Winters leave marks on Mars’ sand dunes
“The process is then reversed in the spring, as the ice sublimates, and this seasonal interplay may be a really important geomorphic process.”
The experiments were inspired by patterns first observed on Martian sand dunes several them was that they appeared to trend both up and down the dune slopes, which ruled out liquid water as the cause.”
To see whether CO2 could be responsible for the sand furrows, Bourke and her research partners place blocks of frozen CO2 on the sandy surface and the CO2 block will generate a vapor layer beneath the block, allowing it to levitate and maneuver downslope, in a similar manner to how pucks glide on an icehockey table, carving a channel in its wake.
“At the terminus, the block will sublimate and erode a pit. It will then disappear without a trace other than the roughly circular depression beneath it.”
Similar formations, called gullies, are formed by water and ice migrating down rocky slopes on Earth, but the terminuses are usually marked by debris deposits, not a depression, which suggested Martian gullies and furrows are indeed formed by CO , not water.
The lab tests showed under certain conditions, frozen CO2 blocks can sublimate fast enough to burrow directly into the sand and become swallowed up in less than a minute, leaving only a slight depression behind.
Mckeown said, “This process is really unlike anything seen to occur naturally on Earth — the bed appears fluidized and sand is kicked up in every direction.
“When we first observed this particular effect, it was a really exciting moment.”
The researchers described the effects of sublimating CO2 on sand in a new paper published in the journal Scientific Reports.