A strong signal of life on Mars has been detected by scientists at the US National Aeronautics and Space Admin- istration (Nasa) and the European Space Agency.Each group has independently discovered tantalising evidence of methane in the Martian atmosphere. Methane, a waste product of living organisms on Earth, could also be a by-product of alien microbes living under the surface of the Red Planet.The detection of methane has been the holy grail of scientists studying the Martian atmosphere, as its presence could provide unequivocal proof that there is life beyond Earth.Neither Nasa nor the European Space Agency (ESA) has publicly announced the findings, but specialists who have seen the data believe the discovery is genuine - although they are unsure what it means in terms of confirming the presence of life.The discovery comes weeks after Nasa and ESA announced new findings relating to the presence of huge bodies of water on Mars which could have supported life.The European effort is led by Vittorio Formisano, of the Institute of Physics and Interplanetary Science in Rome, who operates the methane-detecting spectrometer on board the Mars Express spacecraft orbiting the planet. "We can identify the presence of methane in the Martian atmosphere and we've been able to evaluate how much of it there would be," Professor Formisano said. "Globally, if I average all the data I have, I can find something of the order of 10 or 10.5 parts per billion. It's detectable, but only if I average a lot of data."Methane is destroyed by the intense ultraviolet radiation on Mars because the gas has a relatively short photochemical lifetime of about 300 years, so if it is present there must be something producing it continually, Professor Formisano said. "[Its presence] is significant and very important.
If it is present you need a source," he added.The second group to detect signals of methane in the Martian atmosphere is led by Michael Mumma of Nasa's Goddard Space Flight Centre in Maryland, who used powerful spectroscopic telescopes based on Earth.This team is even believed to have detected variations in the concentrations of methane, with a peak coming from the ancient Martian seabed of Meridiani Planum, which is being explored by a Nasa rover.
Methane has been found in the Martian atmosphere which scientists say could be a sign that life exists today on Mars.
It was detected by telescopes on Earth and has recently been confirmed by instruments onboard the European Space Agency's orbiting Mars Express craft.
Methane lives for a short time in the Martian atmosphere so it must be being constantly replenished.
There are two possible sources: either active volcanoes, none of which have been found yet on Mars, or microbes.
Spectral signature
The spectral signature of the gas was seen by the Infrared Telescope on Hawaii and the Gemini South Observatory in Chile.
Scientists see two possibilities, both of them scientifically important, but one of them is sensational
Scientists operating the Mars Express Planetary Fourier Spectrometer (FPS) have announced they have detected the presence of methane in the Red Planet's atmosphere, too.
The world's largest telescope, the twin Keck facility on Hawaii, has looked but has yet to report its findings.
But further evidence of methane on Mars will be presented at a meeting next month by a consortium of astronomers using the Canada-France-Hawaii telescope.
Volcanic explanation
Methane is not a stable molecule in the Martian atmosphere. If it was not replenished in some way, it would only last a few hundred years before it vanished.
Scientists see two possibilities, both of them scientifically important, but one of them is sensational.
Nasa's Infrared Telescope detected methane last year
It is possible that the methane is being produced by volcanic activity. Lava deposited on to the surface, or released underground, could produce the gas.
This explanation has some difficulties, however. So far, no active volcanic hotspots have been detected on the planet by the many spacecraft currently in orbit.
If active volcanism were responsible then it would be a major discovery with important implications. The heat released by any volcanism would melt the vast quantities of sub-surface ice discovered on the planet, producing an environment suitable for life.
Life on Mars?
On Earth, there are organisms called methanogens - microbes that produce methane from hydrogen and carbon dioxide. These organisms do not need oxygen to thrive, and they are thought to be the type of microbes that could possibly live on Mars.
The twin US space agency rovers that landed on the Red Planet in January will be unable to answer the question of the methane's origin as they are designed for geological work.
But future missions could include sensors to analyse the methane to determine where it came from.
The failed Beagle 2 mission had a device that could have sniffed the Martian atmosphere for methane.
04-03-2004 07:41 PM
