Dust storms are common on Mars But every decade or so, something unpredictable happens: A series of runaway global storm on mars break out, covering the entire planet in a dusty haze.
Last year, a fleet of NASA spacecraft got a detailed look at the life cycle of the 2018 global dust storm that ended the Opportunity rover’s mission.
And while scientists are still puzzling over the data, two papers recently shed new light on a phenomenon observed within the storm: dust towers, or concentrated clouds of dust that warm in sunlight and rise high into the air.
Scientists think that dust-trapped water vapor may be riding them like an elevator to space, where solar radiation breaks apart their molecules. This might help explain how Mars’ water disappeared over billions of years.
Dust towers are massive, churning clouds that are denser and climb much higher than the normal background dust in the thin Martian atmosphere. While they also occur under normal conditions, the towers appear to form in greater numbers during global storms.
A tower starts at the planet’s surface as an area of lifted dust about as wide as the state of Rhode Island. By the time a tower reaches a height of 50 miles (80 kilometers), as seen during the 2018 global dust storm, it may be as wide as Nevada.
As the tower decays, it can form a layer of dust 35 miles (56 kilometers) above the surface that can be wider than the continental United States.
The recent findings on dust towers come courtesy of NASA’s Mars Reconnaissance Orbiter (MRO), which led by the agency’s Jet Propulsion Laboratory in Pasadena, California.
Though global dust storms cloak the planet’s surface, MRO can use its heat-sensing Mars Climate Sounder instrument to peer through the haze.
The instrument designed for measuring dust levels. Its data, coupled with images from a camera aboard the orbiter called the Mars Context Imager (MARCI), enabled scientists to detect many swelling dust towers.
Dust towers appear throughout the Martian year, but MRO observed something different during the 2018 global dust storm.
But during a global storm, dust towers renewed for weeks. In some cases, many towers are seen for as long as 3 1/2 weeks.
The rate of dust activity surprised Heavens and other scientists. But especially intriguing is the possibility that dust towers act as “space elevators” for other material, transporting them through the atmosphere.
When airborne dust heats up, it creates updrafts that carry gases along with it, including the small quantity of water vapor sometimes seen as wispy clouds on Mars.
With time and more data, the MRO team hopes to better understand the dust towers created within global storms and what role they may play in removing water from the Red Planet’s atmosphere.