It was designed primarily to photograph smooth areas of the lunar surface for selection and verification of safe landing sites for the Surveyor and Apollo missions.

The spacecraft experienced a temporary failure of the Canopus star tracker (probably due to stray sunlight) and overheating during its cruise to the Moon.

The star tracker problem was resolved by navigating using the Moon as a reference, and the overheating was abated by orienting the spacecraft 36 degrees off-Sun to lower the temperature.

[13] NASA extended the camera innovation further by developing the film onboard the spacecraft and then scanning the photos for transmission via a video signal.

[10] The early end of the nominal one-year mission resulted from a shortage of remaining attitude control gas and other deteriorating conditions and was planned to avoid transmission interference with Lunar Orbiter 2.