Mission type | Space rendezvous |
---|---|
Operator | NASA |
COSPAR ID | 1965-104A |
SATCAT no. | 1839 |
Mission duration | 1 day, 1 hour, 51 minutes, 24 seconds |
Distance travelled | 694,415 kilometers (374,954 nautical miles) |
Orbits completed | 16 |
Spacecraft properties | |
Spacecraft | Gemini SC6 |
Manufacturer | McDonnell. Phrase m |
Launch mass | 3,546 kilograms (7,818 lb) |
Crew | |
Crew size | 2 |
Members | |
Start of mission | |
Launch date | December 15, 1965, 13:37:26 UTC |
Rocket | Titan II GLV,s/n 62-12561 |
Launch site | Cape Kennedy LC-19 |
End of mission | |
Recovered by | USS Wasp |
Landing date | December 16, 1965, 15:28:50 UTC |
Landing site | North Atlantic Ocean 23°35′N67°50′W / 23.583°N 67.833°W |
Orbital parameters | |
Reference system | Geocentric |
Regime | Low Earth orbit |
Perigee altitude | 270 kilometers (150 nautical miles) |
Apogee altitude | 274 kilometers (148 nautical miles) |
Inclination | 28.9 degrees |
Period | 89.95 minutes |
Epoch | December 15, 1965 [1] |
(L-R) Stafford, Schirra |
Gemini 6A (officially Gemini VI-A) [2] was a 1965 crewed United States spaceflight in NASA's Gemini program. The mission, flown by Wally Schirra and Thomas P. Stafford, achieved the first crewed rendezvous with another spacecraft, its sister Gemini 7. Although the Soviet Union had twice previously launched simultaneous pairs of Vostok spacecraft, these established radio contact with each other, but they had no ability to adjust their orbits in order to rendezvous and came no closer than several kilometers of each other, while the Gemini 6 and 7 spacecraft came as close as one foot (30 cm) and could have docked had they been so equipped.
Gemini 6A was the fifth crewed Gemini flight, the 13th crewed American flight, and the 21st crewed spaceflight of all time (including two X-15 flights over 100 kilometers (54 nautical miles)).
Position | Astronaut | |
---|---|---|
Command Pilot | Walter M. Schirra Jr. Second spaceflight | |
Pilot | Thomas P. Stafford First spaceflight |
Position | Astronaut | |
---|---|---|
Command Pilot | Virgil I. Grissom [3] | |
Pilot | John W. Young | |
This was the prime crew of Gemini 3. |
The original Gemini 6 mission, scheduled for launch on October 25, 1965, at 12:41 pm EDT, had a planned mission duration of 46 hours 47 minutes, completing a total of 29 orbits. It was to land in the western Atlantic Ocean south of Bermuda.
The mission was to include four dockings with the Agena Target Vehicle. The first docking was scheduled for five hours and forty minutes into the mission. The second was scheduled for seven hours and forty-five minutes, the third at nine hours and forty minutes, and the fourth and final docking at ten hours and five minutes into the mission. The final undocking would take place at 18 hours and 20 minutes into the mission. At 23 hours and 55 minutes into the mission, while the spacecraft passed over White Sands, New Mexico, the crew was to attempt to observe a laser beam originating from the ground. The retrorockets were scheduled to be fired at 46 hours and 10 minutes into the mission over the Pacific Ocean on the 29th orbit. [4]
Original mission plans also included the first live television coverage of the recovery of a U.S. spacecraft at sea from the recovery ship, the U.S. aircraft carrier Wasp. The Wasp was fitted with ground station equipment by ITT to relay live television, via the Intelsat I (nicknamed the "Early Bird") satellite. [5]
On October 25, 1965, Schirra and Stafford boarded their Gemini 6 craft to prepare for launch. Fifteen minutes later, the uncrewed Atlas-Agena target vehicle was launched. After a successful burn of the Atlas booster, the Agena's engine fired to separate it from the Atlas. But immediately after the Agena's engine fired at the six-minute mark in the flight, telemetry was lost. A catastrophic failure apparently caused the vehicle to explode, as Range Safety was tracking multiple pieces of debris falling into the Atlantic Ocean. After 50 minutes, the Gemini launch was canceled. [6] [7]
Agena | GATV-5002 |
---|---|
Mass | 3,261 kilograms (7,189 lb), 7800 lbs. |
Launch site | LC-14 |
Launch date | October 25, 1965 |
Launch time | 15:00:04 UTC |
Exploded | 15:06:20 UTC |
After reviewing the situation, NASA decided to launch an alternate Gemini 6A mission, eight days after the launch of Gemini 7, which was scheduled as a 14-day long-duration mission in December. Gemini 6A would perform the first rendezvous of two spacecraft in orbit, using Gemini 7 as the target, though they would not dock. The crews also discussed the possibility of Stafford performing an EVA from 6A to 7, swapping places with Gemini 7 pilot Jim Lovell, but the commander of Gemini 7, Frank Borman, objected, pointing out that it would require Lovell to wear an uncomfortable EVA suit on a long-duration mission. [8]
