A strong signal of life on Mars
has been detected by scientists at the US National Aeronautics and Space
Administration (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.
This could indicate a subterranean
source of methane which is pumping out the gas, either due to some residual
geological activity or because of the presence of living organisms producing
it as a waste gas.
Asked whether the continual production
of methane is strong evidence of a biological origin of the gas, Dr
Mumma said: "I think it is, myself personally."
He added: "It's difficult to imagine
that primordial methane [from geological activity] would continue outgassing
for four billion years [the age of Mars]. This looks very intriguing."
Both teams of scientists are now busy validating their results before
their respective organisations are prepared to go public on the implications.