Life on Mars 'could exist' as satellite shows gullies were carved by melting snow

The surface of Mars has been shaped by water thawing and freezing more recently than thought - and that means the planet is more likely to be able to sustain life.

Researchers from the University of Gothenburg analysed the surface of the planet from satellite images, and found it had striking similarities to the Arctic landscape of Svalbard.

Gullies on Mars have been eroded by snow and water - and permafrost and sub-surface ice are now thought to exist on Mars.

"This suggests that water has played a more extensive role than previously envisioned, and that environments capable of sustaining life could exist," say the researchers.

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The study found that the surface had been shaped by repeated freeze and thaw cycles - more recently than thought.

Mars is a changing planet, and in recent geological time repeated freeze and thaw cycles has played a greater role than expected in terms of shaping the landscape.

"Despite the fact that Svalbard is considerably warmer than Mars, the arctic landscape shows a number of striking similarities to certain parts of Mars," say the researchers.

One important common feature is the presence of permafrost and frozen subsurface water.

“In my thesis work, I have compared aerial images from Svalbard with the same resolution as satellite images from Mars, and combined with field-work we increase the ground resolution even further” explains Dr Andreas Johnsson from the University of Gothenburg’s Department of Earth Sciences, who has worked together with planetary researchers from Germany.

Having studied hundreds of gullies on Mars and compared these with Svalbard, the researchers found evidence that the gullies on Mars were likely formed by melting snow and water erosion.

Field work has supplemented the interpretation of aerial images.

“The ability to get a first-hand experience with landforms that have been studied using aerial images is a unique feeling. One important insight we have gained is that, despite the high image resolution for both Svalbard and Mars, the camera can’t capture everything.

"What appears to be fine-grained sediment on an aerial image of Svalbard can actually turn out to be a very rocky area which has implications for certain types of landforms. It’s important to bear this in mind when studying images of Mars.”

Since Mars has a cyclical climate, the same conditions could recur in the future.

The existence of liquid water is a vital component if life on Mars is to be possible.

“Research on Earth has shown that organisms can survive in extreme cold environments with limited access to liquid water,” continues Dr Johnsson. “Studying various areas on Mars therefore enables us to investigate whether there could be environments with conditions capable of supporting life.”