Galileo discoveries boost possibility of Europa ocean

Galileo discoveries boost possibility of Europa ocean

By MATTHEW FORDAHL

LOS ANGELES (January 10, 2000 10:11 p.m. EST http://www.nandotimes.com) - New evidence from the Galileo spacecraft bolsters theories that a liquid ocean lies beneath the crust of Jupiter's moon Europa, NASA scientists reported Monday after analyzing results from the probe's latest flyby.

The findings indirectly support the case for life beneath the moon's icy crust. Some experts believe primitive organisms could survive just as they do deep in the Earth's ocean near volcanic vents.

"Certainly if you are going to look for other environments where life might form or be able to survive, this might be a good one," said Torrence Johnson, Galileo's project scientist at NASA's Jet Propulsion Laboratory in Pasadena.

Galileo took measurements of Europa's magnetic field during a Jan. 3 flyby 218 miles above the moon. Researchers hoped to see if the moon's magnetic north pole had changed since previous encounters.

The magnetic north pole did indeed reverse and appears to do so about every 5 1/2 hours, something that would make it very difficult to use. An underground layer of conductive liquid - like saltwater - best explains the magnetic flip-flop, scientists said.

"I think these findings tell us that there is indeed a layer of liquid water beneath Europa's surface," said Margaret Kivelson, a spacecraft scientist. "This new evidence certainly makes the argument for the presence of an ocean far more persuasive."

Images from previous Galileo encounters as well as the Voyager spacecraft had strongly suggested an ocean exists beneath the smooth, reflective surface. But researchers could not be certain that it still existed, if it ever did.

"All the geological evidence relates to the period during which those geologic features formed," Johnson said. "Most geologists feel it's very recent, but there are some other people in the field who say the surface could be up to 500 million years old."

The latest findings are particularly important because they suggest liquid water is still present beneath the surface.

"The universe and the solar system are actually swimming in water, but most of it's frozen," Johnson said. "Liquid water is what's important to the biologist - liquid water and a source of energy."

Galileo, which arrived at Jupiter in 1995, is not scheduled to make any more encounters of Europa. Another spacecraft, the Europa Orbiter, is currently being developed for launch in 2003. It would start circling the moon in 2008.