Images from the Mars Reconnaissance Orbiter of the surface of Mars have revealed long thin tracks, which scientists are calling linear gullies.

Images from the Mars Reconnaissance Orbiter of the surface of Mars have revealed long thin tracks, which scientists are calling linear gullies, that they believe were made by blocks of frozen carbon dioxide.
The gullies are evidence that the blocks of dry ice were carried down on clouds of carbon dioxide gas, which scientists compared to a dry ice hovercraft.

Dry ice does not form naturally on the Earth’s surface, but on Mars, where there are more extreme conditions, carbon dioxide freezes into blocks during winter.

Then in the spring, the dry ice goes directly from a solid to a gas.

Co-author of the study, Candice Hansen of the Planetary Science Institute in Tucson, Arizona said: “Mars Reconnaissance Orbiter is showing that Mars is a very active planet. Some of the processes we see on Mars are like processes on Earth, but this one is in the category of uniquely Martian.”