View source for Gemini 11

{{Short description|1966 NASA crewed spaceflight}}
{{Use American English|date=January 2014}}
{{Infobox spaceflight
| name               = Gemini XI
| image              = Gemini 11 Agena.jpg
| image_caption      = Gemini XI conducting a tether experiment using the Agena Target Vehicle
| mission_type       = {{Unbulleted list
   | [[Space rendezvous]]
   | [[Docking and berthing of spacecraft|Spacecraft docking]]
   | [[Extravehicular activity]]
   }}
| operator           = [[NASA]]
| mission_duration   = {{Time interval|September 12, 1966, 14:42:26|September 15, 1966, 13:59:35|show=dhms}}
| orbits_completed   = 44
| spacecraft         = [[Gemini (spacecraft)|Gemini]] SC11
| manufacturer       = [[McDonnell Aircraft]]
| launch_mass        = {{cvt|8374|lb|kg|disp=flip}}
| landing_mass       = {{cvt|4230|lb|kg|disp=flip}}
| crew_size          = 2
| crew_members       = {{Unbulleted list|[[Pete Conrad|Charles "Pete" Conrad Jr.]]|[[Richard F. Gordon Jr.]]}}
| crew_EVAs          = 2
| crew_EVA_duration  = 2&nbsp;hours and 41&nbsp;minutes
| launch_date        = {{start-date|September 12, 1966, 14:42:26|timezone=yes}}&nbsp;[[UTC]] (9:42:26&nbsp;am&nbsp;[[Eastern Standard Time|EST]])
| launch_rocket      = {{nowrap|[[Titan II GLV]]}} <!--{{nowrap|s/n }}-->
| launch_site        = [[Cape Canaveral Air Force Station|Cape Kennedy]], [[Cape Canaveral Air Force Station Launch Complex 19|LC-19]]
| recovery_by        = {{USS|Guam|LPH-9|6}}
| landing_date       = {{end-date|September 15, 1966, 13:59:35|timezone=yes}}&nbsp;UTC
| landing_site       = [[Atlantic Ocean]] ({{Coord|24|15|N|70|0|W|type:event|name=Gemini 11 splashdown}})
| orbit_reference    = [[Geocentric orbit]]
| orbit_regime       = [[Low Earth orbit]]
| orbit_periapsis    = {{cvt|298|km|mi nmi}}
| orbit_apoapsis     = {{cvt|1374|km|mi nmi}}
| apsis              = gee
| orbit_inclination  = 28.8°
| orbit_period       = 101.57&nbsp;minutes
| orbit_epoch        = September 14, 1966<ref name="satcat">{{Cite web |last=McDowell |first=Jonathan |title=SATCAT |url=http://planet4589.org/space/log/satcat.txt |access-date=March 23, 2014 |publisher=Jonathan's Space Pages}}</ref>
| docking            = {{Infobox spaceflight/Dock
   | docking_target     = [[Agena target vehicle#Flight statistics|GATV-5006]]
   | docking_type       = dock
   | docking_date       = September 12, 1966, 16:16:00&nbsp;UTC <!--check whether spacecraft undocked and then redocked during this time-->
   | undocking_date     = September 14, 1966, 16:55:00&nbsp;UTC
   | time_docked        = 2&nbsp;days and 39&nbsp;minutes
 }}
| insignia           = Gemini 11 patch.png
| insignia_caption   = Mission patch
| crew_photo         = Gemini 11 prime crew (Gordon and Conrad).jpg
| crew_photo_caption = [[Richard F. Gordon Jr.|Gordon]] and [[Pete Conrad|Conrad]]
| programme          = [[Project Gemini]]
| previous_mission   = [[Gemini 10]]
| next_mission       = [[Gemini 12]]
}}

