NASA probes surveying Mars have noticed something very interesting – the sand dunes they’ve photographed have been changing the longer they’ve been monitoring.
Here’s a picture of what’s happening:
From the BBC:
Vast sand dunes near the northern pole of Mars are not frozen relics of a distant past, but shift and change every Martian year, data have shown.
A hi-tech camera aboard Nasa’s Mars Reconnaissance Orbiter has spotted UK-sized dune fields that are among the most dynamic on the Red Planet.
Causes, says a report in Science, include carbon dioxide gas that freezes solid onto the dunes each winter.
As it thaws in spring, the gas released destabilises, causing sand avalanches.