIKIPEDIA—I want to thank the many unknown authors who con- tribute to that encyclopedia. I am also grateful to Dr. Roman Brasja and Prof. Arnold Benz for helpful com- ments. Finally, I want to thank my children Roland, Christina and Alina and my girl- friend Anita for their understanding of my scientific passion. Graz, Austria Arnold Hanslmeier Contents 1 Water on Earth, Properties of Water .................. 1 1.1TheRoleofWaterinHistory.................... 1 1.1.1WaterinAncientCultures.................. 1 1.1.2 Modern Society and Water ................. 5 1.2TheChemicalElementsWaterConsistsof............. 6 1.2.1 Hydrogen .......................... 6 1.2.2 Oxygen ............................ 8 1.3 Water, Chemical and Physical Properties .............. 11 1.3.1 Chemical Properties . ................... 11 1.3.2 Physical Properties of Water ................. 12 1.3.3 Evaporation and Condensation ............... 16 1.3.4Ice.............................. 17 + 1.3.5 H2O ............................ 19 1.4ChemicalReactionsandWater................... 20 1.4.1 Chemical Bonds ....................... 20 1.4.2AcidsandpHValue..................... 20 1.4.3Hydrates,WaterinCrystals................. 20 1.4.4 Water: Spectral Signatures .................. 21 1.5TheHydrologicCycle........................ 22 1.5.1 Evaporation and Precipitation Balance . ......... 22 1.5.2 The Hydrologic Cycle and Climate Change ......... 24 2 Life and Water .............................. 25 2.1LifeandEnvironment........................ 25 2.1.1 The Importance of Water .................. 25 2.1.2 Definition of Life . ................... 25 2.1.3EvolutionofLife....................... 27 2.1.4 Life Under Extreme Conditions ............... 30 2.2WaterandOtherSolvents...................... 30 2.2.1 The Importance of Solvents to Life ............. 30 2.2.2OtherSolventsthanWater.................. 32 2.3EnergyforLife............................ 33 vii viii Contents 2.3.1Energy............................ 33 2.3.2MetabolicDiversity..................... 33 2.3.3SolarEnergy......................... 34 2.3.4 Photosynthesis and Respiration ............... 35 3 Water on Planets and Dwarf Planets .................. 37 3.1ClassificationofObjectsintheSolarSystem............ 37 3.1.1Overview........................... 37 3.1.2 Physical Parameters of Planets ............... 38 3.2 Terrestrial Planets .......................... 38 3.2.1Earth............................. 39 3.2.2Mercury........................... 40 3.2.3 Venus ............................. 41 3.2.4Mars............................. 44 3.2.5 The Early Sun and Evolution of Terrestrial Planets ..... 47 3.2.6 Dry Venus–Humid Earth–Climate Changes on Mars .... 49 3.3 Giant Planets ............................. 58 3.3.1Jupiter............................ 58 3.3.2Saturn............................ 60 3.3.3 Uranus ............................ 61 3.3.4Neptune........................... 62 3.3.5 Water on Giant Planets ................... 65 3.4 Dwarf Planets ............................ 66 3.4.1Pluto............................. 67 3.4.2 Ices on Other Dwarf Planets ................. 69 4 Satellites of Planets in the Solar System ................ 71 4.1 Galilean Satellites .......................... 71 4.1.1Io............................... 71 4.1.2Europa............................ 73 4.1.3 Callisto ............................ 77 4.1.4Ganymede.......................... 77 4.2 Satellites of Saturn .......................... 79 4.2.1Overview........................... 79 4.2.2Titan............................. 80 4.2.3 Other Satellites of Saturn .................. 84 4.3 Satellites of Uranus and Neptune .................. 93 4.3.1 The Satellites of Uranus ................... 93 4.3.2 The Satellites of Neptune .................. 97 4.4TheEarthMoon........................... 99 4.4.1 Water on the Moon? . ...................100 5 Water on Small Solar System Bodies ..................105 5.1 Clouds of Particles ..........................105 5.1.1TheKuiperBelt.......................105 5.1.2TheOortCloud.......................110 Contents ix 5.2Comets................................112 5.2.1EarlyObservations......................112