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The prospects for finding life beyondEarth may be brightening. Today, scientists are reporting evidence for yet another potential habitat in our solar system: Saturn’s moonEnceladus. Scientists mining new data from theCassini spacecraft say they may have found evidence thatEnceladus—the planet’s fourth-largest moon—hosts liquid water.

If the results hold up, this would bring to four the number of bodies in the solar system—includingEarth—that display active volcanism.And since life as biologists know it requires liquid water and a source of energy,Enceladus would join Jupiter’s moonEuropa and Saturn’s moon Titan, as well as Mars, as possible spots beyondEarth where simple forms of life may have gained or still maintain a footholD、
The discovery, however, is bittersweet for many scientists. NASA’s proposed budget for fiscal 2007 calls for a 50 percent cut in its astrobiology program.Although the program is a tiny piece of the agency’s overall spending plan for science, it’s a significant source of money for probing fundamental questions of how and why life emerged onEarth and whether life arose elsewhere in the universe.
A、50-percent cut "is almost a going-out-of-business-level cut" in a vibrant line of research that stands as one pillar supporting PresidentBush’s vision for space exploration, says planetary scientist Sean Solomon, who heads theDepartment of Terrestrial Magnetism at theCarnegie Institution of Washington.
Nevertheless, the research in today’s issue of the journal Science is the sort of thing that continues to light a fire under the fielD、Its report about liquid water under the icy surface ofEnceladus is a "radical conclusion," acknowledgesCarolyn Porco, who leads the imaging team working with data from theCassini orbiter.But if the team is right, "we have significantly broadened the diversity of solar-system environments" that might have rolled out the welcome mat "for living organisms," she concludes. Images released last fall show the moon ejecting vast plumes of material near its unexpectedly warm south pole.As the team pondered the evidence, they nixed several explanations, including the idea that the particles in the plumes were driven by vapor billowing out as ice reached the surface and immediately turned into a gas. The last idea standing: Liquid water was venting from reservoirs near the surface, perhaps only tens of meters below the frigid crust. This explanation also helped solve the riddle of puzzlingly high levels of oxygen atoms found in Saturn’s neighborhooD、
Confirmation could come with additional flybys. If water—and perhaps life—is present, it wouldn’t be "luxuriant," notes Jeffrey Kargel, a researcher at the University ofArizona at Tucson. It likely would face tough conditions—nasty chemicals, very low temperatures, and little energy to drive it. still, he adds, it’s premature to cross the moon off the list of possible "outposts" for life beyondEarth. Yet the prospect of building on these results could be dimmer with the threat of budget cuts. The proposed reductions post several challenges, researchers say.
One is the loss of important financial leverage. While money for experiments and other research related to astrobiology can come from other funding agencies, such as the National Science Foundation or even the National Institutes of Health, NASA’s program often provides the crucial missing piece that turns demanding and sometimes dangerous fieldwork into exciting results.
One of the biggest successes over the program’s 10-year history has been to help revolutionize the way science is done.Answering questions about the origins of life onEarth and the prospects for life elsewhere require strong collaborations. From radio astronomers to biologists and geologists studying the evolution ofEarth, groups are working together in ways they never thought of a decade ago, addsEdward Young, a geochemist at the University ofCa