NASA Mars Exploration Rover Status Report, November 27, 2018: Mars atmospheric opacity (tau) over the rover site remains at a storm-free level of 0.8.
Since loss of signal on Sol 5111 (June 10, 2018), 359 recovery commands have been radiated including on both polarizations. No signal from Opportunity has been heard. Opportunity likely experienced a low-power fault, a mission clock fault and an up-loss timer fault. The project has been listening for the rover over a broad range of times, frequencies and polarizations using the Deep Space Network (DSN) Radio Science Receiver.
They have been commanding “sweep and beeps” throughout the daily DSN pass with both right-hand and left-hand circular polarization to address a possible complexity with certain conditions within mission clock fault. [More at link]