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Gemini Program (1962-1966) Early Unmanned NASA Craft | Mercury | Gemini | Apollo | Clementine | Lunar Prospector | Hubble Space Telescope
Overview The Gemini program was made of mainly twelve launched vehicles. Two of them were unmanned, while the last ten carried two people into Earth orbit each. The program was designed as a bridge between the Mercury and Apollo programs. The Gemini missions lasted for periods ranging from five hours to 14 days. The objectives were to primarily test equipment and mission procedures and to train astronauts and ground crews for future Apollo missions. The general objectives of the program included: Long duration flights, testing of the ability to maneuver a spacecraft, achievement of rendezvous and docking of two vehicles in Earth orbit, conduct experiments in space operation outside of a spacecraft, active control of reentry to achieve a precise landing, and onboard orbital navigation. The total cost of the program was approximately $1.28 billion. Missions Gemini 1
Launch of Gemini 1 took place from Complex 19. Six minutes after launch, the Titan 2 booster placed the Gemini spacecraft and the attached 2nd stage in a 160.5x320.6 km orbit with a period of 89.3 minutes. An excess speed of 22.5 km/hr sent the spacecraft 33.6 km higher than planned. Mission plans did not include separation of spacecraft from the 3.05 meter diameter, 5.8 meter long Titan stage 2 - both orbited as a unit. The planned mission included only three orbits and ended about 4 hours 50 minutes after launch with the third pass over Cape Kennedy. The spacecraft was tracked until it reentered the atmosphere and disintegrated on the 64th orbital pass over the southern Atlantic on April 12. The systems functioned well within planned tolerances and the mission was deemed a successful test. Gemini 2
This was the second uncrewed Gemini test mission, consisting of a sub-orbital ballistic flight and reentry with the primary objectives being to demonstrate the adequacy of the spacecraft reentry module's heat protection during a maximum heating rate return, the structural integrity of the spacecraft, and the performance of spacecraft systems. Secondary objectives included obtaining test results on communications, cryogenics, fuel cell and reactant supply system, and further qualification of the launch vehicle. The flight was launched successfully from complex 19 to a maximum altitude of 171.2 km. The spacecraft was run by an onboard automatic sequencer. At 6 minutes 54 seconds after launch, retrorockets were fired and the spacecraft cartwheeled into a reentry attitude. The spacecraft reentered the atmosphere and landed by parachute in the Atlantic Ocean 3419 km southeast of the launch site 18 minutes 16 seconds after launch. The landing was 26 km short of the planned impact point. The spacecraft was successfully recovered by the aircraft carrier U.S.S. Lake Champlain, which was 84 km from the splashdown point, at 15:52 UT. All goals were achieved except test results on the fuel cells because the system had failed before liftoff and was turned off. The capsule was in excellent condition and the heat shield and retrorockets functioned as planned. The temperature in the cooling system of the spacecraft was found to be too high. Gemini 3
Gemini 3 was the first crewed Earth-orbiting spacecraft of the Gemini series. Its primary objectives were to demonstrate the crewed qualifications of the Gemini spacecraft including evaluation of the two-man Gemini design, the worldwide tracking network, orbit attitude and maneuver system (OAMS), control of reentry flight path and landing point, spacecraft systems, and spacecraft recovery. Secondary objectives included evaluation of flight crew equipment and effects of low level launch vehicle oscillations (POGO) on the crew, performance of three experiments, and to obtain photographic coverage from orbit. Gemini 3 was launched from Complex 19 and inserted 5 minutes 54 seconds later into a 161.2x224.2 km orbit with a period of 88.3 minutes. At the end of the first orbit, Grissom effected the first orbital maneuver, which lowered the orbit to a near-circular 158x169 km. On the second orbit, Grissom altered the spacecraft inclination by 0.02°. Near the end of the third orbit, at 4:21:23 ground elapsed time(GET), the perigee was lowered to 84 km to allow the orbit to decay naturally in case of retrorocket failure. Reentry began at the end of the third orbit and was manually controlled with retrofire at 4:33:23 GET. At an altitude of 90 km, about 7 kg of water were injected into the ionized plasma sheath resulting in improved communications during the blackout period. Splashdown occurred in the Atlantic in the vicinity of Grand Turk Island, at 22.43° N, 70.85° W, at 4:52:31 GET. Due to less-than-expected spacecraft lift during reentry, the spacecraft landed 111 km short of the target point. Both astronauts became seasick, removed their suits, and left the spacecraft at about 3:00 p.m. EST. They were picked up by helicopter and taken to the recovery ship U.S.S. Intrepid at 3:28 p.m. EST, where they were found to be in good condition. The Gemini capsule was recovered at 5:03 p.m. EST. Two of the three experiments were performed successfully; the third, sea urchin egg growth in zero-G, was not due to a mechanical failure. The photography objective was only partially achieved because of an improper lens on the 16 mm camera. All other mission objectives were achieved. Gemini 4
