Nasa’s Search For Life In Desert Comes Up Dry ; Yet, Researchers Hope To Have Better Luck With Mars Project

The Atacama Desert of northern Chile may be the world’s driest desert, but areas of it nevertheless teem with life. So why can’t NASA scientists find life there?

True, NASA-funded scientists who participated in an Atacama field experiment in April found plenty: pesky flies, a variety of lichens and vultures circling overhead, a sure indication that mice skittered nearby.

But counterparts at the space agency’s Ames Research Center in Moffett Field, Calif., poring over photos and instrument data transmitted from the field, never found anything they considered proof of life.

If this team of NASA and academic researchers, assigned to develop robotic technology for finding life on Mars, can’t detect life known to exist 5,000 miles away in the Atacama, how could they hope to determine whether life exists on an alien planet 35 million miles away?

Yet the researchers, who gathered at Carnegie Mellon University in Pittsburgh last week, were pleased that what they discerned about the desert’s geology by remote sensing had closely matched what scientists on the ground observed.

The results were encouraging, considering this was the first field experiment in what will be a three-year project, said Nathalie Cabrol, a planetary scientist at Ames and lead scientist of the Life in the Atacama Project.

But a host of issues remain for the dozens of researchers who are building the robot and the life-sensing instruments, which must eventually mesh to become a machine capable of scientific exploration.

“If I see a bush in front of my rover, there’s not too much to discuss,” Cabrol said. But if life is sparse, more subtle or resembles non-living features, how do researchers pick out the signature of life? What features might prove something is living? What combination of sensors is needed to detect that signature?

With two robotic rovers now hurtling toward Mars to search for signs of water, the development of life-sensing robots gains greater urgency in the planetary community. If Mars Exploration Rovers are successful in their quest when they land on the Red Planet in January, the logical follow-up mission would be a search for life.

Growing evidence that Mars is geologically active, with subsurface magma, suggests that water may be present not only as ice, but also as groundwater. And the combination of magma and water greatly enhances the prospects for finding life, he contended.

But no one knows how to prove life exists by remote sensing. As this year’s Atacama field experiment underscored, even the human eye can be tricked in extreme environments.

Searching along the edges of the Salar Grande, an evaporated salt lake, the researchers came across numerous rocks covered by lichens. But they also were fooled by rocks that appeared to be covered with bumpy, green lichens, said Alan Waggoner, director of CMU’s Molecular Biosensor and Imaging Center.

The lifelike bumps were simply salt that, through evaporation, had effloresced to form puffy mounds. The green outer layer turned out to be oxidized copper.