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NewsHour
Backgrounders
June 10, 1997:
A Gergen dialogue
with William Broad about his book "The Universe Below."
April 10, 1997:
NASA scientists explain the
findings from Europa.
Browse the NewsHour's science
coverage.
Outside
Links
Browse stories from the New York Times by William J. Broad and others on Europa. (note:
free, but registration is required.)
Browse Simon & Schusters' page on "The Universe Below: Discovering the Secrets of the Deep Sea."
|
 Patricia
Banville of Fredericksburg, VA, asks:
Is there any possibility that NASA's landing of Explorer on the planet
Mars might jeopardize any possible life on that planet by introducing alien
materials to the biosphere/ecosystem that might exist there?
William Broad responds:
Yes and no. The infection of other worlds by
Earth organisms is a serious issue, as suggested by the 1992 report, "Biological
Contamination of Mars," by the National Academy of Sciences. The report
made a number of suggestions to decrease the likelihood of the transfer
of terrestrial microbes. On the other hand, other landers from Earth have
already touched down over the decades on the Martian surface, which is
clearly inhospitable to earthly life. Moreover, the sterilization standards
for spacecraft are much better today than they were for the Soviet probes
that touched down in 1971, or the American ones in 1975. So if terrestrial
microbes can in fact be transferred, they probably already have been in
the past! C'est la vie!
Patricia, an honest answer your very good question
has a complicating feature, however, since space scientists believe that
many TONS of Earth and
Mars are transferred to one another EACH YEAR
by the process of asteroids slamming into planetary bodies and knocking
clouds of debris back into space. That mechanism is thought to account
for Mars rock ALH84001, which was found in antarctica in 1984 and is now
suspected of harboring fossil Martian life. A ongoing question among planetary
scientists is whether life on such rocky debris could ever survive the
rigors of space travel and the fires of planetary reentry.
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