MarCO (or Mars Cube One) was a Mars flyby mission launched alongside NASA's InSight Mars lander mission. It consisted of two 6U-sized cubesats, MarCO-A and MarCO-B, that provided a real-time communications link to Earth for InSight during its entry, descent, and landing - when InSight was out of line of sight from the Earth.

MarCO (or Mars Cube One) was a Mars flyby mission launched alongside NASA's InSight Mars lander mission. It consisted of two 6U-sized cubesats, MarCO-A and MarCO-B, that provided a real-time communications link to Earth for InSight during its entry, descent, and landing -- when InSight was out of line of sight from the Earth. They also constituted a technology demonstration and tested the cubesats' endurance in deep space. These were the first cubesats to operate beyond Earth orbit, built by NASA's Jet Propulsion Laboratory.