Researchers believe that the mysterious looking tracks that have been observed on sand dunes on the planet Mars may have been caused by tumbling chunks of frozen carbon dioxide, dry ice, according to NASA.
After observing the gullies on the Martian dunes from pictures taken by NASA's Mars Reconnaissance Orbiter (MRO) researchers went out to sand dunes in Utah and California with some dry ice and tried to recreate what they had seen on our red neighbor.
"I have always dreamed of going to Mars," Serina Diniega, a planetary scientist at NASA's Jet Propulsion Laboratory said. "Now I dream of snowboarding down a Martian sand dune on a block of dry ice."
On Earth similar gullies are made by water flow and will have a debris field at their base. The gullies on Mars do not have a debris field; instead many of them have pits at the 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," Diniega said. "In the linear gullies, you're not transporting material. You're carving out a groove, pushing material to the sides."
The linear gullies, as researchers are calling them, occur on sand dunes that are covered by carbon-dioxide frost during the winter. Researchers have theorized that the linear gullies are created by blocks of the carbon-dioxide ice that break off in the early spring when the weather is a little warmer and slide down the dune. Bright spots have been observed within the linear gullies and researchers think the bright spots are the blocks of dry ice, according to NASA.
"Linear gullies don't look like gullies on Earth or other gullies on Mars, and this process wouldn't happen on Earth," Diniega said. "You don't get blocks of dry ice on Earth unless you go buy them."
Candice Hansen of the Planetary Science Institute went and did just that. After sliding the blocks of dry ice down sand dunes she learned that gaseous carbon dioxide from the ice gave it a lubricating layer that helped it slide down the dunes, pushing the sand into small levees as it glided downward. Although the tests were not done in conditions similar to those found on Mars researchers believe that dry ice would act the same way during Martian spring.
"MRO is showing that Mars is a very active planet," Hansen said. "Some of the processes we see on Mars are like processes on Earth, but this one is in the category of uniquely Martian."
To see images of the linear gullies and learn more about MRO click here.