'''Gemini 11''' (officially '''Gemini XI''')<ref name="titans">{{Cite book |last=Hacker |first=Barton C. |url=http://www.hq.nasa.gov/office/pao/History/SP-4203/toc.htm |title=On the Shoulders of Titans: A History of Project Gemini |last2=Grimwood |first2=James M. |date=September 1974 |publisher=NASA |series=NASA History Series |volume=SP-4203 |page=239 |chapter=Chapter 11 Pillars of Confidence |access-date=2013-09-26 |chapter-url=http://www.hq.nasa.gov/office/pao/History/SP-4203/ch11-1.htm |archive-url=https://web.archive.org/web/20100113132344/http://www.hq.nasa.gov/office/pao/History/SP-4203/toc.htm |archive-date=2010-01-13 |url-status=dead}} With Gemini IV, NASA changed to Roman numerals for Gemini mission designations.</ref> was the ninth crewed spaceflight mission of [[NASA]]'s [[Project Gemini]], which flew from September 12 to 15, 1966. It was the 17th crewed American flight and the 25th spaceflight to that time (includes [[X-15]] flights over 100 kilometers (62&nbsp;mi; 54&nbsp;nmi)). Astronauts [[Pete Conrad]] and [[Richard F. Gordon Jr.|Dick Gordon]] performed the first direct-ascent (first orbit) [[Space rendezvous|rendezvous]] with an [[Agena Target Vehicle]], docking with it 1&nbsp;hour 34&nbsp;minutes after launch; used the Agena rocket engine to achieve a record high-[[apogee]] Earth orbit; and created a small amount of [[artificial gravity]] by spinning the two spacecraft connected by a tether. Gordon also performed two [[Extra-vehicular activity|extra-vehicular activities]] for a total of 2 hours 41 minutes.

==Crew==
{{Spaceflight crew
|terminology       = Astronaut
|position1         = Command Pilot
|crew1_up          = [[Pete Conrad|Charles "Pete" Conrad Jr.]]
|flights1_up       = Second
|position2         = Pilot
|crew2_up          = [[Richard F. Gordon Jr.]]
|flights2_up       = First
}}

===Backup crew===
{{Spaceflight crew
|terminology       = Astronaut
|position1         = Command Pilot
|crew1_up          = [[Neil Armstrong|Neil A. Armstrong]]
|position2         = Pilot
|crew2_up          = [[William Anders|William A. Anders]]
}}

===Support crew===
*[[Clifton Williams|Clifton C. Williams Jr.]] (Cape [[Flight controller#Spacecraft communicator (CAPCOM)|CAPCOM]])
*[[John Young (astronaut)|John W. Young]] (Houston CAPCOM)
*[[Alan Bean|Alan L. Bean]] (Houston CAPCOM)

==Mission parameters==
*'''[[Mass]]:''' {{convert|8374|lb|kg|order=flip}}

Highest orbit (followed twice):
*'''[[Perigee]]:''' {{convert|298|km|mi nmi|sp=us}}<ref>{{Cite web |last=Dumoulin |first=Jim |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-url=https://web.archive.org/web/20120201213341/http://science.ksc.nasa.gov/history/gemini/gemini-xi/gemini-xi.html |archive-date=February 1, 2012 |url-status=dead}}</ref>
*'''[[Apogee]]:''' {{convert|1374|km|mi nmi|sp=us}}<ref>{{Cite tweet |number=1833922734012899389 |user=planet4589 |title=For comparison, the best data I have for Gemini 11 suggests an apogee of 1374.0 km (standard height) with a geoid height maxium of 1377.9 km. However this is not an SGP4 dataset and perturbations are not taken into account - could be 2 km off. Clear that Polaris Dawn was higher. |first=Jonathan |last=McDowell |author-link=Jonathan McDowell |date=September 11, 2024 |access-date=September 11, 2024}}</ref>
*'''[[Inclination]]:''' 28.85°
*'''[[Orbital period|Period]]:''' 101.52 min

===Docking===
* '''Docked''': September 12, 1966, 16:16:00 UTC
* '''Undocked''': September 14, 1966, 16:55:00 UTC

