A long-standing mystery of one of the moons of Jupiter is solved, opening many more questions. Data gathered by the Galileo unmanned orbiter reveals that a previously unidentifiable substance on Europa’s surface is sulfuric acid, a compound used as battery acid on Earth. Scientists quickly split into two camps on the origins of the acid: it may be welling up from inside Europa, or it may be volcanic material ejected from Io and then deposited on Europa as the moons’ orbits occasionally bring them into conjunction. Though the presence of sulfuric acid initially dashes hopes of finding life on Europa, the possibility is not completely ruled out by this finding.
