SSS 2009-01-16（在线收听）

This is Scientific American's 60-Second Science. I'm Cynthia Graber. This will just take a minute.

There’s definitely methane on Mars—and there are seasonal variations of how much is being released into the thin Martian atmosphere. Which means that Mars is still active geologically. Or that deep underground, something is or was alive. Or both. NASA and university scientists report the finding in the January 16th issue of the journal Science.

Researchers studying the Martian atmosphere discovered and measured methane levels over the last few years, using telescopes with infrared spectrometers. These instruments identify chemical compounds by analyzing their unique light absorption properties.

They found that Mars methane is being released as concentrated plumes at specific latitudes. Such plumes could come from various kinds of geological events. Underground bacterial communities could also be producing the methane. Or now-extinct living systems could have produced the methane long ago, with it only now being released through pores or fissures created by seasonal temperature variations.

On earth, 90 percent of the methane in the atmosphere comes from the biochemical activity of life. The rest is produced by geochemical processes. The Mars methane’s specific isotopic makeup could reveal whether its origins are biochemical or geological.

Thanks for the minute for Scientific American's 60-Second Science. I'm Cynthia Graber.