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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 committee responsible for the report were chosen for their special competencies and with regard for appropriate balance.
This report has been reviewed by a group other than the authors according to procedures approved by a Report Review Committee consisting of members of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine.
This study was supported by Contract No. NASW-4938 between the National Academy of Sciences and the National Aeronautics and Space Administration. Any opinions, findings, conclusions, and recommendations expressed in this publication are those of the authors and do not necessarily reflect the view of the organizations or agencies that provided support for this project.
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Copyright 1997 by the National Academy of Sciences. All rights reserved.
Cover Illustration: The large picture of the shuttle orbiter was taken from the Mir space station during shuttle mission STS-71 in July 1995. The inset is a scanning electron micrograph of a 0.6 mm diameter crater found on the Solar Maximum Mission Satellite, which was recovered from space in April 1994 by the crew of shuttle mission STS-41C. Source: NASA.
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COMMITTEE ON SPACE SHUTTLE METEOROID/DEBRIS RISK MANAGEMENT
FREDERICK H.HAUCK (chair),
AXA Space, Bethesda, Maryland
KYLE T.ALFRIEND,
Texas A&M University, College Station
DALE B.ATKINSON, consultant,
Springfield, Virginia
DALE R.ATKINSON,
POD Associates, Inc., Albuquerque, New Mexico
G.TAFT DEVERE,
Space Warfare Center, Falcon Air Force Base, Colorado
DONALD H.EMERO,
Rockwell International (retired), Fountain Valley, California
GEORGE J.GLEGHORN,
TRW Space and Technology Group (retired), Rancho Palos Verdes, California
DARREN S.MCKNIGHT,
Titan Research and Technology, Reston, Virginia
WILLIAM P.SCHONBERG,
University of Alabama in Huntsville, Huntsville
Aeronautics and Space Engineering Board Liaison
WILLIAM H.HEISER,
U.S. Air Force Academy, Colorado Springs, Colorado
Aeronautics and Space Engineering Board Staff
PAUL SHAWCROSS, Study Director
JOANN CLAYTON-TOWNSEND,
Aeronautics and Space Engineering Board Director (until July 11, 1997)
MARVIN WEEKS, Senior Project Assistant
AERONAUTICS AND SPACE ENGINEERING BOARD
JOHN D.WARNER (chair),
The Boeing Company, Seattle, Washington
A.DWIGHT ABBOT,
Aerospace Corporation, Los Angeles, California
STEVEN AFTERGOOD,
Federation of American Scientists, Washington, D.C.
GEORGE A.BEKEY,
University of Southern California, Los Angeles
GUION S.BLUFORD, JR.,
NYMA, Inc., Brook Park, Ohio
RAYMOND S.COLLADAY,
Lockheed-Martin Astronautics, Denver, Colorado
BARBARA C.CORN,
BC Consulting, Inc., Searcy, Arizona
STEVEN D.DORFMAN,
Hughes Telecommunications and Space Company, Los Angeles, California
DONALD C.FRASER,
Boston University, Boston, Massachusetts
JAMES M.GUYETTE,
Rolls-Royce North America, Reston, Virginia
FREDERICK H.HAUCK,
AXA Space, Bethesda, Maryland
WILLIAM H.HEISER,
U.S. Air Force Academy, Colorado Springs, Colorado
WILLIAM HOOVER,
U.S. Air Force (retired), Williamsburg, Virginia
BENJAMIN HUBERMAN,
Huberman Consulting Group, Washington, D.C.
JAMES G.O’CONNOR,
Coventry, Connecticut
GRACE M.ROBERTSON,
The Boeing Company, Long Beach, California
GEORGE SPRINGER,
Stanford University, Stanford, California
Staff
JOANN C.CLAYTON-TOWNSEND, Director (until July 11, 1997)
GEORGE M.LEVIN,* Director (from July 14, 1997)
Preface
In 1983, three days into my first shuttle mission, I noticed a small pit in one of the windows of the crew cabin. Spectrographic analysis of the residue left in this tiny pit revealed the presence of titanium and aluminum, suggesting that the orbiter had been hit by a chip of paint that had flaked off of some unknown spacecraft or rocket body. This was one of the first indications that orbital debris might pose a hazard to the space shuttle.
