The Gemini program was the United States’ second manned space program after the Mercury program. Ten manned space flights took place between 1965 and 1966, during which astronauts carried out, among other things, the first American spacewalks (Gemini IV) and the first docking maneuvers (Gemini VIII).
The Gemini program was born out of necessity. After the Mercury flights were discontinued, it was clear from a relatively early stage that there would be a time gap of three or four years until the start of the Apollo missions – valuable years that were urgently needed to develop the necessary technologies (coupling mechanisms, life support systems, space suits, etc.) to develop and test. On December 7, 1961, the Project Gemini was approved. Originally, consideration was given to expanding the existing Mercury system into a two-man spacecraft called the Mercury Mark II. The advantage would have been to save development costs by using existing technology and to be able to sensibly bridge the time until the manned Apollo flight program began. The main changes would have been the installation of a second seat, the installation of a powerful maneuvering unit and the use of an existing upper stage as a docking dummy.
The realized spacecraft differed from Mercury, among other things, in that all elements not required during reentry were relocated to a supply module that could be separated into two phases. Before re-entry, the equipment was first separated. A frustoconical braking unit then remained on the re-entry part, which was also separated after braking. The braking unit would also have been used to separate the capsule from the rocket in the event of an ascent emergency.
After the Mercury program, which demonstrated the fundamental possibility of manned spaceflight, significant progress was made with Gemini in testing in space the maneuvers necessary for a successful lunar flight: rendezvous and coupling of spacecraft, spacewalks, orbit changes, and the cooperation of the Earth station with the Pilots.
Gemini was an extremely successful program that contributed significantly to the first successful manned moon landing.
