UNIVERSITY OF MICHIGAN

Curiosity rover finds organics on Mars.         
Not life, but its chemical building blocks, have been detected on Mars and University of Michigan engineers and planetary scientists played a role in the discovery.

This week, NASA reported that the Curiosity rover found organic molecules—spike of methane in the planet's atmosphere and carbon in Martian rock. Organic molecules are carbon- and often hydrogen-based compounds that make up living things. But they're also found elsewhere.

"This temporary increase in methane—sharply up and then back down—tells us there must be some relatively localized source,"

           Sushil Atreya, a Michigan Engineering professor of atmospheric, oceanic and space sciences, said in a NASA news release. "There are many possible sources, biological or non-biological, such as interaction of water and rock."

The two leading hypotheses, the New York Times reports, are that the methane is a waste product released by living microbes or a result of a rock and water interaction called serpentinization. Both scenarios would likely involve activity beneath the Martian surface. Microbes could conceivably exist in water underground, or they could have existed there in the past when Mars was wetter and warmer. And serpentinization could have happened during hydrothermal activity in the past or even today if aquifers are present underground.

          In either case, the methane that Curiosity detected could have formed very recently, or long ago. If it formed long ago, it could be stored in lattice-like structures called clathrates.

"These are molecular cages of water-ice in which methane gas is trapped. From time to time, these could be destabilised, perhaps by some mechanical or thermal stress, and the methane gas would be released to find its way up through cracks or fissures in the rock to enter the atmosphere," Atreya told the BBC News.

Future Curiosity tests might shed light on the source of the organics.

In 2004, Atreya, who helped conceive of the Curiosity mission decades ago, was on a team that detected trace amounts of methane in Mars' atmosphere with the European Space Agency's Mars Express orbiter. Other research groups reported methane at Mars as well, from Earth-based telescopes and spacecraft orbiting Mars, but those findings have been highly controversial. Curiosity is the first to directly confirm methane on the red planet. It took measurements with the most precise instrument of its kind to ever roll across Mars.

          Atreya is a science lead on Curiosity's Sample Analysis at Mars, or SAM, suite of instruments, which sniffed the Martian air for methane a dozen times to arrive at these latest results. Two consecutive measurements showed a spike of of 7 parts per billion, while other samples showed one-tenth that amount. The spike in methane was seen over a two-month period, but it could have lasted for six months, Atreya told the New York Times.

NASA also announced that the rover found "the first definitive detection of organics in surface materials of Mars" when it detected a carbon-based compound in powder drilled from a rock. These Martian organics could either have formed there or been delivered by meteorites.