As a monster dust storm grew to encircle the Red Planet in June, Opportunity spent most of the month in the dark, presumably sleeping in a hibernation mode as the skies over Endeavour Crater became darker and darker.
Hooray! Curiosity has triumphantly returned to drilling with a successful drill and delivery to its lab instruments at a site named Duluth. It's now studying the dust storm as it drives to new drill sites on Vera Rubin ridge.
Readers, colleagues, friends: it's finally happened. My first book is finally out in the world. Here's an excerpt that explains the design and operation of Curiosity's MMRTG, (it also applies to the future Mars 2020 rover power supply).