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Gemini spacecraft in orbit.
Gemini spacecraft diagram (NASA)
McDonnell Gemini spacecraft
Description
Role: Orbital spaceflight
Crew: two; cmd pilot, pilot
Dimensions
Height:18.6 ft 5.67 m
Diameter: 10 ft 3.05 m
Volume: 90 ft3 2.55 m3
Weights
Reentry module: 4,372 lb 1 983 kg
Retrograde module: 1,303 lb 591 kg
Equipment module: 2,815 lb 1 277 kg
Total: 8,490 lb 3 851 kg
Rocket engines
Retros (solid fuel) x 4: 2,500 lbf ea 11.12 kN
Reentry Control System (N2O4/MMHH) x 16: 25 lbf ea 111 N
OAMS
(N2O4/MMHH) x 2:		 85 lbf ea 378 N
OAMS
(N2O4/MMHH) x 6:		 100 lbf ea 445 N
OAMS
(N2O4/MMHH) x 8:		 25 lbf ea 111 N
Performance
Endurance: 14 days 206 orbits
Apogee: 250 miles 402 km
Perigee: 100 miles 160 km
Spacecraft delta v: 728 ft/s 222 m/s
Gemini spacecraft diagram
McDonnell Gemini Spacecraft

Project Gemini was the second human spaceflight program of the United States of America. It operated between Projects Mercury and Apollo, during the years 1963-1966. Its objective was to develop techniques for advanced space travel, notably those necessary for Project Apollo, whose objective was to land men on the Moon. Gemini missions involved extravehicular activity and orbital maneuvers including rendezvous and docking.

Gemini was originally seen as a simple extrapolation of the Mercury program, and thus early on was called Mercury Mark II. The actual program had little in common with Mercury and was in fact superior to even Apollo in some ways. (See Big Gemini.) This was mainly a result of its late start date, which allowed it to benefit from much that had been learned during the early stages of the Apollo project (which, despite its later launch dates, was actually begun before Gemini).

Its primary difference from Mercury was that the earlier spacecraft had all systems other than the reentry rockets sited within the capsule, nearly all of which had to be accessed through the astronaut's hatchway, while Gemini had many power, propulsion, and life-support systems in a detachable module like a huge bowl; many components in the capsule itself were reachable each through its own small access door. The original intention was for Gemini to use a paraglider instead of a parachute, and the crew to be seated upright controlling the forward motion of the craft before its landing. To facilitate this, the parachute cord does not attach just to the nose of the craft; there is an additional attachment point for balance near the heat shield. This cord is covered by a strip of metal between the doors. Early short-duration missions had their electrical power supplied by batteries; later endurance missions had the first fuel cells in manned spacecraft.

The "Gemini" designation comes from the fact that each spacecraft held two men, as "gemini" in Latin means "twins". Gemini is also the name of the third constellation of the Zodiac and its twin stars, Castor and Pollux.

Unlike Mercury, which could only change its orientation in space, the Gemini capsule could alter its own orbit. It could also dock with other spacecraft--one of which, the Agena Target Vehicle, had its own large rocket engine which was used to perform large orbital changes. Gemini was the first American manned spacecraft to include an onboard computer, the Gemini Guidance Computer, to facilitate management and control of mission maneuvers. It was also unlike other NASA craft in that it used ejection seats, in-flight radar and an artificial horizon - devices borrowed from the aviation industry. Using ejection seats to push astronauts to safety was first employed by the Soviet Union in the Vostok craft manned by cosmonaut Yuri Gagarin.

The design for Gemini was developed by a Canadian, Jim Chamberlin, formerly the chief aerodynamicist on the Avro Arrow fighter interceptor program with Avro Canada. Chamberlin joined NASA along with 25 senior Avro engineers after cancellation of the Arrow program, and became head of the U.S. Space Task Group’s engineering division in charge of Gemini. The main contractor was McDonnell, who had lost out on main contracts for the Apollo Project. McDonnell sought to extend the program by proposing a Gemini craft could be used to fly a cislunar mission and even achieve a manned lunar landing earlier and at less cost than Apollo, but these proposals were rejected.

