December 13

On December 13, 1962, NASA successfully launched Relay 1 aboard an Atlas-Agena rocket. Relay 1 was the first active repeater communications satellite, capable of receiving, amplifying, and retransmitting signals between ground stations. This mission demonstrated the potential of space-based relay systems and paved the way for modern satellite communication networks. During its brief operational life, Relay 1 supported early television and telephone transmission experiments. The success of Relay 1 laid the groundwork for the geosynchronous communication satellites that followed, transforming global communications.

On December 13, 1972, astronauts Eugene Cernan and Harrison Schmitt began the third and final extravehicular activity of Apollo 17. Over nearly seven hours, they collected geological samples, deployed scientific experiments, and captured iconic photographs. Schmitt, the first scientist-astronaut on the Moon, provided key insights into lunar geology. Cernan left his daughter's initials engraved in the lunar dust as a personal tribute. No human has returned to the lunar surface since, cementing Apollo 17 as the concluding chapter of early lunar exploration.