This section needs additional citations for verification .(December 2019) |
Attempt | Planned | Result | Turnaround | Reason | Decision point | Weather go (%) | Notes |
---|---|---|---|---|---|---|---|
1 | 25 Oct 1965, 11:41:00 am | Scrubbed | — | Technical | 25 Oct 1965, 10:54 am | Failure of Atlas-Agena rocket to orbit. [9] Mission plans revised and designated as Gemini 6A. | |
2 | 12 Dec 1965, 9:54:00 am | Scrubbed | 47 days 22 hours 13 minutes | Technical | 12 Dec 1965, 9:54 am (T+00:00:01) | Both engines shut down after ignition due to an electrical plug falling out. | |
3 | 15 Dec 1965, 8:37:26 am | Success | 2 days 22 hours 43 minutes |
The first attempt to launch the 6A mission (second attempt for Gemini spacecraft No. 6) was on December 12, 1965, at 9:54 a.m. EST. [6] All went well right up to ignition; the engines ignited, but after about 1.5 seconds they abruptly shut down. Since the lift-off clock had started in the spacecraft, mission rules dictated that Wally Schirra, as the commander, had to immediately pull the D-ring between his knees and activate the ejection seats, [10] carrying the astronauts away from the disaster that would be the result of a fully fueled Titan II falling back onto LC-19. However, Schirra did not feel any movement and knew that the booster had not lifted, so he decided not to abort. His quick thinking probably saved the mission as the reliability of the Gemini ejector seats was questionable; the astronauts could have been badly injured from high g-forces as the seats had to launch them at least 800 feet, which was deemed a safe distance from an exploding Titan II.
In addition, the cabin interior had been soaking in pure oxygen for hours. Tom Stafford, in a NASA oral history in 1997, later recalled:
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. [11]
Even if the astronauts had not been injured or killed, ejection would ruin the spacecraft and delay the mission for months.
After the Stage I engines ignited and shut down, fuel (UDMH) was leaking out of the PSV drain valve. The fuel had been ignited by the engine start, and the resulting fire was discovered when the Pad Crew inspected the engine compartment. Water spray was initiated and a cap was installed on the drain line. About 60 minutes after the aborted launch, the booster and spacecraft had been made safe and the service tower raised up to it. After removing the propellants from the Titan II, the booster was checked out and they quickly uncovered one culprit, which was an umbilical plug that dropped out of the base of the booster prematurely. This plug sent a lift-off signal to the spacecraft. Testing revealed that some plugs came out more easily than others, so they were replaced by different ones that would stay in place properly.
However, the electrical plug turned out to not be the only problem with the booster. Examination of telemetry also showed that the Titan actually began experiencing thrust decay before the plug dropped out. Engine No. 1 was unaffected and nearly reached 100% thrust at shutdown, while Engine No. 2 never transitioned to in-flight performance levels. Engineers spent all night combing through the first stage, but failed to find any cause for the thrust decay. Eventually however, one technician identified the problem, which was a plastic dust cover inside the gas generator that had been carelessly left inside when the booster was assembled months earlier at the Martin-Marietta plant, blocking the flow of oxidizer. The cover was removed and the Titan II cleared for another launch attempt.
Had the inadvertent electrical disconnect not occurred, the abort sensing system would have sent a shutoff command to the Titan at T+2.2 seconds due to the loss of Engine No. 2 chamber pressure. Since launcher release and liftoff would take place at T+3.2 seconds, a pad fallback still would not have occurred in this scenario and the astronauts would have been safe. [12]
The Titan's batteries were replaced and the fuel prevalves, which had opened, were removed and it was decided to launch without them. The second attempt to launch the 6A mission (third attempt for Gemini spacecraft No. 6) was successful on December 15 at 8:37:26 a.m. EST. All went well through launch and ascent; first stage cutoff occurred at T+160 seconds and second stage cutoff at T+341 seconds. Spacecraft separation occurred at T+361 seconds and the crew entered a 100-by-161-mile (161 by 259 km) orbit.
