From Mike Wall at Space.com:
Ultraviolet (UV) radiation streaming from the sun “activates” chlorine compounds in the Red Planet’s soil, turning them into potent microbe-killers, a new study suggests.
These compounds, known as perchlorates, seem to be widespread in the Martian dirt; several NASA missions have detected them at a variety of locations. Perchlorates have some characteristics that would appear to boost the Red Planet’s habitability. They drastically lower the freezing point of water, for example, and they offer a potential energy source for microorganisms, scientists have said.
But the new study, by Jennifer Wadsworth and Charles Cockell — both of the U.K. Centre for Astrobiology at the University of Edinburgh in Scotland — paints perchlorates in a different light.
Ultraviolet (UV) radiation streaming from the sun “activates” chlorine compounds in the Red Planet’s soil, turning them into potent microbe-killers, a new study suggests. These compounds, known as perchlorates, seem to be widespread in the Martian dirt; several NASA missions have detected them at a variety of locations. Perchlorates have some characteristics that would appear to boost the Red Planet’s habitability. They drastically lower the freezing point of water, for example, and they offer a potential energy source for microorganisms, scientists have said. [The Search for Life on Mars: A Photo Timeline] But the new study, by Jennifer Wadsworth and Charles Cockell — both of the U.K. Centre for Astrobiology at the University of Edinburgh in Scotland — paints perchlorates in a different light.More.
The good news is that we are really finding out instead of speculating.
See also: Breaking, breaking: NASA has not found ET