[meteorite-list] Alien Microbes Could Survive Crash-Landing

From: Mike Groetz <mpg444_at_meteoritecentral.com>
Date: Mon Sep 13 21:10:44 2004
Message-ID: <20040914011038.40917.qmail_at_web41306.mail.yahoo.com>

   I think their survival would depend if the planet
the bacteria came from had a helmet law....

   Sorry- list needs to smile a bit!

Everyone have a good night.
Mike Groetz
(Seriously, this was a very interesting article- Thank
You Ron).


--- Ron Baalke <baalke_at_zagami.jpl.nasa.gov> wrote:

>
>
>
http://www.nature.com/news/2004/040830/full/040830-10.html
>
> Alien microbes could survive crash-landing
> Philip Ball
> Nature
> September 2, 2004
>
> Tough bugs make interplanetary wanderings more
> plausible.
>
> Bacteria could survive crash-landing on other
> planets, a British team
> has found. The result supports to the idea that
> Martian organisms could
> have fallen to Earth in meteorites and seeded life.
>
> Bugs inside lumps of rock can survive impacts at
> speeds of more than 11
> kilometres per second, say the researchers [1]. The
> work also shows that bacteria could survive crashing
> into icy surfaces
> such as Jupiter's moons Europa and Ganymede.
>
> The possibility that Earth's first life came here
> inside space rocks -
> the panspermia hypothesis - was proposed in 1903 by
> the Swedish chemist
> Svante Arrhenius. But the painful landing has always
> been a stumbling
> block.
>
> Mark Burchell and his colleagues at the University
> of Kent, Canterbury,
> have put panspermia to the test by firing lumps of
> porous ceramic
> infiltrated with bacteria into targets. During
> impact, the bacteria are
> crushed by up to a million times atmospheric
> pressure.
>
> "A few years ago everyone said we were crazy," says
> Burchell. "They knew
> it wouldn't work." But in 2001 he and his colleagues
> showed that soil
> bacteria can survive a high-speed impact into soft
> gel [2].
> Most of the microbes died, but enough survived to
> make panspermia
> possible, provided that the bugs don't have to
> travel too far: they
> would probably be sterilized by cosmic rays and UV
> radiation during a
> journey from another solar system.
>
> Crushing blow
>
> But the researchers didn't know whether the
> pressures generated in their
> experiment were comparable to those of a meteorite
> impact. Nor did they
> know how different microbial species would fare.
>
> To find out, the team used a gas-powered gun to fire
> bits of ceramic,
> between 0.1 and 2 millimetres across, into targets
> of gel or ice. The
> projectiles were loaded with cells or spores of the
> soil bacteria
> Rhodococcus erythropolis or Bacillus subtilis.
>
> At similar pressures to those that would be suffered
> inside a meteorite
> as it crashed, around one in every ten million R.
> erythropolis cells and
> a few in every hundred thousand B. subtilis survived
> when they hit the
> gel. A gram of terrestrial soil typically contains a
> billion bacterial
> cells.
>
> The survival rate for an ice target was about ten
> times higher, so
> Burchell and colleagues think that it's not just
> Earth and Mars that
> could have swapped life. The icy moons of Jupiter,
> for instance, at
> least one of which, Europa, has a sub-surface ocean
> of water, could seed
> one another. Or a planet could re-seed itself if, as
> some have suggested
> might have happened on the early Earth, a massive
> impact wiped out all
> life.
>
> References
> 1.. Burchell M. J., Mann J. R. & Bunch A. W.
> Monthly Notices of the
> Royal Astronomical Society , 352. 1273 - 1278
> (2004).
> 2.. Burchell M. J., Mann J. R., Bunch A. W. &
> Brandao P. F. B. Icarus,
> 154. 545 - 547 (2001).
>
>
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>
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>



                
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Received on Mon 13 Sep 2004 09:10:38 PM PDT