Sol 5114, June 14, 2018: Rover Field Report by Larry Crumpler, MER Science Team & New Mexico Museum of Natural History & Science: Opportunity was continuing to gather data from outcrops in Perseverance Valley up until the end of May and the first week of June. But then a dust storm developed to the northwest and unexpectedly expanded into Merdiani Planum where Opportunity is exploring.
In one sol (Mars day) the power output of the solar panels dropped from nearly 700 W-hrs to 123 W-hrs. By the next day the power had dropped to 22 W-hrs. The optical opacity factor of the atmosphere, which is normally described by numbers like 0.3-0.5, sky rocketed to outrageous numbers. During the previous dust storm back in 2007, the opacity was about 5. The last report on Sunday indicated a factor of 10.8! A new Martian record. (…)
We like to keep the power up to 100 W-hrs even in the worst of winter times as a “margin” just to make certain that internal heaters can be called on if a night is particularly cold. But 22 W-hrs will not even operate basic activities, like communication with the orbital relay satellites. Following a last communication on Sunday, we have not received messages from Opportunity. To conserve what energy it has Opportunity therefore is programmed to disconnect the batteries and go into a deep “sleep”, only running a mission clock to keep track of time… [More at link]