The plan called for the rendezvous to take place on the fourth orbit of Gemini 6. Their first burn came 94 minutes after launch when they increased their speed by 5 meters (161⁄2 feet) per second. Due to their lower orbit they were gaining on Gemini 7 and were only 730 miles, (or 1,175 kilometers), behind. The next burn was at two hours and eighteen minutes when Gemini 6A made a phase adjustment to put them on the same orbital inclination as Gemini 7. They now only trailed by 300 miles (483 km).
The radar on Gemini 6A first made contact with Gemini 7 at three hours and fifteen minutes when they were 434 kilometers (270 mi) away. A third burn put them into a 168-by-170-mile (270 by 274 km) orbit. As they slowly gained, Schirra put Gemini 6A's computer in charge of the rendezvous. At five hours and four minutes, he saw a bright star that he thought was Sirius, but this was in fact Gemini 7.
After several more burns, the two spacecraft were only 130 feet (40 meters) apart. The burns had only used 112 lbs. (51 kilograms) of propellant on Gemini 6A, leaving plenty for some fly-arounds. During the next 270 minutes, the crews moved as close as one foot (30 centimeters), talking over the radio. At one stage the spacecraft were stationkeeping so well that neither crew had to make any burns for 20 minutes.
Schirra said that because there is no turbulence in space, "I was amazed at my ability to maneuver. I did a fly-around inspection of Gemini 7, literally flying rings around it, and I could move to within inches of it in perfect confidence". [13] As the crew sleep periods approached, Gemini 6A made a separation burn and slowly drifted more than 30 kilometers (19 mi) from Gemini 7. This ensured that there would not be any accidental collisions while the astronauts slept. [14]
The next day, before reentry, [14] the crew of Gemini 6A had a surprise:
...this is Gemini VI. We have an object, looks like a satellite going from north to south, up in a polar orbit. He's in a very low trajectory traveling from north to south and has a very high climbing ratio. It looks like it might even be a ... Very low. Looks like he might be going to reenter soon. Stand by one ... You might just let me try to pick up that thing. [15]
At that point, the sound of "Jingle Bells" was heard played on an eight-note Hohner "Little Lady" harmonica and a handful of small bells. [16] [17] The Smithsonian Institution claims these were the first musical instruments played in space [18] and keeps the instruments on display.
Gemini 6A fired its retro-rockets and landed within 18 kilometers (11 miles) of the planned site in the Atlantic Ocean northeast of Turks and Caicos. It was the first recovery to be televised live, through a transportable satellite earth station developed by ITT on the deck of the recovery aircraft carrier USS Wasp.
The Gemini 7 and 6A missions were supported by the following U.S. Department of Defense resources: 10,125 personnel, 125 aircraft and 16 ships.[ citation needed ]
Walter Schirra explained the patch in the book All We Did Was Fly to the Moon:
The Gemini 6 patch is hexagonal in shape, reflecting the mission number; and the spacecraft trajectory also traces out the number "6". The Gemini 6 spacecraft is shown superimposed on the "twin stars" Castor and Pollux, for "Gemini". I designed the patch to locate in the sixth hour of celestial right ascension. This was the predicted celestial area where the rendezvous should occur (in the constellation Orion). It finally did occur there.
The original patch had called the flight GTA-6 (for Gemini-Titan-Agena) and showed the Gemini craft chasing an Agena. It was changed when the mission was altered to depict two Gemini spacecraft.
The spacecraft is currently on display at the Stafford Air & Space Museum in Weatherford, Oklahoma, having previously been displayed at the Oklahoma History Center in Oklahoma City. [19] The spacecraft had previously been on display at the Omniplex Science Museum elsewhere in the city. It is on a long-term loan from the Smithsonian Institution.
Before being moved to Oklahoma, the spacecraft was displayed at the St. Louis Science Center in St. Louis, Missouri.[ citation needed ]
Apollo 7 was the first crewed flight in NASA's Apollo program, and saw the resumption of human spaceflight by the agency after the fire that had killed the three Apollo 1 astronauts during a launch rehearsal test on January 27, 1967. The Apollo 7 crew was commanded by Walter M. Schirra, with command module pilot Donn F. Eisele and Lunar Module pilot R. Walter Cunningham.
Apollo 10 was the fourth human spaceflight in the United States' Apollo program and the second to orbit the Moon. NASA, the mission's operator, described it as a "dress rehearsal" for the first Moon landing. It was designated an "F" mission, intended to test all spacecraft components and procedures short of actual descent and landing.
