News in Science

Evidence of ancient Martian lake found

Wet world A US spacecraft orbiting Mars has provided evidence of an ancient crater lake fed by groundwater, adding further support to theories that the Red Planet may once have hosted life.

Spectrometer data from NASA's Mars Reconnaissance Orbiter (MRO) shows traces of carbonate and clay minerals usually formed in the presence of water at the bottom of the 2.2 kilometre deep McLaughlin Crater.

"These new observations suggest the formation of the carbonates and clay in a groundwater-fed lake within the closed basin of the crater," write NASA scientists in a paper published in the online edition of Nature Geoscience.

"Some researchers propose the crater interior catching the water," according to the space agency, adding that "the underground zone contributing the water could have been wet environments and potential habitats."

The crater lacks large inflow channels, so the lake was likely fed by groundwater, the scientists write.

The latest observations "provide the best evidence for carbonate forming within a lake environment instead of being washed into a crater from outside," says Joseph Michalski, lead author of the paper.

The 92-kiloemtre-wide crater sits at the low end of a regional slope several hundreds of kilometres long and, as on Earth, groundwater-fed lakes would be expected to occur at low elevations.

NASA's Mars rover Curiosity has been exploring the planet's surface since its dramatic landing on 6 August, collecting rock samples and beaming back rare images in anticipation of an eventual manned mission.

MRO scientist Rich Zurek, of NASA's Jet Propulsion Laboratory, says the latest findings indicate "a more complex Mars than previously appreciated, with at least some areas more likely to reveal signs of ancient life than others."