A new assessment of the level of radiation on the surface of Europa's satellite showed that it is not so great, and biomolecules are able to remain quite shallow under the ice.
Jupiter's moon Europa is considered one of the most promising bodies for the search for extraterrestrial life in the entire solar system. However, its orbit passes through the radiation belt of a huge planet, receiving millions of times more radiation than we do on Earth. As far as we know, no life can exist in such conditions, although it may well be hidden under the screen of the satellite's ice crust.
For this, it is not even necessary to descend to a depth of 10-30 km, where, as it is assumed, there is a whole ocean of liquid water. New estimates of the radiation level in Europe show that the circumpolar regions receive much less radiation than the really harsh low latitudes: already a few centimeters of ice can serve as a sufficient shield from local radiation. And if, in a few years, a mission goes to the satellite to search for life, it is there that the chances of finding it are maximum.
In an article published in the journal Nature Astronomy, Tom Nordheim and his co-authors are evaluating the possibilities of detecting potential biomarkers on different parts of Europa's surface. Indeed, even if life lurks in a remote depth below the ice crust, the satellite's crust itself is geologically active and constantly renewed, and can carry traces of life closer to the surface.
The further fate of these molecules - and if we talk about life in the only form we know, then we are talking about amino acids and other fairly complex organic compounds - depends on radiation. According to new calculations by Nordheim and his colleagues, Europa's orbital motion leads to an uneven distribution of radiation particles over the surface, and they form two "radiation lenses" centered at the equator - in the anterior and posterior hemispheres.
The radiation level allows organics to remain stable at a depth of 10-20 cm at low latitudes and up to 1 cm at medium and high latitudes. It is worth remembering that NASA officials are now considering a draft Europa Lander mission for launch in 2024. The apparatus should be equipped with spectrometers and a microscope for examining samples, as well as a drill designed for a depth of 10 cm. Apparently, this should be enough to detect "European" life, if only there is one.