“It was an astonishing claim: Mars may have puddles of liquid water on its surface today. That was the conclusion Ron Levin and Daniel Lyddy of Lockheed Martin in Arizona, US, recently came to after analysing an image taken by NASA’s Opportunity rover (see image at left).
In our story about the research, we acknowledge that the claim is highly controversial, citing an outside expert who says it would be “virtually impossible” for liquid water to exist without boiling away in the planet’s thin atmosphere.
But it turns out the claim is impossible for an entirely different – and much more basic – reason: the terrain in question is on the side of a crater, and is therefore sloped too greatly for water to pool into puddles”…. <More>