New research has found that while life would not be able to survive on its surface, due to the moon's lack of atmosphere meaning it is exposed to harsh radiation, but amino acids, which are a signature of life, could be preserved for up to 10 million years just one to three centimetres beneath the surface.
As many missions have revealed by studying Europa's surface, the moon experiences periodic exchanges between the interior and the surface. However, Europa's surface is bombarded by a constant and intense blast of radiation from Jupiter. Using data from the Galileo and Voyager 1 spacecraft, a team of scientists recently produced a map that shows how radiation varies across Europa's surface.
But new research published online Monday in the journal Nature Astronomy suggests that just scratching the surface of Europa's frozen shell, and in just the right spot, might yield evidence of life forms that once existed or perhaps still live there.
Now scientists know where to find regions least altered by radiation, which could be crucial information for the JPL-led Europa Clipper, NASA's mission to orbit Jupiter and monitor Europa with about 45 close flybys. "Does this tell us what is in the ocean, or is this what happened to the materials after they have been radiated?"
Nordheim and his team discovered that the radiation on the surface was at its most intense around the moon's equator, tapering out towards the poles.
Dr Tom Nordheim, a NASA scientist who is an expert on the habitability of icy worlds, said: "These results indicate future missions to Europa's surface do not need to excavate material to great depths to investigate the composition of material and search for potential biosignatures".
"This is the first prediction of radiation levels at each point on Europa's surface and is important information for future Europa missions", said Chris Paranicas, a co-author from the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland.
The answer varies, from 4 to 8 inches (10 to 20 centimeters) in the highest-radiation zones - down to less than 0.4 inches (1 centimeter) deep in regions of Europa at middle- and high-latitudes, toward the moon's poles.
To reach that conclusion, Nordheim tested the effect of radiation on amino acids, basic building blocks for proteins, to figure out how Europa's radiation would affect potential biosignatures.
"The radiation that bombards Europa's surface leaves a fingerprint", Kevin Hand, a co-author of the study, added.
'If we know what that fingerprint looks like, we can better understand the nature of any organics and possible biosignatures that might be detected with future missions, be they spacecraft that fly by or land on Europa'.