Atmospheric scientists may pray for a global dust storm to blow up on Mars, but the rest of us . . . please, no! Just as the Red Planet began to inch into the evening sky, a swath of bright, yellow dust clouds lit up over the dark albedo feature Mare Acidalium at the end of May.
Within days, the gale had moved south and expanded, covering much of Sinus Meridiani, Oxia Palus, and Margaritifer Sinus and coursing the length and breadth of the sprawling Martian canyon system Valles Marineris. This is a big storm. Under the eye of NASA’s Mars Reconnaissance Orbiter, it measures more than 18 million square km (7 million square miles), an area greater than the continent of North America. (But see update at the end of the article.)
While there’s no way to foretell if the gale will balloon into a planet-girdling storm, NASA’s Opportunity rover team has taken precautions to protect the rolling robot, which sits squarely in the storm’s path in Sinus Meridiani. Science operations have been suspended to conserve power.
“A dark, perpetual night has settled over the rover’s location in Mars’ Perseverance Valley,” reads the most recent agency press release, referring to thick clouds blowing dust in the area.
Opportunity made it through the last bad storm in 2007, but this one’s worse. Dust blocks the sunlight used by the rover’s solar panels to create the power needed to run its instruments and stay warm. Mars is no picnic. Although dust storms can limit temperature extremes — analogous to a cloudy day on Earth — the longer they last, the less power available to the rover. Batteries only last so long.
The good news is that NASA engineers received a transmission from Opportunity on Sunday morning, a welcome sign that despite the worsening storm, the rover still has enough battery power to communicate with ground controllers. Meanwhile, the Mars Curiosity rover is still in the clear in the opposite hemisphere, though an increase in dust is expected in the coming days.
The current storm is significantly larger than the 2005 storm but so far pales in comparison to the global storm that wracked the Red Planet in 2001. That one began in the bright, circular feature Hellas, an ancient impact basin with a floor 9 km deep in the planet’s southern hemisphere. The ~10° temperature difference between basin bottom and surface drove winds that spawned a modest storm. But on June 27th that year, the storm exploded in size, spilling out of the basin to eventually cover the entire planet.
No one’s certain on exactly how a big storm gets rolling, but it appears that a positive feedback loop can turn a zephyr into a monster under the right conditions:
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