* it was the first time two separate missions were launched concurrently (Gemini 7 on December 4, and Gemini 6 on December 15)
* first time four American astronauts were in space at one time
* Gemini 7 mission lasted TWO WEEKS - a record that stood for five years, and longer than any of the Apollo missions
I know if I had to spend two weeks in a space capsule the size of a VW Beetle, I'd be a frakkin' basket case.
Gemini 7 was originally intended to fly after Gemini 6, but the original Gemini 6 mission was cancelled after the failure during launch of the Agena Target Vehicle it was meant to rendezvous and dock with. However the objective of rendezvous was so important it was decided to fly Gemini 6 at the same time as Gemini 7, thus using the latter as the rendezvous target.
This 14 day mission required NASA to solve problems of long-duration space flight, not the least of which was stowage (the crew had practiced stuffing waste paper behind their seats before the flight). Timing their workday to match that of ground crews, both men worked and slept at the same time. Gemini VII flew the most experiments – 20 – of any Gemini mission, including studies of nutrition in space. The astronauts also evaluated a new, lightweight spacesuit, which proved uncomfortable if worn for a long time in Gemini's hot, cramped quarters. The high point of the mission was the rendezvous with Gemini VI. But the three days that followed were something of an endurance test, and both astronauts, heeding Pete Conrad's Gemini V advice, brought books along. Gemini VII was the longest space flight in U.S. history, until the Skylab missions of the 1970s. ...
The Gemini 7 crew were Frank Borman and James Lovell.
The Gemini 6 crew were Walter Schirra and Thomas Stafford.