NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the task group responsible for the report were chosen for their special competences and with regard for appropriate balance.
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Cover design by Penny Margolskee. Comet photo courtesy of Dennis di Cicco. Asteroid and Europa images courtesy of NASA/JPL/Caltech.
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TASK GROUP ON SAMPLE RETURN FROM SMALL SOLAR SYSTEM BODIES
Salk Institute for Biological Studies,
University of Maryland
University of California, San Diego
University of Washington
Southwest Research Institute
University of Arizona
University of California, San Diego
MARGARET S. RACE,
Marine Biological Laboratory, Woods Hole
JOSEPH L. ZELIBOR, JR., Study Director
JACQUELINE ALLEN, Project Assistant
SPACE STUDIES BOARD
CLAUDE R. CANIZARES,
Massachusetts Institute of Technology,
MARK R. ABBOTT,
Oregon State University
DANIEL N. BAKER,
University of Colorado
DONALD E. BROWNLEE,
University of Washington
GERARD W. ELVERUM, JR.,
TRW Space and Technology Group
ANTHONY W. ENGLAND,
University of Michigan
MARILYN L. FOGEL,
Carnegie Institution of Washington
Arizona State University
BILL GREEN, former member,
U.S. House of Representatives
ANDREW H. KNOLL,
ROBERTA BALSTAD MILLER,
BERRIEN MOORE III,
University of New Hampshire
MARY JANE OSBORN,
University of Connecticut Health Center
Case Western Reserve University
MORTON B. PANISH,
AT&T Bell Laboratories (retired)
CARLÉ M. PIETERS,
THOMAS A. PRINCE,
California Institute of Technology
PEDRO L. RUSTAN, JR.,
U.S. Air Force (retired)
JOHN A. SIMPSON,
Enrico Fermi Institute
GEORGE L. SISCOE,
EDWARD M. STOLPER,
California Institute of Technology
ROBERT E. WILLIAMS,
Space Telescope Science Institute
MARC S. ALLEN, Director (through December 12, 1997)
JOSEPH K. ALEXANDER, Director (as of February 17, 1998)
COMMISSION ON PHYSICAL SCIENCES, MATHEMATICS, AND APPLICATIONS
ROBERT J. HERMANN,
United Technologies Corporation,
W. CARL LINEBERGER,
University of Colorado,
PETER M. BANKS,
ERIM International, Inc.
LAWRENCE D. BROWN,
University of Pennsylvania
RONALD G. DOUGLAS,
Texas A&M University
JOHN E. ESTES,
University of California at Santa Barbara
MARTHA P. HAYNES,
L. LOUIS HEGEDUS,
Elf Atochem North America, Inc.
JOHN E. HOPCROFT,
CAROL M. JANTZEN,
Westinghouse Savannah River Company
PAUL G. KAMINSKI,
KENNETH H. KELLER,
University of Minnesota
KENNETH I. KELLERMANN,
National Radio Astronomy Observatory
MARGARET G. KIVELSON,
University of California at Los Angeles
Massachusetts Institute of Technology
Sanders, a Lockheed Martin Company
MARSHA I. LESTER,
University of Pennsylvania
NICHOLAS P. SAMIOS,
Brookhaven National Laboratory
University of California at Berkeley
NORMAN METZGER, Executive Director
For the first time since the Apollo program, NASA has specific plans to bring samples to Earth from elsewhere in the solar system. The earliest mission, Stardust, is scheduled to be launched in 1999 and return approximately 7 years later with a collection of cometary and interplanetary material. Other missions in various stages of definition would gather bits from Mars, an asteroid, or the satellites of Jupiter.
Prudence demands giving proper attention to handling extraterrestrial samples so that they pose no risk to Earth's biosphere. At the same time, an unreasonable level of concern could needlessly escalate the cost of sample handling or obviate such missions altogether.
Since Mars is the place most often considered as a possible host of past or present microbial life forms and one from which samples will surely be returned within the next decade, it has received the greatest amount of attention, including a recent study by a task group of the Space Studies Board (National Research Council, 1997, Mars Sample Return: Issues and Recommendations, National Academy Press, Washington D.C.). The present report broadens the scope of consideration to encompass the other bodies in the solar system.
