[meteorite-list] Alien Life Can Survive Trip to Earth, Space Test Shows

From: Mike Groetz <mpg444_at_meteoritecentral.com>
Date: Mon, 12 Nov 2007 15:53:23 -0800 (PST)
Message-ID: <38515.10434.qm_at_web32911.mail.mud.yahoo.com>

http://news.nationalgeographic.com/news/2007/11/071112-space-rock.html

  
Alien Life Can Survive Trip to Earth, Space Test Shows

James Owen
for National Geographic News
 
November 12, 2007
  


We could have alien origins, say scientists who sent
fossilized microscopic life-forms into space and back
inside an artificial meteorite.

The researchers attached the baseball-size rock to the
outside of the European Space Agency's Foton M3
spacecraft to test whether biological material could
survive the round-trip journey.

Sculpted from stone from the Orkney Islands in
northern Scotland, the rock contained fossilized
microbes and the molecular signatures of microbes.

The unmanned spacecraft was launched by rocket from
Kazakhstan's Baikonur Cosmodrome carrying 43
experiments. The craft landed in Kazakhstan on
September 26 after orbiting the planet for 12 days.

"In the bit of rock we got back, some biological
compounds have survived," said project leader John
Parnell from the University of Aberdeen in Scotland.

Preliminary findings suggest that it's possible simple
organisms could arrive via meteorites, he said.

The research also suggests that living microbes would
likely have survived in a slightly bigger rock, he
added.

"This study of organic material is completely new," he
said.

Previous artificial meteorite experiments have
examined only the degree to which rocks melt upon
entering the atmosphere.

(Related news: "Did Comets Make Life on Earth
Possible?" [October 2, 2003].)

The new experiment is part of European Space Agency's
STONE program, which tests effects of reentry on
artificial meteorites.

Microbe Survival

A rock measuring 2.8 inches (7 centimeters) across was
fitted to the exterior of Foton M3.

"It was shielded when it went up into space but
exposed when it came back," Parnell said.

The rock had similar properties to a type of meteorite
known as a carbonaceous chondrite. Such meteorites
contain water and carbon compounds, both essential to
life.

"We wanted to see if a rock that was rich in carbon
and water would suffer a lot of mass loss," Parnell
said. "That was certainly the case. About
three-quarters of the mass of our sample disappeared."

Living microbes probably wouldn't have survived in a
meteorite this size because it reached temperatures of
about 392 degrees Fahrenheit (200 degrees Celsius),
the project leader said.

But "if our rock was bigger, say 20 centimeters (about
8 inches) across, then we can be quite confident that
[the] temperature would not penetrate to the middle,
so that if anything had been living there, it would
have survived."

A much larger meteorite, however, would completely
melt and vaporize on impact, according to Parnell.

"There's a sort of window of opportunity in terms of
size, between being too small and too big," he added.

Microbes are known to live deep inside rocks, and are
found several kilometers down in Earth's crust,
Parnell noted.

Mars Origins?

The theory that says interplanetary organisms seeded
life on different planets, such as Earth, is known as
panspermia.

If panspermia explains the origins of life on Earth,
astrobiologists believe that Mars is the most likely
source. (See pictures of the red planet.)

For instance, studies suggest about 5 percent of
meteorites from Mars eventually end up hitting Earth.

"That journey can take anything up to 15 million
years, but there are a few that will make it very
quickly," Parnell said.

"A very few will make it in a year or so. Those are
the ones which could conceivably bring something
interesting with them."

"The surface of Mars is quite inhospitable, due to
dryness and low temperature, but one could conceive of
subsurface life still being on Mars," he added.
(Related news: "Mars Life May Be Too Deep to Find,
Experts Conclude" [February 2, 2007].)

In the experiment, microbes were also dried onto the
undersides of several artificial meteorites.

"This biological material didn't survive, but it may
have been preserved, or its signatures may have been
preserved," said STONE scientist Charles Cockell of
the Open University in the United Kingdom.

The rocks are still being analyzed, Cockell added.

"We know that life can make it from continent to
continent, but what about from planet to planet?" he
said.

"Of course, at the moment we don't know of life on
another planet, but this experiment is an intriguing
test of an interplanetary version of an old ecological
question."

David Morrison is a senior scientist at the NASA
Astrobiology Institute in Moffett Field, California.

Parnell's project lends credibility to the idea that
meteors from outer space can give rides to hitchhiking
microbes, he told National Geographic News by email.

Whether exchange of life has ever occurred following
the meteorites' impact is a more complex question, but
"we should be open to the possibility that there is
microbial life on Mars that shares a common ancestor
with Earth life," he said.

"It may not be likely, but we cannot exclude the
possibility that we are, in effect, all Martians."
 



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Received on Mon 12 Nov 2007 06:53:23 PM PST