===Space walk===
* Gordon – EVA 1
**'''Start''': September 13, 1966, 14:44:00 UTC
**'''End''': September 13, 1966, 15:17:00 UTC
**'''Duration''': 33 minutes
* Gordon – EVA 2 (stand up)
**'''Start''': September 14, 1966, 12:49:00 UTC
**'''End''': September 14, 1966, 14:57:00 UTC
**'''Duration''': 2 hours and 8 minutes

==Objectives==
* Perform a direct-ascent [[Space rendezvous|rendezvous]] with the [[Agena Target Vehicle]] on the first orbit in support of [[Apollo program|Project Apollo]]. This would simulate a [[Lunar Module]] rendezvous with the [[Apollo Command/Service Module|Command/Service Module]] after a lunar landing.
* Use the Agena rocket engine to put the combined craft in a high-[[apogee]] elliptical orbit.
* Perform two [[Extravehicular activity|extra-vehicular activities]].
* Demonstrate passive attitude stabilization of the two spacecraft connected by a tether and create [[artificial gravity]] by spinning the combined craft.<ref name="Gatland">{{Cite book |last=Gatland |first=Kenneth |title=Manned Spacecraft, Second Revision |pages=180–182 |year=1976 |place=New York, NY, USA |publisher=MacMillan Publishing Co., Inc |isbn=0-02-542820-9}}</ref>
* Perform miscellaneous scientific experiments.
* Perform a computer-controlled [[Atmospheric entry|atmospheric reentry]] to a precision splashdown point.

{| class="wikitable plainrowheaders"
|-
! scope="col" | Gemini 11
! scope="col" | Agena info
|-
! scope="row" | Agena
| GATV-5006
|-
! scope="row" | NSSDC ID:
| 1966-080A
|-
! scope="row" | Mass
| {{convert|7000|lb|kg}}
|-
! scope="row" | Launch site
| LC-14
|-
! scope="row" | Launch date
| September 12, 1966
|-
! scope="row" | Launch time
| 13:05:01 UTC
|-
! scope="row" | 1st perigee
| {{convert|156.4|nmi|km}}
|-
! scope="row" | 1st apogee
| {{convert|165.8|nmi|km}}
|-
! scope="row" | Period
| 90.56 min
|-
! scope="row" | Inclination
| 28.84 deg
|-
! scope="row" | Reentered
| September 15, 1966
|}

==Flight==
{{Multiple image
| image1            = Gemini-Titan 11 Launch - GPN-2000-001020.jpg
| direction         = horizontal
| caption1          = Gemini 11 spacecraft launches on [[Titan II GLV]] rocket
| image2            = Atlas Agena Launch - GPN-2000-001019.jpg
| caption2          = [[Atlas-Agena|Atlas]] rocket launches [[Agena target vehicle]] for the Gemini 11 mission
}}

[[Image:S66-54536.jpg|thumb|Arabian Peninsula (top left) and northeast Africa (bottom) as seen from the orbiting Gemini 11 spacecraft at an altitude of 340 nautical miles during its 27th revolution around Earth. (Taken with a modified 70&nbsp;mm Hasselblad camera.)]]
The direct-ascent rendezvous and docking with the Agena vehicle was achieved approximately 94 minutes after lift-off, depending on the on-board computer and radar equipment with only minimal assistance from ground support.<ref name=Gatland/>

