A crewless spacecraft used to investigate the Moon. Early probes flew past the Moon or crash-landed on it, but later ones achieved soft landings or went into orbit. Soviet probes included the Luna series. US probes (Ranger space probes, Surveyor, Lunar Orbiter) prepared the way for the Apollo project crewed flights.

The first space probe to hit the Moon was the Soviet Luna 2 on 13 September 1959, and Luna 9 performed the first soft landing on 3 February 1966. The first successful US Moon probe was Ranger 7, which took close-up photographs before it hit the Moon on 31 July 1964. Surveyor 1, on 2 June 1966, was the first US probe to soft-land on the lunar surface. Between 1966 and 1967 a series of five Lunar Orbiters photographed the entire Moon in detail, in preparation for the Apollo landings 1969–72.

In March 1990, Japan put a satellite, Hagoromo, into orbit around the Moon. NASA's Clementine probe discovered an enormous crater on the far side of the Moon in 1994, and its Lunar Prospector discovered ice on the Moon in 1998. In 2013, China landed its Chang’e 3 craft on the surface and successfully deployed a rover.