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

From: GERALD FLAHERTY <grf2_at_meteoritecentral.com>
Date: Mon Sep 13 19:23:15 2004
Message-ID: <007d01c499e8$a88cf910$6501a8c0_at_dawnjerry>

Yikees!!!!
----- Original Message -----
From: "Ron Baalke" <baalke_at_zagami.jpl.nasa.gov>
To: "Meteorite Mailing List" <meteorite-list_at_meteoritecentral.com>
Sent: Monday, September 13, 2004 6:54 PM
Subject: [meteorite-list] Alien Microbes Could Survive Crash-Landing


>
>
> 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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Received on Mon 13 Sep 2004 07:23:20 PM PDT