Two days later, the storm resembled thick and heavy smog, covering an area of 7 million square miles. At that point, the storm was still much smaller than a 2007 dust storm that knocked Opportunity out of commission for two weeks. Still, this qualified as the worst storm the rover had encountered in a decade, and engineers on earth came up with a plan to let Opportunity preserve its dwindling power supply. It would wake up briefly in the morning on a Martian day to listen for commands from Earth, sleeps until the next morning, wakes up in the morning, naps until the afternoon, wakes up, takes pictures of the surrounding haze and transmits up to the MRO, then back to sleep. Repeat.