NASA scientists think that sliding chunks of frozen carbon dioxide — dry ice — may be responsible for creating track marks on some Martian sand dunes. Which brings up a totally awesome idea: Snowboarding down a Martian sand dune on a block of dry ice.
NASA calls these strange formations linear gullies, and they measure anywhere from a few hundred feet to an astounding 1.6 miles (2.5 km) long. They were discovered on images beamed back from the Mars Reconnaissance Orbiter’s (MRO's) High Resolution Imaging Science Experiment (HiRISE) camera. Planetary scientists had never seen anything quite like it before, and it’s certainly not something that’s ever been seen here on Earth.
As they were working to solve the mystery, the researchers realized that the tracks were only found on dunes which were covered in frost during the Martian winter. During this season, Mars's southern polar region is covered by a layer of dry ice, sometimes up to several feet deep. When spring arrives, it goes through a sublimation process where it turns directly from solid into gas.
And in fact, NASA determined that the tracks formed during early spring. Some images even showed bright objects in the gullies. The researchers, a team that included planetary scientist Serina Diniega, now theorize that the objects are pieces of dry ice that have broken away from points higher on the slope.
As gravity does its work, and as the sublimation process continues, the chunks of ice rest on a super slippery cushion of gas. They’re essentially turning into miniature hovercrafts, forming furrows as they go. The circular pits themselves likely resulted from the blocks of dry ice completely sublimating away once they stopped moving.
Interestingly, the team tested this hypothesis by conducting outdoor tests here on Earth. And as you’ll see in the video below, it worked remarkably well (be sure to watch it all the way through as it includes an interpretation of what a snowboarding astronaut might look like).
"I have always dreamed of going to Mars. Now I dream of snowboarding down a Martian sand dune on a block of dry ice." — Serina Diniega
Needless to say, the conditions on Mars are far removed from what is experienced on Earth, both in terms of temperature and pressure. But according to the researchers, their calculations show that the dry ice would in fact act similarly during the early Martian spring. Water ice, on the other hand, would stay frozen at the temperatures at which these gullies form.
"MRO is showing that Mars is a very active planet," noted co-author Candice Hansen in a statement. "Some of the processes we see on Mars are like processes on Earth, but this one is in the category of uniquely Martian."
So who’s up for snowboarding down a Martian sand dune on a sled made from dry ice? I'm totally in.
Read the entire study at Icarus: “A new dry hypothesis for the formation of martian linear gullies.”
Image: NASA/JPL-Caltech/Univ. of Arizona.