Methane, a chemical that results from the decay of organic matter, briefly shot up in abundance on Mars, according to readings from the Curiosity rover published in the journal Science. The tenfold spike measured in the atmosphere around the lander, along with organic molecules in a rock-powder sample the robot's drill collected, provide the strongest evidence yet for life on Mars.
the finding is in contrast to data from 2013The finding is in sharp contrast to a 2013 read-out that suggested there wasn't enough methane on Mars to support living microbes — only 1.3 parts per billion. Using Curiosity's onboard sample analysis a dozen times over 20 months showed spikes in late 2013 and early 2014, with measurements finding an average of 7 parts of methane per billion in the atmosphere. With more readings, it may be possible to tell if the emissions came from a biological source by testing the types of isotopes that appear in the gas.
A diagram showing possible methane sources (NASA)
"This temporary increase in methane — sharply up and then back down — tells us there must be some relatively localized source," says Sushil Atreya of the University of Michigan and a member of the Curiosity rover science team, in a a statement from the Jet Propulsion Laboratory. "There are many possible sources, biological or non-biological, such as interaction of water and rock."
That's not all. Curiosity drilled at a Martian formation called the Cumberland and found different organic chemicals in a power made from the mudstone — the first definitive finding of organic materials on the planet, according to a second study, which was presented at the American Geophysical Union and is pending publication. That's not a smoking gun for life, though — the organics could have been delivered by meteorites. Material from the Cumberland rock also suggested that the lakebed lost much of its water before the rock formed, and continued to lose water afterwards.