With a gentle rainbow of topographical changes, and the scalloped detail of active dunes, this digital terrain model is pure indulgence for the eyes. It's also part of an ongoing study on using aeolian processes to investigate sedimentation and atmospheric science on Mars.

Image Credit: NASA/JPL/University of Arizona/USGS

Sand dunes are an aeolian feature, formed by wind-blown sediments. On any planetary body, including Earth and Mars, dunes accumulate where sediment is in easy supply, is carried downwind, and eventually deposited when the winds weaken. Dunes can be used to study atmospheric science, as the existence and shape of the dunes are closely tied to wind circulation patterns and wind strength. Sediments only exist if something is eroded, so looking at dunes can also give hints about the history of the surrounding area. Where did the sand come from, and how did it end up distributed the way it is now?


Mars has a lot of sand dunes, in a wide range of elevations and terrain types. Even better, the dunes are large enough that we can spot them from space, allowing for ongoing monitoring and studying of their patterns from orbiting satellites. One of the big questions is if these dunes are stable, formed in a long-gone climate, or if they still migrate today, shifting in the wind.

Image Credit: NASA/JPL/University of Arizona/USGS

The high-resolution images translate into a meter per pixel, allowing the Mars Reconnaissance Orbiter to track any migration of a meter or farther over the course of the mission.

Technically, the name Iaxartes Tholus is out-dated. It was a label for an albedo feature — a patch of abnormal reflection — that was dropped way back in 1979 for being a disallowed name. Still, it's fun to say, and the area hasn't earned a new name, so I'm going to use it anyway! You can learn more about these dunes, or any other dune fields on Mars, at the NASA astrogeology website.

HiRise has been capturing all sorts of neat landscapes on Mars, including a whole lot of craters.