This is what a Whirlwind Sounds like on Mars
Small dessert whirlwinds have been seen on Mars for more than 40 years. Now NASA researchers have also recorded its wind noise. German-speaking meteorologists refer to them scientifically as “little trombones”, because of their high dust content, they are called “dust devils” in America and in Australia they are known as willy-willies: short whirlpools duration, usually over a distance of a few meters in diameter, which – unlike tornadoes – are formed without the participation of clouds.
Mostly this happens in desert areas, but here you can also find them on dry summer days. Small eddies form when warm air locally begins to rise and begins to circulate. So there is a decrease in pressure inside it and an increase in wind speed in the direction of rotation.
It’s also a well-known phenomenon on Mars since the first two landing missions of the US Viking probes in 1976 – and sometimes a welcome one. Because more than once, the dust devils have shaken red Martian dust off the solar cells of both solar-powered Mars rovers Mars (active on Mars from 2004 to 2011) and Opportunity (2004 to 2018).
Now, NASA researchers have published a recording of the sounds of a dust swirl on Mars in Nature Communications. On September 27, 2021, the Perseverance rover, which has been operating on Mars since February 16, 2021 but, as a nuclear-powered device, is not dependent on a cleaning service, passed. Supercam’s microphone recorded gusts of wind about two seconds apart. Among the winds, the rover was in the eye of the vortex.
The dust devil was also monitored with cameras (see photo) and tracked with tools that record the impact of dust particles. From the data, the researchers concluded that this Martian trombone was at least 25 meters wide and 118 meters high. Their speed when encountering the rover was about 5 meters per second.
The encounter with Perseverance was purely fortuitous – the rover was not deliberately aimed at the tornado. However, previous observations have shown that dust devils form especially frequently in its area of operation – the 45 kilometer wide Jezero crater at the edge of the plain of Isidis Planitia, which was filled with water for a time during the Mersurian period. According to the authors of the study now published, the reason for this is still unclear.
By studying Martian dust swirls, planetary scientists hope to gain better insights into how dust is moved and transported on Mars. By doing so, they hope to better understand Mars’ “dust cycle” and predict dust storms, especially those that hit the entire planet every few years and then disrupt several active Mars probes. Finally, dust is also an environmental phenomenon that affects the devices that humans send to Mars.
