Mars has acid fog which eats away rocks and is caused by volcanic eruptions on the red planet, a new study suggests.

A planetary scientist has pieced together a compelling story about how acidic vapours may have eaten at the rocks in a 100-acre area on Husband Hill in the Columbia Hills of Gusev Crater on Mars.

Shoshanna Cole of Ithaca College in New York, used a variety of data gathered by multiple instruments on the 2003 Mars Exploration Rover Spirit to tease out information from exposures of the ancient bedrock.

The work focused on the ‘Watchtower Class’ outcrops on Cumberland Ridge and the Husband Hill summit, said Prof. Cole, who began studying the area for her PhD thesis at Cornell University. “The special thing about Watchtower Class is that it’s very widespread and we see it in different locations. As far as we can tell, it’s part of the ground there,” which means that these rocks record environments that existed on Mars billions of years ago.

By combining data from previous studies of the area on Mars, Prof. Cole saw some intriguing patterns emerge. Spirit examined Watchtower Class rocks at a dozen locations spanning about 200 meters along Cumberland Ridge and the Husband Hill summit.

The chemical composition of these rocks, as determined by Spirit’s Alpha Proton X-ray Spectrometer, is the same, but the rocks looked different to all of the other instruments.

— PTI