Video: Lake on Mars could have teemed with microbial life
Nasa scientists say enormous crater once harboured an ancient lake that could have supported life
An enormous crater near the northern plains of Mars once harboured an ancient lake that could have supported microbial life, Nasa scientists claim.
The freshwater lake stood for more than one hundred thousand years at the base of Gale Crater, a 150km-wide formation that was created when a meteor punched into the red planet around 3.7bn years ago.
Tests on rock samples by Nasa’s Curiosity rover revealed the presence of fine clay minerals that formed in a standing body of water, and coarse-grained sandstones laid down by river flows that drained into the lake.
“The presence of these minerals tells us the water was likely to be fresh water, which means it’s much more conducive for microbial life,” said Sanjeev Gupta, a geologist at Imperial College, London, and a member of the Curiosity science team.
“These rocks are similar to those we would find if we walked along the Dorset or Devon coast line,” he added.
The Nasa team is not sure how deep or wide the lake was, but suspect it was deep enough not to have dried out periodically, as this would have left traces of crack marks in the rock samples.
The $2.5bn rover landed in on Mars in August 2012 on a mission to explore whether the planet may once have been habitable, though not to look for signs of ancient life itself.
Curiosity’s main objective is to trundle up nearby Mount Sharp, a 5km-high mountain that sits in the middle of Gale Crater. Through measurements of its exposed rock faces at different altitudes, researchers hope to piece together the geological history of the planet.
But Curiosity did not make for Mount Sharp immediately. After relaying details of the Martian soil near its landing site, the rover was steered towards a 5m-deep trough in the crater called Yellowknife Bay. Here, the robotic science laboratory drilled into a rock formation called Sheepbed mudstone and examined the powder with its instruments.
Though a combination of x-ray diffraction experiments and analyses of gases given off when the powder was baked in an onboard oven, researchers identified so-called smectite clay minerals that formed in water and elements crucial for life, including carbon, hydrogen, oxygen, sulphur, nitrogen and phosphorus.
The chemical makeup of the minerals showed that they formed in water with low salinity and a neutral pH, suggesting it was neither too acidic nor too alkaline for life to exist.
Writing in the journal, Science, researchers explain that the conditions in the lake were well suited to support a type of microbial life called chemolithoautotrophs. These organisms are found on Earth and can survive by breaking down rocks and minerals for energy.