Newspaper article The Christian Science Monitor

Making Sure Martian Life Hasn't Hitched Ride on Earthly Craft

Newspaper article The Christian Science Monitor

Making Sure Martian Life Hasn't Hitched Ride on Earthly Craft

Article excerpt

Recent discovery of "could-be" fossils in a Martian meteorite has sharpened an old issue - interplanetary contamination.

The prospect that Mars may once have had life - and may still have it - whets explorers' appetites. But before they launch missions to look for it, they have to be sure they won't make a biological mess. Scientists don't want to "discover" life on Mars that hitched a ride from Earth on their space probes. They also must plan to isolate Mars samples brought here.

Daniel Goldin, administrator of the National Aeronautics and Space Administration (NASA), has said the agency may want to speed up its time table for collecting Mars samples. That means sending a sample-return mission a few years earlier than the 2005 date now provisionally targeted as part of a 10-year Mars exploration program. But Mr. Goldin also has said that NASA "would rather not have a mission" at all until issues of contamination are satisfactorily dealt with. He added that this policy "is non-negotiable."

That puts the bee on NASA to update its biological safety standards quickly. Kenneth Nealson of the University of Wisconsin at Milwaukee says this would be an "urgent" problem if NASA hadn't gotten a jump start on the work. Last year, the agency asked the National Research Council of the National Academy of Sciences to review the standards. Dr. Nealson, who chairs the council committee, says he expects to have recommendations late this year.

This issue is more complicated than just sterilizing everything sent to Mars and locking away everything brought here. Earth and Mars have exchanged material for eons. On average, some 50 kilograms (110 pounds) of Martian meteorites arrive every year. Earth probably has returned the favor. Knocked off the parent planet by the impact of an asteroid or meteorite, material orbits through the inner solar system until captured by the host planet's gravity. Encounters with other planets or with the home planet can alter the material's course. …

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