[Astronomers] Brown and Hand, using the monster 10-meter Keck telescope, discovered the presence of magnesium sulfate—MgSO4, a mineral called epsomite—on Europa’s trailing hemisphere (but not the leading half). This has never been seen before, even by probes sent to look at the moon.
This also contributes to the case that Europa has a large ocean lurking under its icy surface, which could be hospitable for life.
Jupiter’s moon Europa, as seen from NASA’s Galileo spacecraft. Credit: NASA.
Epsomite is the mineral form of Epsom salts, which naturally occur mainly in encrustations and effloresences (coatings on porous rock). But the rare crystalline form is fibrous and looks like fur! And there’s also a rare acicular form — spikey! In my imagination, all the epsomite on Europa is fibrous and acicular.