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COVER: An artist's impression of various forms of mobility that might be employed by future Mars exploration missions. Lander, rover, and balloon images courtesy of the Jet Propulsion Laboratory. Aircraft image courtesy of Malin Space Science Systems. Composite by Penny E. Margolskee.
Copies of this report are available free of charge from:
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Committee on Planetary and Lunar Exploration
RONALD GREELEY,
Arizona State University,
Chair
FRANCES BAGENAL,*
University of Colorado
JEFFREY R. BARNES,
Oregon State University
RICHARD P. BINZEL,
Massachusetts Institute of Technology
WENDY CALVIN,
U.S. Geological Survey
RUSSELL DOOLITTLE,
University of California, San Diego
HEIDI HAMMEL,
Massachusetts Institute of Technology
LARRY HASKIN,
Washington University
BRUCE JAKOSKY,
University of Colorado
KENNETH JEZEK,
Ohio State University
GEORGE McGILL,
University of Massachusetts
HARRY McSWEEN, JR.,
University of Tennessee
MICHAEL MENDILLO,
Boston University
TED ROUSH,*
San Francisco State University
JOHN RUMMEL,*
Marine Biological Laboratory
GERALD SCHUBERT,
University of California, Los Angeles
EVERETT SHOCK,
Washington University
EUGENE SHOEMAKER,*
Lowell Observatory
Staff
DAVID H. SMITH, Study Director
JACQUELINE ALLEN, Senior Program Assistant
SHARON SEAWARD, Program Assistant
ERIN HATCH, Research Associate
STEPHANIE ROY, Research Assistant
BRIDGET ZIEGELAAR, Research Assistant
Space Studies Board
CLAUDE R. CANIZARES,
Massachusetts Institute of Technology,
Chair
MARK R. ABBOTT,
Oregon State University
FRANCES BAGENAL,
University of Colorado, Boulder
DANIEL N. BAKER,
University of Colorado, Boulder
LAWRENCE BOGORAD,*
Harvard University
DONALD E. BROWNLEE,*
University of Washington
ROBERT E. CLELAND,
University of Washington
GERALD ELVERUM, JR.,
TRW Space and Technology Group
ANTHONY W. ENGLAND,*
University of Michigan
MARILYN L. FOGEL,
Carnegie Institution of Washington
RONALD GREELEY,
Arizona State University
BILL GREEN, former member,
U.S. House of Representatives
CHRISTIAN JOHANNSEN,
Purdue University
ANDREW H. KNOLL,
Harvard University
JONATHAN I. LUNINE,
University of Arizona
ROBERTA BALSTAD MILLER,
CIESIN-Columbia University
BERRIEN MOORE III,*
University of New Hampshire
GARY J. OLSEN,
University of Illinois, Urbana
MARY JANE OSBORN,
University of Connecticut Health Center
SIMON OSTRACH,*
Case Western Reserve University
MORTON B. PANISH,*
AT&T Bell Laboratories (retired)
CARLÉ M. PIETERS,*
Brown University
THOMAS A. PRINCE,
California Institute of Technology
PEDRO L. RUSTAN, JR.,
Ellipso Inc.
JOHN A. SIMPSON,*
Enrico Fermi Institute
GEORGE L. SISCOE,
Boston University
EUGENE B. SKOLNIKOFF,
Massachusetts Institute of Technology
EDWARD M. STOLPER,
California Institute of Technology
NORMAN E. THAGARD,
Florida State University
ALAN M. TITLE,
Lockheed Martin Advanced Technology Center
RAYMOND VISKANTA,
Purdue University
PETER VOORHEES,
Northwestern University
ROBERT E. WILLIAMS,*
Space Telescope Science Institute
JOHN A. WOOD,
Harvard-Smithsonian Center for Astrophysics
MARC S. ALLEN, Director (until December 12, 1997)
JOSEPH ALEXANDER, Director (as of February 17, 1998)
Commission on Physical Sciences, Mathematics, and Applications
PETER M. BANKS,
ERIM International Inc.,
Co-chair
W. CARL LINEBERGER,
University of Colorado,
Co-chair
WILLIAM BROWDER,
Princeton University
LAWRENCE D. BROWN,
University of Pennsylvania
MARSHALL H. COHEN,
California Institute of Technology
RONALD G. DOUGLAS,
Texas A&M University
JOHN E. ESTES,
University of California, Santa Barbara
JERRY P. GOLLUB,
Haverford College
MARTHA P. HAYNES,
Cornell University
JOHN L. HENNESSY,
Stanford University
CAROL M. JANTZEN,
Westinghouse Savannah River Company
PAUL KAMINSKI,
Technovation Inc.
KENNETH H. KELLER,
University of Minnesota
MARGARET G. KIVELSON,
University of California, Los Angeles
DANIEL KLEPPNER,
Massachusetts Institute of Technology
JOHN R. KREICK,
Sanders, a Lockheed Martin Company
MARSHA I. LESTER,
University of Pennsylvania
M. ELISABETH PATÉ-CORNELL,
Stanford University
NICHOLAS P. SAMIOS,
Brookhaven National Laboratory
CHANG-LIN TIEN,
University of California, Berkeley
NORMAN METZGER, Executive Director
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Preface
Planetary surfaces and atmospheres are complex, with physical and chemical properties that vary over a large range of spatial scales. To understand such variegated features we need multipoint measurements and/or mobile platforms.
- For planetary atmospheres, scientific payloads carried by a fleet of balloons could enable synoptic measurements of chemical compositions and physical characteristics as functions of depth, latitude, and longitude. Measurements could be made for significantly longer times than those typical of entry probes.
- For planets with solid surfaces, mobility is essential. The case is exemplified for Mars, where spacecraft mobility would enable major advances in understanding climate change and geologic history and in searching for direct evidence of past life. This would require landers that can reach identified targets and there analyze selected materials.
