Cambridge University Press 978-0-521-87201-0 - The Surface of …assets.cambridge.org/97805218/72010/frontmatter/... · 2007. 2. 14. · MICHAEL CARR is a Geologist Emeritus at the

The Surface of Mars

Our knowledge of Mars has grown enormously over thelast decade as a result of the Mars Global Surveyor, MarsOdyssey, Mars Express, and the two Mars Rover missions.

This book is a systematic summary of what we have learntabout the geological evolution of Mars as a result of thesemissions, and builds on the themes of the author’s previous

book on this topic.The surface of Mars has many geological features

that have recognizable counterparts on Earth. Many arehuge in comparison to those on Earth, including volcanoes,

canyons and river channels that are ten times larger thantheir terrestrial equivalents. The book describes the diverseMartian surface features and summarizes current ideas

as to how, when, and under what conditions they formed.It explores how Earth and Mars differ and why the twoplanets evolved so differently. While the author’s main focus

is on geology, he also discusses possible implications of thegeological history for the origin and survival of indigenousMartian life.

Up-to-date and richly illustrated with over twohundred figures, the book will be a principal reference forresearchers and students in planetary science. The compre-hensive list of references will also assist readers in pursuing

further information on the subject.

MICHAEL CARR is a Geologist Emeritus at the U.S.

Geological Survey, and has over 40 years’ experience ofplanetary science research. In the early 1970s Dr. Carr wasa member of the Mariner 9 team and leader of the Viking

Orbiter Imaging team. He was co-investigator on the MarsGlobal Surveyor, the Mars Exploration Rovers, and theHigh Resolution Stereo Camera on Mars Express. He is a

Fellow of the Geological Society of America, the AmericanGeophysical Union, and the American Association for theAdvancement of Science, and was awarded the 1994

National Air and Space Museum Lifetime AchievementAward for his work on Mars. He is also the author of TheSurface of Mars (1981) and Water on Mars (1996).

© Cambridge University Press www.cambridge.org

Cambridge University Press978-0-521-87201-0 - The Surface of MarsMichael H. CarrFrontmatterMore information

http://www.cambridge.org/0521872014

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Cambridge Planetary Science Series

Series editors: F. Bagenal, F. Nimmo, C. Murray, D. Jewitt,R. Lorenz and S. Russell

Books in the series

Jupiter: The Planet, Satellites and Magnetosphere F. Bagenal,T. E. Dowling and W.B. McKinnon

Meteorites: A Petrologic, Chemical and Isotopic SynthesisR. Hutchinson

The Origin of Chondrules and Chondrites D.W.G. SearsPlanetary Rings L. Esposito

The Geology of Mars: Evidence from Earth-Based AnalogsM. Chapman

The Surface of Mars M. Carr






The Surface of MarsMICHAEL H. CARR

U.S. Geological SurveyMenlo Park, CA






CAMBR IDGE UNIVERS I TY PRES S

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� Michael H. Carr 2006

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First published 2006

Printed in the United Kingdom at the University Press, Cambridge

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Carr, M. H. (Michael H.)

The Surface of Mars / Michael H. Carr.

p. cm. � (Cambridge planetary science)

Includes bibliographical references and index.

ISBN-13: 978-0-521-87201-0 (hardback)

ISBN-10: 0-521-87201-4 (hardback)

1. Mars (Planet)�Surface. I. Title. II. Series.

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Contents

Preface page ixMaps xi

1 Overview 1

Telescopic observations 1Orbital and rotational motions 2Global structure and topography 5Atmosphere 5Surface temperatures 9Stability of water 11Global geology 14Meteorites 19

Carbonaceous chondrites and chemicalfractionation 19

Martian meteorites 20

2 Impact craters 23

Crater-forming objects 23Crater morphology 24

Simple craters 24Complex craters 25Multi-ringed basins 26

Crater formation 27Ejecta morphology 31Crater modification 34Crater size frequencies and ages 36Summary 41

3 Volcanism 43

Basaltic volcanism 43Effect of Martian conditions 44Tharsis 46

Tharsis Montes 46Olympus Mons 51Alba Patera 54Small Tharsis shields 57

Elysium 59Lahars and dikes 60

Cerberus�Amazonis 64Hellas�Hesperia 68Plains volcanism 70Volcano�ice interactions 73Summary 74

4 Global structure and tectonics 77

Formation of the core 77Global dichotomy 78Thickness of the lithosphere 84Formation of Tharsis 84Surface indicators of stress 86

Extensional structures 86Compressional structures 89Deformational features related to Tharsis 90

5 Canyons 95

Physiography 96Canyon walls 102Landslides 103Interior layered deposits 105Formation of the canyons 110Summary 111

