Further evidence for water flowing on Mars today has turned up in a paper published recently in Geophysical Research Letters.

Dennis Reiss and his colleagues at Westfälische Wilhelms-Universität Münster used images from the HiRISE (High Resolution Imaging Science Experiment) camera, run by NASA and University of Arizona scientists, and currently onboard the Mars Reconnaissance Orbiter.

Reiss noticed that over a two year period the shape of gullies in the Russell crater dune field (see image). The explanation for this, says Reiss and his team, is that small amounts of ice just under the surface are melting and triggering slurry slides down the dunes. The fact that the pictures, taken in 2006 and 2009 are different suggests that this process is not an ancient relic, but contemporary.

So far so exciting. And this is a great bit of news. But it shouldn’t be forgotten that in late 2006 Michael Malin from instrumentation company Malin Space Science Systems in San Diego, California, published a similar paper using data from the Mars Global Surveyor. Malin saw gullies that grew a few hundred metres over a 4 year period. He didn’t have an explanation other than these gullies were reminiscent of water-formed gullies on Earth.

Reiss speculates more about the processes at work. He suggests that carbon dioxide ice melts during summer months as temperatures rise, and this allows the water ice to melt and start the slurry rolling.

Reiss’s study seems to complement Malin’s work well, and it’s exciting news – water flowing on Mars’s surface today. Next we need to wake up Spirit and get her to rove over to a puddle and splash her wheels in it for undisputable evidence.

Image: NASA/JPL/University of Arizona