Up to 80km high dust towers are observed on Mars during global dust storms. Acting like a space elevator, the phenomenon can explain the disappearance of water from the red planet in its distant past.
On Earth, storms tend to be localized, but things are a bit different on Mars. Global-scale dust storms occur on the red planet about once a decade. One of those storms happened in 2018, and brought down NASA’s Opportunity rover.
Two new studies
led by Nicholas Heavens of Hampton University and the Space Sciences Institute looked at an unusual meteorological phenomenon that occurs during these storms: massive dust towers rising into the upper atmosphere of Mars.
Heavens and his colleagues studied the global dust storms of 2007 and 2018 to learn more about these dust towers. They used data from NASA’s Mars Reconnaissance Orbiter (MRO), equipped with a special heat-sensing Mars Climate Sounder that can penetrate thick layers of dust. The scientists also analyzed images from the Mars Context Imager (MARCI) camera.
Mars under normal conditions and during the 2018 storm
As the research shows, the dust towers are denser and more concentrated than normal dust clouds in the Martian atmosphere, and rise much higher. These giant columns can occur in normal conditions, but more often they appear during global dust storms.
At first, areas of rapidly rising dust form on the surface of Mars. Then, sunlight warms these clouds, causing the plumes to rise up into the Martian sky, similar to how heat from condensing water vapor causes thunderstorms on Earth. At an altitude of about 80km, the dust towers can increase in size.
Unlike the 2007 storm, when the dust towers were observed for only about a day, during the 2018 dust storm they persisted for about four weeks.
These dust towers may act as a transportation system for materials and gases, including water vapor. Back in 2007, scientists noticed that water molecules were delivered to the upper atmosphere of Mars and to a height where solar radiation causes them to break apart and fly into space. This phenomenon is likely the key to how Mars lost all its water, rivers and lakes.
The research was published in the Journal of the Atmospheric Sciences and JGR Planets.