On the Red Planet i have been observed for the first time “megaripples”, huge waves of sand in motion. This phenomenon also occurs on the deserts of our planet and generally consist of coarse sand.
The heaviness of these grains, combined with the very subtle and weak winds of the atmosphere of Mars, it made scientists think that these structures were static and immobile. Not so, and thanks to a study conducted by Simone Silvestro (published in the Journal of Geophysical Research: Planets) of the Capodimonte Astronomical Observatory we know that this phenomenon on Mars is in motion.
By comparing the images taken by the HiRISE camera over several years, Silvestro’s team found that Martian megariples “walk”, but are very slow. Between 2007 and 2016, in fact, the megariples in two Martian sites – the Nili Fossae and McLaughlin crater – were move at average speeds of only 12 centimeters per year, with a maximum recorded speed of 19 centimeters.
The previous comparisons were too short, for this reason the experts did not notice this shift. “We had the opportunity to see them move because we now have more than 10 years of observation“, explains Silvestro. However, these huge sand dunes could move thanks to a little help. The proximity of larger sand dunes located in the areas of the crater of Nili Fossae and McLaughlin could help move the megariples thanks to the presence of finer-grained dunes which provide a high volume of sand flow.