Ranger 1 was a prototype spacecraft launched as part of the Ranger program of uncrewed space missions. Its primary mission was to test the performance of those functions and parts necessary for carrying out subsequent lunar and planetary missions; a secondary objective was to study the nature of particles and fields in the space environment. Due to a launch vehicle malfunction, the spacecraft could reach only Low Earth orbit, rather than the high Earth orbit that had been planned, and was only able to complete part of its mission.