Gemini 10 was a 1966 crewed spaceflight in NASA's Gemini program. It was the 8th crewed Gemini flight, the 16th crewed American flight, and the 24th spaceflight of all time. During the mission, flown by future STS-1 Commander John Young and future Apollo 11 Command Module Pilot Michael Collins, Collins became the first person to perform two extravehicular activities.
Mercury-Atlas 8 (MA-8) was the fifth United States crewed space mission, part of NASA's Mercury program. Astronaut Walter M. Schirra Jr., orbited the Earth six times in the Sigma 7 spacecraft on October 3, 1962, in a nine-hour flight focused mainly on technical evaluation rather than on scientific experimentation. This was the longest U.S. crewed orbital flight yet achieved in the Space Race, though well behind the several-day record set by the Soviet Vostok 3 earlier in the year. It confirmed the Mercury spacecraft's durability ahead of the one-day Mercury-Atlas 9 mission that followed in 1963.
The RM-81 Agena was an American rocket upper stage and satellite bus which was developed by Lockheed Corporation initially for the canceled WS-117L reconnaissance satellite program. Following the division of WS-117L into SAMOS and Corona for image intelligence, and MIDAS for early warning, the Agena was later used as an upper stage, and an integrated component, for several programs, including Corona reconnaissance satellites and the Agena Target Vehicle used to demonstrate rendezvous and docking during Project Gemini. It was used as an upper stage on the Atlas, Thor, Thorad and Titan IIIB rockets, and considered for others including the Space Shuttle and Atlas V. A total of 365 Agena rockets were launched between February 28, 1959 and February 1987. Only 33 Agenas carried NASA payloads and the vast majority were for DoD programs.
The Agena Target Vehicle, also known as Gemini-Agena Target Vehicle (GATV), was an uncrewed spacecraft used by NASA during its Gemini program to develop and practice orbital space rendezvous and docking techniques, and to perform large orbital changes, in preparation for the Apollo program lunar missions. The spacecraft was based on Lockheed Aircraft's Agena-D upper stage rocket, fitted with a docking target manufactured by McDonnell Aircraft. The name 'Agena' derived from the star Beta Centauri, also known as Agena. The combined spacecraft was a 26-foot (7.92 m)-long cylinder with a diameter of 5 feet (1.52 m), placed into low Earth orbit with the Atlas-Agena launch vehicle. It carried about 14,000 pounds (6,400 kg) of propellant and gas at launch, and had a gross mass at orbital insertion of about 7,200 pounds (3,300 kg).
John Watts Young was an American astronaut, naval officer and aviator, test pilot, and aeronautical engineer. He became the 9th person to walk on the Moon as commander of the Apollo 16 mission in 1972. He is the only astronaut to fly on four different classes of spacecraft: Gemini, the Apollo command and service module, the Apollo Lunar Module and the Space Shuttle.
Walter Marty Schirra Jr. was an American naval aviator, test pilot, and NASA astronaut. In 1959, he became one of the original seven astronauts chosen for Project Mercury, which was the United States' first effort to put humans into space. On October 3, 1962, he flew the six-orbit, nine-hour, Mercury-Atlas 8 mission, in a spacecraft he nicknamed Sigma 7, becoming the fifth American and ninth human to travel into space. In December 1965, as part of the two-man Gemini program, he achieved the first space rendezvous, station-keeping his Gemini 6A spacecraft within 1 foot (30 cm) of the sister Gemini 7 spacecraft. In October 1968, he commanded Apollo 7, an 11-day low Earth orbit shakedown test of the three-man Apollo Command/Service Module and the first crewed launch for the Apollo program.
James Arthur Lovell Jr. is an American retired astronaut, naval aviator, test pilot and mechanical engineer. In 1968, as command module pilot of Apollo 8, he became, with Frank Borman and William Anders, one of the first three astronauts to fly to and orbit the Moon. He then commanded the Apollo 13 lunar mission in 1970 which, after a critical failure en route, looped around the Moon and returned safely to Earth.
Gemini 4 was the second crewed spaceflight in NASA's Project Gemini, occurring in June 1965. It was the tenth crewed American spaceflight. Astronauts James McDivitt and Ed White circled the Earth 66 times in four days, making it the first US flight to approach the five-day flight of the Soviet Vostok 5. The highlight of the mission was the first space walk by an American, during which White floated free outside the spacecraft, tethered to it, for approximately 23 minutes.
