View source for Astronomy:Project Gemini

{{Short description|1961–1966 US human spaceflight program}}
{{Infobox space program
| name            = Project Gemini
| image           = [[File:GeminiPatch.png|frameless|upright]]
| alt             = A dark blue circle with the roman numeral for "two" printed in gold
| country         = United States
| organization    = [[Organization:NASA|NASA]]
| purpose         = {{Unbulleted list|Crewed orbital flight|[[Astronomy:Extravehicular activity|Extravehicular activity]]|[[Astronomy:Space rendezvous|Rendezvous]] and [[Engineering:Docking and berthing of spacecraft|docking]]}}
| status          = Completed
| cost            = {{Unbulleted list|$1.3 billion (1967)<ref name="lafleur20100308"/>|${{inflation|US-GDP|1.3|1967|r=1|fmt=c}} billion ({{inflation/year|US-GDP}})}}
| duration        = 1961–1966
| firstflight     = {{Unbulleted list|Gemini 1|{{Start date|1964|04|08}}}}
| firstcrewed     = {{Unbulleted list|[[Astronomy:Gemini 3|Gemini 3]]|{{Start date|1965|03|23}}}}
| lastflight      = {{Unbulleted list|[[Astronomy:Gemini 12|Gemini XII]]|{{Start date|1966|11|11}}}} 
| successes       = 10
| partialfailures = 2 ([[Astronomy:Gemini 8|Gemini VIII]] and [[Astronomy:Gemini 9A|IX-A]])
| launchsite      = {{wipe|Cape Canaveral Air Force Station}}
| crewvehicle     = ''Gemini'' capsule
| launcher        = {{Hlist|[[Engineering:Atlas-Agena|Atlas-Agena]]|Titan II GLV}}
}}
{{United States space program sidebar}}
'''Project Gemini''' ({{IPAc-en|ipa|ˈ|dʒ|ɛ|m|ɪ|n|i}}) was the second {{wipe|United States}} [[Astronomy:Human spaceflight|human spaceflight]] program to fly. Conducted after the first, [[Astronomy:Project Mercury|Project Mercury]], and while the [[Astronomy:Apollo program|Apollo program]] was still in 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 [[Astronomy:Low Earth orbit|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 [[Astronomy:Moon landing|land astronauts on the Moon]]. In doing so, it allowed the United States to catch up and overcome the lead in [[Astronomy:Human spaceflight|human spaceflight]] capability the [[Place:Soviet Union|Soviet Union]] had obtained in the early years of the [[Astronomy:Space Race|Space Race]], by demonstrating mission endurance up to just under 14 days, longer than the eight days required for a round trip to the [[Astronomy:Moon|Moon]]; methods of performing [[Astronomy:Extravehicular activity|extravehicular activity]] (EVA) without tiring; and the [[Astronomy:Orbital maneuver|orbital maneuver]]s necessary to achieve [[Astronomy:Space rendezvous|rendezvous]] and [[Engineering:Docking and berthing of spacecraft|docking]] with another spacecraft. This left Apollo free to pursue its prime mission without spending time developing these techniques.

All Gemini flights were [[Engineering:Rocket launch|launched]] from Launch Complex 19 (LC-19) at {{wipe|Cape Canaveral Air Force Station}} in Florida. Their [[Engineering:Launch vehicle|launch vehicle]] was the Gemini–Titan II, a modified [[Engineering:Intercontinental ballistic missile|Intercontinental Ballistic Missile]] (ICBM).{{efn|name=two|group=note|The only Gemini spacecraft not launched by a Titan II was the reflight of Gemini 2 for a [[Organization:Manned Orbiting Laboratory|Manned Orbiting Laboratory]] test in 1966, which used a Titan IIIC.}} Gemini was the first program to use the newly built Mission Control Center at the Houston Manned Spacecraft Center for [[Engineering:Flight controller#NASA's Flight Controllers|flight control]].{{efn|name=control|group=note|[[Astronomy:Gemini 3|Gemini 3]] used the [[Astronomy:Mercury Control Center|Mercury Control Center]] located at Cape Kennedy for flight control, as the new center was still in test status. Gemini 4 was the first to be guided from Houston, with Mercury Control as a backup. From Gemini 5 through today, all flights are controlled from Houston.}}

The astronaut corps that supported Project Gemini included the "[[Engineering:Mercury Seven|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 [[Astronomy:Outer space#Cislunar space|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 "[[Engineering:Big Gemini|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 [[Engineering:Skylab|Skylab]] – which used existing spacecraft and hardware – thereby eliminating the need for Big Gemini.

==Pronunciation==
The constellation for which the project was named is commonly pronounced {{IPAc-en|ˈ|dʒ|ɛ|m|ɪ|n|aɪ}}, the last syllable rhyming with ''eye''. However, staff of the Manned Spacecraft Center, including the astronauts, tended to pronounce the name {{IPAc-en|ˈ|dʒ|ɛ|m|ɪ|n|i}}, rhyming with ''knee''. NASA's public affairs office issued a statement in 1965 declaring "Jeh-mih-nee" the "official" pronunciation.<ref name="NYTFirstMan">{{cite news |last1=Schwartz |first1=John |title=Why Does 'First Man' Say Gemini as 'Geminee'? NASA Explains. Sorta. |work=The New York Times |date=October 17, 2018|url=https://www.nytimes.com/2018/10/17/movies/first-man-gemini-nasa.html|access-date=November 6, 2018}}</ref> Gus Grissom, acting as Houston capsule communicator when [[Astronomy:Ed White (astronaut)|Ed White]] performed his spacewalk on [[Astronomy:Gemini 4|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''.<ref name="NYTFirstMan"/>

==Program origins and objectives==
The [[Astronomy:Apollo program|Apollo program]] was conceived in early 1960 as a three-man spacecraft to follow [[Astronomy:Project Mercury|Project Mercury]]. Jim Chamberlin, the head of engineering at the [[Engineering:Space Task Group|Space Task Group]] (STG), was assigned in February 1961 to start working on a bridge program between Mercury and Apollo.{{sfnp|Gainor|2001|pages=93, 97–99}} 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.{{sfnp|Gainor|2001|pages=93, 97–99}} Scale models were shown in July 1961 at the McDonnell Aircraft Corporation's offices in St. Louis.{{sfnp|Gainor|2001|pages=93, 97–99}}

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.  [[Organization:NASA|NASA]] approved the two-man / two-vehicle program rechristened Project Gemini (Latin for "twins"), in reference to [[Astronomy:Gemini (constellation)|the third constellation of the Zodiac]] with its twin stars [[Astronomy:Castor (star)|Castor]] and [[Astronomy:Pollux (star)|Pollux]], on December 7, 1961.{{sfnp|Gainor|2001|pages=93, 97–99}} McDonnell Aircraft was contracted to build it on December 22, 1961.{{sfnp|Hacker|Grimwood|1977|pages= XV, 75}} The program was publicly announced on January 3, 1962, with these major objectives:{{sfnp|Loff|2013}}
* 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 [[Astronomy:Space rendezvous|rendezvous]] and [[Engineering:Docking and berthing of spacecraft|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{{efn|name=reentry|group=note|The requirement for a touchdown on land using a paraglider was canceled in 1964.}}

==Team==
Chamberlin designed the Gemini capsule, which carried a crew of two. He was previously the chief aerodynamicist on Avro Canada's [[Engineering:Avro Canada CF-105 Arrow|CF-105 Arrow]] fighter interceptor program.{{sfnp|Murray|Cox|1989|pages=33–34}} 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.{{sfnp|Murray|Cox|1989|pages=33–34}}{{sfnp|Reguly|1965|page=7}} The prime contractor was McDonnell Aircraft Corporation, which was also the prime contractor for the [[Astronomy:Project Mercury|Project Mercury]] capsule.{{sfnp|Hacker|Grimwood|1977|page=75}}

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.{{sfnp|Agle|1998}} Grissom wrote in his posthumous 1968 book ''Gemini!'' that the realization of [[Astronomy:Project Mercury|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, [[Organization:NASA|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.{{sfnp|Farmer|Hamblin|2004|pages=51–54}}

==Spacecraft==
[[File:Gemini spacecraft.jpg|thumb|left|A cutaway illustration of the Gemini spacecraft.  The Adapter module in white, the Reentry module in grey]]
NASA selected McDonnell Aircraft, which had been the prime contractor for the [[Astronomy:Project Mercury|Project Mercury]] capsule, in 1961 to build the Gemini capsule, the first of which was delivered in 1963. The spacecraft was {{convert|18|ft|5|in|m|sp=us}} long and {{convert|10|ft|m|sp=us}} wide, with a launch weight varying from {{convert|7100|to|8350|lb|kg}}.{{sfnp|Gatland|1976|page=42}}

