Martian Gases Pose Life Question
BBC News - 25 February 2005
An Italian scientist working on the Mars Express probe says gases
detected in the planet's atmosphere may indicate life exists on
the Red Planet today.
Vittorio Formisano told a Dutch space conference methane and formaldehyde
could signify biological activity. But the cautious professor, from
the Institute of Interplanetary Space Physics in Rome, said only
soil analysis on the planet could prove it.
Confirmation came through hard data, not "fantasy", he
told BBC News.
"[My observations] should not be taken as a statement that
there is life on Mars today, because we need to go there, to drill
the soil, take samples, and analyse them before possibly concluding
that life is there," Professor Formisano said.
Possible sources
The researcher is principal investigator on the Mars Express Planetary
Fourier Spectrometer (PFS).
The instrument is designed to determine the composition of the Martian
atmosphere, and was able to confirm the presence in the Martian
"air" last March of small quantities of methane.
The observation is fascinating because the gas is short-lived; it
is broken down by sunlight, and should not be detectable unless
it is being constantly replenished in some way.
The conservative view is that the source is geological - volcanic
processes may be producing the gas, although active signs of this
have yet to be observed. There may also be large reserves in the
Martian soil of ancient methane-ice, so-called clathrates, which
are slowly melting and releasing the gas into the atmosphere.
But there is also the theory that microbes are responsible. Some
micro-organisms on Earth, known as methanogens, produce methane
as a waste product and a number of scientists argue similar lifeforms
could exist on the Red Planet, too.
Overlapping areas
Professor Formisano expressed his views on the subject at the European
Space Agency's Mars Express Science Conference in Noordwijk. He
said that if the methane was considered in isolation, it appeared
too small a source to be biogenic in origin.
However, he argued, if the formaldehyde detected in the atmosphere
was viewed as a byproduct of the oxidation of methane, it would
imply much more methane was being produced each year - and this
could be explained by life more easily.
"If you consider only methane which is observed in the Martian
atmosphere, it would be 150 tonnes a year; if you consider formaldehyde
then you have 2.5 million tonnes [of methane] per year, which is
much more," he said. "And the correlation indicates the
sources are in the soil, underground."
PFS data shows that the highest concentrations of methane overlap
with the areas where water vapour and underground water-ice are
also concentrated.
Recent events
One of these areas includes the equatorial Elysium region, where
Mars Express scientists think they may have seen pack ice covered
by a thin "lag" of dust and volcanic ash.
The researchers told the meeting earlier this week that a vast upwelling
of water could have broken through a series of fractures known as
the Cerberus Fossae, flooding an area about 800km by 900km, to a
depth of about 45m. And this was probably a very recent event, said
Professor John Murray, from the Open University, UK.
"This was around five million years [ago]. That may sound old
but in geological terms that is yesterday," he told BBC News.
"We know that these eruptions have occurred throughout Mars'
geological history. The fact that they occurred just five million
years ago essentially tells us we have vast reservoirs of liquid
water beneath the surface today. "Therefore, if life can develop
that is where you are going to find it."
A paper detailing the pack ice discovery will appear next month
in the prestigious scientific journal Nature. A paper discussing
formaldehyde was submitted to Nature by Professor Formisano but
was rejected by "one referee out of three", the Rome scientist
said. And some researchers point out that the area of the spectrum
in which formaldehyde appears in the PFS data coincides with an
area of significant interference from solar radiation.
© BBC MMV
http://news.bbc.co.uk/1/hi/sci/tech/4295475.stm
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