- Given the extensive round-trip communication times involved in interplanetary exploration, a significant degree of autonomy may also be required. Power needs and communication rates will inevitably be major considerations, as will cost.
Given the importance of mobility-related issues to the achievement of priority objectives in the planetary sciences, the Space Studies Board charged the Committee on Planetary and Lunar Exploration (COMPLEX) to review the science that can be uniquely addressed by mobility in exploring the atmospheres and surfaces of planetary bodies. In particular, COMPLEX was asked to address the following questions:
- What are the practical methods for achieving mobility?
- For surface missions, what are the associated needs for sample acquisition?
- What are past examples of planetary mobility systems and how effective have they been in addressing important issues in the planetary sciences?
- What is the state of technology for planetary mobility in the United States and elsewhere, and what are the key requirements for technology development?
- What terrestrial field demonstrations are required prior to spaceflight missions?
Although this project was formally initiated in May 1997, presentations in support of it began in September 1995. They were conducted in a variety of contexts, including COMPLEX's standing oversight of NASA's planetary exploration programs and during the definition and development of the charge for this study. This report also draws on material presented to COMPLEX in the preparation of a number of additional reports. These include "Scientific Assessment of NASA's Solar System Exploration Roadmap" (letter report to Jurgen Rahe, August 23, 1996), "Scientific Assessment of NASA's Mars Sample-Return Mission Options" (letter report to Jurgen Rahe, December 3, 1996), and the Space Studies Board's assessment of the draft Office of Space Science strategic plan (letter report to Wesley Huntress, Jr., August 27, 1997). Many of the presentations dealt primarily with technological issues, but the potential for science was explicitly discussed as well. Background material was also gathered during COMPLEX's February 1997 meeting at the Jet Propulsion Laboratory. In addition, three members of COMPLEX actively participated in one or more field tests of the Russian Marsokhod rover and the facilities of NASA Ames Research Center's Intelligent Mechanisms Group, and two were involved with operational tests of the Sojourner rover carried by the Mars Pathfinder mission. In conjunction with COMPLEX's June 1997 meeting in Flagstaff, Arizona, committee members participated in field trips to the Upheaval Dome impact feature in southeastern Utah and Meteor Crater in northeastern Arizona to gain direct experience of the mobility needed for the characterization of complex geologic features.
Although many COMPLEX members past and present worked on this report, the bulk of the task of assembling their many individual contributions was performed by George McGill with the assistance of Jeffrey Barnes, Richard Binzel, Ronald Greeley, Heidi Hammel, Bruce Jakosky, Hap McSween, Ted Roush, Gerald Schubert, and Everett Shock.
The work of the writing team was made easier thanks to the contributions made by Michael Carr (U.S. Geological Survey), Frank Carsey (Jet Propulsion Laboratory), James Cutts (Jet Propulsion Laboratory), Michael Drake (University of Arizona), Stephen Gorevan (Honeybee Robotics), Andrew Ingersoll (California Institute of Technology), Arthur Lane (Jet Propulsion Laboratory), John Langford (Aurora Flight Sciences), Daniel McCleese (Jet Propulsion Laboratory), Christopher McKay (Ames Research Center), Kenneth Nealson (Jet Propulsion Laboratory), Kerry Nock (Jet Propulsion Laboratory), Paul Schenker (Jet Propulsion Laboratory), Alan Treiman (Lunar and Planetary Institute), Koichiro Tsuruda (Institute of Space and Astronautical Science), Charles Weisbin (Jet Propulsion Laboratory), and Brian Wilcox (Jet Propulsion Laboratory).
This report has been reviewed by individuals chosen for their diverse perspectives and technical expertise, in accordance with procedures approved by the National Research Council's (NRC's) Report Review Committee. The purpose of this independent review is to provide candid and critical comments that will assist the authors and the NRC in making the published report as sound as possible and to ensure that the report meets institutional standards for objectivity, evidence, and responsiveness to the study charge. The contents of the review comments and draft manuscripts remain confidential to protect the integrity of the deliberative process. COMPLEX thanks reviewers Benton Clark (Lockheed Martin Corp.), Larry Crumpler (New Mexico Museum of Natural History and Science), Larry Esposito (University of Colorado), Richard Greenberg (University of Arizona), Roald Sagdeev (University of Maryland), Steven W. Squyres (Cornell University), and Joseph Veverka (Cornell University) for many constructive comments and suggestions. Responsibility for the final content of this report rests solely with the authoring committee and the NRC.
Foreword
The cautious wanderings of the intrepid Sojourner rover across the martian surface in 1997 captured the attention of much of the world—the Jet Propulsion Laboratory's World Wide Web site broke records for the number of visitors hungry for the latest snapshots of the Red Planet. More to the point, Sojourner's ability to snuggle up to one rock after the other and assay its composition multiplied manifold the scientific return of the Mars Pathfinder mission.
This report is a cross-cutting assessment of the role of mobility in meeting the scientific objectives of planetary research as previously set out by the Space Studies Board's Committee on Planetary and Lunar Exploration. For a wider range of scientific goals, the ability to sample multiple locations on a planet's surface or in its atmospheres is found to be of great importance. This leads to some technological and programmatic considerations for developing the most effective means of achieving mobility in planetary environments.
NASA's Space Science Enterprise Strategic Plan1 presages a steady drumbeat of launches to Mars, Europa, and other planetary bodies over the next decade. As with Sojourner, careful attention to the most effective strategies for mobility will significantly enhance the capabilities of these future missions to explore the solar system, providing large scientific returns as they also stimulate public interest.
CLAUDE R. CANIZARES, CHAIR
SPACE STUDIES BOARD
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