MICROBES can hitch a ride to Earth without getting fried, says Benjamin Weiss
of the California Institute of Technology in Pasadena.
He and his colleagues probed slices of the infamous Martian meteorite
ALH84001 with a device that can detect microscopic differences in magnetic
fields. By looking at how the pattern changed when sections of the rock were
heated, they concluded that the interior of the meteorite never got hotter than
40 掳C (Science, vol 290, p 791).
It had been assumed that any rocks knocked off Mars by a meteor impact would
be sterilised by heat during the blast. But the results show that Martian
meteorites can remain cool enough for life to reach Earth from
Mars鈥攁lthough there is no evidence that this has happened.
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