Gemini 4 was launched from Complex 19 and inserted into a 162.3x282.1 km Earth orbit at 15:22:05. The orbit was raised to 166x290 km during the first revolution to attempt a rendezvous with the second stage. This stationkeeping exercise was cancelled early in the second revolution after depletion of 42% of the fuel, for it was determined that use of more fuel would jeopardize other mission objectives. White then donned special gear and pressurized his suit at 3.7 psi. McDivitt depressurized the cabin, bringing the pressure to zero at 2:33:35 P.M. EST, and the hatch was opened at 2:34. White stood two minutes later and exited the spacecraft using a hand-held gas gun at 2:46, becoming the first American to walk in space. White was attached to the spacecraft by an 8 meter tether. The gas gun fuel supply was depleted in 3 minutes, after which White pulled on the tether and twisted his body to maneuver around the spacecraft. The extravehicular activity (EVA) lasted 23 minutes, after which White pulled himself back into the spacecraft. Difficulty was encountered sealing the hatch, but working together the astronauts finally closed it, at 3:10 P.M. EST. Cabin repressurization began at 3:12:50. Drifting flight was maintained for the next 30 hours to conserve propellant. A computer malfunction on the 48th revolution made the planned computer-controlled reentry impossible. A zero-lift ballistic reentry, similar to that used by the Mercury program, was started at the beginning of revolution 62 with retrofire at 11:56:00 A.M. EST on June 7. Gemini 4 splashed down 16 minutes later in the western Atlantic, 27.73° N, 74.18° W, 81 km from the target. Total elapsed mission time was 97:56:12. The crew were recovered by helicopter and flown to the aircraft carrier U.S.S. Wasp at 1:09 P.M. and the capsule was recovered at 2:28 P.M. The experiments performed during the mission were electrostatic charge (MSC-1), proton-electron spectrometer (MSC-2), triaxial magnetometer (MSC-3), two-color Earth limb photos (MSC-4), inflight exerciser (M-3), inflight phonocardiogram (M-4), bone demineralization (M-6), synoptic terrain photos (S-5), synoptic weather photos (S-6), dim and twilight phenomena (S-28), radiation (D-8), and simple navigation (D-9). All experiments were performed successfully. All other objectives except the rendezvous and computer controlled reentry were achieved. Gemini 5
Gemini 5 was launched from Complex 19 and inserted into a 162.0x350.1 km Earth orbit at 14:05:55. The rendezvous evaluation pod (REP), a 34.5 kg optical and electronic duplicate of the Agena planned for use in later Gemini rendezvous missions was deployed two hours into the flight on the second revolution. About 36 minutes into the evaluation of the rendezvous system, the crew noticed the pressure in the oxygen supply tank of the fuel cell system was dropping. At some point earlier in the flight the oxygen supply heater element had failed, and the pressure dropped from nominal pressure of 850 psia to a low of 65 psia 4 hours and 22 minutes into the flight. This was still above the 22.2 psia minimum but it was decided to cancel the REP exercise and power the spacecraft down. An analysis was carried out on the ground and a powering up procedure was started on the seventh revolution. Over the rest of the mission the pressure slowly rose in the fuel cells and sufficient power was available at all times. Four rendezvous radar tests were conducted during the mission, starting on revolution 14 on the second day. On the third day, a simulated rendezvous with a phantom Agena was conducted. On day five, thruster number 7 became inoperative and maneuvering system operation became sluggish. Thruster number 8 failed the next day and the system became increasingly erratic. Limited experimental and operational activities continued throughout the remainder of the mission. Retrofire was made on revolution 120 (one revolution early due to a threatening tropical storm near the landing area) at 12:27:42 UTC on August 29. Splashdown occurred in the western Atlantic at 29.73° N, 69.75° W after a total mission time of 190:55:14. Splashdown was 169 km short of the target due to a ground-based computer program error. The crew arrived onboard the aircraft carrier U.S.S. Lake Champlain at 9:26 and the spacecraft was recovered at 16:50. All objectives were achieved except rendezvous with the REP and pilot tests associated with the rendezvous and the demonstration of controlled reentry to a predetermined landing point. Scientific studies included zodiacal light, synoptic terrain, synoptic weather photography, and a cloud top spectrometer experiment. In addition, five medical and seven technological experiments were performed during the mission. One photography experiment was cancelled because of cancellation of the rendezvous maneuver. The mission demonstrated human ability to adapt to weightlessness over an extended period and then readapt to normal gravity and was considered successful. Gemini 6A
