PASADENA, California -- The Galileo spacecraft swooped within 124 miles of Jupiter's frozen moon Europa, its blistered surface strengthening suspicions that a briny ocean harboring life could lie beneath an icy crust.
The near-pass Tuesday [Dec 16] was Galileo's closest look at Europa, which has become a major target for exploration because it likely has two elements needed to support life: water and heat.
"Europa really is the gem of the solar system," Ronald Greeley, an Arizona State University geologist, said at a briefing by mission officials at NASA's Jet Propulsion Laboratory.
Scientists will have to wait a few weeks to get the latest pictures snapped by Galileo, but instruments recently detected signs of magnesium salts that bolstered the belief that an ocean could be under Europa's cracked-ice surface.
Signs of magnesium sulfate, a mineral normally formed on Earth where salt water evaporates, were picked up on Europa by analysis of light reflected off the surface. It could mean a liquid ocean rich in brine exists or recently existed beneath Europa's crackled, frozen expanses, experts say.
"That briny water somehow was erupted or extruded or squirted to the surface" where evaporation took place, said Tom McCord, University of Hawaii professor and a Galileo investigator.
Salts like those on Europa can be found in dry lake beds in the Earth's deserts, McCord said.
The smallest of Jupiter's four major moons, Europa is believed to have both water and internal heat from the friction of tidal forces and from radioactive sources such as uranium. But whether that heat is sufficient for maintaining a "liquid ocean" remains an open question, said project scientist Torrence Johnson.
Although Galileo's official mission life-span is now concluded, the spacecraft is functioning so well that NASA officials hope to keep it active for at least two more years.
Original file name: CNI - Europa.nearest pass.final
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