The National Aeronautics and Space Administration’s Gemini missions investigated techniques needed to fulfill President Kennedy’s challenge to land Apollo astronauts on the Moon before 1970.
Project Gemini started with the spacecraft Mercury Mark II, which would perform orbital maneuvers and expand crew size to two astronauts. When President John F. Kennedy committed the United States to achieving a lunar landing, the Gemini program’s goals became long-duration flight, rendezvous and docking, working outside the spacecraft, and controlled reentry. It was necessary to master all these goals prior to sending men to the Moon and returning them safely to Earth.
Gemini’s launch vehicle was the Titan 2 booster,
Two test flights were scheduled. Gemini 1 launched on April 8, 1964. It was not separated from the Titan 2 second stage. Gemini 1 demonstrated the booster’s capability to put Gemini spacecraft into orbit. The flight control team was exercised through a full countdown and ascent. Mission duration was only three orbits. Gemini 1 remained in space until April 12, when it reentered destructively. Gemini 2 flew a suborbital trajectory on January 19, 1965, landing downrange and verifying that the heat shield could safely return astronauts.
Gemini 3, launched on March 23, 1965, with Gus Grissom and John Young aboard, demonstrated that astronauts could pilot their spacecraft. Thrusters fired on the first, second, and third orbits, increased orbital perigee, slightly changed orbital inclination, and decreased orbital apogee, respectively. Grissom and Young conducted two scientific experiments. Neither worked well, but they demonstrated that Gemini spacecraft could support future research. Gemini 3 splashed down considerably off target.
Launched on June 3, 1965, James A. McDivitt attempted to rendezvous Gemini IV back to its spent Titan 2 second stage using only eyesight. That proved difficult, and McDivitt ceased trying, saving fuel for a four-day American spaceflight endurance record. Ed White, attached only by an umbilical cable, exited his hatch and entered the vacuum of space. He remained floating outside effortlessly for twenty-three minutes. This first NASA mission commanded from the new Manned Spacecraft Center in Houston ended with a splashdown on June 7.
On Gemini V, Gordon Cooper and Pete Conrad were to double the NASA endurance record. Their spacecraft incorporated fuel cells using cryogenic oxygen and hydrogen to produce water and electricity. Gemini V launched on August 21, 1965, and carried a rendezvous evaluation pod (REP) to incorporate radar data during rendezvous. Major difficulties with fuel-cell plumbing forced the powering down of Gemini V after the REP’s release; it seemed as though Gemini V might have to terminate before day’s end. Meanwhile, the REP’s batteries died, killing the rendezvous evaluation. Fuel-cell status improved later in the mission, and Gemini V splashed down on August 29.
Gemini VI was the first attempt at rendezvous and docking with an Agena craft. On October 25, 1965, an Atlas-Agena lifted off. Unfortunately all telemetry from Agena 6 was lost. It failed to reach orbit, and Gemini VI was scrubbed. Awaiting resolution of Agena 6’s failure, Gemini managers proceeded to prepare for Frank Borman and Jim Lovell’s two-week-long mission. Meanwhile, a bold plan was advanced using their spacecraft as a target for Gemini VI-A if the pad team drastically compressed a normal 63-day facility turnaround cycle after Gemini VII launched. NASA administrator James E. Webb approved the concept.
Borman and Lovell launched on December 4, 1965. While Gemini VII settled into orbit, within hours Gemini VI-A’s booster underwent erection on Pad 19. A Gemini VI-A December 12 launch attempt provided one of the most dramatic moments of the program. Wally Schirra and Tom Stafford noted first-stage ignition, but those engines shut down without raising the booster. If Schirra had initiated abort procedures, the spacecraft would have been ruined, and the dual rendezvous would have been lost.
Three days later, Gemini VI-A launched and began a rendezvous incorporating thruster firings, computer calculations, and radar data input over four orbits. Schirra was able to approach within one foot of Gemini VII’s nose, and Gemini VI-A and VII flew in formation. Schirra then separated to a safe distance, and the next day, December 16, Gemini VI-A splashed down. Gemini VII remained in orbit until splashing down on December 18. Borman and Lovell set a record for time in orbit (330 hours) that would stand for five years.
