Gemini 6A

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Gemini VI-A
Gemini 7 in orbit - GPN-2006-000035.jpg
Gemini VI-A (foreground) and Gemini VII make the first rendezvous in orbit between two manned spacecraft
Operator NASA
COSPAR ID 1965-104A
SATCAT № 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
Launch mass 3,546 kilograms (7,818 lb)
Crew
Crew size 2
Members Walter M. Schirra, Jr.
Thomas P. Stafford
Start of mission
Launch date December 15, 1965, 13:37:26 (1965-12-15UTC13:37:26Z) UTC
Rocket Titan II GLV, s/n 62-12561
Launch site Cape Canaveral LC-19
End of mission
Landing date December 16, 1965, 15:28:50 (1965-12-16UTC15:28:51Z) UTC
Landing site North Atlantic Ocean
23°35′N 67°50′W / 23.583°N 67.833°W / 23.583; -67.833
Orbital parameters
Reference system Geocentric
Regime Low Earth
Perigee 161 kilometers (87 nautical miles)
Apogee 259.4 kilometers (140.1 nautical miles)
Inclination 28.97 degrees
Period 88.7 minutes
Epoch December 15, 1965[1]

Gemini 6A patch.png Gemini 6 prime crew.jpg
(L-R) Stafford, Schirra


Project Gemini
← Gemini 7 Gemini 8

Gemini 6A (officially Gemini VI-A)[2] was a 1965 manned United States spaceflight in NASA's Gemini program. The mission achieved the first manned 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, but 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 manned Gemini flight, the 13th manned American flight, and the 21st manned spaceflight of all time (includes X-15 flights over 100 kilometers (54 nautical miles).

Crew[edit]

Position Astronaut
Command Pilot Walter M. Schirra, Jr.
Second spaceflight
Pilot Thomas P. Stafford
First spaceflight

Backup crew[edit]

Position Astronaut
Command Pilot Virgil I. Grissom
Pilot John W. Young

Support crew[edit]

Mission parameters[edit]

Stationkeeping with GT-7[edit]

  • Start: December 15, 1965 19:33 UTC
  • End: December 16, 1965 00:52 UTC

Objective[edit]

Stafford and Schirra before the pre-launch countdown
The Atlas-Agena launches the Agena Target Vehicle for the intended Gemini 6 rendezvous mission, attempted October 25, 1965 but fails.

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 retro rockets were scheduled to be fired at 46 hours and 10 minutes into the mission over the Pacific Ocean on the 29th orbit.[3]

Original mission plans also included the first live television coverage of the recovery of a US spacecraft at sea from the recovery ship, the US 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.[4]

Original mission cancelled[edit]

On October 25, 1965, Schirra and Stafford boarded their Gemini 6 craft to prepare for launch. Fifteen minutes later, the unmanned Atlas-Agena target vehicle was launched. After a successful burn of the Atlas booster, the Agena's secondary engines fired to separate it from the Atlas. But immediately after the Agena's primary engine fired at the six minute mark in its 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.[5][6]

After reviewing the situation, NASA decided to launch an alternate Gemini 6A mission, eight days after the launch of Frank Borman's and Jim Lovell's Gemini 7. Gemini 6A would perform the first rendezvous using 7 as the target, though it would not dock. The crews also discussed the possibility of Stafford performing an EVA from 6A to 7, swapping places with Lovell, but Borman objected, pointing out that it would require Lovell to wear an uncomfortable EVA suit on a long-duration mission.[7]

Gemini 6 Target Vehicle Info
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

Flight[edit]

First launch attempt[edit]

The launch abort of Gemini 6A, attempted December 12, 1965.

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.[5] All went well right up to ignition; the engines ignited, but then a plug fell out of the bottom of the rocket, starting the onboard computer. This was not meant to happen until the rocket had actually lifted off, and the onboard computer detected no upward motion, causing it to abort the launch. At this point, mission rules called for a pad abort to get the astronauts away from the rocket as quickly as possible, as it would explode on impact with the pad if lifted and fell even the smallest distance.

