NASA's Mars Exploration Rover (MER) mission was a robotic space mission involving two Mars rovers, Spirit and Opportunity, exploring the planet Mars. It began in 2003 with the launch of the two rovers to explore the Martian surface and geology; both landed on Mars at separate locations in January 2004. Both rovers far outlived their planned missions of 90 Martian solar days: MER-A Spirit was active until March 22, 2010, while MER-B Opportunity was active until June 10, 2018.
Artist's conception of MER rovers on Mars
Launch of MER-A Spirit
Launch of MER-B Opportunity
Spirit and Opportunity by the numbers
Uncrewed spacecraft or robotic spacecraft are spacecraft without people on board. Uncrewed spacecraft may have varying levels of autonomy from human input, such as remote control, or remote guidance. They may also be autonomous, in which they have a pre-programmed list of operations that will be executed unless otherwise instructed. A robotic spacecraft for scientific measurements is often called a space probe or space observatory.
A replica of Sputnik 1 at the U.S. National Air and Space Museum
A replica of Explorer 1
An illustration's of NASA's planned Orion spacecraft approaching a robotic asteroid capture vehicle
A collage of automated cargo spacecraft used in the past or present to resupply the International Space Station