Armstrong and Scott flew Gemini VIII; their mission plan was essentially that of Gemini VI with spacewalking (extravehicular activity
Gemini IX was an ambitious mission investigating rendezvous and docking profiles, as well as spacewalking techniques. Like Agena 6, Agena 9 failed to reach orbit. The mission was scrubbed on May 17, 1966, after this latest launch failure. After Agena 6, a special alternative docking target called an Augmented Target Docking Adapter
The ATDA launched on June 1, 1966, but Gemini IX-A, with Stafford and Gene Cernan aboard, could not launch that day. While Gemini IX-A’s problem was fixed, telemetry indicated that something anomalous had occurred, casting doubt that ATDA docking could be achieved. Gemini IX-A launched on June 3 and after three orbits flew into close proximity of the slowly rotating ATDA. Stafford described what he termed an “angry alligator.” The ATDA’s partially opened payload shroud remained attached. Consideration was given to bumping Gemini IX-A’s nose on the ATDA or having Cernan using cutting tools while spacewalking to free the docking collar; fortunately, conservatism prevailed, and docking was scrapped, although several rendezvous profiles were tested.
Cernan left the spacecraft and quickly found spacewalking not so easy as had White. Cernan’s life support system was unable to keep him cool while he was working heavily. Behind the spacecraft’s adapter section, Cernan attempted to plug himself into a backpack unit that he was to fly out from Gemini IX-A. Cernan’s visor fogged over, obscuring his vision. After resting, Cernan returned to the cabin. Gemini IX-A ended with a precise splashdown on June 6, 1966.
The window of opportunity to launch Gemini X was tied to the orbital position of Agena 8 as well as the liftoff time for Agena 10. The latter launched on time on July 18, 1966, and at 3:40
With Agena 10 attached to Gemini X’s nose, Collins performed a spacewalk while standing up in his open hatch. Agena 10’s engine fired to rendezvous with Agena 8. Young undocked Agena 10 and then approached Agena 8. With Young maintaining Gemini X just feet from Agena 8, Collins floated over to it and removed equipment that had been exposed to space for months. Gemini X splashed down on July 21.
After Agena 11 reached orbit on September 10, 1966, Gemini XI launched within a 1.5-second-long window of opportunity. Conrad achieved docking by first orbit’s end. Richard Gordon performed experiments standing up in his open hatch. During the next spacewalk, Gordon tried attaching a tether between Gemini and Agena 11. After less than ten minutes, although he did affix that line, an exhausted Gordon returned inside the spacecraft. Agena 11’s propulsion system fired to boost Gemini XI up to a record orbital altitude of 850 miles. Gemini XI concluded on September 15 with the spacecraft’s computer controlling a very precise splashdown.
Lovell and Buzz Aldrin conducted rendezvous and docking exercises during the final Gemini mission from November 11 to 15, 1966, but the biggest thing for which Gemini XII would be remembered was 5.5 hours of spacewalking successfully conducted by Aldrin over the course of two standup exercises and one umbilical exercise. Aldrin had trained in a neutral buoyancy facility and used special tools, as well as tethers and foot restraints, to lessen his workload. Project Gemini ended with one final, safe splashdown.
In twenty-one months, ten different two-man astronaut crews flew highly ambitious Gemini missions. Each mission drew upon the experience of preceding ones. Astronauts built experience that made possible the goal of landing on the Moon—which would be realized through NASA’s succeeding Apollo program. Gemini flights demonstrated that astronauts could survive in space for sufficient time to allow an Apollo mission to go to the Moon and back, and that astronauts could react to problems, fly precise maneuvers, dock with other spacecraft, work in pressure suits, follow precise reentry trajectories, and safely splash down in the ocean near recovery vessels. Without Gemini experience, the Apollo program’s many successful missions to the Moon would not have been possible.
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Hacker, Barton, and James M Grimwood. On the Shoulders of Titans: A History of Project Gemini. NASA SP-4203. Washington, D.C.: Superintendent of Documents, 1977. This is the definitive history of the Gemini program. -
Harland, David M. How NASA Learned to Fly in Space. Burlington, Ont.: Apogee Books, 2004. A mission-by-mission flight log with good descriptions of engineering and science topics. -
Heppenheimer, T. A. Countdown: A History of Space Flight. New York: Wiley, 1999. An overview of space program development. -
Tobias, Russ, and David G. Fisher, eds. USA in Space. 3 vols. Pasadena, Calif.: Salem Press, 2006. This massive, three-volume reference work covers all major American space missions in detailed, illustrated articles, including each of the Gemini missions.
Congress Creates the National Aeronautics and Space Administration
Pioneer Space Program Is Launched
First Human Orbits the Earth
Glenn Becomes the First American to Orbit Earth
Soviet Cosmonaut Conducts First Space Walk
Gemini VI and VII Complete an Orbital Rendezvous
Surveyor Program Prepares NASA for Piloted Moon Landings
Soyuz 4 and 5 Spacecraft Dock in Orbit
First Humans Land on the Moon
Apollo 13 Crew Survives Onboard Explosion