NASA's Perseverance studies the wild winds of Jezero Crater
During its first couple hundred days in Jezero Crater, NASA's Perseverance Mars rover saw some of the most intense dust activity ever witnessed by a mission sent to the Red Planet's surface. Not only did the rover detect hundreds of dust-bearing whirlwinds called dust devils, Perseverance captured the first video ever recorded of wind gusts lifting a massive Martian dust cloud.
A paper recently published in Science Advances chronicles the trove of weather phenomena observed in the first 216 Martian days, or sols. The new findings enable scientists to better understand dust processes on Mars and contribute to a body of knowledge that could one day help them predict the dust storms that Mars is famous for—and that pose a threat to future robotic and human explorers.
"Every time we land in a new place on Mars, it's an opportunity to better understand the planet's weather," said the paper's lead author, Claire Newman of Aeolis Research, a research company focused on planetary atmospheres. She added there may be more exciting weather on the way: "We had a regional dust storm right on top of us in January, but we're still in the middle of dust season, so we're very likely to see more dust storms."
Perseverance made these observations primarily with the rover's cameras and a suite of sensors belonging to the Mars Environmental Dynamics Analyzer (MEDA), a science instrument led by Spain's Centro de Astrobiología in collaboration with the Finnish Meteorological Institute and NASA's Jet Propulsion Laboratory in Southern California. MEDA includes wind sensors, light sensors that can detect whirlwinds as they scatter sunlight around the rover, and a sky-facing camera for capturing images of dust and clouds.
"Jezero Crater may be in one of the most active sources of dust on the planet," said Manuel de la Torre Juarez, MEDA's deputy principal investigator at JPL. "Everything new we learn about dust will be helpful for future missions."
The study authors found that at least four whirlwinds pass Perseverance on a typical Martian day and that more than one per hour passes by during a peak hourlong period just after noon.
The rover's cameras also documented three occasions in which wind gusts lifted large dust clouds, something the scientists call "gust-lifting events." The biggest of these created a massive cloud covering 1.5 square miles (4 square kilometers). The paper estimated that these wind gusts may collectively lift as much or more dust as the whirlwinds that far outnumber them.
"We think these gust-liftings are infrequent but could be responsible for a large fraction of the background dust that hovers all the time in the Martian atmosphere," Newman said.
Why Is Jezero Different?
While wind and dust are prevalent all over Mars, what the researchers are finding seems to set Jezero apart. This greater activity may be linked to the crater being near what Newman describes as a "dust storm track" that runs north to south across the planet, often lifting dust during the dust storm season.
Newman added that the greater activity in Jezero could be due to factors such as the roughness of its surface, which can make it easier for the wind to lift dust. That could be one explanation why NASA's InSight lander—in Elysium Planitia, about 2,145 miles (3,452 kilometers) away from Jezero Crater—is still waiting for a whirlwind to clear its dust-laden solar panels, while Perseverance has already measured nearby surface dust removal by several passing whirlwinds.
"Perseverance is nuclear-powered, but if we had solar panels instead, we probably wouldn't have to worry about dust buildup," Newman said. "There's generally just more dust lifting in Jezero Crater, though average wind speeds are lower there and peak wind speeds and whirlwind activity are comparable to Elysium Planitia."
In fact, Jezero's dust lifting has been more intense than the team would have wanted: Sand carried in whirlwinds damaged MEDA's two wind sensors. The team suspects the sand grains harmed the thin wiring on the wind sensors, which stick out from Perseverance's mast. These sensors are particularly vulnerable because they must remain exposed to the wind in order to measure it correctly. Sand grains blown in the wind, and likely carried in whirlwinds, also damaged one of the Curiosity rover's wind sensors (Curiosity's other wind sensor was damaged by debris churned up during its landing in Gale Crater).
With Curiosity's damage in mind, the Perseverance team provided an additional protective coating to MEDA's wires. Yet Jezero's weather still got the better of them. De la Torre Juarez said the team is testing software changes that should allow the wind sensors to keep working.
"We collected a lot of great science data," de la Torre Juarez said. "The wind sensors are seriously impacted, ironically, because we got what we wanted to measure."