NASA has finally declared that the Mars rover Opportunity—the longest-living robot sent to another planet—is dead. NASA initially lost contact with the robot after it was caught in a global dust storm on Mars last June, which likely coated its solar panels in a fatal layer of dust. The agency made repeated attempts to communicate with Opportunity over the last several months, hoping wind might blow the dust off, or the sun would revive the robot. Opportunity leaves behind a surprisingly long and successful legacy. Initially designed to last just three months, it spent 15 years exploring the surface of Mars, sending back footage and crucial information that has shaped how research is done on Mars. Other rovers had only found potential evidence of past life on Mars, but Opportunity discovered ancient lake beds and evidence that flowing water once existed on the Red Planet.