In the past most scientists have said that long, narrow grooves in the slopes of Martian sand dunes offer evidence of liquid water on the surface of the red planet.
This is because, planetary scientists believe, the melt-water flows would have eroded the channels.
But a NASA systems engineer, Serina Diniega, has another theory: that hunks of frozen carbon dioxide — dry ice — may slide down Martian sand dunes on a pillow of gas similar to miniature hovercraft, marking grooves on the way down.
“I dream of snowboarding down a Martian sand dune on a block of dry ice,” Diniega said.
That’s quite a dream. So what’s the evidence? Images from a satellite in orbit around the planet, the Mars Reconnaissance Orbiter, show sand dunes on Mars covered by a carbon dioxide frost during the Martian winters. Any by comparing images during warmer and colder seasons, Diniega and her colleagues found that the grooves form during early spring.
The theory is that, as sublimation occurs during the warming months, blocks of dry ice break off and move down the slopes carving out grooves and forming pits at the bottom. Their study is published in Icarus (see abstract).
To test the theory, other scientists performed experiments with water and carbon dioxide ice blocks on terrestrial dunes — sliding dry ice blocks down sand dunes — and the experiments show that dry ice blocks on Earth move in a similar manner to the grooves observed on Mars.
Of course we won’t know for sure until we send some surfers to Mars.