Mars Exploration Rovers (Spirit & Opportunity)

NASA's Mars Exploration Rover campaign sent the twin rovers Spirit and Opportunity to opposite sides of Mars to investigate geology and evidence of past water. The campaign opened when Spirit launched aboard Delta II 7925 vehicle D298 from Space Launch Complex 17A on June 10, 2003. Opportunity followed aboard Delta II 7925H vehicle D299 from Space Launch Complex 17B on July 8 UTC. Spirit landed in Gusev Crater in January 2004 and operated until communications ended in 2010; NASA concluded recovery efforts in 2011. Opportunity landed in Meridiani Planum three weeks after Spirit and operated until a planet-wide dust storm ended communications in 2018; NASA declared its mission complete in 2019.