Gemini 6A was scheduled to launch on December 12, 1965, but the launch was aborted one second after engine ignition because an electrical umbilical separated prematurely. This was the first time an astronaut mission was aborted after ignition start. The mission launched successfully from Complex 19 and was inserted into a 161.0x259.4 km orbit at 13:43:25. At this point, Gemini 6A trailed Gemini 7 by about 1900 km. Four major thruster burns were performed starting at 14:11 to catch up to Gemini 7. First radar lock indicated a distance of 396 km. Two more major thruster burns preceded the final braking maneuver at 19:27 UTC. Rendezvous was technically achieved and stationkeeping begun at 19:33 with the two Gemini spacecraft in zero relative motion at a distance of 110 meters. Stationkeeping maneuvers involving the spacecraft circling each other and approaching and backing off continued for 5 hours 19 minutes over three and a half orbits. During the maneuvers, all four astronauts on both spacecraft took turns in the formation flying activities and photographs were taken from both spacecraft. This marked the first time two spacecraft were maneuvered with respect to each other by their crews. At the end of stationkeeping Gemini 6 fired thrusters to move to a position roughly 50 km away from Gemini 7 for drifting flight during the sleep period. Near the end of the 15th revolution, the retrorockets were fired at 14:53:24 on December 16 and splashdown occurred at 23.58° N, 67.83° W only 13 km from the target. This was the first successful controlled reentry to a predetermined point in the U.S. manned space flight program. The crew remained inside the spacecraft during recovery operations. The spacecraft and crew were brought aboard the aircraft carrier U.S.S. Wasp at 16:32. Total mission elapsed time was 25:51:24. All primary mission objectives were achieved. The only major malfunction was the failure of the delayed time telemetry tape recorder at 20 hours 55 minutes into the mission, resulting in loss of the last 4:20 of delayed time telemetry. The crew conducted three scientific experiments: Synoptic terrain photography, synoptic weather photography, and dim light photography. The fourth experiment, measurement of radiation in spacecraft, was only partly completed. Gemini 7
Gemini 7 was the fourth crewed Earth-orbiting spacecraft of the Gemini series, having been launched before Gemini 6A. It carried its astronauts on a 14-day mission. Its mission priorities were to demonstrate a 2-week flight, perform stationkeeping with the Gemini launch vehicle stage 2, evaluate the 'shirt sleeve' environment and the lightweight pressure suit, act as a rendezvous target for Gemini 6, and demonstrate controlled reentry close to the target landing point. The crew members had three scientific, four technological, four spacecraft, and eight medical experiments to perform. Gemini 7 was launched from Complex 19 and inserted into a 161.6x328.2 km orbit at 2:36:11. Immediately after separation Gemini 7 began stationkeeping operations with the Titan II second stage at distances from 6 meters to 80 km over a period of 17 minutes. On the third revolution the perigee was raised to 230 km to ensure an orbital lifetime of 15 days. On December 6, 45 hours into the mission, Lovell removed his spacesuit to evaluate the shirtsleeve environment. The first five days were spent conducting experiments and spacecraft tests. On December 9 the orbit was circularized to 299.7x303.7 to prepare for the rendezvous exercise with Gemini 6A. On December 10, 140 hours into the mission, Lovell put his suit back on and Borman removed his. Some 20 hours later Lovell removed his suit as well and both astronauts operated without suits for the remainder of the mission except for the rendezvous with Gemini 6A and reentry. Experiments were conducted over the next few days, and on December 15 Gemini 6A was launched. Gemini 6A caught up to Gemini 7 and rendezvous was technically achieved and stationkeeping begun on 15 December at 19:33 UTC with the two Gemini spacecraft in zero relative motion at a distance of 110 meters. Stationkeeping maneuvers involving the spacecraft circling each other and approaching and backing off continued for 5 hours 19 minutes over three and a half orbits. During the maneuvers, all four astronauts on both spacecraft took turns in the formation flying activities and photographs were taken from both spacecraft. This marked the first time two spacecraft were maneuvered with respect to each other by their crews. At the end of stationkeeping Gemini 6A fired thrusters to move to a position roughly 50 km away from Gemini 7 for drifting flight during the sleep period. Gemini 6A returned to Earth on December 16. Gemini 7 remained in Earth orbit and reentered two days later. Retrorockets were fired at the end of revolution 206 on December 18 at 13:28:07 to begin the reentry sequence. Splashdown followed in the western Atlantic southwest of Bermuda at 25.42° N, 70.10° W, only 12.2 km from the target point. The astronauts were recovered by helicopter and brought aboard the aircraft carrier U.S.S. Wasp at 14:37. The spacecraft was recovered at 15:08. Total mission elapsed time was 330:35:01, making this the longest anyone had ever stayed in space. The astronauts were pronounced in "better than expected" physical condition after their two week flight. All primary mission objectives were successfully completed. The three scientific experiments - synoptic terrain photography, synoptic weather photography, and visual acuity in the space environment - were all completed successfully. All other onboard experiments were performed except landmark contrast measurement and star occultation navigation, due to equipment failure. Only partially completed were in-flight sleep analysis, proton-electron spectrometer, and optical communication. Minor malfunctions related to fuel cells and attitude control thruster occurred but did not hamper the mission. Gemini 8
