Search for signs of life on Jupiter moon attract scientific gathering

Search for signs of life on Jupiter moon attract scientific gathering

By CANDICE HUGHES

PADUA, Italy (October 14, 1999 12:19 a.m. EDT http://www.nandotimes.com) - Hundreds of cosmic scientists gathered in Galileo's homeland Wednesday, hoping to learn from a spacecraft named Galileo whether a heavenly body discovered by the Renaissance astronomer four centuries ago might support life.

The NASA spacecraft Galileo, winding down a two-year, $30 million probe of Jupiter, made its closest-ever flyby of the planet's moons earlier this week, passing within 380 miles of Io, Jupiter's innermost large moon.

But many of the scientists here are more interested in Jupiter's fourth largest moon, Europa, spotted by Galileo in 1610. Much of the NASA probe's data on Europa is still being analyzed.

"There should be dozens of high-resolution images, close-ups hundreds of times better than anything we've seen before," said Torrance Johnson, the Galileo project scientist.

In the world of planetary science, Europa is very hot these days. Not in terms of temperature - the surface is blindingly bright ice and the thermometer hovers around minus 260 degrees - but in terms of the search for life beyond Earth.

Some scientists here believe that Europa, the brightest object in our solar system other than the Sun, may have the elements needed for life: water, a heat source deep in the core and organic molecules.

They acknowledge that conditions are extreme, but say they are finding evidence that microbes can exist under the harshest conditions deep inside our own planet, in rocks from the bottom of the oceans.

Other researchers reported in a recent issue of the journal Science that Europa probably could not support life because any oceans beneath the frozen surface could barely support single-cell organisms let alone complex species. They said a layer of ice at least 6 miles deep blocks the sun's life-sustaining energy from the water.

Scientists have also reported finding evidence of frozen sulfuric acid on Europa's surface.

Sulfuric acid is an extremely corrosive substance found in battery acid on Earth, as well as in the dreaded acid rain, and the discovery gave them pause at first, one of the Galileo scientists, Robert Carlson, admitted. Then he talked things over with astrobiologists, who said sulfur can be a source of food for microbes.

"It's not as bad as I thought. In fact, it might be good," Carlson said as he discussed his findings Wednesday, midway through the annual convention of the American Astronomical Society's Division of Planetary Sciences.

A group of scientists from the University of Arizona presented an analysis of Europa's geology that suggests conditions in the moon's watery crust change slowly enough for some forms of life to adapt and evolve.

With so much tantalizing evidence pointing to the conditions for life on Europa, scientists are eager to learn more. The Galileo spacecraft will make several more passes by Europa before funding runs out next year.

Hopes are now centered on a new spacecraft aimed solely at Europa. If all goes well, NASA's Europa Orbiter Mission will take off in November 2003 and reach Europa five years later. The space agency is soliciting ideas for the orbiter from the scientific community.

Four centuries ago, Galileo had to face the Inquisition. Now, American space scientists face congressional budget-cutters. Johnson said the orbiter will have a small payload of scientific instruments. "We just can't take all the things people would like," he said.