NASA has taken snapshots of avalanches down a steep Martian slope. Researchers were actually looking at the Northern-spring thaw in the planet’s carbon dioxide frost when they spotted the cloud of dust and ice resulting from the rock and ice fall (NASA press release, news coverage from USA, China, Australia).

This cloud can be seen in the middle of the right hand side of this false colour picture. The top of the cliff is on the left of the picture – the white stuff is carbon-dioxide frost). Slightly lower down the slope, to the right of the frost, the pink/brown layers are ice and dust (more details from NASA).

The cliff is over 700 meters tall and slopes at up to 60 degrees. Further to the right, the darker sections are probably also mainly ice, but with shallow-ish 20-degree gradients, and dunes.

“It’s great to see something so dynamic on Mars. A lot of what we see there hasn’t changed for millions of years,” says Ingrid Daubar Spitale, one of the NASA team and a researcher at the University of Arizona, Tucson (press release).

Possible explanations for the avalanche include the disappearance of the carbon dioxide frost; expansion and contraction of ice due to temperature variations; and meteorite impact. Further analysis should reveal how much of the slide was dust and how much ice. This could in turn reveal more about the Martian water cycle.

The images come from the High Resolution Imaging Experiment on NASA’s Mars Reconnaissance Orbiter. Another picture released by Hirise is this rather spectacular shot of Earth and the Moon from Mars, which is currently exciting the Bad Astronomy blog (more details from NASA).

Images: NASA/JPL-Caltech/University of Arizona