Giant, raging dust storms may explain how Mars' water disappeared over billions of years
Occurring every decade or so, these dust storms blanket the entire planet in a dusty haze and a large number of thick clouds of dust or dust towers reach high into the air, say scientists.
Giant global dust storms may have stripped Mars of its water reserve, according to two recent studies. These findings could provide clues to how the Red Planet lost its lakes and rivers, transforming into the freezing, dry desert it is today, say experts.
"Global dust storms are really unusual. We really don't have anything like this on the Earth, where the entire planet's weather changes for several months," says Mars Climate Sounder scientist David Kass of Jet Propulsion Laboratory (JPL), in a statement.
These findings stem from the most recent 2018 global dust storm that ended Opportunity rover's 14-year-old cruise on the planet. From their study, the authors propose that the storms may have ferried water vapor from the surface into space. These findings back a previous study performed on the same type of storm that hit the planet in 2007. Scientists studying this also made similar speculations.
Dust storms are a common sight on Mars. But storms, like the 2018 global dust storm, are different, say experts. Occurring every decade or so, these dust storms blanket the entire planet in a dusty haze. One of the effects is that these storms give rise to a phenomenon, where large number of thick clouds of dust or dust towers are carried high into the air.
"Normally the dust would fall down in a day or so," says the paper's lead author, Nicholas Heavens of Hampton University in Hampton, Virginia. But during a global storm, he adds, dust towers are renewed continuously for weeks.
Storms like the 2018 global dust storm can reach a height of 50 miles, which may have been as wide as Nevada. And as the storm quietens down, it can form a layer of dust 35 miles above the surface -- wider than the continental United States. While they also occur under normal conditions, the towers appear to form in greater numbers during global storms, according to NASA.
These observations come from NASA's Mars Reconnaissance Orbiter (MRO). The instrument, which can see past the thick global dust storms, is designed specifically for measuring dust levels. Its data, coupled with images from a camera aboard the orbiter called Mars Context Imager (MARCI), enabled scientists to detect numerous swelling dust towers.
Data from the instrument revealed that water vapor from Mars' surface hitched a ride on these dust towers. Scientists believe that once these particles reach space, the intense solar radiation could have separated the water vapor from the dust particles.
However, scientists believe they do not know enough about these storms. Because they have studied fewer than a dozen to date, scientists cannot say with certainty what causes global dust storms, they say.