Gemini 11 used the rocket on its Agena target vehicle to raise its apogee to {{convert|853|mi|km}}, the highest Earth orbit ever reached by a crewed spacecraft at the time.<ref name="agle199809">{{Cite magazine |last=Agle |first=D. C. |date=September 1998 |title=Flying the Gusmobile |url=https://www.airspacemag.com/flight-today/flying-the-gusmobile-218187/?all |magazine=Air & Space |language=en}}</ref> The perigee was {{convert|179|mi|km}}, and maximum velocity (at perigee) was {{convert|17967|mph|km/h}}.<ref name=Gatland/> The apogee record stood until the [[Polaris Dawn]] in 2024; men have achieved greater distances from Earth by flying to the Moon in the [[Apollo program]].{{Efn|If Apollo had progressed as planned, the record would have been broken by the '''E mission''', a [[medium Earth orbit]]al test of the complete Apollo spacecraft, with an apogee of {{convert|3500|nmi|km}} planned to be flown in March 1969. But the first [[Lunar Module]] was not ready in time for the '''D mission''' planned for December 1968, which was a [[low Earth orbit]] test (see [[List of Apollo missions#Alphabetical mission types|List of Apollo missions]]). Therefore, the E mission was cancelled and replaced with the D mission in March, and Gemini 11's apogee record stood.}} The maximum operational altitude of the [[Space Shuttle]] was much lower, at {{convert|386|mi|km}} for the [[STS-31]] flight in 1990. The September 2021 [[SpaceX]] flight of [[Inspiration4]], while having an apogee higher than most Space Shuttle flights, only reached {{convert|585|km|mi}}.<ref>{{Cite tweet |number=1438336379830915072 |user=spacex |title=Second phasing burn complete. Dragon and the @inspiration4x crew have reached a circular orbit of 585km – a new Dragon altitude record |date=15 September 2021}}</ref>

The crew docked and undocked four times and still had sufficient Gemini maneuvering fuel for an unplanned fifth rendezvous. They did not remain in the high orbit, but changed it back to a near-circular one at {{convert|184|mi|km}}.<ref name=Gatland/>

Gordon's first EVA, planned to last for two hours, involved fastening a {{convert|100|ft|m|adj=on}} tether, stored in the Agena's docking collar, to the Gemini's docking bar for the passive stabilization experiment. Gordon achieved this, but as with previous Gemini EVAs, trying to work for an extended period proved more fatiguing than in ground simulation, and the EVA had to be terminated after only half an hour.

The passive stabilization experiment proved to be troublesome. Conrad and Gordon separated the craft in a nose-down (i.e., Agena-down) position, but found that the tether would not be kept taut simply by the Earth's gravity gradient, as expected. They were able to generate a small amount of artificial gravity, about 0.00015&nbsp;g, by firing their side thrusters to slowly rotate the combined craft like a slow-motion pair of [[bolas]].<ref name=Gatland/>

Gordon successfully performed a second EVA standing up with his head and shoulders out of the hatch to photograph the Earth, clouds, and stars. This was not tiring and lasted more than two hours.<ref name=Gatland/>

===Scientific experiments===
The 12 scientific experiments were:<ref>{{Cite web |title=NASA Gemini 11 Press Kit |url=https://mira.hq.nasa.gov/history/ws/hdmshrc/all/main/DDD/39988.pdf |url-status=dead |archive-url=https://web.archive.org/web/20110721063621/https://mira.hq.nasa.gov/history/ws/hdmshrc/all/main/DDD/39988.pdf |archive-date=21 July 2011 |access-date=2011-02-10}}</ref>
* Mass Determination: To test a technique and accuracy of a direct-contact method of determining the mass of an orbiting object, in this case the Agena Target Vehicle.
* Night Image Intensification: To test the usefulness and performance of a low-light-level television system as a supplement to unaided vision in observing surface features primarily when such features are in darkness and spacecraft pilots are not [[Adaptation (eye)|dark-adapted]].
* Power Tool Evaluation: To evaluate man's capability to perform work tasks in space, including the comparison of ability to work tethered and untethered, and to evaluate the performance of the minimum-reaction power tool.
* Radiation and Zero G Effects on Blood and Neurospora: To determine whether weightlessness enhances the effects of radiation on human [[white blood cell]]s and ''[[Neurospora crassa]]'' fungi.<ref>{{Cite journal |last=Bender |first=M. A. |display-authors=etal |date=September 1971 |title=Radiation and zero-gravity effects on human leukocytes and Neurospora crassa |url=https://ntrs.nasa.gov/search.jsp?R=19720006414 |url-status=live |journal=Nasa. Manned Spacecraft Center the Gemini Program Biomed. Sci. Expt. Sum. |publisher=NASA |archive-url=https://web.archive.org/web/20170122164032/https://ntrs.nasa.gov/search.jsp?R=19720006414 |archive-date=22 January 2017 |access-date=22 January 2017}}</ref>
* Synoptic Terrain Photography: To obtain high-quality photographs for research in geology, geophysics, geography, oceanography, and related fields.
* Synoptic Weather Photography: To obtain selective high-quality photographs of clouds to study the fine structure of the Earth's weather system.
* Nuclear Emulsion: To study the cosmic radiation incident on the Earth's atmosphere, to obtain detailed chemical composition of the heavy primary nuclei, and to search for rare particles.
* Airglow Horizon Photography: To measure by direct photography the heights at which atomic oxygen and [[sodium layer]]s occur in the upper atmosphere.
* Ultraviolet Astronomical Camera: To test the techniques of ultraviolet photography under vacuum conditions and to obtain ultraviolet radiation observations of stars in wavelength region of 2,000 to 4,000&nbsp;[[angstrom]]s by spectral means.
* Ion Wake Measurement: To determine and measure the ion and electron wake structure and perturbation of the ambient medium produced by an orbiting vehicle, and to study the changes in the ion flux and wake caused by thruster firings.
* Earth-Moon Libration Region Photography: To investigate the regions of the [[Lagrangian point|L4 and L5 libration points]] of the Earth–Moon system to determine the possible existence of clouds of particulate matter orbiting the Earth in these regions ([[Kordylewski clouds]]).
* Dim-Light Photography and Orthicon: To obtain photographs of various faint and diffuse astronomical phenomena.

