AN EXOBIOLOGICAL STRATEGY

FOR MARS EXPLORATION







Prepared by the Exobiology Program Office, NASA HQ
January 1995




This strategy was formulated at the request of Dr. Michael A. Meyer, Discipline Scientist for the Exobiology Program, NASA Headquarters. The writing group consisted of:
Dr. Michael H. Carr, USGS
Dr. Benton Clark, Martin-Marietta Aerospace
Dr. David J. DesMarais, NASA Ames Research Center
Dr. Donald L. DeVincenzi, NASA Ames Research Center
Dr. Jack D. Farmer, NASA Ames Research Center
Dr. John M. Hayes, Indiana University
Dr. Heinrich Holland, Harvard University
Dr. Bruce Jakosky, University of Colorado
Dr. Gerald F. Joyce, Scripps Research Institute
Dr. John F. Kerridge, University of California, San Diego & NASA HQ (chair)
Dr. Harold P. Klein, Santa Clara University
Dr. Andrew H. Knoll, Harvard University
Dr. Gene D. McDonald, Cornell University
Dr. Christopher P. McKay, NASA Ames Research Center
Dr. Michael A. Meyer, NASA HQ
Dr. Kenneth H. Nealson, University of Wisconsin
Dr. Everett L. Shock, Washington University
Dr. David M. Ward, Montana State University

In addition, Dr. Carl Sagan, Cornell University, provided helpful advice.



TABLE OF CONTENTS

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EXECUTIVE SUMMARY
INTRODUCTION
Purpose of strategy document
Outline of approach
THE PRESENT STATE OF KNOWLEDGE
The geological history of Mars
Evolution of the martian atmosphere
Results of Viking biology experiments
SEARCH FOR EVIDENCE OF PREBIOTIC CHEMISTRY
Introduction
The geochemical context for prebiotic chemistry
Objectives for flight experiments
THE SEARCH FOR EXTINCT LIFE
Introduction
Experience with Earth's early fossil record: Relevance for Mars
Key sites of Mars
Objectives for flight experiments
Sample return
THE SEARCH FOR EXTANT LIFE
Introduction
Critical review of Viking biology experiments
Possible habitats for extant life
Objectives for flight experiments
OBSERVATIONS/MEASUREMENTS REQUIRED FOR EXOBIOLOGY
Orbital experiments
Landed experiments
Returned samples
PLANNED MISSIONS: ANTICIPATED MEASUREMENTS AND OBSERVATIONS
The 1996 opportunity
The 1998 opportunity
The 2001 opportunity
The 2003 opportunity
NECESSARY MEASUREMENTS/OBSERVATIONS MISSING FROM CURRENT PLANS
SITE SELECTION
Introduction
High-resolution orbital imaging
Duration of hydrological systems
High-priority sites for extinct martian life
High-priority sites for extant life
PLANETARY PROTECTION FOR MARS MISSIONS
RECOMMENDATIONS
Support of basic R & A
Instrument development
Mobility and sample acquisition
Mission planning
Site selection
ADDITIONAL READING