The New York Times today reports on NASA’s recent announcement of methane detection in the Martian atmosphere:
Subsurface Martian cows are highly unlikely. But scientists are seriously considering the possibility of bacteria.
When the presence of methane was reported in 2004 by three teams of scientists, the findings generated surprise and skepticism because only a few explanations seemed to be plausible.
One was geothermal chemical reactions involving water and heat in volcanoes or underground hot springs. But evidence for recent volcanism on Mars is scarce. Also, volcanoes would be expected to spew other gases like sulfur dioxide, and those are not plentiful in the planet’s atmosphere.
A second possibility is biological. On Earth, a class of bacteria known as methanogens breathes out methane as a waste product.
NASA’s current Mars strategy is to look for signs of water and perhaps life in the planet’s distant past. “Perhaps we need to also think in terms of present-day life holding on somewhere in the subsurface,” said Lisa M. Pratt, a professor of geological sciences at Indiana University who participated in the news conference but was not involved with the research.
Even if the source turns out to be geological in origin or to have come from long-extinct bacteria, the sites would still be prime locations to look for other microbes that thrive on methane as food. “It gives us a bull’s-eye to go after,” Dr. Pratt said.