===Reentry===
The mission ended with the first totally automatic, computer-controlled [[Atmospheric reentry|reentry]] by the U.S., which brought Gemini 11 down {{convert|2.8|mi|km}} from its recovery ship [[USS Guam (LPH-9)|USS ''Guam'']], only {{convert|1.5|mi|km}} from the planned position.<ref name=Gatland/>

Astronaut recovery was done by United States Navy [[Helicopter Anti-Submarine Squadron 3]].

The Gemini 11 mission was supported by 9,054 [[United States Department of Defense]] personnel, 73 aircraft, and 13 ships.<ref>{{Cite book |last=Hacker |first=Barton C. |url=https://history.nasa.gov/SP-4203.pdf |title=On the Shoulders of Titans - The History of Project Gemini |last2=Grimwood |first2=James M. |date=1977 |page=596 |chapter=Appendix G DoD Support |access-date=December 18, 2022}}</ref>

==Insignia==
[[File:Gemini 11 Flown Sterling Silver Fliteline Medallion.jpg|thumb|Gemini 11 space-flown [[NASA space-flown Robbins medallions of the Apollo missions#Gemini mission space-flown Fliteline medallions|Fliteline Medallion]]]]
Since Conrad and Gordon were both members of the [[US Navy]], the [[Embroidered patch|embroidered mission patch]] was designed in Navy colors: blue and gold. Stars are used to mark the major milestones of the mission. The first orbit Agena rendezvous is marked by a small gold star just above the Earth, to the left. The Agena docking is marked by a large star on the left. The star at the top marks the record high apogee reached by Gemini 11. Note that the scale is greatly exaggerated; their maximum altitude of {{convert|850|mi|km}} is roughly the distance from [[St. Louis, Missouri|St. Louis]] to [[Cape Canaveral Air Force Station|Cape Kennedy]]. Finally, the star on the right marks Dick Gordon's spacewalk. The docking, record apogee and spacewalk are also shown on the patch by the Agena, orbital apogee path and spacewalking astronaut.

