Surfing ice theory on Mars gullies
The long grooves in sand dunes of Mars - first spotted more than 10 years ago - might be a result of blocks of dry ice surfing down the slopes during the Martian spring, according to scientists.
A team of scientists led by Serina Diniega at Nasa's jet propulsion laboratory in California has proposed that the linear gullies, mostly several hundred metres long and about 10 metres wide, were caused as the frost layer on the surface of the planet warmed up.
Writing in the journal Icarus, Diniega said the vast majority of seasonal frost on Mars was made of carbon dioxide. As seasonal temperatures rose, blocks of the dry ice could break off and fall from higher slopes on to the lower ones. The ice blocks then slide down the lower slopes, leaving behind the gullies.
Diniega's team experimented by sending blocks of dry ice down dunes in Utah and produced similar gullies.