Spirit rover
Spirit, MER-A is a robotic rover on Mars
Mars Rover
A Mars rover is an automated motor vehicle which propels itself across the surface of the planet Mars after landing.Rovers have several advantages over stationary landers: they examine more territory, they can be directed to interesting features, they can place themselves in sunny positions to...

, active from 2004 to 2010. It was one of two rovers
Rover (space exploration)
A rover is a space exploration vehicle designed to move across the surface of a planet or other astronomical body. Some rovers have been designed to transport members of a human spaceflight crew; others have been partially or fully autonomous robots...

 of NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

's ongoing Mars Exploration Rover
Mars Exploration Rover
NASA's Mars Exploration Rover Mission is an ongoing robotic space mission involving two rovers, Spirit and Opportunity, exploring the planet Mars...

 Mission. It landed successfully on Mars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...

 at 04:35 Ground UTC on January 4, 2004, three weeks before its twin, Opportunity
Opportunity rover
Opportunity, MER-B , is a robotic rover on the planet Mars, active since 2004. It is the remaining rover in NASA's ongoing Mars Exploration Rover Mission...

 (MER-B), landed on the other side of the planet. Its name was chosen through a NASA-sponsored student essay competition. The rover became stuck in late 2009, and its last communication with Earth was sent on March 22, 2010.

The rover completed its planned 90-sol mission.