In addition to the clock fault, Opportunity is presumed to be in two other "fault modes” tripped when the rover automatically shuts down to maintain her health. The assumption is that the robot tripped a low-power fault shortly after sending telemetry received on June 10th, and an uploss fault, when the uploss timer timed out in early July, as reported in last issue of The MER Update. In the fault hierarchy, the engineers would address the uploss fault next, because it is linked to the UHF antenna, and then, the low power fault.

Provided all that goes well, the rover, Mars willing, will be off and roving. But this is Mars. Anything can and could have happened. The state of the rover and her systems and instrument is a complete unknown. There is the chance, after nearly 12 weeks, the team may hear nothing or the rover may wake up and for some reason not be operational. “There is just no way of knowing anything really about the rover, other than Opportunity is still there, because we can take pictures of it from orbit,” said Zurek. Actually, word is there is a plan to schedule the High Resolution Imaging Science Experiment (HiRISE) camera onboard MRO for imaging Opportunity sometime in September, when MRO orbits around Endeavour.

On the other hand, the unknowns on Mars don’t change the simulations and the power and environmental modeling data produced on Earth. There are sound scientific and engineering reasons for team members and officials to still be optimistic.

MER engineers, for example, performed studies on the state of the rover’s batteries before the storm, as well as reviewed and re-ran temperature models for Perseverance Valley into next year. "The batteries were in good health before the storm," said MER Power Team Lead Jennifer Herman. “It is possible that they sustained damage during the dust storm, but I don’t believe it could have been enough degradation to be mission-ending,” she said.

As for the rover itself, because dust storms tend to warm the environment – and the 2018 storm began as the rover was entering the Martian spring – the ‘bot and her instruments, according to the models, should have stayed warm enough to easily pull through. Nothing has happened since, that the team knows of, to change that thinking.

Prior to the storm, Opportunity was fairly clean, producing ample amounts of energy around 650 watt-hours out of a total capability when she was new and pristine of around 905-950 watt-hours. She was in good shape. Then the storm hit Endeavour somewhat like a blinding blizzard on the Dakota plains, where the snow is carried sideways as well as down by the winds. Nearby lifting centers lingered around Endeavour churning up dust for several sols or Martian days.

Once Opportunity shut down, the MER operations team didn’t just sit around waiting. “We’ve been working hard, even before we lost contact to explore every possibility for recovery,” said Rover Planner Ashley Stroupe, who holds the distinction of being designated the first woman driver on Mars. “We are genuinely dedicated to making the most of this priceless asset because that is our responsibility. In recent weeks, we have been looking into how the rover will behave under these previously untested conditions, and we’re ready.”

Most of the MER scientists with expertise on Martian dust and dust storms believe that Opportunity is most likely dirty with dust. “The dust that was in the atmosphere there had to go somewhere,” said Lemmon. “It’s now, 75% or so, on the surface, and the rover’s solar arrays probably got their share of it.”

The team’s last measure of dust accumulation, on Opportunity’s Sol 5107 (June 6, 2018), was .65, meaning 65% of the light on the solar arrays could penetrate the dust layer. The Tau was 4.9 that sol, but the engineers also know the Tau rose to 10.8 by Sol 5111, (June 10, 2018). “It took a lot of wind and dust to cause the Tau to rise from 4.9 to 10.8,” said Herman. “We don’t know if any of those winds at any point cleaned some of the dust off the solar arrays – that’s possible. It’s also possible the winds just blew more dust on to them."