Dust devils are rotating, narrow updrafts of hot air, typically tens or hundreds of meters tall, that are made visible by dust lifted from the surface of a planet. Dust devils are common on Mars, where they transport substantial amounts of dust from the surface into the atmosphere, making them a key part of the martian dust cycle and climate. Dust devils cannot be directly simulated by Mars global climate models, which makes direct observations of martian dust devils invaluable. Hot air in dust devils rises because it is less dense than surrounding cooler air, and as a result, the passage of dust devils can be detected not only by dust-blocking sunlight but also by a sensitive barometer, such as the one onboard the Mars 2020 Perseverance rover.
Brian Jackson from Boise State University examined the first 89 martian days of data from the Mars Environmental Dynamics Analyzer’s (MEDA) Pressure Sensor and Radiative and Dust Sensor aboard Perseverance. The goal of this work was to determine what percentage of dust-devil-like vortices actually contained dust and how many of these passed over Perseverance in a day. To do this, Jackson first removed variations in pressure on timescales greater than 500 seconds, because these are not caused by vortices. Then, he matched the filtered data to the pressure signal expected from the passage of a vortex. Jackson found that 5 ± 2 vortices were detected per martian day, and about one fourth of those vortices were dust devils. Not only do dust devils lift dust from the surface of Mars, they also lift dust off of rovers and landers, allowing extended operation of surface-based solar-powered instruments. These results have implications for future exploration of Mars since in regions with high dust devil activity, like near Perseverance, solar power is likely to be more efficient than elsewhere on Mars. READ MORE