Martian dust storms can reach incredible scales. Recently, scientists have studied them and found out the mechanisms that are responsible for the possibility of local phenomena growing into all-planetary ones.
Study of Martian dust storms
In a new study, planet scientists at the University of Colorado at Boulder have begun to figure out the factors that cause large dust storms on Mars — weather events that sometimes plunge the entire planet into a swirl of dust. The team found that relatively warm and sunny days can contribute to their occurrence.
Heshani Pieris, lead author of the study, says the findings are the first step toward predicting extreme weather conditions on Mars, just as scientists on Earth do.
“Dust storms have a significant effect on rovers and landers on Mars, not to mention what will happen during future crewed missions to Mars,” said Pieris, a graduate student at the Laboratory for Atmospheric and Space Physics (LASP) at CU Boulder.
To examine the dust storms under a magnifying glass, the researchers relied on actual observations from NASA’s Mars Reconnaissance Orbiter satellite. They have now identified weather patterns that may be hiding about two-thirds of the major dust storms on Mars.
“We need to understand what causes some of the smaller or regional storms to grow into global-scale storms,” said Hayne, a LASP researcher and associate professor of astrophysical and planetary sciences. “We don’t know how the physics of dust storms originate on the surface of the Earth. We don’t even fully understand the basic physics of how dust storms start at the surface.”
Dust death
Many storms begin as small ones circling the ice caps at the planet’s north and south poles, usually in the second half of the Martian year (a year on Mars lasts 687 Earth days). These storms can develop at breakneck speed, moving toward the equator until they cover millions of square miles and last for days.
In the 2015 movie “The Martian,” starring Matt Damon, one such apocalyptic storm was featured, which felled a satellite dish and scattered astronauts. Reality is less cinematic. Mars’ atmosphere is much thinner than Earth’s, so dust storms on the Red Planet can’t generate much force. But they can still cause trouble.
For example, in 2018, a global dust storm buried the solar panels of NASA’s Opportunity rover under a layer of dust. The rover soon died.
“Even though the wind pressure may not be enough to knock over equipment, these dust grains can build up a lot of speed and pelt astronauts and their equipment,” Hayne said.
Weather conditions for dust storms
In the ongoing study, Pieris and Hayne focused on two weather patterns that occur each year on Mars, known as storms “A” and “C.”
The team analyzed observations of Mars from the Mars Climate Sounder instrument aboard the Mars Reconnaissance Orbiter over eight Martian years. Particularly, Pieris and Hayne looked for periods of unusual warmth — or weeks when more sunlight filtered through Mars’ thin atmosphere and baked the planet’s surface.
They found that about 68% of the planet’s major storms were preceded by a sharp rise in surface temperatures. In other words, the planet heated up, and after a few weeks, conditions became dusty.
The team can’t prove that these favorable conditions actually cause dust storms. But, according to Pieris, similar phenomena cause storms on Earth. For example, during hot summers in Boulder, Colorado, warm air near the ground can rise through the atmosphere, often forming high gray clouds that indicate rain.
“When you heat up the surface, the layer of atmosphere right above it becomes buoyant, and it can rise, taking dust with it,” Pieris said.
Now she and Hayne are collecting observations from the past years on Mars to further investigate these explosive weather patterns. Eventually, they’d like to get to the point where they can look at real-time data from the Red Planet and predict what might happen in the coming weeks.
“This study is not the end all be all of predicting storms on Mars,” Pieris said. “But we hope it’s a step in the right direction.”
Provided by phys.org
