An artist's sketch of Opportunity on the surface of Mars

Opportunity, also known as MER-B (Mars Exploration Rover – B) or MER-1, and nicknamed Oppy, was a robotic rover that was active on Mars from 2004 to 2018.

It was launched on July 7, 2003, as part of NASA's Mars Exploration Rover program, it landed in Meridiani Planum on January 25, 2004, three weeks after its twin Spirit (MER-A) touched down on the other side of the planet Mars.