6 Channels, valleys, and gullies 113

Outflow channels 113Circum-Chryse channels 114

Description 114Mode of formation 116

Tharsis 121Amazonis and Elysium Planitiae 122

Description 122Mode of formation 126

Utopia Planitia 127Hellas 129Argyre 130The poles 130

Valley networks 131General description 132Drainage basins 137Origin 139

Noachian valleys 140Post-Noachian valleys 144

Gullies 144Summary 147

7 Lakes and oceans 149

Paleolakes in the cratered uplands 149Argyre and Hellas 156

vii






Northern oceans 160Shorelines 164Evidence for marine sediments 167Evidence for ice 168Possible fate of a northern ocean 168

Summary 171

8 Ice 173

The stability of ice 174Spectral evidence for ice 175Permafrost 175Ice-rich surficial deposits at high latitudes 177Fretted terrain 178

Terrain softening 179Lobate debris aprons 180Lineated valley fill 184Origin of the fretted valleys 185

Glaciers 187Other possible indicators of ground ice 188

Crater ejecta patterns 188Polygonal fractures 189Thermokarst 191

Summary 191

9 Wind 193

Entrainment of particles by the wind 193Dust storms 195Wind streaks and tails 197Dunes, ripples, and drifts 198Regional eolian deposits 203Wind erosion 204Summary 205

10 Poles 211

The present polar environments 211General description of polar terrains 212Northern polar deposits 212

Upper unit 212Basal unit 218

Southern polar deposits 221The Dorsa Argentea Formation 222

The CO2 residual cap 225Summary 226

11 The view from the surface 229

Vikings 1 and 2 229Mars Pathfinder 231Mars Exploration Rovers 231

Spirit 232Gusev crater regional context 232Gusev plains 235Columbia Hills 238

Clovis class 239Wishstone class 240Peace class 241Watchtower class 241Backstay class 242

Opportunity 244Regional context 244

The Meridiani rocks and soils 246The Burns Formation 246Post-depositional alteration 252Groundwater movement 253Evaporitic sources 254

Summary 254

12 Climate change 257

Noachian climate 257Greenhouse warming 258Retention of a dense CO2 atmosphere 260Post-Noachian climate history 262Recent climate changes 265Summary 265

13 Implications for life 267

The origin of life 268Habitability 271Survival 272ALH84001 273Looking for life 274Summary 274

14 Summary 277

Reference 283Index 297

viii Contents






Preface

This book summarizes our knowledge of the morphol-ogy of the martian surface and speculates on howthe surface evolved to its present state. Duringthe last three decades our knowledge of Mars hasincreased dramatically. A succession of orbitingspacecraft (Table I) have observed the planet atever-increasing resolution, rovers have traversed thesurface, analyzing and scrutinizing rocks along theway, and ever more sophisticated techniques are beingused to analyze increasing numbers of martianmeteorites. The planet has had a complicated history.The aim of the book is to summarize our under-standing of the nature and sequence of the processesthat led to the present configuration of the surface.While the book is intended for the serious studentor researcher, technical jargon is avoided to the extentthat it is possible without compromising precision. It ishoped that the book will be readable to informednon-Mars specialists as well as those active in the field.

Sufficient documentation is provided to enable thereader to dig more deeply wherever he or she wishes.Heavy reliance is placed on imaging data. Otherevidence is referred to where available, but at thepresent time, imaging is by far the most comprehensiveglobal data set that we have in terms of areal coverageand resolution range.

Exploration of Mars has captured world-wideinterest. Mars is an alien planet yet not so alien as to beincomprehensible. The landscape is foreign yet we canstill recognize familiar features such as volcanoes andriver channels. We can transport ourselves through oursurrogate rovers to a surface both strange and familiarand readily imagine some future explorers following intheir paths. While past speculations about martiancivilization may now seem absurd, the possibility thatMars may at one time have hosted some form of liferemains plausible. It remains the strongest scientificdriver of the Mars Exploration program. The life

Table I. Mars missions

Mariner 4 US 11/28/1964 Flew by 7/15/1965; first S/C images

Mariner 6 US 2/24/1969 Flew by 7/31/1969; imaging and other dataMariner 7 US 3/27/1969 Flew by 8/5/1969; imaging and other dataMars 2 USSR 5/19/1971 Crash landed; no surface dataMars 3 USSR 5/28/1971 Crash landed; no surface data

Mariner 8 US 5/8/1971 Fell into Atlantic OceanMariner 9 US 5/30/1971 Into orbit 11/3/1971; mapped planetMars 4 USSR 7/21/1973 Failed to achieve Mars orbit

Mars 5 USSR 7/25/1973 Into orbit 2/12/1975; imaging and other dataMars 6 USSR 8/5/1973 Crash landedMars 7 USSR 8/9/1973 Flew by Mars