The Gemini program cost $5.4 billion dollars. See NASA Budget.

Announcement

The National Aeronautics and Space Administration (NASA) announced December 7, 1961, a plan to extend the existing manned space flight program by the development of a two-man spacecraft. The program was officially designated Gemini on January 3, 1962.

Team

The Gemini program was managed by the Manned Spacecraft Center, 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 V.

The Manned Spacecraft Center Gemini effort was headed by Dr. Robert R. Gilruth, director of the Center, and Charles W. Matthews, Gemini Program Manager. The Gemini spacecraft was designed by Canadian Jim Chamberlin, who joined the Gemini Program in 1961 after being recruited by NASA shortly after the AVRO Arrow project was dismantled by the Canadian Diefenbaker government.

Program objectives

The Gemini Program was conceived after it became evident to NASA officials that an intermediate step was required between the projects Mercury and Apollo. The major objectives assigned to Gemini were:

  • To subject two men and supporting equipment to long-duration flights, a requirement for projected later trips to the Moon or deeper space.
  • To effect rendezvous and docking with other orbiting vehicles, and to maneuver the docked vehicles in space, using the propulsion system of the target vehicle for such maneuvers.
  • To perfect methods of reentry and landing the spacecraft at a pre-selected land-landing point.
  • To gain additional information concerning the effects of weightlessness on crew members and to record the physiological reactions of crew members during long-duration flights.

After 10 successful flights, the Gemini program clearly placed the United States in the lead over the Soviet Union in manned spaceflight. The flight of Gemini VIII included the successful emergency recovery of the tumbling orbiting capsule by Neil Armstrong.

Gemini Applications

The United States Air Force had an interest in the system, and decided to use their own modification of the spacecraft as the crew vehicle for the Manned Orbiting Laboratory. To this end, one of the unmanned Gemini spacecraft was refurbished and flown again atop a mockup of the MOL, sent into space by a Titan III-M. This was the first time a spacecraft went into space twice.

The USAF also had the notion of adapting the Gemini spacecraft for trying out military applications, such as crude observation of the ground (no specialized reconnaissance camera could be carried) and practicing making rendezvous with suspicious satellites. This project was called Blue Gemini. The US Air Force did not like the fact that Gemini would have to be recovered by the US Navy, so they intended for Blue Gemini eventually to use the paraglider and land on three skids, something from the original design of Gemini.

At first some within NASA welcomed sharing of the cost with the USAF, but it was later agreed that NASA was better off operating Project Gemini by itself. MOL was cancelled in 1968 and Blue Gemini too was cancelled without any use by military astronauts.

In 2005, NASA Administrator Michael Griffin announced that the new Crew Exploration Vehicle, an Apollo-derived spacecraft, would use the Gemini/Agena chasedown and docking technique when NASA starts sending crews back out to the Moon by 2019. The CEV, which will replace the Space Shuttle (which currently lands on a conventional runway similar to the early Gemini and Blue Gemini paraglider/skids technique), will use deployable airbags, eliminating a large naval recovery force.

Astronauts

The following astronauts flew Gemini missions:

From the Mercury Seven:

From Astronaut Group 2: From Astronaut Group 3:

Crew Selection

Deke Slayton as head of the Astronaut Office had the main role in the choice of crews for the Gemini program. This selection process, with the prospect of more ambitious missions that would follow with Apollo, became even more political than in the Mercury Program. With Gemini it became a procedure that each flight had a primary crew and backup crew and that the backup crew would rotate to primary crew status three flights later. Slayton also intended for first choice of mission commands to be given to the four remaining active astronauts of the Mercury Seven, Alan Shepard, Gus Grissom, Gordon Cooper and Wally Schirra. John Glenn had retired from NASA in January 1964 and Scott Carpenter, who was blamed by some in NASA management for the problematic reentry of Aurora 7, was on leave to participate in the Navy's SEALAB project and was grounded from flight in July 1964. Slayton himself continued to be grounded due to his heart problem.

