News flash! NASA's Mars Curiosity rover has measured a 10X spike in methane, an organic chemical in the atmosphere and detected other organic molecules in a rock sample gathered by the robotic laboratory’s drill.
So since it is probably not coming from belching cows like here on Earth, where is the methane coming from?
"This temporary increase in methane -- sharply up and then back down -- tells us there must be some relatively localized source," said Sushil Atreya of the University of Michigan, Ann Arbor, and Curiosity rover science team. "There are many possible sources, biological or non-biological, such as interaction of water and rock."
Organic molecules, often loaded with carbon and hydrogen, are thought of as chemical building blocks of life (but they can exist without the presence of life). Curiosity's findings from atmospheric and rock samples don't tell us whether Mars has living microorganisms (or has ever had them), but the data shows that Mars is chemically active and may have favorable conditions for life.