Are Methane Plumes a Sign of Life on Mars?

NASA researchers have discovered vast clouds of methane on Mars. The find triggered speculation that the gas is being produced by microbial life forms on the Red Planet, though geologic processes might also be the source.

A news release  on NASA's web site details the findings, which are based on observations by the agency's NASA's Infrared Telescope Facility and the W.M. Keck observatory, both in Hawaii.

 NASA scientists say the discovery indicates that Mars is still alive, either in a biological or geological sense.

 "Methane is quickly destroyed in the Martian atmosphere in a variety of ways, so our discovery of substantial plumes of methane in the northern hemisphere of Mars in 2003 indicates some ongoing process is releasing the gas," says NASA astrobiologist Michael Mumma "At northern mid-summer, methane is released at a rate comparable to that of the massive hydrocarbon seep at Coal Oil Point in Santa Barbara, Calif."

According to Encyclopedia Britannica, methane is a colorless, odorless gas that occurs abundantly in nature on Earth. Methane can be produced by the anaerobic bacterial decomposition of vegetable matter under water, which is why it is commonly called "swamp gas." Methane also is released by animals such as cows and termites, and by rice plants. The gas also is released during volcanic activity and other geologic processes, but Sky & Telescope reports that 90 percent of the methane on earth comes from biological sources.

The presence of methane on Mars initially was detected by telescopes on Earth and confirmed back in 2004 by the European Space Agency's orbiting Mars Express probe. That same year, according to New Scientist, analysis of satellite data ruled out volcanic activity as the source of Martian methane, but did not resolve the question of where the gas comes from.

NASA scientists believe that if microscopic Martian life is producing the methane, it likely resides far below the surface, where it's still warm enough for liquid water to exist. Liquid water, as well as energy sources and a supply of carbon, are necessary for all known forms of life.

NASA scientist Mumma notes that on Earth, microorganisms thrive between 1.2 to 1.9 miles beneath the Witwatersrand basin of South Africa, where natural radioactivity splits water molecules into molecular hydrogen and oxygen. The organisms use the hydrogen for energy.

"It might be possible for similar organisms to survive for billions of years below the permafrost layer on Mars, where water is liquid, radiation supplies energy, and carbon dioxide provides carbon," Mumma says.

 NASA was set to unveil the discovery in a 2 p.m. Thursday video conference on its web site, but a British tabloid, the Sun, apparently broke the agency's news embargo and leaked the story early, generating a sensation on Twitter and across the Web.

The Sun reports that British space scientist Colin Pillinger , who led the unsuccessful Beagle 2 mission to Mars in 2003, believes that the NASA discovery points to the existence of life on the planet.

"'The most obvious source of methane is organisms," the Sun quoted Pillinger as saying. "So if you find methane in an atmosphere, you can suspect there is life. It's not proof, but it makes it worth a much closer look.'"