In late 1963, Slayton selected Alan Shepard and Thomas Stafford for Gemini 3, James McDivitt and Ed White for Gemini 4, and Wally Schirra and John Young for Gemini 5 (the first Agena rendezvous mission). Gemini 3 was backed up by Gus Grissom and Frank Borman, who were also slated for Gemini 6, the first long-duration mission. Finally Pete Conrad and James Lovell were assigned as the backup for Gemini 4.

Delays in the production of the Agena Target Vehicle caused the first rearrangement of the crew rotation. The Schirra and Young mission was bumped to Gemini 6 and they now were the backup crew for Shepard and Stafford. Grissom and Borman now had their long-duration mission assigned to Gemini 5.

The second rearrangment occurred when Alan Shepard developed Meniere's disease, an inner ear problem. Gus Grissom was moved to command Gemini 3. Slayton felt that Young was a better personality match with Grissom and switched Stafford and Young. Finally Slayton tapped Gordon Cooper to command the long-duration Gemini 5. Again for reasons of compatibility he moved Pete Conrad from being the backup commander of Gemini 4 to be the pilot of Gemini 5, and Frank Borman to the backup command of Gemini 4. Finally he assigned Neil Armstrong and Elliot See to be the backup crew for Gemini 5.

The third rearrangement of crew assignment occurred when Deke Slayton felt that Elliot See wasn't up to the physical demands of EVA on Gemini 8. He reassigned Elliot See to be the prime commander of Gemini 9 and put Dave Scott as pilot of Gemini 8 and Charles Bassett as the pilot of Gemini 9.

The fourth and final rearrangement of the Gemini crew assignment occurred after the deaths of Elliot See and Charles Bassett in a plane crash in St. Louis. The backup crew of Tom Stafford and Eugene Cernan was moved up to become the new prime crew of Gemini 9. James Lovell and Edwin "Buzz" Aldrin were moved from being the backup crew of Gemini 10 to be the backup crew of Gemini 9. This cleared the way through the crew rotation for Lovell and Aldrin to become the prime crew of Gemini 12. Along with the deaths of Grissom, White, and Chaffee in the fire of Apollo 1, this rearrangement is what finally determined the makeup of the early Apollo crews. These events were decisive in determining who would be in position to walk on the Moon.

In his autobiography "Deke!" Slayton relates that he would probably have replaced Aldrin with Eugene Cernan, the backup pilot for Gemini 12, if the second flight of the AMU had flown on Gemini 12.

Missions

Gemini involved 12 flights, including two unmanned flight tests of the equipment.

Unmanned

Mission Rocket LV Serial No Mission Dates Launch Time Duration Remarks
Gemini 1 Titan II GLV-1 12556 April 8-12, 1964 16:01 UTC 03d 23h First test flight of Gemini
Gemini 2 Titan II GLV-2 12557 January 19, 1965 14:03 UTC 00d 00h 18m 16s Suborbital flight to test heat shield

