A growing Martian dust storm has forced the Opportunity science team to suspend science operations and to reconfigure the rover’s operations to increase its chances of surviving the storm.

In a matter of days, the storm had ballooned. It now spans more than 7 million square miles (18 million square kilometers) — an area greater than North America — and includes Opportunity’s current location at Perseverance Valley. More importantly, the swirling dust has raised the atmospheric opacity, or “tau,” in the valley in the past few days. This is comparable to an extremely smoggy day that blots out sunlight. The rover uses solar panels to provide power and to recharge its batteries.

Opportunity’s power levels had dropped significantly by Wednesday, June 6, requiring the rover to shift to minimal operations.

This isn’t Opportunity’s first time hunkering down in bad weather: in 2007, a much larger storm covered the planet. That led to two weeks of minimal operations, including several days with no contact from the rover to save power. The project’s management prepared for the possibility that Opportunity couldn’t balance low levels of power with its energy-intensive survival heaters, which protect its batteries from Mars’ extreme cold. It’s not unlike running a car in the winter so that the cold doesn’t sap its battery charge.There is a risk to the rover if the storm persists for too long and Opportunity gets too cold while waiting for the skies to clear.

In other words, there is a possibility that the rover might not make it through this period of low sunlight. Nonetheless, the rover did send four images down yesterday, though the four images are essentially dust filled, and are likely aimed at the far distance to help gauge the extent of the storm.