S-IVB

The S-IVB was the third stage of the Saturn V rocket and the second stage of the Saturn IB, manufactured by the Douglas Aircraft Company for NASA's Apollo program. It was responsible for pushing the Apollo spacecraft out of Earth orbit and onto a lunar trajectory. Spent S-IVB stages floating in space have occasionally been misidentified as UAPs or 'alien' objects by amateur astronomers and in early space anomaly lore.

Spent S-IVB rocket stages in space have historically been a source of UAP misidentifications during and after the Apollo program.