Gemini 8 was launched from Complex 19 and inserted into a 159.9x271.9 km orbit at 16:47:36. Over the next six hours, the spacecraft performed 9 maneuvers to rendezvous with the Gemini Agena Target Vehicle (GATV), which had been launched earlier (at 14:00 UTC). The rendezvous phase ended at 21:39, with the spacecraft 45 meters apart with zero relative motion. Stationkeeping and other maneuvers were performed for about half an hour, and then Gemini 8 moved in and docked with the GATV on the 5th revolution at 23:14, the first docking ever to take place in space. About 27 minutes after docking at 22:41, the combined vehicle began to go into a violent yaw and tumble. Armstrong disengaged the Gemini capsule from the GATV causing it to roll, pitch, and yaw even more rapidly than when it was connected to the GATV, approaching a rate of one revolution per minute. The astronauts fought to control the spacecraft for three minutes. Armstrong managed to deactivate the OAMS and in a final attempt to counteract the violent tumbling all 16 reentry control system (RCS) thrusters were utilized to damp out the roll. This maneuver succeeded in stabilizing the spacecraft at 23:06:30 but ended up using 75% of the RCS fuel. It was then discovered that one of the 25-pound Orbit Atitude and Maneuver System (OAMS) roll thrusters (thruster no. 8) on Gemini 8 had been firing continuously, causing the tumbling. Apparently it had short-circuited while being used to maneuver the Gemini-GATV combination and had stuck open. Due to the premature use of the reentry control system, an immediate landing was required by Gemini safety rules, so the planned EVA and other activities were cancelled. Retrofire took place on the 7th revolution at 2:45:49 on March 17 UTC, just over 10 hours after launch, and the spacecraft splashed down in the western Pacific Ocean about 800 km west of Okinawa at 25.22° N, 136.00° E, 2 km from the target. USAF frogmen parachuted from a C-54 rescue plane within minutes and affixed a flotation collar around the spacecraft. The crew was picked up by the recovery ship U.S.S. Mason 3 hours later, and the spacecraft at 6:37 UTC. Total mission elapsed time was 10:41:26. Early termination of the mission precluded achievement of many mission objectives, but the rendezvous and docking were accomplished, as was the evaluation of the auxiliary tape memory unit and demonstration of controlled reentry. Of the six scientific experiments only the Agena micrometeorite collection was successful. The others - zodiacal light photography, frog egg growth, synoptic terrain photography, nuclear emulsions, and spectrophotography of clouds - were incomplete. The Agena Target Vehicle remained in orbit and maneuvers were performed by ground command, including successfully placing it into circular orbit. Gemini 9A
Gemini 9A was the seventh crewed Earth-orbiting spacecraft of the Gemini series. It carried astronauts Tom Stafford and Gene Cernan. Primary mission objectives were to demonstrate (1) rendezvous techniques and docking with a target vehicle to simulate maneuvers to be carried out on future Apollo missions, (2) an ExtraVehicular Activity (EVA) spacewalk to test the Astronaut Maneuvering Unit (AMU), and (3) precision landing capability. Scientific objectives included obtaining zodiacal light and airglow horizon photographs. Two micrometeorite studies were to be carried out, and there were also one medical and two technological experiments. The mission was originally scheduled for launch (as Gemini 9) on May 17, but it was postponed when the Gemini Agena Target Vehicle failed to achieve orbit due to a booster failure earlier that day. The replacement Augmented Target Docking Adapter (ATDA) was launched successfully into Earth orbit on June 1, but telemetry indicated that the shroud had failed to jettison properly. Gemini 9 was to launch shortly thereafter but ground equipment failure resulted in a postponement until June 3. Gemini 9A was launched from Complex 19 and inserted into a 158.8x266.9 km orbit. After three orbital maneuvers, rendezvous within 8 meters of the ATDA was achieved on the third revolution. It was confirmed that the launch shroud on the ATDA had failed to deploy and was blocking the docking port. The flight plan was then revised to include two equiperiod passive re-rendezvous maneuvers in place of the docking. The first, using optical techniques without on-board radar, was completed at 20:15 UTC, and the second, a rendezvous from above simulating rendezvous of an Apollo command module with a lunar module after abort from the moon, was completed at 11:21 UTC on June 4, and final departure from the ATDA took place at 12:38. The scheduled EVA was postponed due to crew fatigue and the second day was devoted to experiments. On June 5 at 15:02, the Gemini capsule was depressurized and the hatch above Cernan opened. Cernan was out of the spacecraft at 15:19, attached by an 8 meter long tether which was connected to Gemini's oxygen supply. He had no gas maneuvering unit as was used on Gemini 4. He retrieved the micrometeorite impact detector attached to the side of the capsule and then moved about the spacecraft. He had great difficulty maneuvering and maintaining orientation on the long tether. He took photographs of