The Gemini spacecraft used ejection seats for this purpose instead of a launch escape tower as had been used on Project Mercury. The ejection seats were designed to be used only in flight, and trying to use them on the pad would have been extremely dangerous and probably fatal, as Schirra and Stafford would have fallen about 10 stories to the ground without benefit of their parachutes, which would have been ineffective at that height. Since neither had detected any upward motion, Schirra made the decision not to eject.

The Martin and Air Force teams who erected and tested the rocket found that some plugs on the rocket were able to pull out more easily than others. They replaced them with ones that were harder to pull out, and a safety wire was added to make sure that the rocket had lifted off.

However, another problem was found as the engineers examined the thrust versus time graph. They found that the thrust rose nominally but started to decrease before the plug had fallen out. Through the night, engineers examined the rocket engine piece by piece until they found that a plastic cover had been left in the gas generator port. With this problem solved, the rocket and spacecraft were rescheduled for a launch three days after the first attempt.

Rendezvous[edit]

Launch of Gemini 6A from Pad 19, December 15, 1965.

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 and the crew entered a 161 by 259 kilometers orbit, or as per the actual flight specifications, a 100 by 161 nautical mile 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 per second, 16½ 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 483 kilometers (300 mi).

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 x 170 mile (270 by 274 kilometer) 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.

The crew of Gemini 6A took this photo of Gemini 7 when they were about 7 meters apart

After several more burns, the two spacecraft were only 130 feet (40 meters) apart. The burns had only used 112 lbs. (51 kilograms) of fuel on Gemini 6A, giving plenty of fuel 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.

As the sleep periods approached, Gemini 6A made a separation burn and slowly drifted out to 16 kilometers (9.9 mi). This ensured that there would not be any accidental collisions in the night.

A Christmas surprise[edit]

But before everyone went to sleep, the crew of Gemini 6A had a surprise for everyone:

Gemini VII, 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.[8]

At that point, the sound of "Jingle Bells" was heard played on an 8-note Hohner "Little Lady" harmonica and a handful of small bells.[9][10] The Smithsonian Institution claims these were the first musical instruments played in space [11] and keeps the instruments on display.

Reentry[edit]

Gemini 6A reentered the next day, landing within 18 kilometers (11 miles) of the planned site northeast of Turks and Caicos in the Atlantic Ocean, the first truly accurate reentry. It was also 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]

Insignia[edit]

Original mission patch, showing the designation GTA-6

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.

Spacecraft location[edit]

The spacecraft is currently on display at the Oklahoma History Center in Oklahoma City, after having been on display at the Omniplex Science Museum elsewhere in the city. It is on a long term loan from the Smithsonian Institution. Before coming to Oklahoma, the spacecraft was displayed at the St. Louis Science Center in St. Louis, Missouri.

See also[edit]

References[edit]

 This article incorporates public domain material from websites or documents of the National Aeronautics and Space Administration.

  1. ^ McDowell, Jonathan. "SATCAT". Jonathan's Space Pages. Retrieved March 23, 2014. 
  2. ^ Hacker, Barton C.; Grimwood, James M. (September 1974). "Chapter 11 Pillars of Confidence". On the Shoulders of Titans: A History of Project Gemini. NASA History Series. SP-4203. NASA. p. 239.  With Gemini IV, NASA changed to Roman numerals for Gemini mission designations.
  3. ^ "Here Is The Condensed Flight Plan For Gemini 6", Williamson, WV Daily News, Oct 25, 1965
  4. ^ "Live TV From Wasp For Gemini-6 Flight,", Pittsburgh Post-Gazette, Oct 22, 1965
  5. ^ a b Astronautix
  6. ^ "Gemini 6 Space Shot Fails", Glasgow Herald, Oct 26, 1965
  7. ^ "Toughest Space Assignment Yet By Gemini, They'll Try It Twice", Ocala Star-Banner, Oct 29, 1965
  8. ^ "Gemini VI Voice Communications". NASA. p. 116, timestamp 23:57:30. 
  9. ^ "NASA Mum on 'Jingling'", Palm Beach Post, Dec 17, 1965
  10. ^ The Song from Outer Space on YouTube
  11. ^ Smithsonian magazine, December 2005

External links[edit]