Extremophiles Survive Simulated Conditions on Europa
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, 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.
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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: Comparative Suvival Analysis Of
Deinococcus Radiodurans and The Haloarchaea
Natrialba Magadii And
Haloferax volcanii, Exposed To Vacuum Ultraviolet Irradiation
