Volume: 02, Issue: 07 04/07/2004 
Artist’s conception of Mars Express orbiting the Red Planet. Image Credit: ESA -Illustration by Medialab.
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Color image of the Hecates Tholus volcano. Image credit ESA/DLR/FU Berlin (G. Neukum).
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Other Articles in This Issue:
Cassini Reveals New Atmospheric Features on Saturn
Shuttle Technology Gets Hearts Pumping
Most Precise Gyroscopes Ready to Test Einstein Theory
Chat Live about Martian Geology and Rovers

Mars Express Discovers Methane in Martian Atmosphere

The European Space Agency’s (ESA) Mars Express spacecraft has made an exciting discovery: methane has been detected in the Martian atmosphere. While it is too early to draw any conclusions on the origin of the gas, scientists are planning their next course of action to uncover more information.

The presence of methane has been confirmed thanks to the observations of the Planetary Fourier Spectrometer (PFS) onboard Mars Express. This instrument is able to detect the presence of particular molecules by analyzing their 'spectral fingerprints' - the specific way each molecule absorbs the sunlight it receives.

The measurements confirm so far that the amount of methane is very small – about 10 parts in a thousand million – so scientists must collect and analyze more data to fully grasp the methane production process. Methane, unless it is continuously produced by a source, only survives in the Martian atmosphere for a few hundred years because it quickly oxidizes to form water and carbon dioxide, both present in the Martian atmosphere. There must, therefore, be a mechanism that refills the atmosphere with methane.

“The first thing to understand is how exactly the methane is distributed in the Martian atmosphere,” said Vittorio Formisano, Principal Investigator for the PFS instrument. “Since the methane presence is so small, we need to take more measurements. Only then will we have enough data to make a statistical analysis and understand whether there are regions of the atmosphere where methane is more concentrated.”

Once this is done, scientists will try to establish a link between the planet-wide distribution of methane and possible atmospheric or surface processes that may produce it.

“Based on our experience on Earth, the methane production could be linked to volcanic or hydro-thermal activity on Mars,” Formisano added. “The High Resolution Stereo camera (HRSC) on Mars Express could help us identify visible activity, if it exists, on the surface of the planet.”

If data supports this hypothesis, it would be a remarkable discovery. Current volcanic activity has thus far never been detected on Mars.

Other hypotheses could also be considered. On Earth, methane is a by-product of biological activity, such as fermentation.

“If we have to exclude the volcanic hypothesis, we could still consider the possibility of life,” Formisano said.

Thanks to the PFS instrument, scientists are also gathering precious data about isotopes in atmospheric molecules such as water and carbon dioxide – data that is crucial to understanding how the planet and its atmosphere were formed. The PFS also provides important clues about water-cloud formation on the top of volcanoes and shows the presence of active photochemical processes in the atmosphere.

“In the next few weeks, the PFS and other instruments onboard Mars Express will continue gathering data on the Martian atmosphere, and by then we will be able to draw a more precise picture,” says Agustin Chicarro, ESA Mars Express Project Scientist.

One of the aims of the Mars Express mission is to continue analyzing in detail the chemical composition of the Martian atmosphere, known to consist of 95% percent carbon dioxide plus 5% of minor constituents. It is also from these minor constituents, which scientists expect to be oxygen, water, carbon monoxide, formaldehyde and methane, that we may get further important information on the evolution of the planet and possible implications for the presence of past or present life.

For more information about the Mars Express spacecraft, visit:

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