[meteorite-list] Extremophiles Survive Simulated Conditions on Europa

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue, 4 Oct 2011 14:10:12 -0700 (PDT)
Message-ID: <201110042110.p94LAC5d002150_at_zagami.jpl.nasa.gov>

http://www.technologyreview.com/blog/arxiv/27215/

Extremophiles Survive Simulated Conditions on Europa
Technology Review (MIT)
October 3, 2011

Astrobiologists have reproduced the conditions on the surface of Europa
and found that some extremophiles survive

A couple of weeks of ago, we looked at a study indicating that in Earth
ejecta is more likely to end up in the Jovian system than on Mars
<http://www.technologyreview.com/blog/arxiv/27092/>, at least in some
scenarios. That raised the possibility that life from Earth could have
made its way to places like the Jovian moon Europa, which astronomers
believe has a large salt water ocean beneath its icy crust.

But this would only possible if terrestrial bugs can survive the intense
vacuum and radiation in interplanetary space. Astrobiologists have
studied the way many creatures survive in a space-like conditions.
They've looked at bacteria, fungi, viruses and even biomolecules such as
DNA. Some lucky bugs have even survived the journey to the Moon and back.

But one branch of life has been largely ignored in these tests--archae.
That's surprising since these bacteria-like bugs often flourish in
extreme conditions on Earth.

Today, Ximena Abrevaya at the Universidad de Buenos Aires in Argentina
and a few pals go some way to righting this wrong. These guys created a
vacuum similar to that which exists on the surface of Europa. They then
placed three organisms in it: the salt-loving archae Natrialba magadii
and Haloferax volcanii and the radiation-resistant bacteria
Deinococcus radiodurans.

They then bombarded these creatures with the levels of ultraviolet
radiation that might occur on the surface of Europa and waited to see
what happened. None of Haloferax volcanii survived. But small
amounts of both Natrialba magadii and Deinococcus radiodurans did.

That's interesting because Deinococcus radiodurans is well known as
one of the hardiest organisms on the planet. Numerous experiments have
shown that it can survive levels of radiation, vacuum, acidity, cold and
dehydration that would kill almost everything else.

For that reason, Deinococcus radiodurans has always been a candidate
for seeding life elsewhere in the Solar System.

But now it looks as if it would have a companion on such a journey in
the form of Natrialba magadii, an organism only isolated from the
salty waters of Lake Magadi in Kenya in 1984.

Before getting too excited, however, it's important to note that these
experiments have a weakness: the tests lasted only for three hours.

That's not long compared to interplanetary journey times: Earth ejecta
takes tens of thousands of years to reach other bodies. However, the
journey on a spacecraft from Earth would be much shorter, just a few years.

So if Abrevaya and co's experiment tells us anything, it's the
importance of sterilising spacecraft before they leave here.

It's just possible that right now, small colonies of Deinococcus
radiodurans and Natrialba magadii are flourishing in the weak
sunshine and cool wind around Viking 1 and 2.

Ref: arxiv.org/abs/1109.6590 <http://arxiv.org/abs/1109.6590>:
Comparative Suvival Analysis Of Deinococcus Radiodurans and The
Haloarchaea Natrialba Magadii And /Haloferax volcanii, Exposed To
Vacuum Ultraviolet Irradiation
Received on Tue 04 Oct 2011 05:10:12 PM PDT