Gemini from the full length of the tether and finally moved to the back of the capsule where the Astronaut Maneuvering Unit (AMU) was mounted. He was scheduled to don the AMU, disconnect from the Gemini oxygen supply (although he would still be attached to the spacecraft with a longer, thinner tether) and move to 45 meters from the capsule. The task of donning the AMU took "four to five times more work than anticipated", overwhelming Cernan's environmental control system and causing his faceplate to fog up, limiting his visibility. It was also discovered that the AMU radio transmissions were garbled. These problems caused Stafford to recall Cernan to the spacecraft. He reentered the spacecraft at 17:05 and the hatch was closed at 17:10. Cernan was the third person to walk in space and his total time of 2 hours, 8 minutes was the longest spacewalk yet. Retrofire occurred at the end of the 45th revolution on June 6 at 13:26:17 UTC. Splashdown was in the western Atlantic at 27.87° N, 75.00° W, 550 km east of Cape Kennedy and 0.7 km from the target point. The astronauts stayed inside the spacecraft and were brought aboard the recovery ship U.S.S. Wasp at 14:53. Total mission elapsed time was 72:20:50. Of the primary objectives, three rendezvous techniques were demonstrated, although docking could not be achieved due to the failure of the augmented target-docking shroud to jettison. Testing of the AMU was not completed. The Agena micrometeorite experiment hardware was lost when the Agena target vehicle failed to achieve orbit. Other experiments functioned normally. Gemini 10
Gemini 10 was the eighth crewed Earth-orbiting spacecraft of the Gemini series. Its primary purpose was to conduct rendezvous and docking tests with the Agena target vehicle. The mission plan included a rendezvous with the Gemini 8 Agena target, two extravehicular activity (EVA) excursions, and the performance of 15 scientific, technological, and medical experiments. The scientific experiments were related to zodiacal light, synoptic terrain, and synoptic weather photography, micrometeorite collections, UV astronomical camera, ion wake measurements, and meteoroid erosion. Gemini 10 was launched from Complex 19 and inserted into a 159.9x268.9 km orbit. At orbit insertion Gemini 10 was about 1600 km behind the Gemini Agena Target Vehicle 10 (GATV-10) which had been launched into a near circular orbit about 100 minutes earlier. Rendezvous with GATV-10 was achieved on the 4th revolution at 15:43 and at 16:13:03 docking was achieved. A large out-of-plane error in the initial orbit required the Gemini to use 60% of its fuel for the rendezvous, over twice the planned amount. As a result, most of the mission plan was revised. To conserve fuel, Gemini 10 remained docked to GATV-10 for the next 39 hours and used the GATV propulsion system for maneuvers. The planned docking practice runs were cancelled. A 14-second burn of the GATV-10 primary propulsion system was used to raise the dual spacecraft apogee to 764 km. While the spacecraft were docked, a bending mode test was conducted to study spacecraft dynamics and other experiments were performed. Another burn of GATV-10 at 20:58 UTC on July 19 brought the spacecraft into the same orbit as the GATV-8, which had been launched on March 16 for the Gemini 8 mission. At 21:44, the Gemini cabin pressure was reduced to zero and the hatch was opened. Collins stood up in his seat 3 minutes later and began photographing stellar UV radiation. Partway into the standup EVA Young and Collins began to experience severe eye irritation from an unidentified source and Young ordered termination of the EVA. Collins sat down and the hatch was closed at 22:33, and a high oxygen flow rate was used to purge the environmental control system. Gemini 10 separated from GATV-10 at 19:00 UTC on July 20. A series of maneuvers using its own thrusters brought Gemini 10 within about 15 meters of GATV-8. At 23:01 (48:41 ground elapsed time) the cabin was evacuated and the hatch opened for Collins to begin his second EVA. Collins left the spacecraft 6 minutes later attached to an umbilical cord and traveled to the GATV-8. Despite difficulties due to lack of handholds on the target vehicle, Collins removed the fairing and retrieved the micrometeoroid detection equipment. During the EVA he lost his camera. He also retrieved the micrometeorite experiment mounted on the Gemini 10 spacecraft, but this apparently floated out of the hatch and was lost when Collins reentered the capsule. The EVA was limited to 25 minutes of outside activity due to lack of fuel. Collins reentered the capsule at 23:32 and the hatch was closed at 23:40. The hatch was reopened again at 00:53 UTC on July 21 to jettison 12 items before reentry. After about three hours of stationkeeping Gemini 10 moved away from GATV-8. At 1:59, the crew performed an anomaly adjust maneuver to minimize reentry dispersions resulting from the retrofire maneuver. Retrorocket ignition took place during the 43rd revolution on July 21 at 20:30:50 UTC and splashdown occurred in the western Atlantic at 26.74° N, 71.95° W, 875 km east of Cape Kennedy and 6.3 km from the target point. The crew was picked up by helicopter and taken to the recovery ship U.S.S. Guadalcanal at 21:34 and the spacecraft was aboard at 22:01. Total mission elapsed time was 70:46:39. Of the primary objectives, only the docking practice was not accomplished due to lack of fuel, although the fuel budget also resulted in small revisions in some of the other objectives. The first rendezvous and docking maneuvers were successfully accomplished. All experiments obtained data except for the Gemini 10 micrometeorite collector, which was lost by floating out of the spacecraft. The landmark contrast measurement experiment was deleted due to lack of fuel. Gemini 10 demonstrated the ability of an astronaut to travel to another spacecraft and back and the use of powered, fueled satellite to provide propulsion for a docked spacecraft. Gemini 11