Viking 1 US 8/20/1975 Landed on surface 7/20/1976; orbiter mappingViking 2 US 9/9/1975 Landed on surface 9/3/1976; orbiter mappingPhobos 1 USSR 7/7/1988 Lost 9/2/1988Phobos 2 USSR 7/12/1988 Mars and Phobos remote sensing

Mars Observer US 9/22/1992 Failed Mars orbit insertionPathfinder US 12/4/1996 Landed 7/4/1997; lander and roverGlobal Surveyor US 11/7/1996 Into orbit 9/11/1997; imaging and other data

Odyssey US 4/7/2001 Into orbit 10/24/2001: imaging, remote sensingSpirit Rover US 6/10/2003 Landed in Gusev 1/3/2004Opportunity Rover US 7/7/2003 Landed in Meridiani 1/24/2004

Mars Express Europe 6/2/2003 In orbit 12/25/2003; imaging, remote sensingReconnaissance Orbiter US 8/12/2005 In orbit 3/10/2006; imaging, remote sensing

ix






theme is constantly in the background throughout thebook. Impacts have implications for survival of anyearly life, and may have resulted in cross-fertilizationof Mars and Earth. Large floods may have temporarilyaffected global climates and provided temporaryrefuges in the resulting lakes and seas. Volcanicactivity may have created hydrothermal systems inwhich life could thrive. Conditions on early Mars mayhave been very similar to those on early Earth, at atime when life had already taken hold. Thus, while thebook is not explicitly about life, almost every chapterhas implications for the topic.

The book is intended as a replacement for anearlier book (Carr, 1981) that summarized our under-standing of the planet as it was shortly after comple-tion of the Viking missions. This book is different fromthe original in several ways. The field was much lessmature when the first book was written. I was able toread most of the literature and examine most of theimaging data. Neither of these tasks is possible anylonger. Approximately 500 papers are published onMars each year and the number is increasing. One canno more write a book about Mars and reference all therelevant papers, than one can about the Earth.Similarly, the book has been written without seeingmost of the available imaging.

Over 200,000 images have been taken just withthe Mars Orbiter Camera on Mars Global Surveyor,and a comparable amount of imaging data has beenacquired by THEMIS on Mars Odyssey, the HighResolution Stereo Camera on Mars Express, and theMars rovers. In addition to the imaging there are vastamounts of other remote sensing data, as well asanalytical data from the surface and from meteorites.Clearly, summarizing all this data has involved a greatdeal of simplification.

The book is a snapshot of a moving picture.Following Viking there was almost a twenty-yeardrought during which barely any data was returnedfrom the planet. But since the landing of MarsPathfinder in 1996 and the insertion of Mars GlobalSurveyor into orbit in 1997, we have been receiving asteady stream. Along with the new data have come newideas as to how the planet has evolved. The pace ofchange is rapid because our knowledge of the planet isstill rudimentary and the data flux is high. It could be

argued that the time is inopportune for a summary

because of the rate of change. But change will

continue. After two decades, new interpretations of

the Viking data were still forthcoming. It will likely

also take decades to digest the data currently being

returned. I hope that there will never be a time when

the field stabilizes and a good time to write a summary

arrives.The book was written in 2005 and 2006. I had

just retired after having participated in almost every

mission to Mars since the late 1960s, including several

months of Mars Exploration Rovers (MER) opera-

tions at Jet Propulsion Laboratory (JPL). The book

has benefited significantly from the continuous infor-

mal science discussions that are part of participating in

missions. The Mars Rover end-of-day discussions,

when the scientists would gather and exchange ideas

about any topic that had intrigued them, were

particularly stimulating. The Mars Orbiter Laser

Altimeter (MOLA) team on Mars Global Surveyor

held regular meetings on different science topics that

were always fun. Of course, the book has benefited

mostly from the engineers who have built and operated

the spacecraft that have flown all the science instru-

ments to Mars in recent years. Without sound

engineering there is no science. The engineers do

most of the hard work acquiring the data. The

scientists have the fun of interpreting it all.Two people deserve special mention for the

help they provided. Phil Christensen, of Arizona State

University, the THEMIS Principal Investigator,

offered to make mosaics of areas of interest for

illustrations. Some of the most spectacular images in

the book are these THEMIS mosaics. Jim Head of

Brown University is also a major contributor to the

book. Jim has unusually broad expertise in planetary

science, and is possibly the most prolific author in the

field of planetary geology. He agreed to review all the

chapters as they were written and provided numerous

insightful comments that added greatly to the accuracy

and comprehensiveness of the final product. Above all

he provided encouragement to keep at it.

Michael H. CarrU. S. Geological Survey

Menlo Park, CA 94025, USA

x Preface






xi






xii Maps






Maps xiii






xiv Maps






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Cambridge University Press 978-0-521-87201-0 - The Surface of …assets.cambridge.org/97805218/72010/frontmatter/... · 2007. 2. 14. · MICHAEL CARR is a Geologist Emeritus at the