Gemini 11
Ninth crewed Gemini mission, set altitude record and tested tether artificial gravity.
Gemini 11, designated Gemini XI officially, marked the ninth crewed mission in NASA’s Project Gemini, operating between September 12 and 15, 1966. At that point, it represented the 17th American flight with a crew and the 25th spaceflight overall, counting X-15 missions that exceeded 100 kilometers in altitude. The crew consisted of astronauts Pete Conrad and Dick Gordon. They accomplished the first direct-ascent rendezvous—docking with an Agena Target Vehicle just 1 hour and 34 minutes after launch, during the initial orbit. Using the Agena’s rocket engine, they pushed their spacecraft into a record-setting high-apogee Earth orbit. Additionally, they generated a modest amount of artificial gravity by spinning the two linked vehicles, connected by a tether. Gordon carried out two separate extra-vehicular activities, totaling 2 hours and 41 minutes.
The backup crew included support personnel, with Clifton C. Williams Jr. serving as Cape CAPCOM, and John W. Young and Alan L. Bean as Houston CAPCOMs. The spacecraft massed 3,798 kilograms. Its highest orbit, achieved twice, had a perigee of 298 kilometers and an apogee of 1,374 kilometers, with an inclination of 28.85° and a period of 101.52 minutes. Docking occurred on September 12, 1966, at 16:16:00 UTC, and undocking on September 14, 1966, at 16:55:00 UTC. Gordon’s first spacewalk began on September 13 at 14:44:00 UTC and ended at 15:17:00 UTC, lasting 33 minutes. His second, a stand-up EVA, started on September 14 at 12:49:00 UTC and concluded at 14:57:00 UTC, for a duration of 2 hours and 8 minutes.
The mission’s objectives included performing a direct-ascent rendezvous with the Agena on the first orbit to support Project Apollo, simulating a Lunar Module rendezvous with the Command/Service Module after a lunar landing. The crew also used the Agena’s engine to place the combined craft into a high-apogee elliptical orbit, conducted two EVAs, demonstrated passive attitude stabilization of the two spacecraft linked by a tether, and created artificial gravity by spinning them. They carried out miscellaneous scientific experiments and executed a computer-controlled atmospheric reentry to a precise splashdown point.
During the flight, the direct-ascent rendezvous and docking with the Agena occurred about 94 minutes after liftoff, relying heavily on the onboard computer and radar, with minimal ground assistance
- Mission
- Gemini 11
- Launch Date
- September 12, 1966
- Crew
- Pete Conrad (Command Pilot), Dick Gordon (Pilot)
- Duration
- September 12–15, 1966
- Orbit Apogee
- 1,374 kilometers (854 mi)
- Orbit Perigee
- 298 kilometers (185 mi)
- Notable Achievement
- First direct-ascent rendezvous and highest crewed Earth orbit at the time
Lore & Background
Gemini 11 achieved the first direct-ascent rendezvous and docking with an Agena Target Vehicle approximately 94 minutes after lift-off, relying on on-board computer and radar with minimal ground support. The crew used the Agena rocket engine to raise their apogee to 854 miles (1,374 km), the highest Earth orbit ever reached by a crewed spacecraft at the time, a record that stood until Polaris Dawn in 2024. They also created a small amount of artificial gravity, about 0.00015 g, by firing side thrusters to slowly rotate the docked Gemini-Agena stack.
Dick Gordon performed two extra-vehicular activities totaling 2 hours 41 minutes. The first EVA, planned for two hours, involved fastening a 10
Reader's Guide
Gemini 11's significance lies in its demonstration of critical techniques for lunar missions. The first-orbit direct-ascent rendezvous simulated the rendezvous a Lunar Module would perform with the Command/Service Module after a lunar landing, a key requirement for Project Apollo. The record high-apogee orbit, while not directly used for Apollo, proved the ability to achieve high orbits using an Agena engine, and the tether experiment provided early data on artificial gravity generation. The mission also tested computer-controlled reentry, improving precision landing capabilities. The 12 scientific experiments, including mass determination, night image intensification, and cosmic radiation studies, contributed to broader space science. Gemini 11's altitude record remained unbroken by crewed spacecraft until 2024, highlighting its place in spaceflight history. The mission also reflected internal NASA debates about using Gemini for lunar missions, as Pete Conrad advocated for a circumlunar flight using a Transtage, though this did not occur.
Did You Know?
- Gemini 11 achieved the highest Earth orbit ever reached by a crewed spacecraft at the time, with an apogee of 1,374 kilometers (854 mi).
- The crew created a small amount of artificial gravity, about 0.00015 g, by spinning the two spacecraft connected by a tether.
- Dick Gordon's first EVA was cut short to 33 minutes due to fatigue, though it was planned for two hours.
- The mission ended with the first totally automatic, computer-controlled reentry by the U.S., landing only 1.5 miles from the planned position.
More in Successful space missions 1-24
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