[meteorite-list] Mars Express Confirms Methane in the Martian Atmosphere

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:32:56 2004
Message-ID: <200403301648.IAA10672_at_zagami.jpl.nasa.gov>


Mars Express confirms methane in the Martian atmosphere
European Space Agency
30 March 2004

During recent observations from the ESA Mars Express
spacecraft in orbit around Mars, methane was detected in
its atmosphere.
Whilst it is too early to draw any conclusions on its
origin, exciting as they may be, scientists are thinking
about the next steps to take in order to understand more.

>From the time of its arrival at Mars, the Mars Express
spacecraft started producing stunning results. One of the
aims of the mission is analysing 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 important information on the
evolution of the planet and possible implications for the
presence of past or present life.

The presence of methane has been confirmed thanks to the
observations of the Planetary Fourier Spectrometer (PFS) on
board Mars Express during the past few weeks. This instrument
is able to detect the presence of particular molecules by
analysing 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 its
production process is probably small. However, the exciting
question "where does this methane come from?" remains.

Methane, unless it is continuously produced by a source, only
survives in the Martian atmosphere for a few hundreds of years
because it quickly oxidises to form water and carbon dioxide,
both present in the Martian atmosphere. So, there must 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,"
says Vittorio Formisano, Principal Investigator for the
PFS instrument. "Since the methane presence is so
small, we need to take more measurements. Only then
we will 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. The
High Resolution Stereo camera (HRSC) on Mars Express could help
us identify visible activity, if it exists, on the surface of
the planet", continues Formisano. Clearly, if it was the case,
this would imply a very important consequence, as present
volcanic activity had never been detected so far 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," concludes Formisano.

"In the next few weeks, the PFS and other instruments on-board
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.
Thanks to the PFS instrument, scientists are also gathering
precious data about isotopes in atmospheric molecules such as
water and carbon dioxide - very important to understand how the
planet was formed and to add clues on the atmospheric escape. The
PFS also gives important hints about water-cloud formation on the
top of volcanoes, and shows the presence of active photochemical
processes in the atmosphere.
Received on Tue 30 Mar 2004 11:48:16 AM PST

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