Developments in Brief : Jupiter Photographs Suggest Ice Volcano
Thin, fuzzy images seen in space photos suggest that one of Jupiter’s moons, Europa, has formed cold volcanoes that spew huge fountains of ice crystals and frozen water droplets.
Tantalizing clues hinting that ice volcanoes exist are emerging from a few indistinct pictures taken by America’s durable Voyager 2 spacecraft as it passed near Jupiter in 1979. Europa is the smallest of Jupiter’s four major moons.
According to astronomer Allan F. Cook II of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., analysis of the “stretched” pictures indicates there may be four volcanic vents on Europa, spurting plumes as high as 60 miles above the surface.
If the finding is correct, “it would be the first ice volcanoes ever observed,” said astronomer-geologist Eugene Shoemaker at the U.S. Geological Survey in Flagstaff, Ariz. “Many of our colleagues think it is an optical artifact (illusion), but Cook and I think there is a very good chance this is real.”
But many astronomers are not yet convinced that cold volcanoes exist. “I’m basically kind of an agnostic on that,” said Torrence Johnson, a planetary scientist at the Jet Propulsion Laboratory in Pasadena. “They may have a detection of something. But then it may be something else,” rather than ice eruptions.
But Johnson, chief scientist on the upcoming Galileo mission to Jupiter, acknowledged that the Voyager flights to the outer solar system--Jupiter, Saturn and Uranus--have turned up so many surprises almost anything seems possible now.
Whatever the answer, Europa is an enigma. Its icy crust seems to be relatively young because it is almost devoid of large impact craters. A relatively smooth surface laced with a net-like pattern of ice-filled fissures implies some process may exist that repaves the surface with new material. Scientists have calculated that Europa may be covered with a sheet of ice perhaps six miles thick, and beneath the ice crust may be an ocean of liquid, consisting primarily of water. Cold volcanoes would erupt at places where the crust splits. Water emerging in plumes would quickly turn to ice.
