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Policies Needed For Reporting Potential Hazards Of Asteroid Collisions

NOTE: The report cited in this release is available online at
   http://www.nap.edu/readingroom/enter2.cgi?0309060834.html

*****

National Research Council
Washington, D.C.

Contacts: Ellen Bailey Pippenger, Media Relations Associate
Dumi Ndlovu, Media Relations Assistant
(202) 334-2138; e-mail news@nas.edu

Date: May 13, 1998

Publication Announcement

Policies Needed for Reporting Potential Hazards Of Asteroid Collisions
with Earth

Recent news of a possible asteroid collision with Earth in 2028
sparked intense scientific and popular interest worldwide. When
further data revealed that the asteroid had virtually no chance of
hitting this planet, the episode prompted the astronomy community to
re-evaluate how they communicate such information to the public.

NASA and astronomers should develop protocols for reporting
information about asteroids that appear to pose a potential hazard to
Earth, says a new report from a National Research Council committee,
which began its work before the recent episode. These protocols will
be important because several telescope facilities and new instruments
now coming into operation will dramatically increase the rate by which
scientists are able to discover asteroids and comets whose orbits
approach Earth. With the flood of discoveries expected within the next
decade also will come the risk of false alarms.

Some 400 Earth-approaching asteroids and comets larger than one
kilometer in diameter have been discovered so far, but only an
estimated 10 percent of the objects this size have been identified. Of
the thousands that may be discovered, some initially -- for a few
days, weeks, or even years -- may seem likely to collide with Earth,
until enough data have been collected to determine accurate orbits and
interpreted to show otherwise. Policies for handling such potentially
important information will be needed. International scientific
organizations, such as the International Astronomical Union, could
play a role in this task, the report says.

Most asteroids orbit the sun in a belt between Jupiter and Mars, but
thousands have orbits that sometimes take them uncomfortably close to
Earth. Geological processes such as erosion tend to erase scars left
when asteroids and comets occasionally hit Earth, but there are some
notable exceptions, such as Arizona's Meteor Crater. Moreover, there
is evidence that an asteroid or comet some five to 10 kilometers in
diameter created an enormous crater in Yucatan, Mexico, some 65
million years ago. That event has been implicated in the extinction of
dinosaurs and other living organisms. This information, coupled with
recent evidence of the collision of Comet Shoemaker-Levy 9 with
Jupiter in 1994, has led to increased scientific and public interest
in assessing the likelihood that a large object might hit Earth again.

Although asteroids and comets are potential hazards to Earth, these
tiny worlds offer a trove of clues to the solar system's birth and
early history, the report says. Exploration of asteroids also may be
used as stepping stones toward manned missions to Mars. Comets are
frozen chunks of ice and dust thought to be left from the formation of
the planets in the solar system. Asteroids are minor planets, some
made from almost pure mixtures of nickel and iron like those at the
Earth's core or from minerals similar to those found in the Earth's
crust, and others from exotic combinations of carbon compounds.

To better understand the scientific opportunities posed by asteroids
and comets, the report recommends that priorities be given to the
following areas:

Telescopic studies. NASA, other government agencies, and private
research organizations should further coordinate their programs using
ground-based telescopes to search for and study asteroids and comets.
Because a typical asteroid or comet is very faint and travels by Earth
so quickly, the opportunity to view it may last no more than a few
days or a week at most. To conduct the detailed observations that
these fleeting objects require, routine or priority access to existing
infrared and optical telescopes is needed. Otherwise, telescopes
dedicated to characterizing the asteroids and comets discovered by
ongoing search programs should be developed.

Laboratory investigations. More research is needed to increase
understanding of extraterrestrial materials, such as meteorites, which
are believed to come from asteroids. Laboratory studies can address,
for example, the puzzle of how the environment in space changes the
surfaces of asteroids to such an extent that the physical
characteristics of the most common varieties of asteroids and
meteorites do not match. NASA, other government agencies, and private
research organizations should support additional laboratory
investigations of samples of these space-borne objects. New analytical
instruments, such as those necessary to study very small samples of
meteorites, also are needed.