The Gemini crew capsule (referred to as the Reentry Module) was essentially an enlarged version of the Mercury capsule. Unlike Mercury, the [[Engineering:Retrorocket|retrorocket]]s, electrical power, propulsion systems, oxygen, and water were located in a detachable Adapter Module behind the Reentry Module. A major design improvement in Gemini was to locate all internal spacecraft systems in modular components, which could be independently tested and replaced when necessary, without removing or disturbing other already tested components.
[[File:Gemini heat shield.jpg|thumb|Unablated Gemini heat shield]]
[[File:Gemini Spacecraft Heat Shield.jpg|thumb|Ablated Gemini heat shield]]

===Reentry module===
Many components in the capsule itself were reachable through their own small access doors. Unlike Mercury, Gemini used completely solid-state electronics, and its modular design made it easy to repair.{{sfnp|Dryden|1964|page=362}}

Gemini's emergency [[Astronomy:Launch escape system|launch escape system]] did not use an escape tower powered by a solid-fuel rocket, but instead used aircraft-style [[Engineering:Ejection seat|ejection seat]]s. The tower was heavy and complicated, and NASA engineers reasoned that they could do away with it as the Titan II's [[Chemistry:Hypergolic propellant|hypergolic propellant]]s would burn immediately on contact. A Titan II booster explosion had a smaller blast effect and flame than on the cryogenically fueled Atlas and Saturn. [[Engineering:Ejection seat|Ejection seat]]s were sufficient to separate the astronauts from a malfunctioning launch vehicle. At higher altitudes, where the ejection seats could not be used, the astronauts would return to Earth inside the spacecraft, which would separate from the launch vehicle.{{sfnp|Dryden|1964|page=364}}

The main proponent of using ejection seats was Chamberlin, who had never liked the Mercury escape tower and wished to use a simpler alternative that would also reduce weight. He reviewed several films of Atlas and Titan II ICBM failures, which he used to estimate the approximate size of a fireball produced by an exploding launch vehicle and from this he gauged that the Titan II would produce a much smaller explosion, thus the spacecraft could get away with ejection seats.

Maxime Faget, the designer of the Mercury LES, was on the other hand less-than-enthusiastic about this setup. Aside from the possibility of the ejection seats seriously injuring the astronauts, they would also only be usable for about 40 seconds after liftoff, by which point the booster would be attaining Mach 1 speed and ejection would no longer be possible. He was also concerned about the astronauts being launched through the Titan's exhaust plume if they ejected in-flight and later added, "The best thing about Gemini was that they never had to make an escape."<ref>Glen E. Swanson, ed., "Before This Decade Is Out: Personal Reflections on the Apollo Program," [[Social:Dover Publications|Dover Publications]] 2012, p. 354.</ref>

The Gemini ejection system was never tested with the Gemini cabin pressurized with pure oxygen, as it was prior to launch. In January 1967, the fatal [[Engineering:Apollo 1|Apollo 1]] fire demonstrated that pressurizing a spacecraft with pure oxygen created an extremely dangerous fire hazard.<ref>{{cite magazine |last=Betancourt |first=Mark |date=October–November 2018 |title=Abort! |url=https://www.airspacemag.com/space/abort-180970364/ |magazine=Air & Space/Smithsonian |page=39 |volume=33 |issue=5 |access-date=March 16, 2019}}</ref> In a 1997 oral history, astronaut Thomas P. Stafford commented on the Gemini 6 launch abort in December 1965, when he and command pilot [[Biography:Wally Schirra|Wally Schirra]] nearly ejected from the spacecraft:

{{Quote|text=So it turns out what we would have seen, had we had to do that, would have been two Roman candles going out, because we were 15 or 16 psi, pure oxygen, soaking in that for an hour and a half. You remember the tragic fire we had at the Cape. (...) Jesus, with that fire going off and that, it would have burned the suits. Everything was soaked in oxygen. So thank God. That was another thing: NASA never tested it under the conditions that they would have had if they would have had to eject. They did have some tests at China Lake where they had a simulated mock-up of Gemini capsule, but what they did is fill it full of nitrogen. They didn't have it filled full of oxygen in the sled test they had.<ref>{{cite web |url=https://historycollection.jsc.nasa.gov/JSCHistoryPortal/history/oral_histories/StaffordTP/StaffordTP_10-15-97.htm |title=Thomas P. Stafford Oral History |last=Vantine |first=William |work=Johnson Space Center Oral History Project |date=October 15, 1997 |access-date=March 16, 2019 |publisher=[[Organization:NASA|NASA]]}}</ref>}}

Gemini was the first astronaut-carrying spacecraft to include an onboard computer, the Gemini Guidance Computer, to facilitate management and control of mission maneuvers. This computer, sometimes called the Gemini Spacecraft On-Board Computer (OBC), was very similar to the [[Engineering:Saturn Launch Vehicle Digital Computer|Saturn Launch Vehicle Digital Computer]]. The Gemini Guidance Computer weighed {{convert|58.98|lb}}. Its [[Core memory|core memory]] had 4096 [[Memory address|addresses]], each containing a 39-bit [[Word (computer architecture)|word]] composed of three 13-bit "syllables". All numeric data was [[Engineering:26-bit|26-bit]] two's-complement integers (sometimes used as fixed-point numbers), either stored in the first two syllables of a word or in the [[Accumulator (computing)|accumulator]]. Instructions (always with a 4-bit [[Opcode|opcode]] and 9 bits of operand) could go in any syllable.{{sfnp|Tomayko|1988|pages=10–19}}{{sfnp|Burkey|2012}}<ref>{{cite web|url=http://www-03.ibm.com/ibm/history/exhibits/space/space_gemini.html|title=IBM Archives: IBM and the Gemini Program|date=23 January 2003}}</ref><ref>C. A. Leist and J. C. Condell, [http://ed-thelen.org/comp-hist/gemini_manual_rev_a_9-30-11.pdf "Gemini Programming Manual"], 1966</ref>

Unlike Mercury, Gemini used in-flight [[Engineering:Radar|radar]] and an [[Engineering:Attitude indicator|artificial horizon]], similar to those used in the aviation industry.{{sfnp|Tomayko|1988|pages=10–19}} Like Mercury, Gemini used a [[Engineering:Joystick|joystick]] to give the astronauts manual control of yaw, pitch, and roll. Gemini added control of the spacecraft's [[Translation (geometry)#Translations in physics|translation]] (forward, backward, up, down, and sideways) with a pair of T-shaped handles (one for each crew member). Translation control enabled [[Engineering:Docking and berthing of spacecraft|rendezvous and docking]], and crew control of the flight path. The same controller types were also used in the Apollo spacecraft.{{sfnp|Agle|1998}}

[[File:Gemini paraglider.JPG|thumb|Gemini paraglider during tests at [[Organization:Edwards Air Force Base|Edwards Air Force Base]] in August 1964.]]
The original intention for Gemini was to land on solid ground instead of at sea, using a [[Engineering:Rogallo wing|Rogallo wing]] rather than a parachute, with the crew seated upright controlling the forward motion of the craft. To facilitate this, the airfoil did not attach just to the nose of the craft, but to an additional attachment point for balance near the heat shield. This cord was covered by a strip of metal which ran between the twin hatches.<ref>{{cite web|work=Vintage Space|url=https://vintagespace.wordpress.com/2011/05/22/losing-rogallo-from-gemini/ |title=Losing Rogallo from Gemini |publisher=Amy Shira Teitel |date=2011-05-22 |access-date=2012-12-23}}</ref> This design was ultimately dropped, and parachutes were used to make a sea landing as in Mercury. The capsule was suspended at an angle closer to horizontal, so that a side of the heat shield contacted the water first. This eliminated the need for the landing bag cushion used in the Mercury capsule.

===Adapter module===
The adapter module in turn was separated into a Retro module and an Equipment module.

====Retro module====
The Retro module contained four solid-fuel TE-M-385 Star-13E retrorockets, each spherical in shape except for its rocket nozzle, which were structurally attached to two beams that reached across the diameter of the retro module, crossing at right angles in the center.<ref>{{Cite book|url=http://www.spaceaholic.com/index.php/Detail/Object/Show/object_id/15|title = Rocket Motor, TE-M-385, Solid Propellant, Gemini Spacecraft Retro}}</ref> Re-entry began with the retrorockets firing one at a time. Abort procedures at certain periods during lift-off would cause them to fire at the same time, thrusting the Descent module away from the Titan rocket.

====Equipment module====
Gemini was equipped with an Orbit Attitude and Maneuvering System (OAMS), containing sixteen thrusters for [[Translation (geometry)|translation]] control in all three perpendicular axes (forward/backward, left/right, up/down), in addition to [[Astronomy:Spacecraft attitude control|attitude control]] (pitch, yaw, and roll angle orientation) as in Mercury. Translation control allowed changing [[Astronomy:Orbital inclination|orbital inclination]] and altitude, necessary to perform [[Astronomy:Space rendezvous|space rendezvous]] with other craft, and [[Engineering:Docking and berthing of spacecraft|docking]] with the Agena Target Vehicle (ATV), with its own rocket engine which could be used to perform greater orbit changes.