==Potential lunar missions==

Gemini 11's record altitude was ultimately the result of an internal race to [[the Moon]]. As early as 1961, NASA's [[Jim Chamberlin]] and [[McDonnell Aircraft]] had advocated using Gemini spacecraft to get to the Moon sooner than [[Apollo program|Apollo]]. Their proposals considered using [[Centaur rocket stage|Centaur]] rockets to boost the Gemini on a circumlunar trajectory (similar to the Soviet's [[Zond program]]), lunar orbit missions using Centaur rockets for translunar injection and Agena for lunar orbit insertion, and even lunar landing missions using Gemini in place of the [[Apollo Command Module]] and a small open-cockpit [[Advanced_Gemini#Lunar_landing|Langley Light LM]] in place of the [[Apollo Lunar Module]]. Multiple Titan or [[Saturn IB]] rockets, and even the abandoned [[Saturn C-3]] were considered as the launch vehicles.

Pete Conrad liked these ideas and together with McDonnell corporations strongly advocated his Gemini 11 to be circumlunar. Discretely called 'Gemini - Large Earth Orbit', the plan would use a [[Titan IIIC]]-launched Transtage. The Gemini 11 crew would be launched with the [[Titan II GLV]] as they did in reality, and would dock with the Transtage, which would then boost them to translunar velocity. Conrad managed to stir Congressional interest, but NASA administrator [[James E. Webb|James Webb]] informed them that any extra funds Congress cared to appropriate for such a project would be better spent accelerating the Apollo program. After further internal struggles, Conrad finally got NASA approval for the Agena on his Gemini 11 flight to boost him onto two record highly elliptical 1,370 km orbits. This high flight was the only remnant of lunar Gemini.<ref>{{Cite web |title=Gemini: Lunar Gemini |url=http://www.astronautix.com/g/geminilunargemini.html |url-status=dead |archive-url=https://web.archive.org/web/20160713062213/http://www.astronautix.com/g/geminilunargemini.html |archive-date=July 13, 2016}}</ref>
==Spacecraft location==
{{multiple image
| align = right
| image1 = Gemini 11 capsule (front) at California Science Center.jpg
| width1 = 200
| alt1 = Gemini 11 front
| caption1 = 
| image2 = Gemini 11 capsule (rear) at California Science Center.JPG
| width2 = 200
| alt2 = Gemini 11 rear
| caption2 = 
| footer = The Gemini 11 capsule on display at the [[California Science Center]] in Los Angeles
}}

The spacecraft is on display at the [[California Science Center]] in [[Los Angeles, California]].

==See also==
{{Portal|Spaceflight}}
* [[Agena Target Vehicle]]
* [[Extra-vehicular activity]]
* [[List of spacewalks]]
* [[Splashdown (spacecraft landing)|Splashdown]]
* [[Space exploration]]
* [[U.S. space exploration history on U.S. stamps]]
* [[Space capsule]]
* [[Space suit]]

== Notes ==
{{Notelist}}

==References==
{{Include-NASA}}
{{Reflist}}

==External links==
{{Commons category|Gemini 11}}
*[https://web.archive.org/web/20110721063621/https://mira.hq.nasa.gov/history/ws/hdmshrc/all/main/DDD/39988.pdf NASA Gemini 11 press kit - Sep 2, 1966]
*{{Internet Archive short film | gemini_xi | Gemini XI }}
*[http://www.genedorr.com/patches/Intro.html Spaceflight Mission Patches]
*[https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1966-081A NASA Space Science Data Coordinated Archive]
*[https://web.archive.org/web/20090521121750/http://usspaceobjectsregistry.state.gov/search/index.cfm U.S. Space Objects Registry]

{{Gemini program}}
{{NASA space program}}
{{Orbital launches in 1966}}
{{Authority control}}

{{S-start}}
{{Succession box
 | title  = Human altitude record
 | years  = 1966-1968
 | with   = 
 | before = [[Gemini 10]] crew
 | after  = [[Apollo 8]] crew
}}
{{S-end}}

[[Category:Extravehicular activity]]
[[Category:Human spaceflights]]
[[Category:Project Gemini missions]]
[[Category:Spacecraft launched in 1966]]
[[Category:Spacecraft launched by Titan rockets]]
[[Category:September 1966]]
[[Category:Pete Conrad]]
[[Category:Richard F. Gordon Jr.]]
[[Category:Successful space missions]]