 Gemini XI conducting a tether experiment using the Agena Target Vehicle | |
| Mission type | |
|---|---|
| Operator | NASA |
| COSPAR ID | 1966-081A |
| SATCATno. | 02415 |
| Mission duration | 2 days, 23 hours, 17 minutes and 9 seconds |
| Orbits completed | 44 |
| Spacecraft properties | |
| Spacecraft | Gemini SC11 |
| Manufacturer | McDonnell Aircraft |
| Launch mass | 3,798 kg (8,374 lb) |
| Landing mass | 1,920 kg (4,230 lb) |
| Crew | |
| Crew size | 2 |
| Members | |
| EVAs | 2 |
| EVA duration | 2 hours and 41 minutes |
| Start of mission | |
| Launch date | September 12, 1966, 14:42:26 (1966-09-12UTC14:42:26Z) UTC (9:42:26 am EST) |
| Rocket | Titan II GLV |
| Launch site | Cape Kennedy,LC-19 |
| End of mission | |
| Recovered by | USS Guam |
| Landing date | September 15, 1966, 13:59:35 (1966-09-15UTC13:59:36Z) UTC |
| Landing site | Atlantic Ocean (24°15′N70°0′W / 24.250°N 70.000°W /24.250; -70.000 (Gemini 11 splashdown)) |
| Orbital parameters | |
| Reference system | Geocentric orbit |
| Regime | Low Earth orbit |
| Perigee altitude | 298 km (185 mi; 161 nmi) |
| Apogee altitude | 1,374 km (854 mi; 742 nmi) |
| Inclination | 28.8° |
| Period | 101.57 minutes |
| Epoch | September 14, 1966[1] |
| Docking withGATV-5006 | |
| Docking date | September 12, 1966, 16:16:00 UTC |
| Undocking date | September 14, 1966, 16:55:00 UTC |
| Time docked | 2 days and 39 minutes |
 Mission patch .jpg) Gordon andConrad | |
Gemini 11 (officiallyGemini XI)[2] was the ninth crewed spaceflight mission ofNASA'sProject Gemini, which flew from September 12 to 15, 1966. It was the 17th crewed American flight and the 25th spaceflight to that time (includesX-15 flights over 100 kilometers (62 mi; 54 nmi)). AstronautsPete Conrad andDick Gordon performed the first direct-ascent (first orbit)rendezvous with anAgena Target Vehicle, docking with it 1 hour 34 minutes after launch; used the Agena rocket engine to achieve a record high-apogee Earth orbit; and created a small amount ofartificial gravity by spinning the two spacecraft connected by a tether. Gordon also performed twoextra-vehicular activities for a total of 2 hours 41 minutes.
| Position | Astronaut | |
|---|---|---|
| Command Pilot | Charles "Pete" Conrad Jr. Second spaceflight | |
| Pilot | Richard F. Gordon Jr. First spaceflight | |
| Position | Astronaut | |
|---|---|---|
| Command Pilot | Neil A. Armstrong | |
| Pilot | William A. Anders | |
Highest orbit (followed twice):
| Gemini 11 | Agena info |
|---|---|
| Agena | GATV-5006 |
| NSSDC ID: | 1966-080A |
| Mass | 7,000 pounds (3,200 kg) |
| Launch site | LC-14 |
| Launch date | September 12, 1966 |
| Launch time | 13:05:01 UTC |
| 1st perigee | 156.4 nautical miles (289.7 km) |
| 1st apogee | 165.8 nautical miles (307.1 km) |
| Period | 90.56 min |
| Inclination | 28.84 deg |
| Reentered | September 15, 1966 |
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.[5]
Gemini 11 used the rocket on its Agena target vehicle to raise its apogee to 853 miles (1,373 km), the highest Earth orbit ever reached by a crewed spacecraft at the time.[6] The perigee was 179 miles (288 km), and maximum velocity (at perigee) was 17,967 miles per hour (28,915 km/h).[5] The apogee record stood until thePolaris Dawn in 2024; men have achieved greater distances from Earth by flying to the Moon in theApollo program.[a] The maximum operational altitude of theSpace Shuttle was much lower, at 386 miles (621 km) for theSTS-31 flight in 1990. The September 2021SpaceX flight ofInspiration4, while having an apogee higher than most Space Shuttle flights, only reached 585 kilometres (364 mi).[7]
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 184 miles (296 km).[5]
Gordon's first EVA, planned to last for two hours, involved fastening a 100-foot (30 m) 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 g, by firing their side thrusters to slowly rotate the combined craft like a slow-motion pair ofbolas.[5]
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.[5]
The 12 scientific experiments were:[8]
The mission ended with the first totally automatic, computer-controlledreentry by the U.S., which brought Gemini 11 down 2.8 miles (4.5 km) from its recovery shipUSSGuam, only 1.5 miles (2.4 km) from the planned position.[5]
Astronaut recovery was done by United States NavyHelicopter Anti-Submarine Squadron 3.
The Gemini 11 mission was supported by 9,054United States Department of Defense personnel, 73 aircraft, and 13 ships.[10]
Since Conrad and Gordon were both members of theUS Navy, theembroidered 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 850 miles (1,370 km) is roughly the distance fromSt. Louis toCape 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.
Gemini 11's record altitude was ultimately the result of an internal race tothe Moon. As early as 1961, NASA'sJim Chamberlin andMcDonnell Aircraft had advocated using Gemini spacecraft to get to the Moon sooner thanApollo. Their proposals considered usingCentaur rockets to boost the Gemini on a circumlunar trajectory (similar to the Soviet'sZond 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 theApollo Command Module and a small open-cockpitLangley Light LM in place of theApollo Lunar Module. Multiple Titan orSaturn IB rockets, and even the abandonedSaturn 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 aTitan IIIC-launched Transtage. The Gemini 11 crew would be launched with theTitan 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 administratorJames 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.[11]
_at_California_Science_Center.jpg)
_at_California_Science_Center.JPG)
The spacecraft is on display at theCalifornia Science Center inLos Angeles, California.
This article incorporatespublic domain material from websites or documents of theNational Aeronautics and Space Administration.
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| Preceded by Gemini 10 crew | Human altitude record 1966-1968 | Succeeded by Apollo 8 crew |