Early short-duration missions had their electrical power supplied by batteries; later endurance missions used the first [[Physics:Fuel cell|fuel cell]]s in crewed spacecraft.

Gemini was in some regards more advanced than Apollo because the latter program began almost a year earlier. It became known as a "pilot's spacecraft" due to its assortment of jet fighter-like features, in no small part due to Gus Grissom's influence over the design, and it was at this point where the US crewed space program clearly began showing its superiority over that of the Soviet Union with long duration flight, rendezvous, and extravehicular capability.{{efn|name=advanced|group=note|During the ten crewed flights of the Gemini program, the Soviets made no crewed flights, and despite achieving the first EVA, did no more EVAs until January 1969.}} The Soviet Union during this period was developing the [[Engineering:Soyuz (spacecraft)|Soyuz]] spacecraft intended to take cosmonauts to the Moon, but political and technical problems began to get in the way, leading to the ultimate end of their crewed lunar program.

==Launch vehicle==
The Titan II debuted in 1962 as the Air Force's second-generation ICBM to replace the Atlas. By using hypergolic fuels, it could be stored longer and be easily readied for launch in addition to being a simpler design with fewer components. The only caveat was the propellant mix (nitrogen tetroxide and [[Chemistry:Hydrazine|hydrazine]]) were extremely toxic compared to the Atlas' liquid oxygen/RP-1. However, the Titan had considerable difficulty being man-rated due to early problems with [[Engineering:Pogo oscillation|pogo oscillation]]. The launch vehicle used a radio guidance system that was unique to launches from Cape Kennedy.

==Astronauts==
[[File:Astronauts White and McDivitt Inside Gemini IV Spacecraft - GPN-2002-000031.jpg|thumb|Astronauts White and McDivitt inside the Gemini 4 spacecraft, 1965]]
[[File:Gemini8.1966.ws.jpg|thumb|Gemini 8 prime crew and other astronauts at prelaunch breakfast, 1966]]
[[Biography:Deke Slayton|Deke Slayton]], as director of flight crew operations, had primary responsibility for assigning crews for the Gemini program. Each flight had a primary crew and backup crew, and the backup crew would rotate to primary crew status three flights later. Slayton intended for first choice of mission commands to be given to the four remaining active astronauts of the [[Engineering:Mercury Seven|Mercury Seven]]: Alan Shepard, Grissom, Cooper, and Schirra. ([[Biography:John Glenn|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 ''[[Astronomy:Mercury-Atlas 7|Aurora 7]]'', was on leave to participate in the Navy's SEALAB project and was grounded from flight in July 1964 due to an arm injury sustained in a motorbike accident. Slayton himself continued to be grounded due to a heart problem.)

Titles used for the left-hand (command) and right-hand (pilot) seat crew positions were taken from the U.S. Air Force pilot ratings, ''Command Pilot'' and ''Pilot''. Sixteen astronauts flew on 10 crewed Gemini missions:

[[File:Gemini 4 Astronauts Meet Yuri Gagarin.jpg|thumb|[[Biography:Yuri Gagarin|Yuri Gagarin]] shakes hand with Gemini 4 astronauts, 1965]]
{| class="wikitable sortable" style="font-size:1.00em; line-height:1.5em;"
|- class="is-sticky"
! Group
! Astronaut
! Service
! Mission, prime crew position
! Mission, backup crew position
|-
| rowspan="3" | [[Engineering:Mercury Seven|Astronaut Group 1]]
| Gordon Cooper
| rowspan="2" | USAF
| [[Astronomy:Gemini 5|Gemini 5]] Command Pilot
| Gemini 12 Command Pilot
|-
| Virgil "Gus" Grissom
| [[Astronomy:Gemini 3|Gemini 3]] Command Pilot
| Gemini 6A Command Pilot
|-
| [[Biography:Wally Schirra|Walter M. Schirra]]
| USN
| [[Astronomy:Gemini 6A|Gemini 6A]] Command Pilot
| Gemini 3 Command Pilot
|-
| rowspan="13" | Astronaut Group 2
| rowspan=2|Neil Armstrong
| rowspan=2|Civilian{{efn|name=armstrong|group=note|Armstrong had left the US Navy and was already a NASA test pilot when he and Elliot See became the first civilian astronauts in Astronaut Group 2; see Armstrong's [https://history.nasa.gov/ap11ann/astrobios.htm#Armstrong NASA biography] and a [http://www.nasa.gov/vision/space/features/armstrong_ambassador_of_exploration.html description of his receiving a NASA award], among others.}}
|rowspan=2|[[Astronomy:Gemini 8|Gemini 8]] Command Pilot
| Gemini 5 Command Pilot
|-
| Gemini 11 Command Pilot
|-
| Frank Borman
| USAF
| [[Astronomy:Gemini 7|Gemini 7]] Command Pilot
| Gemini 4 Command Pilot
|-
| rowspan="2" | [[Biography:Pete Conrad|Charles "Pete" Conrad]]
| rowspan="2" | USN
| [[Astronomy:Gemini 5|Gemini 5]] Pilot
| rowspan=2|Gemini 8 Command Pilot
|-
| [[Astronomy:Gemini 11|Gemini 11]] Command Pilot
|-
| rowspan="2" | [[Biography:Jim Lovell|Jim Lovell]]
| rowspan="2" | USN
| [[Astronomy:Gemini 7|Gemini 7]] Pilot
| Gemini 4 Pilot
|-
| [[Astronomy:Gemini 12|Gemini 12]] Command Pilot
| Gemini 9A Command Pilot
|-
| James McDivitt
| rowspan="4" | USAF
| [[Astronomy:Gemini 4|Gemini 4]] Command Pilot
| {{n/a}}
|-
| rowspan="2" | Thomas P. Stafford
| [[Astronomy:Gemini 6A|Gemini 6A]] Pilot
| rowspan=2|Gemini 3 Pilot{{efn|name=stafford|group=note|Stafford was originally selected as the Pilot on the prime crew of Gemini 3 alongside Alan Shepard; following Shepard's grounding as a result of Ménière's disease, Stafford swapped places with John Young.}}
|-
| [[Astronomy:Gemini 9A|Gemini 9A]] Command Pilot
|-
| [[Astronomy:Ed White (astronaut)|Ed White]]
| [[Astronomy:Gemini 4|Gemini 4]] Pilot
| Gemini 7 Command Pilot
|-
| rowspan="2" | John Young
| rowspan="2" | USN
| [[Astronomy:Gemini 3|Gemini 3]] Pilot
| rowspan=2|Gemini 6A Pilot
|-
| [[Astronomy:Gemini 10|Gemini 10]] Command Pilot
|-
| rowspan="5" | Astronaut Group 3
| [[Biography:Buzz Aldrin|Edwin "Buzz" Aldrin]]
| USAF
| [[Astronomy:Gemini 12|Gemini 12]] Pilot
| Gemini 9A Pilot
|-
| [[Biography:Gene Cernan|Eugene Cernan]]
| USN
| [[Astronomy:Gemini 9A|Gemini 9A]] Pilot
| Gemini 12 Pilot
|-
| Michael Collins
| USAF
| [[Astronomy:Gemini 10|Gemini 10]] Pilot
| Gemini 7 Pilot
|-
| [[Biography:Richard F. Gordon Jr.|Richard F. Gordon]]
| USN
| [[Astronomy:Gemini 11|Gemini 11]] Pilot
| Gemini 8 Pilot
|-
| [[Biography:David Scott|David Scott]]
| USAF
| [[Astronomy:Gemini 8|Gemini 8]] Pilot
| {{n/a}}
|-
!colspan=5|Astronauts selected but did not fly
|-
|Astronaut Group 1
|Alan Shepard
|USN
|Gemini 3 Command Pilot{{efn|name=Shepard|group=note|Shepard was originally selected as the Command Pilot of Gemini 3, but was grounded following a diagnosis of [[Medicine:Ménière's disease|Ménière's disease]], an inner ear disorder.}}
|{{n/a}}
|-
|Astronaut Group 2
|Elliot See
|Civilian{{efn|name=See|group=note|See had left the United States Navy and was employed as a test pilot and engineer for [[Company:General Electric|General Electric]] when he was selected as part of Astronaut Group 2}}
|Gemini 9 Command Pilot{{efn|name=nine|group=note|See and Bassett were the original prime crew for Gemini 9, but were killed in a plane crash on February 28, 1966}}
|Gemini 5 Pilot
|-
|rowspan=4|Astronaut Group 3
|[[Biography:William Anders|William Anders]]
|rowspan=2|USAF
|{{n/a}}
|Gemini 11 Pilot
|-
|Charles Bassett
|Gemini 9 Pilot{{efn|name=nine|group=note}}
|{{n/a}}
|-
|Alan Bean
|USN
|{{n/a}}
|Gemini 10 Command Pilot
|-
|[[Astronomy:Clifton Williams|Clifton Williams]]
|USMC
|{{n/a}}
|Gemini 10 Pilot
|}

===Crew selection===
In late 1963, Slayton selected Shepard and Stafford for Gemini 3, McDivitt and White for Gemini 4, and Schirra and Young for Gemini 5 (which was to be the first Agena rendezvous mission). The backup crew for Gemini 3 was Grissom and Borman, who were also slated for Gemini 6, to be the first long-duration mission. Finally Conrad and Lovell were assigned as the backup crew for [[Astronomy:Gemini 4|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 became the backup crew for Shepard and Stafford. Grissom and Borman then had their long-duration mission assigned to Gemini 5.

