Illustration of NASA's Curiosity Rover using a rock-vaporising laser instrument, ChemCam to analyse rocks and soil. Unfortunately, Curiosity did not have the capability to dig deep enough to find the life for Lineweaver's study.
Credit: NASA
SYDNEY: Large expanses of Mars could sustain life, according to a study by Australian scientists who modelled conditions on Mars to examine how much of the red planet was habitable.
Astrobiologist Charley Lineweaver's team, from the Australian National University in Canberra, compared models of temperature and pressure conditions on Earth with those on Mars to estimate how much of the distant planet was liveable for Earth-like organisms.
While just 1% of Earth's volume - from core to upper atmosphere - was occupied by life, Lineweaver said their world-first modelling showed 3% of Mars was habitable, though most of it was underground. The results were published in Astrobiology. yesterday.
"What we tried to do, simply, was take almost all of the information we could and put it together and say 'is the big picture consistent with there being life on Mars?'," said Lineweaver. "And the simple answer is yes... There are large regions of Mars that are compatible with terrestrial life."
Conditions right for life on Mars
Where previous studies had taken a "piecemeal" approach by examining particular sites on Mars for signs of life, Lineweaver said his research was a "comprehensive compilation" of the entire planet using decades of data.
Frozen water has been found at the poles on Mars and the ANU study examined how much of the planet could sustain water "that could be habitable by Earth-like standards by Earth-like microbes".
The low-pressure environment of Mars means water cannot exist as a liquid and will vapourise on the surface, but Lineweaver said the conditions are right underground, where the weight of the soil gives the added pressure required.
Warm enough for life
It would also be warm enough, at certain depths, for bacteria and other micro-organisms to thrive due to heat from the planet's core. The average surface temperature on Mars, Earth's nearest neighbour, is minus 63 degrees Celsius.
Lineweaver said his study was "the best estimate yet published of how habitable Mars is to terrestrial microbes" and a significant finding given mankind had evolved from microbial life.
"It's not important if you want to figure out what the laws of physics are and you want to talk to some intelligent aliens who could build spaceships," he said. "If you're interested in the origin of life and how likely life is to get started on other planets, that's what relevant here."
Curiosity can't dig deep
NASA's Curiosity Rover, the largest, most sophisticated robotic explorer ever built, is en route to Mars and due to land in August 2012. It has a laser beam for zapping rocks and a tool kit to analyse their contents as well as a robotic arm, drill, cameras and sensors to enable it to report back on the Martian weather and atmospheric radiation.
Curiosity is scheduled to land at the Gale Crater, near Mars' equator, chosen for its 5-km-high sediment mountain that will hopefully reveal clues about the planet's wetter past. Lineweaver said the NASA mission "sadly" did not have the capability to dig deep enough to find the life his study had modelled but Curiosity would be able to examine "at least the edges" of what was once the Martian depths at the crater.
"But these have been exposed for a long time and therefore are probably devoid of volatiles and they are not warm like they used to be," he said.
Closest?
Mars isn't the closest. I am pretty sure that title goes to Venus, although if you want to really be problematic, the closest planet to Earth is Luna (the moon), which follows a path around the sun that is only wobbled by the presence of the Earth. It never goes retrograde (backwards) like other plants' moons do, so therefore has the sun as the centre-point of its orbit...
Greg