Gemini 7 was a 1965 crewed spaceflight in NASA's Gemini program. It was the fourth crewed Gemini flight, the twelfth crewed American spaceflight, and the twentieth crewed spaceflight including Soviet flights and X-15 flights above the Kármán line. The crew of Frank Borman and Jim Lovell spent nearly 14 days in space, making a total of 206 orbits. Their spacecraft was the passive target for the first crewed space rendezvous performed by the crew of Gemini 6A.
Gemini 8 was the sixth crewed spaceflight in NASA's Gemini program. It was launched on March 16, 1966, and was the 14th crewed American flight and the 22nd crewed spaceflight overall. The mission conducted the first docking of two spacecraft in orbit, but also suffered the first critical in-space system failure of a U.S. spacecraft which threatened the lives of the astronauts and required an immediate abort of the mission. The crew returned to Earth safely.
Gemini 9A was a 1966 crewed spaceflight in NASA's Gemini program. It was the seventh crewed Gemini flight, the 15th crewed American flight and the 23rd spaceflight of all time. The original crew for Gemini 9, command pilot Elliot See and pilot Charles Bassett, were killed in a crash on February 28, 1966, while flying a T-38 jet trainer to the McDonnell Aircraft plant in St. Louis, Missouri to inspect their spacecraft. Their deaths promoted the backup crew, Thomas P. Stafford and Eugene Cernan, to the prime crew. The mission was renamed Gemini 9A after the original May 17 launch was scrubbed when the mission's Agena Target Vehicle was destroyed after a launch failure. The mission was flown June 3–6, 1966, after launch of the backup Augmented Target Docking Adaptor (ATDA). Stafford and Cernan rendezvoused with the ATDA, but were unable to dock with it because the nose fairing had failed to eject from the docking target due to a launch preparation error. Cernan performed a two-hour extravehicular activity, during which it was planned for him to demonstrate free flight in a self-contained rocket pack, the USAF Astronaut Maneuvering Unit. He was unable to accomplish this due to stress, fatigue, and overheating.
Gemini 11 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. Astronauts Pete Conrad and Dick Gordon performed the first direct-ascent rendezvous with an Agena 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 of artificial gravity by spinning the two spacecraft connected by a tether. Gordon also performed two extra-vehicular activities for a total of 2 hours 41 minutes.
Gemini 12 was a 1966 crewed spaceflight in NASA's Project Gemini. It was the 10th and final crewed Gemini flight, the 18th crewed American spaceflight, and the 26th spaceflight of all time, including X-15 flights over 100 kilometers (54 nmi). Commanded by Gemini VII veteran James A. Lovell, the flight featured three periods of extravehicular activity (EVA) by rookie Edwin "Buzz" Aldrin, lasting a total of 5 hours and 30 minutes. It also achieved the fifth rendezvous and fourth docking with an Agena target vehicle.
Thomas Patten Stafford was an American Air Force officer, test pilot, and NASA astronaut, and one of 24 astronauts who flew to the Moon. He also served as Chief of the Astronaut Office from 1969 to 1971.
Project Gemini was the second United States human spaceflight program to fly. Conducted after the first American crewed space program, Project Mercury, while the Apollo program was still in early 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 low Earth orbit (LEO) missions during 1965 and 1966.
A space rendezvous is a set of orbital maneuvers during which two spacecraft, one of which is often a space station, arrive at the same orbit and approach to a very close distance. Rendezvous requires a precise match of the orbital velocities and position vectors of the two spacecraft, allowing them to remain at a constant distance through orbital station-keeping. Rendezvous may or may not be followed by docking or berthing, procedures which bring the spacecraft into physical contact and create a link between them.
The Atlas-Agena was an American expendable launch system derived from the SM-65 Atlas missile. It was a member of the Atlas family of rockets, and was launched 109 times between 1960 and 1978. It was used to launch the first five Mariner uncrewed probes to the planets Venus and Mars, and the Ranger and Lunar Orbiter uncrewed probes to the Moon. The upper stage was also used as an uncrewed orbital target vehicle for the Gemini crewed spacecraft to practice rendezvous and docking. However, the launch vehicle family was originally developed for the Air Force and most of its launches were classified DoD payloads.
Advanced Gemini was a series of proposals that would have extended the Gemini program by the addition of various missions, including crewed low Earth orbit, circumlunar and lunar landing missions. Gemini was the second crewed spaceflight program operated by NASA, and consisted of a two-seat spacecraft capable of maneuvering in orbit, docking with uncrewed spacecraft such as Agena Target Vehicles, and allowing the crew to perform tethered extra-vehicular activities.
This article incorporates public domain material from websites or documents of the National Aeronautics and Space Administration .
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