Gemini 11 was the ninth crewed Earth-orbiting spacecraft of the Gemini series. The 3-day mission was designed to achieve a first orbit rendezvous and docking with the Agena target vehicle, accomplish two ExtraVehicular Activity (EVA) tests, perform docking practice, docked configuration maneuvers, tethered operations, parking of the Agena target vehicle, and demonstrate an automatic reentry. There were also eight scientific and four technological experiments on board. The scientific experiments were synergistic effect of zero-g and radiation on white blood cells,synoptic terrain photography, synoptic weather photography, nuclear emulsions, airglow horizon photography, UV astronomical photography, Gemini ion wake measurement, and dim sky photography. Gemini 11 was launched from Complex 19 and inserted into a 160.5x279.1 km Earth orbit at 14:48:28. Five spacecraft maneuvers were made to rendezvous with the Gemini Agena Target Vehicle 11 (GATV-11) at 16:07 (1:25 Ground Elapsed Time, GET). The GATV-11 had been launched an hour and a half before Gemini 11. Docking was completed at 16:16 on the first orbit, consuming less fuel than expected. Each astronaut then conducted two docking exercises with the GATV, and then a maneuver at 19:14:14 brought the docked spacecraft into a 287x304 km orbit. The sleep period was spent in docked configuration. On September 13 at 14:44 UTC (24:02 GET), the Gemini cabin atmosphere was evacuated and the hatch opened to begin Richard Gordon's scheduled 107 minute EVA. He was out of the hatch at 14:51, attached by an umbilical cord. He set up a movie camera and retrieved the micrometeorite experiment. The next task, detaching one end of the 30 meter tether from the Agena and attaching it to the Gemini spacecraft docking bar, proved to be exhausting and overstressed Gordon's life support system. After attaching the tether, Gordon stopped to rest astride the GATV, but the heavy perspiration inside the suit obscured his vision and finally blinded his right eye. Conrad ordered him to cancel the power tool evaluation and return to the cabin. Gordon returned to the cabin at about 15:12 and closed the hatch at 15:17 so the cabin could be repressurized. At 16:19, the hatch was opened again to jettison some excess equipment. Following the sleep period, the Agena primary propulsion system was fired for 25 seconds at 7:12:41 UTC on September 14, raising the docked spacecraft apogee to 1374.1 km (a record altitude for an astronaut mission that would stand until Apollo 8 went to the moon). After two orbits, the Agena was fired again for 22.5 seconds to lower the Gemini-Agena back down to a 287x304 km orbit. At 12:49, Gordon opened his hatch to begin a 2 hour 8 minute standup EVA during which he conducted photographic experiments. The hatch was closed at 14:57 and shortly afterwards the spacecraft were undocked and Gemini 11 moved to the end of the 30 meter tether attaching the two spacecraft. At 16:55, Conrad initiated a slow rotation of the Gemini capsule about the GATV which kept the tether taut and the spacecraft a constant distance apart at the ends of the tether. Oscillations occurred initially, but damped out after about 20 minutes. The rotation rate was then increased; oscillations again occurred but damped out and the combination stabilized. The circular motion at the end of the tether imparted a slight artificial "gravitational acceleration" within Gemini 11, the first time such artificial gravity was demonstrated in space. After about three hours the tether was released and the spacecraft moved apart. A fuel cell stack failed at 21:13, but the remaining stacks took over the load satisfactorily. At 9:22 UTC on September 15, a final re-rendezvous maneuver without use of the rendezvous radar, which had malfunctioned, was accomplished. Retrofire occurred at the end of the 44th revolution at 13:24:03 UTC on September 15. This was the first closed-loop, automatic reentry (guided by computer commands directly to the thrusters) in the U.S. space program. Splashdown was in the western Atlantic at 24.25° N, 70.00° W, 4.9 km from the target point. The crew was picked up by helicopter and brought to the U.S.S. Guam at 14:23 and the spacecraft was recovered at 14:58. Total mission elapsed time was 71:17:08. All primary objectives were accomplished, and the last re-rendezvous added to the mission plan due to the favorable fuel supply. Power tool evaluation was not performed due to early termination of EVA and the airglow horizon photography was only partially done due to a fault in the camera. All other experiments were successfully completed. Gemini 12