The second rearrangement occurred when Shepard developed [[Medicine:Ménière's disease|Ménière's disease]], an inner ear problem. Grissom was then moved to command Gemini 3. Slayton felt that Young was a better personality match with Grissom and switched Stafford and Young. Finally, Slayton tapped Cooper to command the long-duration Gemini 5. Again for reasons of compatibility, he moved Conrad from backup commander of Gemini 4 to pilot of Gemini 5, and Borman to backup command of Gemini 4. Finally he assigned Armstrong and Elliot See to be the backup crew for Gemini 5.
The third rearrangement of crew assignment occurred when Slayton felt that See wasn't up to the physical demands of EVA on Gemini 8. He reassigned See to be the prime commander of Gemini 9 and put 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 See and Bassett when their trainer jet crashed, coincidentally into a McDonnell building which held their Gemini 9 capsule in St. Louis. The backup crew of Stafford and Cernan was then moved up to the new prime crew of Gemini 9A. Lovell and 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 Roger Chaffee in the fire of [[Engineering:Apollo 1|Apollo 1]], this final arrangement helped determine the makeup of the first seven Apollo crews, and who would be in position for a chance to be the first to walk on the Moon.

==Missions==
[[File:Gemini 5 control room.jpg|thumb|right|Gemini Mission Control in Houston during Gemini 5]]
In April 1964 and January 1965, two Gemini missions were flown without crews to test systems and the heat shield. These were followed by 10 flights with crews in 1965 and 1966. All were launched by Titan II launch vehicles. Some highlights from the Gemini program:
*  [[Astronomy:Gemini 3|Gemini 3]] (Grissom and Young) was the first crewed Gemini mission, first multi-crewed US mission, and the first crewed spacecraft to use thrusters to change its orbit.
* On [[Astronomy:Gemini 4|Gemini 4]], [[Astronomy:Ed White (astronaut)|Ed White]] became the first American to make an [[Astronomy:Extravehicular activity|extravehicular activity]] (EVA, or "spacewalk") on June 3, 1965.
*[[Astronomy:Gemini 5|Gemini 5]] (August 21–29, 1965) demonstrated the 8-day endurance necessary for an Apollo lunar mission with the first use of [[Physics:Fuel cell|fuel cell]]s to generate its electrical power.
*[[Astronomy:Gemini 6A|Gemini 6A]] accomplished the first [[Astronomy:Space rendezvous|space rendezvous]] with its sister craft [[Astronomy:Gemini 7|Gemini 7]] in December 1965, with Gemini 7 setting a 14-day endurance record for its flight.
*[[Astronomy:Gemini 8|Gemini 8]] achieved the first [[Engineering:Docking and berthing of spacecraft|space docking]] with an uncrewed Agena target vehicle.
*[[Astronomy:Gemini 10|Gemini 10]] established that radiation at high altitude was not a problem, further demonstrated the ability to rendezvous with a passive object, and was the first Gemini mission to fire the Agena's own rocket. Michael Collins would be the first person to meet another spacecraft in orbit, during his second successful EVA.
*[[Astronomy:Gemini 11|Gemini 11]] first direct-ascent (first orbit) rendezvous with an Agena Target Vehicle, docking with it 1 hour 34 minutes after launch. Set a crewed Earth orbital altitude record of {{convert|739.2|nmi|km}} in September 1966, using the Agena target vehicle's propulsion system. This record still stands as of 2022.<ref name="Dumoulin">{{Citation
  | first = Jim
  | last = Dumoulin
  | title = NASA Project Gemini-XI
  | date = August 25, 2000
  | url = http://science.ksc.nasa.gov/history/gemini/gemini-xi/gemini-xi.html
  | access-date = April 12, 2010
  | archive-date = September 18, 2018
  | archive-url = https://web.archive.org/web/20180918011350/https://science.ksc.nasa.gov/history/gemini/gemini-xi/gemini-xi.html
  | url-status = dead
  }}</ref>
*On [[Astronomy:Gemini 12|Gemini 12]], [[Biography:Buzz Aldrin|Edwin "Buzz" Aldrin]] became the first space traveler to prove that useful work ([[Astronomy:Extravehicular activity|EVA]]) could be done outside a spacecraft without life-threatening exhaustion, due to newly implemented footholds, handholds, and scheduled rest periods.

Rendezvous in orbit is not a straightforward maneuver. Should a spacecraft increase its speed to catch up with another, the result is that it goes into a higher and slower orbit and the distance thereby increases. The right procedure is to go to a lower orbit first and which increases relative speed, and then approach the target spacecraft from below and decrease orbital speed to meet it.<ref name="rendezAldrin">{{cite web|author=Buzz Aldrin|publisher=Buzz Aldrin's Share Space Foundation|url= http://buzzaldrin.com/space-vision/rocket_science/orbital-rendezvous/|title=Orbital Rendezvous|date= Fall 2005|access-date=2011-10-09}}</ref> To practice these maneuvers, special rendezvous and docking simulators were built for the astronauts.<ref name="rendezSim">{{cite web |publisher=NASA |url=https://history.nasa.gov/SP-4002/p1b.htm  |title=NASA, Project Gemini|access-date=2011-10-14|archive-url=https://web.archive.org/web/20041107093750/https://history.nasa.gov/SP-4002/p1b.htm|archive-date=2004-11-07}}</ref>

