Methane found on Mars

31 March 2004 | 10:03 Code : 3685 Geoscience events
On Earth, methane is a common by-product of the etabolism of single-celled organisms. So its presence...
Tehran, - Methane has been spotted in the atmosphere of Mars by several researchers, reigniting speculations about the possibility of life on the red planet. On Earth, methane is a common by-product of the metabolism of single-celled organisms. So its presence in the martian atmosphere could be a sign of bacteria still living on the planet. But that isn't the only possible explanation, says Vittorio Formisano of the Institute of Physics of Interplanetary Space in Rome, who helped to confirm the finding. The methane could be produced by purely geological processes, such as volcanic activity. The gas was first seen on Mars by a team of astronomers led by Michael Mumma of NASA's Goddard Space Flight Center in Maryland. They used Earth-based telescopes to detect gaps in the spectrum of infrared light coming from Mars. These gaps occur at wavelengths where methane absorbs radiation. The findings have now been confirmed by Mars Express, the European Space Agency craft that released the ill-fated Beagle 2 lander at Christmas. Present-day source Mars Express is currently orbiting Mars, carrying an instrument called the Planetary Fourier Spectrometer (PFS), which has noted the characteristic spectral fingerprint of methane. "We have detected methane at concentrations of ten parts per billion," says Formisano, who is the principal investigator in the PFS team. Methane cannot exist in the martian atmosphere for longer than about 300 years. The molecules are split apart by sunlight, and the fragments escape the planet's gravity and are lost to space. So researchers say there must be a present-day source of methane on Mars. "At this moment, I cannot state the origin of it," says Formisano. But he says the results are not a great surprise, and suspects that the methane may come from volcanic processes. Although there are no known areas of volcanism on the planet today, Mars' gigantic volcano Mons Olympus was active until 100 million years ago, which is very recent in geological terms. So it might be emitting small amounts of methane now. "You cannot simply switch off the activity," Formisano explains. That could put a damper on speculations that the methane has a biological source. Formisano says that there is too little methane for the organisms producing it to be spread all over the planet: the source would have to be localized. He hopes to use the PFS to look for variations in methane concentration across the planet in order to pinpoint the source.

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