Study: Mission wouldn't have to dig deep

WASHINGTON, July 6 (UPI) -- A rover mission looking for signs of life on Mars may have to dig only 2 to 4 inches under the martian surface to find it, U.S. researchers say.

A study by scientists at the NASA Goddard Space Flight Center in Greenbelt, Md., sought to determine the optimal depths and locations to look for organic molecules like those that compose living organisms as we know them, a release from the American Geophysical Union said Thursday.

Complex carbon structures will be tricky to find because they're vulnerable to cosmic radiation that continuously bombards and penetrates the surface of the Red Planet, the researchers said.

Chances of finding these molecules in the first 2 centimeters (0.8 inches) of Martian soil is close to zero, they said, as that top layer will have absorbed enough cosmic radiation over the course of 1 billion years to destroy all organic material.

However, within 2 to 4 inches beneath the surface, the amount of radiation drops tenfold, they said,

Although radiation at that depth is still at high levels, simple organic molecules, such as a single formaldehyde molecule, could exist, the study said.

That could especially be true around relatively young craters that exhibit freshly exposed rock and soil that was once deeper beneath the surface, making them ideal places for a rover to work.

"When you have a chance to drill, don't waste it on perfectly preserved (landscapes)," Pavlov said. "You want to go to fresh craters because there's probably a better chance to detect complex organic molecules," Alexander Pavlov, lead author of the NASA study, said.

"Let Nature work for you."