Martian Dust Storm Is Now a ‘Planet-Encircling’ Event

The dust storm raging on Mars shows no signs of abating. In fact, it’s still growing in size. NASA says the storm is now a “global” event that completely encircles the planet. The little Opportunity rover is still snoozing through it thanks to a lack of light, but Curiosity is still active. This rover could help us understand why this dust storm is so massive while others dissipate within hours.

NASA detected the start of this dust storm several weeks ago in the vicinity of the Opportunity rover. Since that vehicle is solar-powered, NASA suspended science operations and placed it in a low-power state. The rover made its first few check-ins, but now it has stopped responding to signals. Curiosity was far away from the dust storm when it began, but now it’s fully engulfed as the storm expands to cover most of Mars.

Curiosity should be able to cope with the dust storm better than Opportunity. NASA designed Curiosity with a radioisotope thermoelectric generator (RTG) that produces power from an 11 pound (4.8 kilogram) chunk of plutonium-238 dioxide. So, Curiosity can operate normally even while clouds of dust block the sun. NASA says the atmospheric haze has reached a “tau” rating of 8.0. That’s the highest ever recorded by Curiosity, and it’s doubled in the last few days. The tau reading is over 11 where Opportunity is hunkered down.

This storm is already the largest on Mars in more than a decade, and Curiosity wasn’t present in 2007 to study the last one. Curiosity has taken one of its trademark selfies (seen above) to show how the storm limits visibility, and that was on June 15th when the tau was half of what it is currently. Because Curiosity isn’t affected by the storm, this is the first time NASA has been able to monitor conditions on the ground during a global event.

Storms on Mars are common, particularly during summer in the southern hemisphere. The warmer air circulates faster, suspending dust particles the size of talcum powder grains. Carbon dioxide ice from the pole also evaporates to increase the atmospheric pressure and pick up more dust. Most of these storms never expand beyond the region where they formed, but others just keep growing. NASA hopes that Curiosity can help shed some light on the processes on Mars that lead to monster storms by analyzing the dust up close. Combined with data from orbital missions, scientists might be able to make some progress.