Washington: Earthly microbes can survive
the harsh environment of Mars given a little protection,
Italian astronomers have claimed.
Researchers at University of Padova said that microbes
similar to those on the earth would have a tough time
surviving the harsh environment of Mars but it is not
inconceivable that they could persist there given a little
The finding supports similar, previous work and lends
credence to the theory that if microbial life ever arose on
Mars, it could exist below the planet's surface to this day.
Mars is in most respects a terrible habitat for life as
its winter temperatures can dip below ?100 degrees Celsius,
the atmosphere contains little oxygen and without the benefit
of a robust ozone layer the Martian surface is bombarded with
ultraviolet (UV) solar radiation.
In a paper submitted to Planetary and Space Science,
the researchers presented the results of submitting a number
of terrestrial bacteria to simulated Martian conditions, the
Scientific American reported.
Lead researcher Giuseppe Galletta and his colleagues
introduced bacterial species, including three strains from the
Bacillus genus and a strain of Mycobacterium smegmatis, to
their LISA and mini LISA experimental chambers.
The enclosures provide a rough facsimile of Mars'
surface’ they are cooled by liquid nitrogen to create extreme
Martian cold, bathed in UV light and flooded with a
low-pressure carbon dioxide atmosphere.
The researchers varied the environmental parameters to
simulate the drastically different conditions found on Mars
depending on the season and the time of day.
Galletta and his colleagues found that the bacteria
handled the temperatures, low pressures and lack of oxygen
relatively well but that the UV intensity all but wiped out
the colonies in minutes.
Even the extremophile Deinococcus radiodurans, which
can endure mammoth blasts of gamma rays hundreds of times more
powerful than would kill a human, could not last 10 minutes
under UV exposure.
Similar experiments have been carried out in the past,
including many that have sought to determine the threat of
terrestrial microbes stowing away on Mars-bound spacecraft and
contaminating the Red Planet. In those studies, UV irradiation
was also shown to be a lethal force for bacteria.
The Italian group found that bacterial spores fared much
better than active cells; the Bacillus spores survived for
more than an hour, albeit in low numbers.
The study's authors report that spores shielded from UV
light, as might occur on Mars beneath the frozen surface or in
a cave, stabilise in a dormant state before reactivating in
the presence of liquid water.
"This is important for Mars, because if underground
water exists this may mean that life could survive in some
ecologic niches," Galletta says.
First Published: Tuesday, March 02, 2010, 18:58