Over the last few weeks a massive dust storm has been brewing on Mars, and now it has grown so large that it has engulfed the entire planet.
The storm has now covered both Opportunity and Curiosity, causing NASA to suspend the former's science missions as they wait for it to die down, which could take weeks or possibly even months. Both rovers have measured record atmospheric dust, as the heat from the ground causes the microscopic particles to rise and fill the atmosphere.
Despite how dramatic it all seems on the Red Planet right now, this isn’t actually the first time we’ve seen such massive storms engulf Mars.
In fact, the earliest hint we have of potentially global dust storms comes from 1971 when Mariner 9 arrived at Mars to give us our first orbital images of the planet. Unfortunately, when it got there the view was obscured for a month as dust swirled around Mars, and while we can’t be certain as we didn’t have an entire view of the planet, it seems likely the storm was also raging from pole to pole.
Since then, we’ve spotted roughly half a dozen other massive storms encircling the planet. Scientists think that this is a cycle driven by the seasons on Mars. “Once every three Mars years (about 5.5 Earth years), on average, normal storms grow into planet-encircling dust storms, and we usually call those ‘global dust storms’ to distinguish them,” said NASA's Michael Smith.
While the idea of a storm so big it covers the entire planet might seem terrifying and dangerous, due to the thin atmosphere on Mars – only about 1 percent as dense as that on Earth – the winds in even the largest storms are not likely to be strong enough to cause any significant damage to mechanical equipment.
The biggest threat from these storms comes not from the speed of the wind, but the dust it is carrying. Blocking the sunlight from reaching the surface, the dust storms have already forced NASA to put the solar-powered Opportunity rover into hibernation. They hope that by waiting it out, the rover will survive the worst of the damage.
But even for the nuclear-powered Curiosity, which obviously is unaffected by the sudden drop in light, the dust still represents a problem that scientists back home have had to prepare for. Due to the tiny size of the dust particles on Mars, the material is ever so slightly electrostatic. This means that it sticks to every surface and is difficult to remove, threatening to get into gears and clog things up.
Researchers, however, are not particularly worried about Curiosity, and are rather excited to be able to get a chance to see what exactly goes on in the global dust storms, potentially helping them to understand why they develop in the first place.