[meteorite-list] Meteorite Experiment Deals Blow To 'Bugs From Space' Theory
From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed, 24 Sep 2008 14:17:30 -0700 (PDT)
Meteorite experiment deals blow to 'bugs from space' theory
September 24, 2008
A novel experiment has dealt a setback to a theory that life on Earth
was kick started by bacteria that hitched a ride on space rocks.
The "pan-spermia" hypothesis is that cells were transported to the
infant Earth on rocks that were bumped off other planets or even came
from another star system.
The theory gained a boost in 1996 when a group of US scientists proposed
that a famous meteorite found in Antarctica held traces of fossilised
bacteria that once lived on Mars.
Seeking to find out more, European scientists have devised "artificial
meteorites" to see what happens when rocks bearing fossil traces and
living bacteria are exposed to the fiery heat of entering Earth's
In research to be unveiled on Wednesday, they attached small rocks two
centimetres thick to a Russian unmanned Foton M3 capsule that was
launched in September 2007 and returned to Earth 12 days later.
The samples were imbedded on the capsule's heat shield, which reached a
peak velocity of 7.6 kilometres per second or 27,200 kilometres, per
hour during the controlled descent.
The study was scheduled to be presented on Wednesday at the European
Planetary Science Congress in Muenster, Western Germany.
So far 39 meteorites have been found on Earth that have been attributed
to a Martian origin. The notion is that they were knocked off the planet
in the distant past by an asteroid impact. They then wandered in space
before landing on earth.
But all of these meteorites are of basalt, or volcanic origin. None is
sedimentary. This has perplexed scientists, as there is abundant
evidence for sediments on the Red Planet.
Outcome of the experiment shows Martian sedimentary rocks could survive
entry through Earth's atmosphere.
Received on Wed 24 Sep 2008 05:17:30 PM PDT