The report finds that the degree of caution required in handling material depends on its site of origin. To a high degree of confidence, some returned samples do not need special handling precautions. Others might be in this category, but the degree of confidence is lower. For still others, the samples should be handled with the same degree of containment as would be applied to material from Mars.
In addition, the report considers further research that would inform this issue and reduce areas of uncertainty. Learning how some of Earth's hardier microbes would fare under the extreme conditions of radiation and temperature can help increase our understanding of the sterilization processes that occur naturally in parts of the solar system.
Since NASA has plans to bring Mars rocks back to Earth within a decade, the proper procedures for handling the most suspect samples must be put in place. This report shows that the full machinery of containment will also be required for some material, but certainly not everything, collected in our neighborhood.
Claude R. Canizares, Chair
Space Studies Board
The National Research Council's Space Studies Board provides guidance to NASA on planetary protection, which is the effort to preserve conditions for future biological and organic exploration on planets and other solar system objects and to protect Earth and its biosphere from potential extraterrestrial sources of contamination. In 1997, the Space Studies Board produced the report Mars Sample Return: Issues and Recommendations, which assessed the potential for a viable exogenous biological entity to be included in a sample returned to Earth from Mars as well as the potential for large-scale effects if such an entity were inadvertently introduced into Earth's biosphere. The report provides justification for and recommendations on procedures for the quarantine of samples returned from Mars.
Given the prospect of sample return missions from various small solar system bodies in the next decade, NASA then requested that the Board assess the potential for a living entity to be present in or on samples returned from small solar system bodies such as planetary satellites, asteroids, and comets. Guidance from the new study would extend and generalize to other solar system bodies the published advice regarding Mars.
In response to NASA's request, the Space Studies Board convened the Task Group on Sample Return from Small Solar System Bodies to assess the potential for a living entity to be present in or on samples returned from small solar system bodies by addressing the following:
The potential for a living entity to be contained in or on samples returned from planetary satellites or small solar system bodies, such as asteroids, comets, and meteoroids;
Detectable differences among small solar system bodies that would affect the above assessment;
Scientific investigations that need to be conducted to reduce the uncertainty in the above assessment; and
The potential risk posed by samples returned directly to Earth from spaceflight missions, as compared to the natural influx of material that enters Earth's atmosphere as interplanetary dust particles, meteorites, and other small impactors.
The task group met three times over an 11-month period, reviewed relevant reports, was briefed by representatives from NASA and expert researchers and practitioners on topics related to sample return, and held a workshop to obtain a wide spectrum of perspectives. The task group considered in some detail the following topics:
The possibility that, at some time in the past, life originated on a body from which a sample might be taken, or that life was transported there from elsewhere in the solar system;
The possibility that life still exists on the body either in active or in reactivatable form; and
The potential hazard to terrestrial ecosystems from extraterrestrial life if it exists in a returned sample.
The central concern addressed by the task group in this report is the possibility that samples returned to Earth from small solar bodies might harbor living entities that could harm terrestrial living organisms or disrupt their ecosystems. The primary audience for the task group's report is NASA, those who have a stake in sample return missions and planetary protection, and the public at large.
The task group members wish to thank those individuals who made presentations at the task group meetings, including Sherwood Chang, NASA-Ames; Christopher Chyba, University of Arizona; Ben Clark, Lockheed-Martin; John Cronin, Arizona State University; James Ferris, Rensselaer Polytechnic Institute; Marina Fomenkova, University of California, San Diego; Ted Roush, San Francisco State University; and Perry Stabekis, Lockheed-Martin. Special thanks are given to John Rummel and Michael Meyer for serving as the project's points of contact at NASA and for their presentations to the task group.
Acknowledgment of Reviewers
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 content of the review comments and draft manuscript remain confidential to protect the integrity of the deliberative process. We wish to thank the following individuals for their participation in the review of this report:
Rita R. Colwell, University of Maryland;
Ellis Cowling, North Carolina State University;
Michael Gaffey, Rensselaer Polytechnic Institute;
Donald M. Hunten, University of Arizona;
Marsha I. Lester, University of Pennsylvania;
Harry Y. McSween, Jr., University of Tennessee;
Norman R. Pace, University of California, Berkeley;
Everett L. Shock, Washington University; and
John A. Wood, Harvard University.
Although the individuals listed above provided many constructive comments and suggestions, responsibility for the final content of this report rests solely with the authoring task group and the NRC.