By 1995, the number of reported window impacts had increased dramatically, and the debris hazard had forced planners to modify plans for shuttle mission STS-73. In September 1995, the space shuttle program manager established a Space Shuttle Meteoroid and Debris Damage Team to review the environment modeling and orbiter modeling, to assess the potential for damage from meteoroids and orbital debris, and to “recommend concepts and methods to reduce risk to critical orbiter areas” (Holloway, 1995).
In 1995 and 1996, significant impacts occurred on the orbiter’s payload bay door and rudder speed brake, as well as on the tethered satellite pallet. In May 1996, the manager of the space shuttle program established interim guidelines to “minimize the time spent in sensitive attitudes, minimizing the probability of orbital debris impact to the wing leading edge and orbiter radiators.” He further stated that “mission planning and design should be implemented with the objective of not exceeding a probability of critical penetration of 1/200 while also minimizing the exposure of the orbiter radiators to orbital debris as much as possible” (Holloway, 1996).
The allowable risk of 1/200 means that the hazard from meteoroids and orbital debris is, on some missions, the single greatest threat to the shuttle and crew, slightly larger than the hazard from ascent. To gain an independent, outside
assessment of the threat, and of measures to address it, the National Aeronautics and Space Administration (NASA) asked the National Research Council (NRC) to review the space shuttle program’s strategy for assessing and mitigating the threat posed by meteoroids and orbital debris. In response, the NRC formed the Committee on Space Shuttle Meteoroid/Debris Risk Management, under the auspices of the Aeronautics and Space Engineering Board. (The charge to the committee is contained in Appendix A.) The committee met in April and June of 1997 to receive briefings from NASA and NASA contractors and to deliberate on findings and recommendations. This report is the product of those meetings and of additional data gathering, writing, and discussion during the summer and fall of 1997.
The committee concurs that the threat to the shuttle from meteoroids and orbital debris is real, although the magnitude of the threat and the resulting hazard are not clear. In recent years, researchers have greatly improved models of the debris environment and conducted numerous tests and studies to assess the damage caused by the impact of meteoroids and orbital debris, but no end-to-end assessment has been made of the orbiter’ s survivability in the face of the meteoroid and debris hazard.
Such an assessment is needed, and needed soon. Until the magnitude of the threat—and the uncertainty of the threat assessment—are better known, program managers and mission planners will be forced to balance crew safety against cost and mission goals based on very incomplete information. The assessment will have other benefits as well—improvements in NASA’s environment and impact models will benefit space activities worldwide.
NASA has developed a world-class center of expertise on the meteoroid and orbital debris hazard. Many experts from NASA and NASA contractors briefed the committee and provided us with information essential to this study. The committee thanks them for their professional and candid presentations. I extend my warm thanks to Dr. Bill Heiser, NRC Aeronautics and Space Engineering Board liaison to this project, for his active participation, his counsel, and his insightful critique of our process and text. In closing, I want to thank the members of the committee personally for their time and effort on the study and on writing this report, as well as Paul Shawcross, the study director, for his tireless efforts in bringing this project to fruition.
RICK HAUCK
Committee Chair
REFERENCES
Holloway, T.W. 1995. Space shuttle meteoroid and debris damage team. MA2–95–074. Houston: NASA Johnson Space Center. September 28, 1995.
Holloway, T.W. 1996. Orbital debris mission planning guidelines. MA2–96–082. Houston: NASA Johnson Space Center. May 30, 1996.
List of Tables, Figures, and Boxes
TABLES
2–1 |
Predicted Number of Impacts on Orbiter, |
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2–2 |
Damage Thresholds for Orbiter Components, |
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2–3 |
Risk during EVA, |
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3–1 |
Total Calculated Risk of Critical Failure, |
FIGURES
2–1 |
Survivability analysis, |
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2–2 |
Comparison of meteoroid and debris flux in ISS orbit, |
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2–3 |
Orbiter primary structure, |
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2–4 |
Orbiter systems concentrated along the fore-aft axis, |
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3–1 |
On-orbit impact analysis methodology, |
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3–2 |
Relative critical risks for orbiter components after refinement of critical failure limits, |
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4–1 |
Particle lifetime as a function of diameter and solar activity, |
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5–1 |
The space shuttle alert and maneuver boxes, |
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6–1 |
Window replacements vs. shuttle orientation, |
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6–2 |
Critical penetration risk vs. shuttle orientation, |
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6–3 |
Modification of radiator tube shielding, |
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6–4 |
Use of remote manipulator system to survey orbiter for damage, |
BOXES
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