Intriguing new close-ups of Jupiter's icy companion Europa sent back by the Galileo spacecraft suggest that a huge watery underworld may lie beneath the moon's frozen crust, offering a possible habitat for life, researchers at NASA's Jet Propulsion Laboratory in Pasadena said Tuesday.
In the wake of last week's dramatic discovery of possible ancient life on Mars, NASA chief Dan Goldin warned against jumping the gun. But the prime question on the minds of planetary scientists seemed to be: Could there be life?
Goldin said in an interview that the space agency has shifted its focus toward missions designed to answer specific questions about the origins of the universe and the existence of extraterrestrial life.
Huge chunks of ice resembling arctic ice floes appear to have shifted about on Europa's surface like pieces of a puzzle, suggesting that a lubricating layer of water or mushy ice lies underneath. Water, along with carbon compounds and heat, are considered the necessary ingredients for life.
Researchers have long wondered about possible life on Europa, where thousand-mile-long rift lines crisscross the moon like an interstate highway system that would impress any Angeleno. "I wish we had lanes like these in Southern California," said Ronald Greeley, a geologist at Arizona State University, who said the distinctive black and white striped lanes were five or six miles wide.
The lanes suggest ancient--and possibly current--geological activity. As the huge mass of Jupiter tugs on Europa's thin ice crust, slabs of the crust break off and slide around on the surface, much like continental plates on Earth, researchers believe.
The outer edges of the lanes are dark and diffuse, like shadows, perhaps laid down when dirty ice erupted through fractures in Europa's frozen surface, Greeley speculated. The white center divider might have been laid down later, after the crack "clears its throat," he said, sending up clean, white ice or snow. New lanes are piled on top of older ones like pickup sticks, allowing researchers to reconstruct their history.
Although the images of Europa sent back by Galileo are 100 times better than those taken by the Voyager missions of the 1970s, they are still relative long-shots, snapped while the spacecraft was 96,000 miles out.
On its closest approach next year, Galileo will come within 370 miles of Europa's surface, and Greeley is hoping to see evidence of ice geysers. "But we'll have to be in the right place at the right time," he said.
