Imagine taking a large fully loaded pickup truck onto the ice and bringing it within a foot of another similarly sized pickup, which also happens to be moving. Now imagine instead of on the ice, the maneuvering takes place in space, where even the slightest collision could spell doom for the astronauts; and instead of trucks you have the Gemini 7 craft, eight thousand pounds of it. That creates just a sense of the technical complexity involved in the first rendezvous attempt in space.

On this day, December 15, in 1965, the Gemini 6 spacecraft, piloted by Wally Schirra and Tom Stafford, pulled within a foot of Gemini 7, piloted by Frank Borman and Jim Lovell, completing the first rendezvous in space.

The Gemini 6 was supposed to meet with an unmanned craft originally, but when technical difficulties precluded that mission, NASA scrambled to prepare Gemini 7 to follow and complete the maneuvers instead. Considering the close timelines involved, and the technical complexity of the mission, the Gemini 6 and 7 rendezvous stands as a testament to NASA’s superior organization.