Project Gemini (IPA: ) was the second United States human spaceflight program to fly. It was conducted after the first American crewed space program, Project Mercury, while the Apollo program was still in early development. Gemini was conceived in 1961 and concluded in 1966. The Gemini spacecraft carried a two-astronaut crew. Ten Gemini crews and 16 individual astronauts flew low Earth orbit (LEO) missions during 1965 and 1966.
Gemini's objective was the development of space travel techniques to support the Apollo mission to land astronauts on the Moon. In doing so, it allowed the United States to catch up and overcome the lead in human spaceflight capability the Soviet Union had obtained in the early years of the Space Race, by demonstrating mission endurance up to just under 14 days, longer than the eight days required for a round trip to the Moon; methods of performing extravehicular activity (EVA) without tiring; and the orbital maneuvers necessary to achieve rendezvous and docking with another spacecraft. This left Apollo free to pursue its prime mission without spending time developing these techniques.
All Gemini flights were launched from Launch Complex 19 (LC-19) at Cape Kennedy Air Force Station in Florida. Their launch vehicle was the Titan II GLV, a modified intercontinental ballistic missile. Gemini was the first program to use the newly built Mission Control Center at the Houston Manned Spacecraft Center for flight control. The project also used the Agena target vehicle, a modified Atlas-Agena upper stage, to develop and practice orbital rendezvous and docking techniques.
The astronaut corps that supported Project Gemini included the "Mercury Seven", "The New Nine", and "The Fourteen". During the program, three astronauts died in air crashes during training, including both members of the prime crew for Gemini 9. The backup crew flew this mission.
Gemini was robust enough that the United States Air Force planned to use it for the Manned Orbital Laboratory (MOL) program, which was later canceled. Gemini's chief designer, Jim Chamberlin, also made detailed plans for cislunar and lunar landing missions in late 1961. He believed Gemini spacecraft could fly in lunar operations before Project Apollo, and cost less. NASA's administration did not approve those plans. In 1969, Lukas Bingham proposed a "Big Gemini" that could have been used to shuttle up to 12 astronauts to the planned space stations in the Apollo Applications Project (AAP). The only AAP project funded was Skylab (the first American space station)—which used existing spacecraft and hardware—thereby eliminating the need for Big Gemini.
The constellation for which the project was named is commonly pronounced , the last syllable rhyming with eye. However, staff of the Manned Spacecraft Center, including the astronauts, tended to pronounce the name , rhyming with knee. NASA's public affairs office then issued a statement in 1965 declaring "Jeh'-mih-nee" the "official" pronunciation. Gus Grissom, acting as Houston capsule communicator when Ed White performed his spacewalk on Gemini 4, is heard on flight recordings pronouncing the spacecraft's call sign "Jeh-mih-nee 4", and the NASA pronunciation is used in the 2018 film First Man.
Program origins and objectives
The Apollo program was conceived in early 1960 as a three-man spacecraft to follow Project Mercury. Jim Chamberlin, the head of engineering at the Space Task Group (STG), was assigned in February 1961 to start working on a bridge program between Mercury and Apollo. He presented two initial versions of a two-man spacecraft, then designated Mercury Mark II, at a NASA retreat at Wallops Island in March 1961. Scale models were shown in July 1961 at the McDonnell Aircraft Corporation's offices in St. Louis.
After Apollo was chartered to land men on the Moon by President John F. Kennedy on May 25, 1961, it became evident to NASA officials that a follow-on to the Mercury program was required to develop certain spaceflight capabilities in support of Apollo. NASA approved the two-man / two-vehicle program rechristened Project Gemini (Latin for "twins"), in reference to the third constellation of the Zodiac with its twin stars Castor and Pollux, on December 7, 1961. McDonnell Aircraft was contracted to build it on December 22, 1961. The program was publicly announced on January 3, 1962, with these major objectives:
To demonstrate endurance of humans and equipment in spaceflight for extended periods, at least eight days required for a Moon landing, to a maximum of two weeks
To effect rendezvous and docking with another vehicle, and to maneuver the combined spacecraft using the propulsion system of the target vehicle
To demonstrate Extra-Vehicular Activity (EVA), or space-"walks" outside the protection of the spacecraft, and to evaluate the astronauts' ability to perform tasks there
To perfect techniques of atmospheric reentry and touchdown at a pre-selected location on land
Chamberlin designed the Gemini capsule, which carried a crew of two. He was previously the chief aerodynamicist on Avro Canada's CF-105 Arrow fighter interceptor program. Chamberlin joined NASA along with 25 senior Avro engineers after cancellation of the Canadian Arrow program, and became head of the U.S. Space Task Group's engineering division in charge of Gemini. The prime contractor was McDonnell Aircraft Corporation, which was also the prime contractor for the Project Mercury capsule.
Astronaut Gus Grissom was heavily involved in the development and design of the Gemini spacecraft. What other Mercury astronauts dubbed "Gusmobile" was so designed around Grissom's 5'6" body that, when NASA discovered in 1963 that 14 of 16 astronauts would not fit in the spacecraft, the interior had to be redesigned. Grissom wrote in his posthumous 1968 book Gemini! that the realization of Project Mercury's end and the unlikelihood of his having another flight in that program prompted him to focus all his efforts on the upcoming Gemini program.
The Gemini program was managed by the Manned Spacecraft Center, located in Houston, Texas, under direction of the Office of Manned Space Flight, NASA Headquarters, Washington, D.C. Dr. George E. Mueller, Associate Administrator of NASA for Manned Space Flight, served as acting director of the Gemini program. William C. Schneider, Deputy Director of Manned Space Flight for Mission Operations served as mission director on all Gemini flights beginning with Gemini 6A.
Guenter Wendt was a McDonnell engineer who supervised launch preparations for both the Mercury and Gemini programs and would go on to do the same when the Apollo program launched crews. His team was responsible for completion of the complex pad close-out procedures just prior to spacecraft launch, and he was the last person the astronauts would see prior to closing the hatch. The astronauts appreciated his taking absolute authority over, and responsibility for, the condition of the spacecraft and developed a good-humored rapport with him.
In 1961, NASA selected McDonnell Aircraft, which was the prime contractor for the Project Mercury capsule, to build the Gemini capsule, the first of which was delivered in 1963. The spacecraft was 18 feet 5 inches (5.61 m) long and 10 feet (3.0 m) wide, with a launch weight varying from 7,100 to 8,350 pounds (3,220 to 3,790 kg).