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 top left trigram symbolizes summer, south, and heaven. The top right trigram represents autumn, west, and the moon. The bottom right trigram stands for winter, north, and the Earth. The bottom left trigram represents spring, east, and the sun. Effective date: 21 February 1984.