THE GEMINI LEGACY

When NASA decided in 1962 that Apollo would use the lunar orbit rendezvous mission mode, many people doubted that orbital rendezvous would be feasible. The primary objective of the Gemini program was to explore the issues. The ten manned missions flown between March 1965 and November 1966 not only established that rendezvous and docking was feasible, by testing a variety of techniques it gave the Apollo planners the flexibility of options. This inspired a workaround to the fact that the combined Apollo vehicles exceeded the payload capacity of the Saturn IB, in the form of the dual AS-207/208 rendezvous. Gemini also showed that astronauts could endure the space environment for longer than any Apollo mission would require. Given that the longest American space flight at the time of President Kennedy’s commitment to Apollo was Al Shepard’s 15-minute suborbital arc, on which he was weightless for only a couple of minutes, this was welcome news. The fuel cells that were to power the Apollo spacecraft were tested on Gemini, as were a fully inertial reference platform for guidance and navigation, a spaceborne radar, a state-of-the-art digital computer to process the radar data for rendezvous, and bipropellant ablative thrusters. Gemini established that a spacecraft could be steered through re-entry for recovery at a specific location. This increased confidence in the ‘atmospheric skip’ manoeuvre that was to be used by an Apollo spacecraft returning from the Moon. By enabling astronauts to learn how to operate outside a spacecraft, Gemini inspired a rescue option for the crew of an Apollo lunar module that was unable to dock with its mothership. And, of course, by training a cadre astronauts and flight controllers Gemini allowed Apollo to get off to a running start.

As Robert Gilruth, Director of the Manned Spacecraft Center, observed: ‘‘In order to go to the Moon, we had to learn how to operate in space. We had to learn how to manoeuvre with precision to rendezvous and to dock; to work outside in the hard vacuum of space; to endure long-duration in the weightless environment; and to learn how to make precise landings from orbital flight – that is where the Gemini program came in.’’