Critically, the dust raised the atmospheric opacity in Perseverance Valley, and Opportunity's power levels dropped significantly by Wednesday, 6 June, requiring the rover to shift to minimal operations.
NASA has suspended science operations on its courageous little Mars rover, Opportunity, as a huge dust storm rages over its location in the planet's Perseverance Valley. It means there's still enough charge left in the batteries to communicate with home, despite the fact that the storm is continuing to worsen.
According to NASA, the agency's Mars Reconnaissance Orbiter first detected the dust storm on Friday, 1 June, and NASA immediately notified Opportunity's teams to begin preparing contingency plans in case the dust storm necessitated a change to the rover's nominal operations.
The main concern here isn't the dust storm itself. NASA is having to manage a delicate balance, making sure the rover doesn't run out of energy while maintaining its power-hungry survival heaters - a system that protects the rover's batteries from freezing in the extreme cold.
Despite this, Opportunity did call home yesterday through a communications relay with the Mars Reconnaissance Orbiter - a positive sign despite the worsening dust storm.
As of June 10, the storm had almost doubled the level of atmospheric opacity, or darkness, experienced by the rover in 2007, measured in tau. Although dust storms aren't uncommon on Mars, they can be deadly to the rovers.
"We expect that even if the storm dissipates before becoming a global dust storm, that the amount of dust in Gale will increase over the next several days", Curiosity team member Scott Guzewich wrote in an update last week.
"Full dust storms like this one are not surprising, but are infrequent", NASA officials said in the statement. This is a problem because the rover uses solar panels to provide its power and recharge its batteries. NASA will carefully monitor Opportunity's power levels as the storm continues.
For now, the engineers will just need to wait it out and see how the little robot comes through the storm.
"During southern summer, sunlight warms dust particles, lifting them higher into the atmosphere and creating more wind", the space agency says. This produces more wind, which kicks up even more dust, creating a feedback loop. In 2007 a much larger dust storm covered the entire Martian surface, forcing the rover to switch to minimal operations for a whole two weeks.
The storm formed above the rover beginning on June 3 and has gotten much worse since then. Without the heaters, the rover's batteries would likely fail and doom the mission.
As with the 2007 dust storm event, there is a very real possibility that should a low-power fault program trip and Opportunity goes to sleep that the rover will not wake up again.
Heat is "vitally important" to keeping the spacecraft alive, but also consumes more battery power. Likewise, performing certain actions draws on battery power, but can actually expel energy and raise the rover's temperature. It landed on Mars in 2004 for a planned 90-day mission and is still going strong all these years later.
That's because Opportunity - like NASA's other Martian robots - relies on sunlight for power.