Planetary scientists have captured an image of almost perfectly circular sand dunes on the surface of Mars. While the Red Planet’s sand dunes come in a multitude of shapes and sizes, such well-defined circles are unusual.
The slight asymmetry of the sand dunes shows that their steep sides face south. The University of Arizona, which operates the High-Resolution Imaging Experience (HiRise) camera used to take the image, shown in a statement (opens in a new tab) that this indicates that the sands are blowing south, although Martian winds can be variable.
The image was taken on November 22, 2022, at a latitude of 42.505 degrees and a longitude of 67.076 degrees. It is part of a series of photos taken by the HiRise camera which orbits March on the Mars reconnaissance orbiter (RRM) spatialship.
Related: Mars: everything you need to know about the red planet
The collection of images is used to monitor how frost is retreating and melting on the Martian surface as the red planet reaches the end of its winter season. To illustrate, while this image appears frost-free, a similar image of the same sand dunes taken earlier shows what they looked like while still covered in frost.
The image of the sand dune was taken while the MRO was at an altitude of about 185 miles (300 kilometers) above the Martian surface. Each pixel in the image represents 25 centimeters (9.8 inches).
It is just one of 60 sites on Mars monitored by HiRise. The high-resolution camera has been orbiting the Red Planet since the MRO reached Mars in 2006 and began conducting the planet’s first dedicated survey of sand dunes.
Collecting repeated observations of sand dunes over the Martian year (lasting 687 Earth days) has allowed planetary scientists to monitor how fast the dunes are moving. This revealed that sand dunes from the equator to the poles advance at speeds of up to 3.3 feet (1 meter) per martian year.
The camera recorded a variety of Martian sand dunes with an impressive range of sizes and shapes, revealing much about weather conditions on the red planet. For example, when examining Lyot Crater in the northern lowlands of Mars in 2010, HiRise photographed dune fields that indicated how local winds are channeled through the topology of this complex impact crater of 146 miles wide (236 kilometers).
HiRise also conducts ongoing research that examines glacier-like formations on Mars and examines the crevice-like fractures that punctuate their surfaces. By collecting repeated observations over time, the images can help scientists determine the type of fracture mechanics occurring in so-called “viscous flow features” found at the base of slopes on Mars. It is believed that these deposits were once rich in ice, but the source of this ice is so far a mystery, according to NASA. (opens in a new tab)
On December 21, 2010, the main mission of the MRO ended five years and six months after its launch on August 12, 2005. This new image shows that even 12 years after the end of this mission, the contribution to science made by spacecraft and its HiRise camera is far from complete.
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