Manned

Mission Rocket LV Serial No Command Pilot Pilot Mission Dates Launch Time Duration
Gemini III Titan II GLV-3 12558 Grissom Young March 23, 1965 14:24 UTC 00d 04h
52m 31s
First manned Gemini flight, three orbits.
Gemini IV Titan II GLV-4 12559 McDivitt White June 03-07, 1965 15:15 UTC 04d 01h 56m 12s
Included first extravehicular activity (EVA) by an American; White's "space walk" was a 22 minute EVA exercise.
Gemini V Titan II GLV-5 12560 Cooper Conrad August 21-29, 1965 13:59 UTC 07d 22h 55m 14s
First week-long flight; first use of fuel cells for electrical power; evaluated guidance and navigation system for future rendezvous missions. Completed 120 orbits.
Gemini VII Titan II GLV-7 12562 Borman Lovell December 04-18, 1965 19:30 UTC 13d 18h 35m 01s
When the original Gemini VI mission was scrubbed because its Agena target for rendezvous and docking failed, Gemini VII was used for the rendezvous instead. Primary objective was to determine whether humans could live in space for 14 days.
Gemini VI-A Titan II GLV-6 12561 Schirra Stafford December 15-16, 1965 13:37 UTC 01d 01h 51m 24s
First space rendezvous accomplished with Gemini VII, station-keeping for over five hours at distances from 0.3 to 90 m (1 to 295 ft).
Gemini VIII Titan II GLV-8 12563 Armstrong Scott March 16, 1966 16:41 UTC 00d 10h 41m 26s
Accomplished first docking with another space vehicle, an unmanned Agena stage. A malfunction caused uncontrollable spinning of the craft; the crew undocked and effected the first emergency landing of a manned U.S. space mission.
Gemini IX-A Titan II GLV-9 12564 Stafford Cernan June 03-06, 1966 13:39 UTC 03d 00h 21m 50s
Rescheduled from May to rendezvous and dock with augmented target docking adapter (ATDA) after original Agena target vehicle failed to orbit. ATDA shroud did not completely separate, making docking impossible. Three different types of rendezvous, two hours of EVA, and 44 orbits were completed.
Gemini X Titan II GLV-10 12565 Young Collins July 18-21, 1966 22:20 UTC 02d 22h 46m 39s
First use of Agena target vehicle's propulsion systems. Spacecraft also rendezvoused with Gemini VIII target vehicle. Collins had 49 minutes of EVA standing in the hatch and 39 minutes of EVA to retrieve experiment from Agena stage. 43 orbits completed.
Gemini XI Titan II GLV-11 12566 Conrad Gordon September 12-15, 1966 14:42 UTC 02d 23h 17m 08s
Gemini record altitude, 1,189.3 km (739.2 mi) reached using Agena propulsion system after first orbit rendezvous and docking. Gordon made 33-minute EVA and two-hour standup EVA. 44 orbits.
Gemini XII Titan II GLV-12 12567 Lovell Aldrin November 11-15, 1966 20:46 UTC 03d 22h 34m 31s
Final Gemini flight. Rendezvoused and docked manually with its target Agena and kept station with it during EVA. Aldrin set an EVA record of 5 hours, 30 minutes for one space walk and two stand-up exercises.


Gemini-Titan launches and serial numbers

The Gemini-Titan launch vehicles, like the Mercury-Atlas vehicles before them, were ordered by NASA through the U. S. Air Force and were in reality missiles. The Gemini-Titan II rockets were assigned U.S. Air Force serial numbers, which were painted in four places on each Titan II (on opposite sides on each of the first and second stages). U.S. Air Force crews maintained Launch Complex 19 and prepared and launched all of the Gemini-Titan II launch vehicles.

These are the USAF serial numbers assigned to the Gemini-Titan launch vehicles. They were ordered in 1962 so the serial is "62-12XXX", but only "12XXX" is painted on the Titan II:

  • 12556 - GLV-1 - Gemini 1
  • 12557 - GLV-2 - Gemini 2
  • 12558 - GLV-3 - Gemini 3
  • 12559 - GLV-4 - Gemini 4
  • 12560 - GLV-5 - Gemini 5
  • 12561 - GLV-6 - Gemini 6A
  • 12562 - GLV-7 - Gemini 7
  • 12563 - GLV-8 - Gemini 8
  • 12564 - GLV-9 - Gemini 9A
  • 12565 - GLV-10 - Gemini 10
  • 12566 - GLV-11 - Gemini 11
  • 12567 - GLV-12 - Gemini 12
  • 12568 - GLV-13 Ordered by NASA 1962, not built, cancelled July 30, 1964
  • 12569 - GLV-14 Ordered by NASA 1962, not built, cancelled July 30, 1964
  • 12570 - GLV-15 Ordered by NASA 1962, not built, cancelled July 30, 1964

See also

Further reading

External links

Gemini program | Human spaceflight programmes | Manned spacecraft

Джемини (програма) | Gemini-programmet | Gemini-Programm | Programa Gemini | Programme Gemini | Programma Gemini | תוכנית ג'מיני | Gemini-program | Geminiprogramma | ジェミニ計画 | Program Gemini | Projeto Gemini | Джемини

 

This article is licensed under the GNU Free Documentation License. It uses material from the "Project Gemini".

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