Europa, a moon of Jupiter, is one of the best candidates for finding alien life in our solar system, thanks to a large ocean of liquid water. But detecting any signs of life has so far proved difficult, since that ocean is buried under kilometers of ice.
One solution is to look for life-related molecules brought up to the surface by plumes of water and other geological processes. Researchers thought such molecules wouldn鈥檛 hang around, though, as intense radiation hitting Europa, primarily caused Jupiter and its fellow moon Io, would quickly destroy these tell-tale signs.
Now it seems that that amino acids, which are crucial to all biological processes, could be protected by just a few centimetres of icy crust.
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Easier to find
That would make finding life much easier, says Tom Nordheim of NASA鈥檚 Jet Propulsion Laboratory in Pasadena, California. 鈥淵ou can just scratch the surface instead of drilling deep into it.鈥�
Nordheim鈥檚 team looked at how quickly common amino acids were destroyed by radiation in the lab, then calculated how deep the molecules would need to be buried in order to survive the radiation levels on Europa.
They found that in some areas, amino acids lying about 2 centimeters below the surface could be protected for 10 million years. Even molecules in the areas with the most intense radiation, could survive under just 10 cm of ice.
This could have significant implications for future missions to Europa. So far, planned missions have emphasised orbiters detecting molecules from the plumes of water erupting out of the moon, but these plumes may be inconsistent and unpredictable. The idea that evidence can be sheltered so close the surface strengthens the case for sending a lander as well.
Michel Blanc, of the Research Institute in Astrophysics and Planetology in France, says that landers face their own challenges. 鈥淭he drawback is that the places with geological activities also have the worst topography.鈥� Although Europa鈥檚 surface is unusually smooth overall, any mission to look for evidence of life would have to go to land on聽these rough, difficult places.
Nature Astronomy