Gemini 12 was launched from Complex 19 and inserted into a 160.8x270.6 km Earth orbit at 20:52:40. At 00:32 UTC, rendezvous was achieved with the Gemini Agena Target Vehicle (GATV), which had been launched an hour and a half before Gemini 12. Docking with the GATV was accomplished 28 minutes later, at 4:14 ground elapsed time (GET) on the third orbit, relying heavily on visual sightings due to problems with the onboard radar. During insertion of the GATV into orbit, an anomaly was noted in the primary propulsion system, so the plan to use the GATV to lift the docked spacecraft into a higher orbit was abandoned. Instead, two phasing maneuvers using the GATV secondary propulsion system were accomplished to allow the spacecraft to rendezvous with the November 12 total eclipse over South America at about 14:20 with the crew taking pictures through the spacecraft windows. The first standup EVA took place with the hatch opening at 16:15 UTC (19:29 GET) on November 12 and Aldrin standing on his seat with his upper body out of the hatch. The EVA lasted 2 hours 29 minutes during which Aldrin mounted a camera to the side of the spacecraft and collected a micrometeorite experiment, with the hatch closing at 18:44. On November 13 at 12:16, the crew reported little or no thrust was available from two of the maneuvering thrusters. At 15:34 UTC (42:48 GET), the hatch was opened for the second EVA. Aldrin was outside the spacecraft at 15:38, attached to a 9 meter umbilical cord. He first worked in the hatch and nose area, and then moved along a handrail he had installed to the adapter section where he used foot restraints and tethers to position himself in front of a work panel mounted on the rear of the adaptor where he performed 17 relatively simple manual tasks. He then moved to the target vehicle adapter area and carried out another series of tasks, including use of a torque wrench while tethered. He attached a 30 meter long tether stowed in the GATV adapter to the Gemini adapter bar. About a dozen two-minute rest periods were scheduled during the EVA to prevent Aldrin from becoming overtaxed as happened to previous space walkers. Aldrin reentered the capsule at 17:33 and closed the hatch at 17:40. All tasks were accomplished and total EVA time was 2 hours 6 minutes. At 20:09, Gemini 12 undocked from the GATV, moved to the end of the tether connecting the two vehicles, and began the tether experiment by moving in a circular orbit about the GATV. The tether tended to remain slack, but the crew believed the two craft slowly attained gravity-gradient stabilization. The tether was released at 00:37. On November 14, the hatch was opened at 14:52 UTC (66:06 GET) and Aldrin began the second standup EVA which included photography, additional experiments and the jettison of unused equipment. The EVA ended after 55 minutes when the hatch was closed at 15:47. Minor fuel cell and thruster problems were reported, but did not affect the remainder of the mission. The automatically controlled reentry sequence began with retrofire at the end of revolution 59 on November 15 at 18:46:31 UTC. Splashdown occurred in the western Atlantic at 24.58° N, 69.95° W, 4.8 km from target point. The crew was picked up by helicopter and brought aboard the U.S.S. Wasp at 19:49, the spacecraft was picked up at 20:28. Total mission elapsed time was 94:34:31. All primary mission goals were successfully accomplished except performance of maneuvers using the Agena propulsion system due to fluctuations in the system noticed by ground controllers. There were minor fuel cell and attitude control thruster problems during the mission. The successfully performed scientific experiments were frog egg growth under zero-g, synoptic terrain photography, synoptic weather photography, nuclear emulsions, airglow horizon photography, UV astronomical photography, and dim sky photography. Two micrometeorite collection experiments, as well as three space phenomena photography experiments, were not fully completed. Reentry At the time of reentry, the spacecraft would be maneuvered to the appropriate orientation, and the equipment adaptor section would be detached and jettisoned, exposing the retrorocket module. The retrorockets consisted of four spherical-case polysulfide ammonium perchlorate solid-propellant motors mounted near the center of the reentry adaptor module, each with 11,070 N thrust. They would fire to initiate the spacecraft reentry into the atmosphere, with attitude being maintained by a reentry control system of 16 engines, each with 5.2 N thrust. The retrorocket module would then be jettisoned, exposing the heat shield at the base of the reentry module. Along with the ablative heat shield, thermal protection during reentry was provided by thin Rene 41 radiative shingles at the base of the module and beryllium shingles at the top. Beneath the shingles was a layer of MIN-K insulation and thermoflex blankets. At an altitude of roughly 15,000 meters, the astronauts would deploy a 2.4 meter drogue chute from the rendezvous and recovery section. At 3230 meters altitude, the crew released the drogue which extracts the 5.5 meter pilot parachute. The rendezvous and recovery section was released 2.5 seconds later, deploying the 25.6 meter main ring-sail parachute which was stored in the bottom of the section. The spacecraft was then rotated from a nose-up to a 35° angle for water landing. At this point a recovery beacon was activated, transmitting via an HF whip antenna mounted near the front of the reentry module. Gemini Spacecraft Overview The Gemini spacecraft was a cone-shaped capsule consisting of two components, a reentry module and an adaptor module. The adaptor module made up