Leonard David's INSIDE OUTER SPACE

Perseverance rover images show a gust of wind sweeping dust across the Martian plain beyond the rover’s tracks on June 18, 2021.
Image credit: NASA/JPL-Caltech/SSI

Serving as the exploration zone for NASA’s Perseverance rover is Jezero Crater. It turns out to be a site for swirls of dust…so much so that one device has been damaged on the rover by two passing dust devils.

The rover’s Mars Environmental Dynamics Analyzer is known as MEDA. It produces weather measurements such as wind speed and direction, temperature and humidity, and also gauges the amount and size of dust particles in the Martian atmosphere. The instrument suite was developed and provided by the Spanish Astrobiology Center at the Spanish National Research Council in Madrid, Spain.

Image credit: NASA/JPL-Caltech

Dust devils on Mars are whirlwinds of warm air with winds strong enough to lift dust, and they are abundant on Mars, where they are one of the elements that bring dust to the atmosphere.

Since its landing in February 2020, Perseverance has observed a plethora of dust devils via its MEDA instrument. Word is that a couple of dust devils damaged part of the hardware of the wind sensors of MEDA.

Wind Sensors (a) Image of WS2 on sol 339. (b) Detail of one of the boards of
WS1 on sol 339 showing the thin filament possibly damaged in the boards of WS2. (c) MEDA
data for the DD on sol 313. Wind data from WS2 was unavailable after the vortex produced its
peak pressure drop. Note the shift between pressure and RDS Top 7 data and the failure of WS2
at the time the dust content increases (d) MEDA data for the DD on sol 413. Yellow lines on (c)
and (d) indicate the moment when the failure in one of the WS boards occurred.
Image credit: Ricardo Hueso, et al.

A new paper – “Convective vortices and dust devils detected and characterized by Mars 2020” – details the wicked winds of Mars, published in the Journal of Geophysical Research: Planets.

High abundance of events

“Results for more than 400 Martian days from spring to autumn indicate a high abundance of events with small seasonal variability,” reports the paper, led by Ricardo Hueso of Física Aplicada, Escuela de Ingeniería de Bilbao, Universidad del País Vasco in Bilbao, Spain.

“Terrains with lower thermal inertia warming more efficiently at noon favor the appearance of dust devils. We also found an increased dust devil activity during a short dust storm that covered the region,” Hueso and colleagues note.

Large vortices with diameters of over 300 feet (100 meters) form frequently enough to dominate dust lifting at Jezero. Thanks to MEDA data, three dust devils that size were detected passing within less of 100 feet (30 meters) of the rover.

Intense vortices can put at risk surface hardware on Mars, as evidenced by the MEDA experience. The instrument has two booms. Two dust devils were responsible for damaging part of the hardware of the MEDA wind sensors. These sensors contain fragile elements such as sub-millimeter-wide conducting filaments exposed to the Martian atmosphere.

MEDA location. Image credit: NASA/JPL-Caltech

Different seasons, different terrains

Since dust devils – DDs for short — are common features over most of the surface of Mars, new missions may have to take into account the risks of impacts by speedy sand particles or granules.

“Convective vortices in Jezero seem to be able to raise dust much more efficiently than in locations such as Elysium and Gale crater,” the research paper explains. That’s where NASA’s InSight Mars lander and the Curiosity rover have found no dust lifting activity (InSight), or very low dust lifting activity (Curiosity).

Image credit: NASA

The swirling dust lifting activity at Jezero is probably smaller than the dust lifting at Gusev crater observed by Spirit, but in most of these missions observations over different Martian Years have found strong differences.

“Thus, new observations by Perseverance over different seasons and terrains, exploring properties such as surface roughness and particle size and cohesion from surface images, will help to understand the characteristics that make Jezero so active in developing DDs within its rich population of convective vortices,” the paper concludes.

For access to “Convective vortices and dust devils detected and characterized by Mars 2020,” go to:

https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2022JE007516