Evidence of the gas on the Red Planet raises possibility of biological activity.
Scientists have found more evidence of possible life on Mars.
NASA announced Thursday that its researchers and university scientists found methane in the Red Planet's atmosphere. The finding suggests biological or geological activity.
NASA's Infrared Telescope Facility and the W.M. Keck telescope showed prisms that separate white light into a rainbow and showed three lines that indicate the presence of methane.
"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," Michael Mumma of NASA's Goddard Space Flight Center in Greenbelt, Md., said in a statement.
Mumma, who authored a paper on the finding for Science Express, said that Mars releases methane "at a rate comparable to that of the massive hydrocarbon seep at Coal Oil Point in Santa Barbara, Calif." during its northern midsummer."
Methane is the main component of natural gas. Most of the Earth's methane comes from living organisms as they digest nutrients. However, other events, like iron oxidation, can also cause release of the gas.
"Right now, we do not have enough information to tell whether biology or geology -- or both -- is producing the methane on Mars," Mumma explained. "But it does tell us the planet is still alive, at least in a geologic sense. It is as if Mars is challenging us, saying, 'Hey, find out what this means.' "
NASA said that if microscopic organisms produce methane, they are likely far below the surface, where it's warm enough for water to remain in a liquid state. Water, carbon, and energy sources are necessary for all known forms of life.
"On Earth, microorganisms thrive about 1.2 to 1.9 miles beneath the Witwatersrand basin of South Africa, where natural radioactivity splits water molecules into molecular hydrogen and oxygen," Mumma said. "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."
He said that methane could accumulate in similar underground areas before escaping into the atmosphere through pores or fissures that open during warm seasons.
The team said it found methane over the northern hemisphere of Mars, where there's evidence of ancient ground ice or flowing water.
More research is needed to determine whether the methane came from biological or geological sources.