<gallery widths="180" heights="180">
File:Ed White with Space Gun maneuvering unit.jpg|Edward White during spacewalk, Gemini 4, June 1965
File:Gemini 7 in orbit - GPN-2006-000035.jpg|Rendezvous of Gemini 6A and 7, December 1965
File:The First Docking in Space - GPN-2000-001344.jpg|First docking; Agena target is seen from Gemini 8, March 1966
</gallery>
{| class="wikitable sortable" style="font-size:1.00em; line-height:1.5em;"
|- class="is-sticky"
! Mission
! [[Engineering:Launch vehicle|LV]]&nbsp;serial&nbsp;N<sup>o</sup>
!Spacecraft Nº
! Command&nbsp;Pilot
! Pilot
! Mission dates
! Launch&nbsp;time
! Duration
|-
| rowspan="2" | Gemini 1
| GLV-1 12556
|SC1
|Uncrewed
|Uncrewed
| 8–12 April 1964
| 16:00 [[Physics:Coordinated Universal Time|UTC]]
| 03d 23h<sup>1</sup>
|-
| colspan="7" |First test flight of Gemini; spacecraft was intentionally destroyed during re-entry<br><small>1: The mission duration was 4h 50m, sufficient to achieve all of the mission aims in three orbits; the spacecraft remained in orbit for 3d 23h.</small>
|-
| rowspan="2" | Gemini 2
| GLV-2 12557
|[[Engineering:Gemini SC-2|SC2]]
|Uncrewed
|Uncrewed
| 19 January 1965
| 14:04 UTC
| 00d 00h 18m 16s
|-
| colspan="7" |[[Engineering:Sub-orbital spaceflight|Suborbital flight]] to test heat shield
|-
| rowspan="2" | [[Astronomy:Gemini 3|Gemini 3]]<br /> [[Image:Gemini3.png|frameless|45px]]
| GLV-3 12558
|SC3
| Grissom
| Young
| 23 March 1965
| 14:24 UTC
| 00d&nbsp;04h 52m&nbsp;31s
|-
| colspan="7" | First crewed Gemini flight, three orbits.
|-
| rowspan="2" | [[Astronomy:Gemini 4|Gemini IV]] <br /> [[Image:Gemini Four patch.jpg|frameless|45px]]
| GLV-4 12559
|SC4
| McDivitt
| [[Astronomy:Ed White (astronaut)|White]]
| 3–7 June 1965
| 15:16 UTC
| 04d 01h 56m 12s
|-
| colspan="7" | Included first extravehicular activity (EVA) by an American; White's "space walk" was a 22-minute EVA exercise.
|-
| rowspan="2" | [[Astronomy:Gemini 5|Gemini V]]<br /> [[Image:Gemini5insignia.png|frameless|45px]]
| GLV-5 12560
|SC5
| Cooper
| [[Biography:Pete Conrad|Conrad]]
| 21–29 August 1965
| 14:00 UTC
| 07d 22h 55m 14s
|-
| colspan="7" | First week-long flight; first use of fuel cells for electrical power; evaluated guidance and navigation system for future rendezvous missions. Completed 120 orbits.
|-
| rowspan="2" | [[Astronomy:Gemini 7|Gemini VII]]<br /> [[Image:Gemini VII patch.png|frameless|45px]]
| GLV-7 12562
|SC7
| Borman
| [[Biography:Jim Lovell|Lovell]]
| 4–18 December 1965
| 19:30 UTC
| 13d 18h 35m 01s
|-
| colspan="7" | When the original Gemini VI mission was scrubbed because the launch of the Agena docking target failed, Gemini VII was used as the rendezvous target instead. Primary objective was to determine whether humans could live in space for 14 days. Completed 206 orbits.
|-
| rowspan="2" | [[Astronomy:Gemini 6A|Gemini&nbsp;VI-A]]<br /> [[Image:Gemini 6A patch.png|frameless|45px]]
| GLV-6 12561
|SC6
| [[Biography:Wally Schirra|Schirra]]
| Stafford
| 15–16 December 1965
| 13:37 UTC
| 01d 01h 51m 24s
|-
| colspan="7" | Rescheduled from October to rendezvous with Gemini VII after the original Agena Target Vehicle launch failed. First space rendezvous accomplished, station-keeping for over five hours at distances from {{convert|1|to|300|ft|m|sigfig=2}}. First musical instruments played in space; crew played "Jingle Bells" on a harmonica and a ring of small bells as part of a jocular Santa Claus sighting.<ref>[https://news.google.com/newspapers?id=e30yAAAAIBAJ&sjid=YrcFAAAAIBAJ&dq=gemini%20harmonica&pg=2397%2C6613483 "NASA Mum on 'Jingling'"]{{Dead link|date=October 2023 |bot=InternetArchiveBot |fix-attempted=yes }}, ''Palm Beach Post'', Dec 17, 1965</ref><ref>{{YouTube|id=HqfIEQKnkJU|title=The Song from Outer Space}}</ref>
|-
| rowspan="2" | [[Astronomy:Gemini 8|Gemini VIII]]<br /> [[Image:Ge08Patch orig.png|frameless|45px]]
| GLV-8 12563
|SC8
| Armstrong
| [[Biography:David Scott|Scott]]
| 16–17 March 1966
| 16:41 UTC
| 00d 10h 41m 26s
|-
| colspan="7" | Accomplished first docking with another space vehicle, an uncrewed Agena Target Vehicle. While docked, a Gemini spacecraft thruster malfunction caused near-fatal tumbling of the craft, which, after undocking, Armstrong was able to overcome; the crew effected the first emergency landing of a crewed U.S. space mission.
|-
| rowspan="2" | [[Astronomy:Gemini 9A|Gemini IX-A]]<br /> [[Image:Ge09Patch orig.png|frameless|45px]]
| GLV-9 12564
|SC9
| Stafford
| [[Biography:Gene Cernan|Cernan]]
| 3–6 June 1966
| 13:39 UTC
| 03d 00h 20m 50s
|-
| colspan="6" | Rescheduled from May to rendezvous and dock with the Augmented Target Docking Adapter (ATDA) after the original Agena Target Vehicle launch failed. The ATDA shroud did not completely separate, making docking impossible (right). Three different types of rendezvous, two hours of EVA, and 44 orbits were completed. ||[[File:Gemini 9 Docking target.jpg|100px]]
|-
| rowspan="2" | [[Astronomy:Gemini 10|Gemini X]]<br /> [[Image:Gemini 10 mission patch original.png|frameless|45px]]
| GLV-10 12565
|SC10
| Young
| Collins
| 18–21 July 1966
| 22:20 UTC
| 02d 22h 46m 39s
|-
| colspan="7" | First use of the Agena Target Vehicle's propulsion systems. The spacecraft also rendezvoused with the Agena Target Vehicle from Gemini VIII. Collins had 49 minutes of EVA standing in the hatch and 39 minutes of EVA to retrieve experiments from the Agena. 43 orbits completed.
|-
| rowspan="2" | [[Astronomy:Gemini 11|Gemini XI]]<br /> [[Image:Gemini 11 patch.png|frameless|45px]]
| GLV-11 12566
|SC11
| [[Biography:Pete Conrad|Conrad]]
| [[Biography:Richard F. Gordon Jr.|Gordon]]
| 12–15 September 1966
| 14:42 UTC
| 02d 23h 17m 09s
|-
| colspan="7" | Gemini record altitude with apogee of {{convert|739.2|nmi|km}}<ref name="Dumoulin" /> reached using the Agena Target Vehicle propulsion system after first orbit rendezvous and docking. Gordon made a 33-minute EVA and two-hour standup EVA. 44 orbits.
|-
| rowspan="2" | [[Astronomy:Gemini 12|Gemini XII]]<br /> [[Image:Gemini 12 insignia.png|frameless|45px]]
| GLV-12 12567
|SC12
| [[Biography:Jim Lovell|Lovell]]
| [[Biography:Buzz Aldrin|Aldrin]]
| 11–15 November 1966
| 20:46 UTC
| 03d 22h 34m 31s
|-
| colspan="7" | Final Gemini flight. Rendezvoused and docked manually with the target Agena and kept station with it during EVA. Aldrin set an EVA record of 5 hours and 30 minutes for one space walk and two stand-up exercises, and demonstrated solutions to previous EVA problems. 59 orbits completed
|}

==Gemini-Titan launches and serial numbers==
{{multiple image
| align     = right
| direction = horizontal
| header    =
| footer    = Left: All Gemini launches from GT-1 through GT-12. Right: USAF serial number location on Titan II
| image1    = Gemini Profiles.jpg
| width1    = 290
| alt1      = All Gemini Launches from GT-1 through GT-12
| caption1  =
| image2    = GPN-2000-000612.jpg
| width2    = 100
| alt2      = USAF serial number location on Titan II
| caption2  =
}}

The Gemini-Titan II launch vehicle was adapted by NASA from the U.S. Air Force Titan II ICBM. (Similarly, the [[Engineering:Atlas LV-3B|Mercury-Atlas]] launch vehicle had been adapted from the USAF [[Engineering:SM-65 Atlas|Atlas missile]].) The Gemini-Titan II rockets were assigned 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). USAF crews maintained Launch Complex 19 and prepared and launched all of the Gemini-Titan II launch vehicles. Data and experience operating the Titans was of value to both the U.S. Air Force and NASA.

The USAF serial numbers assigned to the Gemini-Titan launch vehicles are given in the tables above. Fifteen Titan IIs were ordered in 1962 so the serial is "62-12XXX", but only "12XXX" is painted on the Titan II. The order for the last three of the 15 launch vehicles was canceled on July 30, 1964, and they were never built. Serial numbers were, however, assigned to them prospectively: ''12568'' - GLV-13; ''12569'' - GLV-14; and ''12570'' - GLV-15.

==Program cost==
From 1962 to 1967, Gemini cost $1.3 billion in 1967 dollars (${{format price|{{Inflation|US-GDP|1300000000|1967|r=2}}}} in {{Inflation-year|US-GDP}}{{inflation-fn|US-GDP}}).<ref name="lafleur20100308">{{cite news | url=http://www.thespacereview.com/article/1579/1 | title=Costs of US piloted programs | work=The Space Review | date=2010-03-08 | access-date=February 18, 2012 | author=Lafleur, Claude}}</ref> In January 1969, a NASA report to the US Congress estimating the costs for Mercury, Gemini, and Apollo (through the first crewed Moon landing) included $1.2834 billion for Gemini: $797.4 million for spacecraft, $409.8 million for launch vehicles, and $76.2 million for support.<ref>{{cite book
  | last = Wilford
  | first = John Noble
  | title = We Reach the Moon
  | url = https://archive.org/details/wereachmoonnewyo00wilf
  | url-access = registration
  | publisher = Bantam Books
  | date = July 1969
  | location = New York
  | page = [https://archive.org/details/wereachmoonnewyo00wilf/page/67 67]
  }}
</ref>

==Current location of hardware==

===Spacecraft===
* Gemini 1: Intentionally disintegrated upon re-entry to the atmosphere
* Gemini 2: {{wipe|Air Force Space and Missile Museum}}, {{wipe|Cape Canaveral Air Force Station}}, Florida
* Gemini III: Grissom Memorial, Spring Mill State Park, Mitchell, Indiana
* Gemini IV: National Air and Space Museum, Washington, D.C.
* Gemini V: [[Organization:Johnson Space Center|Johnson Space Center]], NASA, Houston, Texas
* Gemini VI: Stafford Air & Space Museum, Weatherford, Oklahoma
* Gemini VII: Steven F. Udvar-Hazy Center, Chantilly, Virginia
* Gemini VIII: Armstrong Air and Space Museum, Wapakoneta, Ohio
* Gemini IX: Kennedy Space Center, NASA, Merritt Island, Florida
* Gemini X: Kansas Cosmosphere and Space Center, Hutchinson, Kansas
* Gemini XI: California Museum of Science and Industry, Los Angeles, California
* Gemini XII: Adler Planetarium, Chicago, Illinois

