Perseverance Watches a Dust Devil Whirl Past

On August 30th, 2023, on the 899th Martian day (sol 899) of its mission, NASA’s Perseverance rover spotted a dust devil while exploring the Jezero Crater. The images taken by one of the rover’s Navigation Cameras (NavCams) were used to make a video (shown below), which is composed of 21 frames taken four seconds apart and sped up 20 times. Similar to small, short-lived whirlwinds on Earth, these vertical columns of wind form when pockets of hot air near the surface rise quickly through cooler air above it. By studying them, scientists hope to learn more about Mars’ atmosphere and improve their weather models.

The dust devil was spotted at the western rim of the Jezero Crater at a location nicknamed “Thorofare Ridge.” Using data from the images, mission scientists determined that this dust devil was about 4 km (2.5 mi) from the rover and measured about 60 meters (200 feet) in diameter. While the images only captured the swirling vortex’s bottom 118 m (387 ft), the scientists could also estimate its full height. They also calculated that it was moving from east to west at speeds of about 19 km/h (12 mph).

Said Mark Lemmon, a planetary scientist at the Space Science Institute (SSI) and a member of the Perseverance science team, in a recent NASA press release:

“We don’t see the top of the dust devil, but the shadow it throws gives us a good indication of its height. Most are vertical columns. If this dust devil were configured that way, its shadow would indicate it is about 1.2 miles (2 kilometers) in height.”

Dust devils are a common phenomenon on Mars are typically grow much larger than those found on Earth (due to the low-pressure conditions). Like the much larger dust storms that can sometimes encompass the entire planet, these whirlwinds are one of the mechanisms responsible for moving and redistributing dust around Mars. While they are most prominent during the spring and summer, scientists can’t predict when they’ll appear at a specific location. For this reason, the Perseverance rover routinely monitors the atmosphere in all directions for indications of them.

Characterizing Mars’ atmosphere is one of the many objectives of the Perseverance mission and its colleague, the Curiosity rover. When a dust devil is spotted, the rovers will take multiple images, which mission scientists will analyze to learn more about atmospheric dynamics on Mars. The images are always taken in black-and-white to reduce the amount of data sent back to Earth.

Further Reading: NASA