It was that same atmospheric variability that killed Opportunity. The trouble started on June 1, 2018, when the Mars Reconnaissance Orbiter beamed home photos of a burgeoning dust storm. Such tempests can last for weeks at a time, and this one cast Opportunity into darkness. Its solar panels near-useless, NASA scientists worried that Opportunity might not emerge into the light before Martian winter made temperatures plummet. Without the battery reserves necessary to keep its systems warm, they knew, its circuitry would suffer catastrophic damage—the same fate met by its twin, Spirit, in 2010.