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

[GERALD FLAHERTY]

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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