The mysterious red streaks that mark the icy surface of Europa, the moon of Jupiter that conceals a large ocean beneath its surface, could be formed by water and salt crystals generated by the combination of cold and very high pressures. The finding by an international group of researchers led by the University of Washington has been published in the journal of the National Academy of Sciences (PNAS).
Europa is one of the very few bodies in the Solar System in which liquid water is always present, although it is located under a layer of ice thousands of meters thick. For this reason it is considered one of the most important sites to search for possible forms of alien life.
As observed by the probes that have studied it closely, the icy surface of Europa is marked by long, deep red streaks due to the presence of salts crystals whose origin had so far been a mystery. By replicating in laboratory conditions the temperatures and the very high pressures existing in the depths of the oceans of Europa, it was possible to reconstruct for the first time the origin of these strange crystals, composed of a few salt molecules and which develop through a series of hitherto little-investigated chemical reactions.
According to the authors, these crystals could have formed about ten kilometers beneath the ice and at temperatures of -50 degrees Celsius, before later being pushed slowly towards the surface. It is a discovery that clarifies for the first time the mechanisms that might have led to the strange coloration of Europa and that could also prove useful in the commercially available energy storage devices that use salt crystals . The researchers now hope to be able to confirm their theory by analyzing samples of Europa's ice thanks to upcoming space missions such as the European Space Agency's (ESA) Juice, which will start in April, or NASA's Europa Clipper, scheduled for 2024.
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