the base of the spacecraft. It was a truncated cone 228.6 cm high, 304.8 cm in diameter at the base and 228.6 cm at the upper end where it attached to the base of the reentry module. The re-entry module consisted of a truncated cone which decreased in diameter from 228.6 cm at the base to 98.2 cm, topped by a short cylinder of the same diameter and then another truncated cone decreasing to a diameter of 74.6 cm at the flat top. The reentry module was 345.0 cm high, giving a total height of 573.6 cm for the Gemini spacecraft. The adaptor module was an externally skinned, stringer framed structure, with magnesium stringers and an aluminum alloy frame. The adaptor was composed of two parts, an equipment section at the base and a retrorocket section at the top. The equipment section held fuel and propulsion systems and was isolated from the retrorocket section by a fiber-glass sandwich honeycomb blast shield. The retrorocket section held the re-entry rockets for the capsule. The reentry module consisted mainly of the pressurized cabin which held the two Gemini astronauts. Separating the reentry module from the retrorocket section of the adaptor at its base was a curved silicone elastomer ablative heat shield. The module was composed predominantly of titanium and nickle-alloy with beryllium shingles. At the narrow top of the module was the cylindrical reentry control system section and above this the rendezvous and recovery section which holds the reentry parachutes. The cabin held two seats equipped with emergency ejection devices, instrument panels, life support equipment, and equipment stowage compartments in a total pressurized volume of about 2.25 cubic meters. Two large hatches with small windows could be opened outward, one positioned above each seat. 
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Gemini
1 was an uncrewed orbital test of the Titan 2 launch vehicle, the Gemini spacecraft
structural integrity, and the launch vehicle-spacecraft compatibility. The test
covered all phases through the orbital insertion phase. Other objectives were
to check launch vehicle-spacecraft launch heating conditions, launch vehicle
performance, launch vehicle flight control system switch-over circuits, launch
vehicle orbit insertion accuracy, and the malfunction detection system. This
was the first production Gemini spacecraft and launch vehicle.
Gemini
4 was the second crewed mission of the Gemini series and carried its crew on
a 4-day, 62-orbit, 98-hr flight. The mission included the first American spacewalk.
The objective of the mission was to test the performance of the astronauts and
capsule and to evaluate work procedures, schedules, and flight planning for an
extended length of time in space. Secondary objectives included demonstration
of extravehicular activity in space, conduct stationkeeping and rendezvous maneuvers,
evaluate spacecraft systems, demonstrate the capability to make significant in-plane
and out-of-plane maneuvers and use of the maneuvering system as a backup reentry
system, and conduct 11 experiments.
Gemini
5 was the third crewed Earth-orbiting spacecraft of the Gemini series. The flight
was designed to last eight days and test rendezvous procedures. The major objectives
of this mission were to demonstrate a long-duration crewed flight, evaluate the
effects of long periods of weightlessness on the crew, and test rendezvous capabilities
and maneuvers using a rendezvous evaluation pod. Secondary objectives included
demonstration of all phases of guidance and control systems to support rendezvous
and controlled reentry guidance, to evaluate the fuel cell power system and rendezvous
radar, to test the capability of either pilot to maneuver the spacecraft in orbit
to close proximity with another object, and to conduct 17 experiments.
Gemini
6A was the fifth crewed Earth-orbiting spacecraft of the Gemini series, having
been launched after Gemini 7, with the intent of making rendezvous with Gemini
7 in Earth orbit. The mission priorities were to demonstrate on-time launch procedures,
closed-loop rendezvous capabilities, and stationkeeping techniques with Gemini
7. Other objectives were to evaluate the spacecraft reentry guidance capabilities,
and conduct spacecraft systems tests and four experiments. This mission was originally
designated Gemini 6 and scheduled for launch on October 25 but was cancelled
when the Agena target vehicle failed to go into orbit an hour earlier.
Gemini
8 was the sixth crewed Earth-orbiting spacecraft of the Gemini series. The primary
mission objectives were to perform rendezvous and four docking tests with the
Agena target vehicle and to execute an ExtraVehicular Activity (EVA) experiment.
Other objectives included parking the Agena in a 410 km circular orbit, performing
a re-rendezvous with the Agena, conduct systems evaluation, evaluate the auxiliary
tape memory unit, and demonstration of controlled reentry. Ten technological,
medical, and scientific experiments were carried on board.
Gemini
12 was the tenth and final flight of the Gemini series. This mission was scheduled
to perform rendezvous and docking with the Agena target vehicle, conduct three
ExtraVehicular Activity (EVA) operations, conduct a tethered stationkeeping exercise,
perform docked maneuvers using the Agena propulsion system to change orbit, and
demonstrate an automatic reentry. There were also 14 scientific, medical, and
technological experiments on board.