<gallery widths="185" mode="packed">
Gemini2x.jpg|''Gemini 2'' at Air Force Space and Missile Museum in 2006
Gemini3 Capsule.jpg|''Gemini III'' at Grissom Memorial in 2011
Gemini IV Capsule.jpg|''Gemini IV'' at National Air and Space Museum in 2009
Gemini V Space Center Houston.JPG|''Gemini V'' at Johnson Space Center in 2011
Gemini VI-A Oklahoma History Center.JPG|''Gemini VI-A'' at Stafford Air & Space Museum in 2011
Gemini VII Capsule.jpg|''Gemini VII'' at Steven F. Udvar-Hazy Center in 2009
Gemini VIII Capsule.jpg|''Gemini VIII'' at Armstrong Air and Space Museum in 2010
Gemini IX-A Kennedy Space Center.JPG|''Gemini IX-A'' at Kennedy Space Center in 2011
Gemini X Capsule.jpg|''Gemini X'' at Kansas Cosmosphere and Space Center in 2010
Gemini 11 capsule (front) at California Science Center.jpg|''Gemini XI'' at California Museum of Science and Industry in 2013
Gemini XII Capsule.jpg|''Gemini XII'' at Adler Planetarium in 2010
</gallery>

===Trainers and boilerplates===
* Gemini 3A (2411): St. Louis Science Center, St. Louis, Missouri.<ref>{{Cite web |title=St. Louis Science Center |url=http://heroicrelics.org/slsc/index.html |access-date=2023-05-25 |website=heroicrelics.org}}</ref><ref>{{Cite web |date=2019-04-08 |title=A Field Guide to American Spacecraft |url=http://www.americanspacecraft.com/pages/gemini/gem-3a.html |access-date=2023-09-20 |archive-url=https://web.archive.org/web/20190408182829/http://www.americanspacecraft.com/pages/gemini/gem-3a.html |archive-date=2019-04-08 }}</ref>
* Gemini MOL-B (2411): National Museum of the United States Air Force, Wright-Patterson Air Force Base, Dayton, Ohio<ref>{{Cite web |date=2019-03-14 |title=A Field Guide to American Spacecraft {{!}} Gemini MOL-B |url=http://americanspacecraft.com/pages/gemini/gem-molb.html |access-date=2023-09-20 |archive-url=https://web.archive.org/web/20190314002254/http://americanspacecraft.com/pages/gemini/gem-molb.html |archive-date=2019-03-14 }}</ref>
* Gemini Mission Simulator (5143): U.S. Space & Rocket Center, Huntsville, Alabama<ref>{{Cite web |date=2019-04-10 |title=A Field Guide to American Spacecraft |url=http://www.americanspacecraft.com/pages/gemini/GemSRCTr.html |access-date=2023-09-20 |archive-url=https://web.archive.org/web/20190410005334/http://www.americanspacecraft.com/pages/gemini/GemSRCTr.html |archive-date=2019-04-10 }}</ref>
* Gemini Trainer: Discovery Center, Fresno, California
* Gemini Trainer: Kentucky Science Center, Louisville, Kentucky<ref>{{Cite web |date=2019-04-08 |title=A Field Guide to American Spacecraft |url=http://www.americanspacecraft.com/pages/gemini/GemLSCTr.html |access-date=2023-09-20 |archive-url=https://web.archive.org/web/20190408190805/http://www.americanspacecraft.com/pages/gemini/GemLSCTr.html |archive-date=2019-04-08 }}</ref>
* Gemini Water Egress Trainer: Texas Air Museum, Slaton, Texas<ref>{{cite web | url=https://thetexasairmuseum.org/exhibits/ | title=Exhibits – Texas Air Museum }}</ref>
* Gemini Trainer: Kalamazoo Air Museum, Kalamazoo, Michigan<ref>{{Cite web |date=2019-04-08 |title=A Field Guide to American Spacecraft |url=http://www.americanspacecraft.com/pages/gemini/Sit-in.html |access-date=2023-09-20 |archive-url=https://web.archive.org/web/20190408191205/http://www.americanspacecraft.com/pages/gemini/Sit-in.html |archive-date=2019-04-08 }}</ref>
* Trainer: Pate Museum of Transportation, Fort Worth, Texas<ref>{{Cite web |date=2019-04-10 |title=A Field Guide to American Spacecraft |url=http://www.americanspacecraft.com/pages/gemini/mod-pate.html |access-date=2023-09-20 |archive-url=https://web.archive.org/web/20190410003842/http://www.americanspacecraft.com/pages/gemini/mod-pate.html |archive-date=2019-04-10 }}</ref>
* GATV (6165): National Air and Space Museum, Washington, D.C. (not on display)<ref>[https://web.archive.org/web/20180919111426/https://airandspace.si.edu/collection-objects/target-adapter-agena https://airandspace.si.edu/collection-objects/target-adapter-agena] (Wayback Machine 2018-09-19)</ref><ref>{{Cite web |date=2019-03-28 |title=A Field Guide to American Spacecraft {{!}} Gemini Index |url=http://americanspacecraft.com/pages/gemini/index.html |access-date=2023-09-20 |archive-url=https://web.archive.org/web/20190328125555/http://americanspacecraft.com/pages/gemini/index.html |archive-date=2019-03-28 }}</ref>
* El Kabong: Kalamazoo Air Museum, Kalamazoo, Michigan<ref>{{Cite web |date=2019-03-22 |title=A Field Guide to American Spacecraft |url=http://www.americanspacecraft.com/pages/gemini/elkabong.html |access-date=2023-09-20 |archive-url=https://web.archive.org/web/20190322160200/http://www.americanspacecraft.com/pages/gemini/elkabong.html |archive-date=2019-03-22 }}</ref>
* MSC 312: Private residence, Holden, MA<ref>{{Cite web |date=2019-03-29 |title=A Field Guide to American Spacecraft |url=http://www.americanspacecraft.com/pages/gemini/holdenbp.html |access-date=2023-09-20 |archive-url=https://web.archive.org/web/20190329065217/http://www.americanspacecraft.com/pages/gemini/holdenbp.html |archive-date=2019-03-29 }}</ref>
* MSC 313: Private residence, San Jose, California<ref>{{Cite web |date=2019-04-10 |title=A Field Guide to American Spacecraft |url=http://www.americanspacecraft.com/pages/gemini/sanjosebp.html |access-date=2023-09-20 |archive-url=https://web.archive.org/web/20190410020805/http://www.americanspacecraft.com/pages/gemini/sanjosebp.html |archive-date=2019-04-10 }}</ref>
* Paresev 1A (Rogallo Test Vehicle): Steven F. Udvar-Hazy Center, Chantilly, Virginia
* TTV-1 (6873) paraglider capsule: Steven F. Udvar-Hazy Center, Chantilly, Virginia<ref>{{Cite web |date=2019-04-08 |title=A Field Guide to American Spacecraft |url=http://www.americanspacecraft.com/pages/gemini/ttv-1.html |access-date=2023-09-20 |archive-url=https://web.archive.org/web/20190408192114/http://www.americanspacecraft.com/pages/gemini/ttv-1.html |archive-date=2019-04-08 }}</ref>
* TTV-2 paraglider capsule: Museum of Scotland, [[Place:Edinburgh|Edinburgh]]<ref>{{Cite web |date=2019-04-01 |title=A Field Guide to American Spacecraft |url=http://www.americanspacecraft.com/pages/gemini/TTV-2.html |access-date=2023-09-20 |archive-url=https://web.archive.org/web/20190401192051/http://www.americanspacecraft.com/pages/gemini/TTV-2.html |archive-date=2019-04-01 }}</ref>
* Gemini boilerplate: {{wipe|Air Force Space and Missile Museum}}, Cape Canaveral Space Force Station, Florida<ref>{{Cite web |date=2019-04-08 |title=A Field Guide to American Spacecraft |url=http://www.americanspacecraft.com/pages/gemini/cc-bp.html |access-date=2023-09-20 |archive-url=https://web.archive.org/web/20190408194753/http://www.americanspacecraft.com/pages/gemini/cc-bp.html |archive-date=2019-04-08 }}</ref>
* Gemini boilerplate: {{wipe|Air Force Space and Missile Museum}}, Cape Canaveral Space Force Station, Florida<ref>{{Cite web |date=2019-04-10 |title=A Field Guide to American Spacecraft |url=http://www.americanspacecraft.com/pages/gemini/cc-bp2.html |access-date=2023-09-20 |archive-url=https://web.archive.org/web/20190410020859/http://www.americanspacecraft.com/pages/gemini/cc-bp2.html |archive-date=2019-04-10 }}</ref>
* Ingress/Egress Trainer: U.S. Space & Rocket Center, Huntsville, Alabama<ref>{{Cite web |title=U.S. Space and Rocket Center |url=http://heroicrelics.org/ussrc/index.html |access-date=2023-05-25 |website=heroicrelics.org}}</ref><ref>{{Cite web |date=2019-03-20 |title=A Field Guide to American Spacecraft |url=http://www.americanspacecraft.com/pages/gemini/hof-gem.html |access-date=2023-09-20 |archive-url=https://web.archive.org/web/20190320123856/http://www.americanspacecraft.com/pages/gemini/hof-gem.html |archive-date=2019-03-20 }}</ref>
* MSC-307: USS ''Hornet'' Museum, former NAS Alameda, Alameda, California<ref>{{Cite web |date=2019-04-08 |title=A Field Guide to American Spacecraft |url=http://www.americanspacecraft.com/pages/gemini/bp-hornet.html |access-date=2023-09-20 |archive-url=https://web.archive.org/web/20190408192109/http://www.americanspacecraft.com/pages/gemini/bp-hornet.html |archive-date=2019-04-08 }}</ref>
<gallery mode="packed">
File:Gemini-B.jpg|Gemini MOL-B,  National Museum of the United States Air Force.
File:Gemini Mission Simulator.JPG|Gemini Mission Simulator, U.S. Space & Rocket Center.
File:Gemini Trainer at the TAM.jpg|Gemini Water Egress Trainer, Texas Air Museum.
File:Air Zoo December 2019 101 (Gemini crew trainer).jpg|Gemini Trainer, Kalamazoo Air Museum.
File:Air Zoo December 2019 102 (El Kabong I Gemini boilerplate).jpg|El Kabong, Kalamazoo Air Museum.
File:NASA Paresev Gemini Paraglider Research Vehicle I-A ‘N9765C’ (51281690231).jpg|Paresev 1A, Steven F. Udvar-Hazy Center.
File:Gemini TTV-1 Paraglider Capsule.jpg|TTV-1, Steven F. Udvar-Hazy Center.
File:Paraglider Gemini spacecraft.jpg|TTV-2, Museum of Scotland.
File:GeminiBP.jpg|Gemini boilerplate, {{wipe|Air Force Space & Missile Museum}}.
File:USS Hornet Museum - 0034.jpg|MSC-307, USS ''Hornet'' Museum  
</gallery>