Robotic and manned spacecraft missions. Spacecraft that pass by,
rendezvous with, or obtain samples from asteroids orbiting near Earth
provide important information on the detailed physical
characteristics, composition, and geologic histories of planetary
bodies that is otherwise unobtainable. Moreover, Earth-approaching
asteroids or comets are among the most accessible objects in the solar
system. Indeed, some are easier to reach than the moon. NASA's Galileo
missions, for example, provided a wealth of information about
asteroids Ida and Gaspra orbiting between Mars and Jupiter. Last year,
a NASA spacecraft made detailed observations of another asteroid,
Mathilde. The spacecraft is currently en route to a February 1999
rendezvous with Eros, one of the largest Earth-approaching asteroids.
NASA should continue such missions and improve spacecraft technology,
such as propulsion and navigation systems, to allow additional
low-cost rendezvous and sample-return missions.

Should the United States choose to undertake further manned
exploration beyond Earth, a strong case can be made for beginning with
missions to Earth-approaching asteroids, the report says. Because
missions to these asteroids represent deep-space exploration with
moderate technical challenges, they would be the least-expensive next
step in human exploration of space and could provide the experience
and technology needed for fruitful missions to Mars and beyond. Five
percent of Earth-approaching asteroids are readily accessible by
relatively short space flights.

A primary concern would be keeping the length of the mission as short
as possible to minimize hazards and risks to which astronauts are
exposed, including weightlessness, radiation, meteoroid impact, and
equipment failure. Further research should be conducted to study
specific technical requirements necessary for a six- to 12-month
round-trip expedition. With the anticipated increase in discoveries of
Earth-approaching asteroids, there likely will be opportunities for
missions to one or more asteroids each year.

The study was funded by the NASA. The National Research Council is the
principal operating agency of the National Academy of Sciences and the
National Academy of Engineering. It is a private, non-profit
institution that provides science advice under a congressional
charter. A committee roster follows.

Copies of The Exploration of Near-Earth Objects are available from the
National Academy Press for $10.00 (prepaid) plus shipping charges of
$4.00 for the first copy and $.50 for each additional copy; tel. (202)
334-3313 or 1-800-624-6242. Reporters may obtain a copy from the
Office of News and Public Information (contacts listed above).

NATIONAL RESEARCH COUNCIL
Commission on Physical Sciences, Mathematics, and Applications
Space Studies Board

Committee on Planetary and Lunar Exploration

Ronald Greeley (chair)
Professor of Geology
Department of Geology
Arizona State University
Tempe

Jeffrey R. Barnes
Associate Professor
College of Oceanic and Atmospheric Sciences
Oregon State University
Corvallis

Richard P. Binzel
Professor
Department of Earth, Atmospheric, and Planetary Sciences
Massachusetts Institute of Technology
Cambridge

Wendy Calvin
Geophysicist
Astrogeology Team
U.S. Geological Survey
Flagstaff, Ariz.

Russell F. Doolittle*
Research Professor of Biochemistry
Center for Molecular Genetics
University of California
San Diego

Heidi Hammel
Principal Research Scientist
Department of Earth, Atmospheric, and Planetary Sciences
Massachusetts Institute of Technology
Cambridge

Larry A. Haskin
Professor of Chemistry and Earth and Planetary Sciences
Department of Earth and Planetary Sciences
Washington University
St. Louis

Bruce Jakosky
Associate Professor, Atmospheric and Space Physics
Laboratory for Atmospheric and Space Physics
University of Colorado
Boulder

Kenneth Jezek
Director, Byrd Polar Research Center, and
Professor, Department of Geological Sciences
Ohio State University
Columbus

George E. McGill
Professor Emeritus
Department of Geosciences
University of Massachusetts
Amherst

Harry Y. McSween Jr.
Professor
Department of Geological Sciences
University of Tennessee
Knoxville

Michael Mendillo
Professor, Department of Astronomy, and
Professor, Department of Electrical and Computer Engineering
Boston University
Boston

Gerald Schubert
Professor of Geophysics and Planetary Physics
Department of Earth and Space Science
University of California
Los Angeles

Everett Shock
Associate Professor
Department of Earth and Planetary Sciences
Washington University
St. Louis

RESEARCH COUNCIL STAFF

David H. Smith
Senior Program Officer

_________________________________________
(*) Member, National Academy of Sciences