NASA spots sledding marks in Martian sand dunes

Not toboggans, but dry ice carving gullies into sand dunes

NASA scientists have seen evidence that there's been sledding on Mars.

No, They don't mean there are Martians on toboggans. What NASA scientists have found is that hunks of frozen carbon dioxide, also known as dry ice, may have slid down Martian sand dunes on cushions of gas, like miniature hovercrafts. The sliding digs furrows, called linear gullies, into the sand.

linear gullies in Martian sand dunes
NASA's Mars Reconnaissance Orbiter snapped images of linear gullies in Martian sand dunes. Scientists believe they were caused by sliding hunks of dry ice. (Image: NASA/JPL-Caltech/Univ. of Arizona)

NASA's Mars Reconnaissance Orbiter captured images of the linear gullies from space.

Researchers from the space agency tested their theory by performing experiments on sand dunes in Utah and California.

"I have always dreamed of going to Mars," said Serina Diniega, a planetary scientist at NASA's Jet Propulsion Laboratory. "Now I dream of snowboarding down a Martian sand dune on a block of dry ice."

The grooves in the sand dunes have been found to be relatively constant -- measured at an average of a few yards across. They also have raised banks along the sides.

Scientists don't believe the gullies were caused by water flows because water generally leaves aprons of debris at the end of the gullies. Many of these Martian gullies instead have pits at the bottom end.

"In debris flows, you have water carrying sediment downhill, and the material eroded from the top is carried to the bottom and deposited as a fan-shaped apron," said Diniega, in a statement. "In the linear gullies, you're not transporting material. You're carving out a groove, pushing material to the sides."

NASA reported that the gullies are found on sand dunes that spend the Martian winter covered by carbon-dioxide frost. By comparing before-and-after images from different seasons, scientists said they found that the grooves are formed in early spring.

A few of the images captured by the orbiter show objects, believed to be chunks of dry ice, in the gullies.

"[The Mars orbiter] is showing that Mars is a very active planet," said Candice Hansen, of the Planetary Science Institute in Tucson, Ariz. "Some of the processes we see on Mars are like processes on Earth, but this one is in the category of uniquely Martian."

The orbiter is one of several NASA machines studying the Red Planet.

Mars rovers Opportunity and Curiosity are working on the Martian surface, looking for evidence that the planet could be, or has been, able to support life.

This article, NASA spots sledding marks in Martian sand dunes, was originally published at

Sharon Gaudin covers the Internet and Web 2.0, emerging technologies, and desktop and laptop chips for Computerworld. Follow Sharon on Twitter at @sgaudin, on Google+ or subscribe to Sharon's RSS feed . Her email address is

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