Aug. 31 (UPI) -- The weeks-long Martian dust storm is waning, and Opportunity rover can finally see clearly. NASA scientists think the rover will soon receive enough sunlight to recharge its batteries and resume its science mission.
Mars' tau level is the measure of the concentration of particulate matter in the Martian atmosphere. Once the tau level surrounding Opportunity dips below 1.5, scientists will attempt to resume communication with the rover.
Scientists haven't traded messages with Opportunity since June 10.
While Mars' massive dust storms, which crop up every several years, can disrupt on-the-ground scientific missions, they also offer scientists a unique opportunity to study Mars' atmosphere and weather patterns.
Planetary scientists still don't entirely understand how and why Martian dust storms form and grow. But with each new storm, scientists gain a new dataset to aid analysis and modeling efforts.
Scientists have been tracking the progress of the storm and estimating tau levels using photographs captured by the NASA's Mars Reconnaissance Orbiter and its Mars Color Imager.
"The dust haze produced by the Martian global dust storm of 2018 is one of the most extensive on record," said MRO scientist Rich Zurek. "MARCI images of the Opportunity site have shown no active dust storms for some time within 3,000 kilometers [about 1,900 miles] of the rover site."
Even though the skies are clearing, scientists can't be certain of the health of Opportunity's operation systems. It's possible the dust storm caused damage.
"In a situation like this you hope for the best but plan for all eventualities," said Callas. "We are pulling for our tenacious rover to pull her feet from the fire one more time. And if she does, we will be there to hear her."