Well, that's going to make Ridley Scott's Martian look a lot less credible, isn't it?
When NASA mumbled that it was set to make a major Mars announcement, we (and the rest of the internet) guessed it had something to do with water. And we were all right.
A team of NASA scientists has discovered "definitive signs of liquid water" on the surface of our apparently barren neighbour.
Back in 2011, Ojha and McEwen published a report on "warm-season flows" - dark patterns in the sands of Mars that have been observed to grow from early spring of one Mars year to mid-summer of the following year (seen above). The report proposed that the tendrils might indicate the flow of salt water - though further evidence was required.
Now, in a paper published in the journal Nature Geoscience, a team from NASA has claimed to have identified waterlogged molecules - salts, shown in the above gif - in readings taken from orbit. It's as close as we've come to striking a pickaxe into the rocky surface and seeing a jet of water eject from the surface.
"This, I think, gives a focus of where we should look more closely," said Alfred S. McEwen, a professor of planetary geology at the University of Arizona and the principal investigator of images from a high-resolution camera on NASA’s Mars Reconnaissance Orbiter. "That’s a direct detection of water in the form of hydration of salts. There pretty much has to have been liquid water recently present to produce the hydrated salt."
The NASA team was able to use existing instruments on the Mars Reconnaissance Orbiter to analyse the previously-discovered "recurrent slope linae" (RSL) streaks that they believed might indicated moisture. "It’s very definitive there is some sort of liquid water," said Mr. Ojha, the lead author of the Nature Geoscience article.
The discovery poses several interesting questions: where is the water coming from - the atmosphere above or the ground below? And if there is a water source, could there still be some form of life that was once abundant on Mars? NASA can't send any of its rovers to investigate, as they fear they may contain trace elements of biological elements from Earth that could provide a false positive test, or contaminate the source.
The New York Times has word that the Curiosity Rover team might stage a 'drive by' observation, without running over the RSL streaks.
What next - cheese on the Moon?