Whiff of Life?

Science magazine is reporting today that Mars Express (pictured above, CREDIT:ESA) may have found a signature of current bacterial life on Mars. They found traces of methane that has one of two different sources, volcanoes or (current!) life.

At a press conference in Paris held earlier this month, Formisano reported finding spectral emissions of methane around a wavelength of 3.3 micrometers. "We have seen methane on Mars," he tells Science. "A very little amount, but the result is clear." Even the apparent concentration of 10.5 parts per billion "is extremely interesting from a scientific point of view," he says, "because you need a source for methane." Otherwise, any methane in the martian atmosphere would be destroyed by solar radiation within a few hundred years.

Either of the two possible sources for martian methane would be noteworthy. It could be oozing out of the interior of the planet through erupting or even quiescent volcanoes, or through hot springs. No sign of such ongoing activity has turned up yet in remote sensing from orbit, although Mars apparently erupted lavas as it cooled into the geologically recent past (Science, 4 August 2000, p. 714).

The other possibility is the Holy Grail and World Cup of astrobiology combined. Bacteria could be living somewhere deep beneath the apparently sterile surface, perhaps chewing on the rock and spewing methane as a byproduct. "I have no reason to exclude one origin or the other," says Formisano. "I can only say we see methane."