=== Mockups and models ===
A number of detailed Gemini models and mockups are on display:<ref>{{Cite web |date=2019-03-28 |title=A Field Guide to American Spacecraft {{!}} Gemini Index |url=http://americanspacecraft.com/pages/gemini/index.html |access-date=2023-09-20 |archive-url=https://web.archive.org/web/20190328125555/http://americanspacecraft.com/pages/gemini/index.html |archive-date=2019-03-28 }}</ref>

* Gemini Model - Intrepid Sea, Air & Space Museum, New York, NY
* Gemini Model - The Discovery Center, Fresno, CA
* Gemini Model (built for From the Earth to the Moon)- Evergreen Aviation Museum, McMinnville, Oregon
* Gemini Sit-in Model - KSC Visitors Center, Kennedy Space Center FL
* Gemini Model - Science Museum Oklahoma, Oklahoma City, OK
* Gemini Model (made by McDonnell) - [[Company:Boeing|Boeing Prologue Room]], St. Louis, MO
* Gemini Model (made by McDonnell) - Museum of Science & Industry, Chicago, IL
* Gemini Sit-in Model - Neil Armstrong Air and Space Museum, Wapakoneta, OH
* Gemini Mockup (winner of the 1967 Revell contest) - Oregon Museum of Science and Industry, Portland, OR
* Gemini Model (made by McDonnell) - San Diego Air & Space Museum, San Diego, CA 
* Gemini Model - Stafford Air & Space Museum, Weatherford, OK
<gallery mode="packed">
File:At the Intrepid Museum 2023 192.jpg|Gemini model, Intrepid Sea, Air & Space Museum.
File:Gemini Capsule Reproduction (6586731511) (8).jpg|Gemini model, Evergreen Aviation Museum.
File:Florida by Piotrus 207.JPG|Gemini sit-in model, KSC Visitors Center.
File:Gemini-replica-armstrong-museum.jpg|Gemini sit-in model, Neil Armstrong Air and Space Museum.
File:Space exhibit - Oregon Air and Space Museum - Eugene, Oregon - DSC09771.jpg|Gemini mockup, Oregon Air and Space Museum.
File:Stafford Air & Space Museum, Weatherford, OK, US (89).jpg|Gemini model, Stafford Air & Space Museum.  
</gallery>

==Proposed extensions and applications==

===Advanced Gemini===
{{main|Engineering:Advanced Gemini}}
[[File:MOL USAF.png|thumb|Illustration of a Gemini B reentry vehicle separating from the Manned Orbiting Laboratory (MOL).]]
McDonnell Aircraft, the main contractor for Mercury and Gemini, was also one of the original bidders on the prime contract for Apollo, but lost out to [[Company:North American Aviation|North American Aviation]]. McDonnell later sought to extend the Gemini program by proposing a derivative which could be used to fly a [[Astronomy:Outer space|cislunar]] mission and even achieve a crewed lunar landing earlier and at less cost than Apollo, but these proposals were rejected by NASA.

A range of applications were considered for Advanced Gemini missions, including military flights, space station crew and logistics delivery, and lunar flights. The Lunar proposals ranged from reusing the docking systems developed for the Agena Target Vehicle on more powerful upper stages such as the Centaur, which could propel the spacecraft to the Moon, to complete modifications of the Gemini to enable it to land on the lunar surface. Its applications would have ranged from crewed lunar flybys before Apollo was ready, to providing emergency shelters or rescue for stranded Apollo crews, or even replacing the Apollo program.

Some of the Advanced Gemini proposals used "off-the-shelf" Gemini spacecraft, unmodified from the original program, while others featured modifications to allow the spacecraft to carry more crew, dock with space stations, visit the Moon, and perform other mission objectives. Other modifications considered included the addition of wings or a parasail to the spacecraft, in order to enable it to make a horizontal landing.

===Big Gemini===
{{Main|Engineering:Big Gemini}}
[[File:Big Gemini.png|thumb|Big Gemini concept space station supply ship.]]
Big Gemini (or "Big G") was another proposal by McDonnell Douglas made in August 1969. It was intended to provide large-capacity, all-purpose access to space, including missions that ultimately used Apollo or the Space Shuttle.

The study was performed to generate a preliminary definition of a logistic spacecraft derived from Gemini that would be used to resupply an orbiting space station. Land-landing at a preselected site and refurbishment and reuse were design requirements. Two baseline spacecraft were defined: a nine-man minimum modification version of the Gemini B called Min-Mod Big G and a 12-man advanced concept, having the same exterior geometry but with new, state-of-the-art subsystems, called Advanced Big G.<ref>{{cite web|title=The Big G|author=Dwayne Day|date=December 7, 2015|url=https://www.thespacereview.com/article/2879/1
|publisher=The Space Review|access-date=March 20, 2023}}</ref> Three launch vehicles-[[Astronomy:Saturn IB|Saturn IB]], [[Engineering:Titan (rocket family)|Titan IIIM]], and [[Astronomy:Saturn INT-20|Saturn INT-20]] (S-IC/S-IVB) were investigated for use with the spacecraft.

===Military applications===
The Air Force had an interest in the Gemini system, and decided to use its own modification of the spacecraft as the crew vehicle for the Manned Orbital Laboratory. To this end, the Gemini 2 spacecraft was refurbished and flown again atop a mockup of the MOL, sent into space by a Titan IIIC. This was the first time a spacecraft went into space twice.

The USAF also thought of adapting the Gemini spacecraft for 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 [[Engineering:Blue Gemini|Blue Gemini]]. The USAF 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 airfoil and land on three skids, carried over 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 Gemini by itself. Blue Gemini was canceled in 1963 by Secretary of Defense Robert McNamara, who decided the NASA Gemini flights could conduct necessary military experiments. MOL was canceled by Secretary of Defense Melvin Laird in 1969, when it was determined that uncrewed spy satellites could perform the same functions much more cost-effectively.

==In media==
* Two Gemini capsules (codenamed "Jupiter" instead of "Gemini") are featured in the plot of the 1967 ''James Bond'' film ''You Only Live Twice''.
* A modified one-person Gemini capsule is used to send an astronaut (played by James Caan) to the Moon in the 1968 film ''Countdown''.
* Gemini missions 4, 8 and 12 feature in the first episode of the HBO series ''From the Earth to the Moon'
*Like other US space programs, Gemini was covered in the 1985 PBS series "Spaceflight"
* Some aspects of the Gemini program relating to astronaut Neil Armstrong were touched upon in the 2018 film ''First Man''.
* Many episodes of the television show ''I Dream of Jeannie'' featured launch pad and launch footage of various Gemini missions.
* [[Gemini (protocol)|Gemini]], is a [[Application layer|layer 7]] telecom standard named after the Gemini missions.  Its non-standard [[Port (computer networking)#Port number|port number]], 1965, is a reference to the first mission date.

