[LINK] "Alien Life on Mars? NASA Rover Spots Methane, a Possible Sign of Microbes"

[rfmcdonald]

National Geographic's Dan Vergano writes about the recent discovery of methane spikes by the Curiosity rover on Mars. They might indicate life, but not necessarily.

On Earth, most methane, better known as natural gas, is released by microbes that belch out the gas as they digest food. The rover mission scientists hedge the new results carefully, saying there's no way to tell whether the methane spikes have a geological or biological origin.

"It is a very, very puzzling result," says planetary scientist Joel Levine of the College of William and Mary in Williamsburg, Virginia, who was not part of the study team. "Either Mars is geologically alive, which would be surprising, or Mars is biologically alive, which would have profound implications."

Decades of up-and-down measurements of methane in the Martian atmosphere have intrigued scientists hunting for signs of life on Mars. So when Curiosity first recorded a sudden tenfold increase in methane in November 2013, scientists were startled.

"It was an 'oh, my gosh' moment," said planetary scientist Christopher Webster of NASA's Jet Propulsion Laboratory, who led the study team. Reported in the journal Science and presented Tuesday at the American Geophysical Union meeting, the spikes, he said, "disappeared only six weeks later."

Curiosity went on to record a total of four sharp jumps in methane concentrations in the Martian air during its travels. The pulses lasted only a few weeks and lingered over a small area, roughly 2,625 feet (800 meters) of the rover's path. That points to a local, concentrated vent as the origin of the releases, says team scientist Sushil Atreya of the University of Michigan at Ann Arbor, most likely to the north of the rover inside Gale Crater.