Last Lake on Mars

A newly discovered 18-square-mile salt flat (roughly the size of Boulder) likely represents the evaporated remains of one of the last potentially habitable surface lakes to exist on the Red Planet. The lake’s estimated age—no older than 3.6 billion years old—dates it to a time period after which scientists believe Mars could no longer sustain large amounts of surface water. “We can be pretty certain this is one of the last instances of a sizeable lake on Mars,” said Brian Hynek, an associate professor at the Laboratory for Atmospheric and Space Physics (LASP). Hynek and his colleagues estimate the lake's salinity to have been about 2.8 parts per thousand (ppt), far less salty than the 35 ppt of the Earth’s oceans and, therefore, possibly once hospitable to microbial life.