Europa ice flows hint at watery interior.Ever since it reached Jupiter in 1995, the Galileo spacecraft has thrilled astronomers with close-up views of the giant planet and its companions. Jupiter's moon Europa has excited special interest because of the possibility that its interior harbors water. New photos of Europa released by NASA NASA: see National Aeronautics and Space Administration. NASA in full National Aeronautics and Space Administration Independent U.S. last week buoy hopes of finding water-and perhaps life-under the frozen moon's surface. These photos, the sharpest ever taken there, show giant ribbons of once- mobile ice covering parts of Europa. The discovery provides evidence that geologic activity heats ice under the surface to a near-liquid state, which allows it to gush through the solid ice crust, say scientists. "[These are] the first flows we've seen on any of the icy moons of Jupiter," says Ronald Greeley of Arizona State University Arizona State University, at Tempe; coeducational; opened 1886 as a normal school, became 1925 Tempe State Teachers College, renamed 1945 Arizona State College at Tempe. Its present name was adopted in 1958. in Tempe. Wide flows can be traced for hundreds of kilometers in the photos. "This would suggest that [they are] a really thick, viscous mass, probably water-ice," says Greeley. Planetologists must add this icy volcanism volcanism or vulcanism Any of various processes and phenomena associated with the surface discharge of molten rock or hot water and steam, including volcanoes, geysers, and fumaroles. to the list of processes forever smoothing the moon's face, says Robert Sullivan Robert Sullivan can refer to:
Much smoother than other Jovian moons, Europa bears relatively few scars from its encounters with meteors. Because few craters dot the moon's surface, Sul- livan suggests it was repaved recently, within the last few million years. "Europa is unlike any other body in the solar system solar system, the sun and the surrounding planets, natural satellites, dwarf planets, asteroids, meteoroids, and comets that are bound by its gravity. The sun is by far the most massive part of the solar system, containing almost 99.9% of the system's total mass. ," says Paul Schenk of the Lunar and Planetary Institute The Lunar and Planetary Institute (LPI) is a NASA-funded research institute, dedicated to studies of the solar system, its evolution and formation. The Institute is part of the Universities Space Research Association, located in Houston, Texas. in Houston, noting that its combination of solid core and icy crust makes it unusual. The exotic conditions on Europa may be able to support life, according to Sullivan. Along with relatively common organic chemicals, the moon possesses water (SN: 7/6/96, p. 8) and some internal energy to power its ice flows. The new discovery of these flows causes scientists to wonder whether internal heat could melt enough ice to form an ocean beneath the planet's surface. It is not likely that Galileo will conclusively determine whether Europa has interior oceans, says physicist James W. Head of Brown University in Providence, R.I., who says that challenge awaits future explorers. |
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