==See also==
* [[Engineering:List of crewed spacecraft|List of crewed spacecraft]]
* Splashdown (spacecraft landing)
* [[Physics:Timeline of hydrogen technologies|Timeline of hydrogen technologies]]
* US space exploration history on US stamps

==References==

===Notes===
{{reflist|group="Note"|colwidth=30em}}

{{reflist|group=note}}

===Citations===
{{Include-NASA}}
{{reflist|2}}

===Books===
* {{Cite book
   | last1       = Farmer
   | first1      = Gene
   | last2       = Hamblin
   | first2      = Dora Jane
   | title       = First On the Moon: A Voyage With Neil Armstrong, Michael Collins and Edwin E. Aldrin, Jr.
   | publisher   = Little, Brown and Company
   | year        = 2004
   | location    = Boston
   | isbn        = 978-0-7607-5510-5
}}
* {{Cite book |last1       = French
 |first1      = Francis
 |last2       = Brugess
 |first2      = Colin
 |title       = In the Shadow of the Moon: A Challenging Journey to Tranquility, 1965–1969
 |publisher   = University of Nebraska
 |year        = 2007
 |location    = Lincoln, Nebraska
 |isbn        = 978-0-8032-1128-5
 |url-access  = registration
 |url         = https://archive.org/details/inshadowofmoonch0000fren
}}
* {{cite book |last1     = Gainor
 |first1    = Chris
 |title     = Arrows to the Moon: Avro's Engineers and the Space Race
 |publisher = Apogee Books
 |location  = Burlington, Ontario
 |isbn      = 978-1-896522-83-8
 |year      = 2001
 |url       = https://archive.org/details/arrowstomoonavro0000gain
}}
* {{cite book
 | last = Gatland
 | first = Kenneth
 | title = Manned Spacecraft
 | edition = Second
 | publisher = Macmillan
 | location = New York
 | year            = 1976
 }}
* {{cite book
   | last1           = Hacker
   | first1          = Barton C.
   | last2           = Grimwood
   | first2          = James M.
   | year            = 1977
   | title           = On the Shoulders of Titans: A History of Project Gemini
   | series          = NASA SP-4203
   | publisher       = National Aeronautics and Space Administration
   | location        = Washington, D.C.
   | url             = https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19780012208_1978012208.pdf
   | access-date      = 2015-01-02
  }}
* {{cite book
   | last1           = Harland
   | first1          = David M.
   | year            = 2004
   | title           = How NASA Learned to Fly in Space: An Exciting Account of the Gemini Missions
   | publisher       = Apogee Books
   | location        = Burlington, Ontario
   | url             = https://books.google.com/books?id=_mxYAAAAYAAJ&q=editions:BqbnF_7z4jUC
   | access-date      = 2015-01-03
   | isbn            = 978-1-894959-07-0
}}
* {{cite book
   | last1           = Kranz
   | first1          = Gene
   | year            = 2001
   | title           = Failure Is Not an Option: Mission Control from Mercury to Apollo 13 and Beyond
   | publisher       = Simon & Schuster
   | location        = New York
   | url             = https://archive.org/details/isbn_9780743200790
   | url-access      = registration
   | access-date      = 2015-01-03
   | isbn            = 978-0-7432-0079-0
}}
* {{cite book
   | last1           = Murray
   | first1          = Charles A.
   | last2           = Cox
   | first2          = Catherine Bly
   | year            = 1989
   | title           = Apollo: The Race to the Moon
   | location        = New York
   | publisher       = Simon & Schuster
   | isbn            = 978-0-671-61101-9
}}
* Shayler, David J.  ''Gemini'', Springer-Verlag Telos, 2001, {{ISBN|1-85233-405-3}}
* {{cite book
   | last1           = Tomayko
   | first1          = James E.
   | year            = 1988
   | title           = Computers in Spaceflight: The NASA Experience
   | chapter         = The Gemini Digital Computer: First Machine in Orbit
   | publisher       = National Aeronautics and Space Administration
   | location        = Washington, D.C.
   | url             = https://history.nasa.gov/computers/ch1-1.html
   | access-date      = 2015-01-04
}}

===Articles===
* {{cite journal
  | last             = Agle
  | first            = D.C.
  | title            = Flying the Gusmobile
  | journal          = Air and Space Magazine
  | volume           = 12
  | issue            = 4
  | location         = Washington, D.C.
  | publisher        = Smithsonian Institution
  | url              = http://www.airspacemag.com/flight-today/flying-the-gusmobile-218187/?all
  | access-date       = 2015-01-03
  | date             = September 1998
 }}
* {{cite journal
  | last             = Agle
  | first            = D.C.
  | title            = Riding the Titan II
  | journal          = Air and Space Magazine
  | volume           = 12
  | issue            = 4
  | publisher        = Smithsonian Institution
  | location         = Washington, D.C.
  | url              = http://www.airspacemag.com/flight-today/riding-the-titan-ii-223545/
  | access-date       = 2015-01-03
  | date             = September 1998a
 }}
* {{cite web
 |last1       = Burkey
 |first1      = Ronald
 |title       = Gemini Spacecraft On-Board Computer (OBC)
 |url         = http://www.ibiblio.org/apollo/Gemini.html
 |access-date  = 2015-01-04
 |archive-url  = https://web.archive.org/web/20141215051553/http://www.ibiblio.org/apollo/Gemini.html
 |archive-date = 2014-12-15
 |url-status     = live
 |date        = 2012-01-08
}}
* {{cite journal
  | last             = Dryden
  | first            = Hugh
  | title            = Footprints on the Moon
  | journal          = National Geographic Magazine
  | volume           = 125
  | issue            = 3
  | pages            = 357–401
  | publisher        = [[Organization:National Geographic Society|National Geographic Society]]
  | location         = Washington, D.C.
  | url              = http://ngm-beta.nationalgeographic.com/archive/footprints-on-the-moon/
  | access-date       = 2015-01-04
  | date             = March 1964
* {{cite web
 |last1       = Loff
 |first1      = Sarah
 |title       = Gemini: Stepping Stone to the Moon
 |url         = http://www.nasa.gov/mission_pages/gemini/#.VKi1GsaWt78
 |website     = Gemini: Bridge to the Moon
 |publisher   = National Aeronautics and Space Administration
 |access-date  = 2015-01-04
 |archive-url  = https://web.archive.org/web/20141221151510/http://www.nasa.gov/mission_pages/gemini/
 |archive-date = 2014-12-21
 |location    = Washington, D.C.
 |date        = 2013-10-21
 |url-status     = dead
}}
* {{cite news
   | last1           = Reguly
   | first1          = Robert
   | title           = Canadians who helped Gemini 'Go'
   | work            = Toronto Daily Star
   | date            = 1965-09-03
   | location        = Toronto
   | page            = 7
}}
* [https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19690027123_1969027123.pdf Project Gemini&nbsp;—A Chronology (NASA report SP-4002) (PDF format)]
* [https://www.scribd.com/doc/11483899/Gemini-Mid-Program-Conference-Including-Experiment-Results Gemini Midprogram Conference&nbsp;—Including Experiment Results (NASA report SP-121)&nbsp;—Manned Spacecraft Center&nbsp;—Houston, Texas, February 23–25, 1966]
* Gemini Summary Conference (NASA report SP-138)&nbsp;—Manned Spacecraft Center&nbsp;—Houston, Texas, February 1–2, 1967

==External links==
{{Commons}}
* [https://www.nasa.gov/mission_pages/gemini/index.html NASA Project Gemini images and videos]
* [http://science.ksc.nasa.gov/history/gemini/gemini.html NASA Project Gemini science site] {{Webarchive|url=https://web.archive.org/web/20110604073400/http://science.ksc.nasa.gov/history/gemini/gemini.html |date=2011-06-04 }}
* [http://www.hq.nasa.gov/office/pao/History/diagrams/gemini.html Project Gemini Drawings and Technical Diagrams] {{Webarchive|url=https://web.archive.org/web/20210117182710/https://www.hq.nasa.gov/office/pao/History/diagrams/gemini.html |date=2021-01-17 }}
* [http://www.ibiblio.org/mscorbit/document.html Gemini familiarization Manuals (PDF format).]
* [https://history.nasa.gov/series95.html NASA History Series Publications] (many of which are on-line)
* [https://web.archive.org/web/20121004235603/http://www.umsl.edu/%7Ewhmc/exhibits/gemini/index.htm Project Gemini McDonnell Employee Video Interviews and Archival Documents: Western Historical Manuscripts Collection in St. Louis, Missouri]

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[[Category:Engineering projects|Gemini]]
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