CMU Robotics CMU's robotic rover Zoe traverses the Atacama Desert in Chile. Click photo for larger image.

A Carnegie Mellon University rover called Zoe is the first robot to remotely detect life, finding fluorescent signals from both visible lichens and microscopic bacteria in Chile's barren Atacama Desert.

The NASA-sponsored field test last fall thus demonstrated that scientists can use robots to identify life in harsh regions, a critical technology as automated exploration on Mars shifts from a search for water to a search for life.

"The rover found 'em all by itself," said Alan Waggoner, director of CMU's Molecular Biosensor and Imaging Center, which developed the robot's life-detection instrument. The findings are being announced this week at the Lunar and Planetary Science Conference in Houston, where Waggoner spoke yesterday.

"The fact that we were able to detect life is great," said Nathalie Cabrol, a planetary scientist at NASA's Ames Research Center in California and the lead scientist for the Life in the Atacama project. It's the first time that an instrument that has been integrated with a robotic rover has made such a discovery, said Cabrol, who speaks at the conference today.

The two NASA rovers that have explored Mars since January last year, Spirit and Opportunity, were designed to study the planet's geology and search for signs of water. Based on the findings from those robots, many scientists suspect that it may be possible to find signs of ancient life, or even existing life, on the Red Planet.

NASA uses the Atacama to test life-detection technology and techniques that might be used on Mars because the Chilean desert is one of the driest places on Earth. Just as no one expects to go to Mars and see a tree, large parts of the Atacama appear lifeless. So if a robot can detect desert life that isn't obvious to even a human observer, the thinking goes, it might be possible to use a robot to find living things, if they exist, on Mars.

The solar-powered Zoe rover explored two areas of the Atacama -- a coastal area where fog or other precipitation is common and a drier area farther inland. The lichens that Zoe discovered in the coastal area were pretty obvious, Waggoner said. But in the drier, interior portion of the Atacama, Zoe found only microscopic bacteria.

The CMU instrument detects life by looking for natural fluorescence from cells that contain chlorophyll. It also can spray four special dyes on soil samples that fluoresce only when they bind to one of four types of substances associated with life -- DNA, protein, lipids or carbohydrates.

Waggoner said only two of those dyes -- for DNA and protein -- were used in last fall's field test. The two other dyes, after undergoing further development, will be added during a final field test scheduled for this fall.

The device looked for life on the desert surface. Images from the device were transmitted to Pittsburgh during the field test, where scientists tried to determine whether the images showed living things or not. Field crews retrieved samples of each area analyzed by the device; those samples were then sent to a laboratory to confirm whether they contained life or not.

Cabrol said a life-detection instrument destined for Mars would be designed differently. Scientists expect that existing or ancient life on Mars would probably be found below the surface, so the instrument would have to dig up and process samples.

"But the principles [of how the detection occurs] would be the same," she added.

Waggoner said additional work is planned prior to this fall's field tests to rule out the possibility of false positives -- signals suggesting life where none exists. For instance, the researchers need to ensure that the minerals themselves don't fluoresce and that there is no "funny interaction" between the dyes and the rocks.

	CMU Robotics Zoe navigates the Atacama Desert. Click photo for larger image.