Mars is famous for its dust storms whether fictional as in the movie “The Martian” or for real. Right now, a for-real storm has NASA concerned for the health of the Opportunity rover, which has been trundling across the Red Planet for nearly 15 years. According to the agency “a dark, perpetual night has settled over the rover’s location in Mars’ Perseverance Valley” caused by thick, blowing dust. The storm, which began at the end of May, has now spread across an area larger than North America or more than 7 million square miles (18 million square km).
Opportunity made it through the last bad storm in 2007, but this one’s worse. Dust blocks sunlight, the precious resource the rover soaks up with its solar panels and coverts to electricity to run its instruments and keep it warm. Mars is no picnic. Although dust storms can limit temperature extremes — something like a cloudy day on Earth — data show the rover’s temperature to be about –20°F (–29°C).
NASA engineers received a transmission from Opportunity on Sunday morning, a welcome sign despite the worsening dust storm. Data from the transmission let engineers know the rover still has enough battery charge to communicate with ground controllers. In the meantime however, science operations have been suspended to conserve power.
Opportunity needs to run its heaters for the same reason you keep your car running during bitter winter weather — the heat generated keeps parts and fluids from freezing. There is a risk to the rover if the storm persists for too long, Opportunity will get too cold while waiting for the skies to clear and power to flow again.
Dust storms certainly aren’t unusual on Mars, but big ones can sometimes “go global,” spreading across the entire planet. On Earth, it’s easy to see a global storm because next to nothing is visible on the planet’s surface. No dark markings, no polar ice caps. No fun. Let’s hope that doesn’t happen both for Opportunity’s sake and for those of us who are eager to follow Mars up close through out telescopes this summer.
Dust storms occur when the sun warms the ground, heating the air near the surface. Warm air rises, creating winds and carrying dust aloft. Right now, with the planet closer to the sun than usual, heating is more intense. Even a relatively small storm can develop into a larger one or multiple smaller dust events can coalesce into a bigger regional storm like the current one, driving clouds of powdery dust across vast swaths of the planet.
Martian winds can reach 60 mph but because the atmosphere is only 1% that of Earth, a powerful storm would only feel like a breeze to an astronaut caught in the storm. The frightening, equipment-toppling winds depicted in “The Martian” were science fiction, not fact. Dust storms are more common during the southern hemisphere summer when a fair part of the south polar cap is rapidly vaporizing in the heat. This storm in contrast began in the planet’s northern hemisphere only days after the fall equinox (southern spring).
We’ll be watching and reporting.