Remember hearing that Mars has (or had) oceans of methane or water on its surface? Well, that story just popped up again and this time with some harder evidence to support it. I suppose that if this new evidence supports it enough we should send an army of robots to find out for us! Hooray Robots!

 "Taylor Perron of the University of California, Berkeley, and colleagues think that massive wobbles in the planet’s rotation may explain the mystery of Martian sea.

"Working with a mathematical model of Mars, the team found that volcanic eruptions and asteroid impacts could have caused the planet’s poles to shift in the past, a phenomenon called true polar wander. A side effect of this would have been large-scale deformation in the crust, accounting for the strangely varying coastline heights.

If correct, the team’s findings make it likely that a body of water once covered one-third of the Martian surface – about the size of the Pacific Ocean – near the equator, then later migrated into the northern hemisphere as the poles shifted. "We’ve turned what has been a monkey wrench for us into a piece of evidence that supports the idea there were oceans on Mars," says Perron.

The final piece of the puzzle, he adds, will be finding how enough water to fill the basin is now buried in the crust. The basin has been dry for at least the past 2 billion years."

Journal reference: Nature (vol 447, p 840)