Can Extremophiles Survive on Europa?

A team of astrobiologists from Argentina have recreated the conditions of Jupiter moon Europa, to see if extremophile bacteria could survive the unwelcoming conditions of the Jovian system.

Interplanetary space is generally considered lethal to organisms thanks to high levels of radiation, intense vacuum conditions and extreme temperatures. But the team, lead by Ximena Abrevaya at the University of Buenos Aires, wanted to see if any hardy critters could tough it out.

Finding a likely candidate would certainly help recent research at the National Autonomous University of Mexico, where researchers used a computer simulation to find if life could spread into space, hitchhiking on space-faring rocks.

That team found that particles ejected from the Earth could reach as far as Jupiter and one of its 64 moons, Europa, which astronomers reckon has a huge salt water ocean underneath its icy crust. A good breeding ground for life. But could anything survive the trip?

The team from Buenos Aires created a vacuum with conditions similar to those which exist on the surface of Europa. They then placed three organisms in it: the hypersaline-tolerent Natrialba magadii, the salt-obsessed Haloferax volcanii and the ultra-hardy, all-around survivor Deinococcus radiodurans.

The researchers then blasted these critters with ultraviolet radiation at levels that might occur on Europa. After three hours of extensive radiation, the results came back: none of the H. volcanii survived, but small numbers of D. radiodurans and N. magadii could tough out the toxic rays.

D. radiodurans are well-known survivors, often called the world's toughest bacteria for their ability to shrug off extremely low temperatures, a complete lack of water, deadly vacuums and acid. In a past experiment using simulated Martian soil, 30 percent of a community of D. radiodurans survived for 10 days. These guys are tough.

But now astrobiologists will want to take a closer look at N. magadii, to see if they're as hardy as D. radiodurans. The team writes, in the paper: "Much longer exposure times need to be tested to see if at least a small number of cells of N. magadii and D. radiodurans could survive the V-UV and vacuum damages present in space without any protection."

Studying to see if microbes have the ability to survive in space conditions has many applications in astrobiology. "For example, it is important to develop planetary protection procedures, life support systems and energy fuel cells based on a number of microbial species," the team writes.

"It is also important to avoid forward contamination," they conclude. You don't want to discover life on Europa, claim it's aliens, but later find out it's just life from Earth that's hitched a ride to Jupiter on a meteorite or a spaceship.

 by "environment clean generations"