German-speaking meteorologists refer to them scientifically as “little trombones”, because of their high dust content, they are called “dust devils” in America, in Australia they are known as willy-willies: short whirlpools duration, usually a few meters in diameter, which – unlike tornadoes – form without the involvement of clouds. This often happens in desert areas, but you can also find them here on dry summer days. Small vortices form when warm air locally begins to rise and begins to rotate. So there is a drop in pressure inside them and an increase in wind speed in the direction of rotation.
Ulf von Rauchhaupt
Editor of the “Science” section of the Frankfurter Allgemeine Sunday newspaper.
They are also a well-known phenomenon on Mars since the first landing missions of the two American “Viking” probes in 1976 – and sometimes a welcome one. Because more than once, dust devils have blown red Martian dust from the solar cells of both solar-powered rovers Spirit (active on Mars from 2004 to 2011) and Opportunity (2004 to 2018). Now, NASA researchers have published the recording of the sounds of a dust swirl on Mars in “Nature Communications”. On September 27, 2021, it passed directly by the Perseverance rover, which has been operating on Mars since February 16, 2021, but which, as a nuclear-powered device, does not depend on a cleaning service. The microphone on the Supercam instrument recorded two gusts of wind about two seconds apart. In the windless range, the rover was in the eye of the vortex.
Images of the buggy dust swirl taken with the Perseverance rover’s navigation camera (Navcam) in Jezero Crater on Mars. The images were processed to reveal the amount of dust in the air. The dust color scale ranges from low (blue) to high (yellow). :Image: NASA
The dust devil has also been observed with cameras (see photo) and tracked with instruments that record the impact of dust particles. From the data, the researchers concluded that this Martian trombone was 25 meters wide and at least 118 meters high. Their speed when they found the rover was about 5 meters per second.
The encounter with Perseverance was purely coincidental – the rover was not deliberately directed towards the hurricane. However, previous observations have shown that dust devils form frequently in its operational area – the 45-kilometer-wide Jezero crater at the edge of the Isidis Planitia plain, which was filled with water for a time during the Marsurian period. According to the authors of the study now published, the reason for this is still unclear.
Published/updated:
Published/updated:
Published/updated:
By studying Martian dust swirls, planetologists hope to gain better insights into how dust is lifted and transported on Mars. By doing so, they hope to better understand Mars’ “dust cycle” and predict dust storms, particularly those that occur across the planet every few years and then disrupt the various active Mars probes. Finally, dust is also an environmental phenomenon that affects the hardware that humans ship to Mars.