Brown deposits could come from water-rock interaction on the seafloor, a promising sign for a habitable environment
JPL-Caltech/NASA, SETI Institute
Salt from a subsurface sea on Jupiter’s moon Europa might scribble the rust-colored bands that crisscross the satellite’s icy surface.
The salt is probably deposited on the surface by liquid water that intermingles with a rocky seabed, researchers report May 15 in Geophysical Research Letters. Deposits of NaCl — ordinary table salt — are normally white. But planetary scientists Kevin Hand and Robert Carlson, of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., speculated that harsh radiation around Jupiter might add a dash of color. The planet’s magnetic field traps passing electrons, some of which smack into Jupiter’s moons.