Gemini 6A

Mission name	Gemini 6A
Spacecraft name	Gemini 6A
Booster	Titan II #62-12561
Insignia	Gemini 6A patch.png
Insignia size	220px
Sign	Gemini 6A
Crew members	2
Launch pad	LC-19 (CCAF)
Launch	December 15, 1965, 13:37:26 UTC
Landing	December 16, 1965, 15:28:50 UTC North Atlantic Ocean
Duration	1d/01:51:24
Orbits	16
Apogee
Perigee
Period	88.7 min.
Inclination	28.97°
Distance
Mass
Crew photo	Gemini 6 prime crew.jpg
Crew caption	(L-R) Stafford, Schirra
Previous	Gemini 7
Next	Gemini 8

Gemini 6A (officially Gemini VI-A) 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 Gemini 6A and 7 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 .

Crew

Backup crew

Mission parameters

Mass: Perigee: Apogee:

Inclination: 28.97°

Period: 88.7 min

Stationkeeping with GT-7

Start: December 15, 1965 19:33 UTC

End: December 16, 1965 00:52 UTC

Objectives

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 5 hours 40 minutes into the mission. The second at 7 hours 45 minutes, the third at 9 hours 40 minutes and the fourth and final docking at 10 hours 5 minutes into the mission. The final undocking would take place at 18 hours 20 minutes into the mission.

At 23 hours 55 minutes into the mission, while the spacecraft passed over White Sands, NM, the crew were to attempt to observe a laser beam originating from the ground.

The retro rockets were scheduled to be fired at 46 hours 10 minuttes into the mission while over the Pacific Ocean on the 29 orbit.

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 to relay live television, via the Intelsat I (nicknamed the "Early Bird" satellite).

However, after a control failure in the unmanned Agena target required its destruction six minutes after its liftoff (when the crew was already sitting in their capsule awaiting their launch), the mission was canceled.

Reviewing the situation, NASA decided to substitute an alternate mission: a meeting in space of two Gemini spacecraft. The new mission would be known as Gemini 6-A, and would launch eight days after the launch of Frank Borman's and Jim Lovell's Gemini 7.

{| border="1" cellspacing="0" align="Left" !Gemini 6 !Agena Info |- |Agena |GATV-5002 |- |Mass |, 7800 lbs. |- |Launch site |LC-14 |- |Launch date |October 25, 1965 |- |Launch time |15:00:04 UTC |- |Exploded |15:06:20 UTC |}

Flight

First launch attempt

The first launch attempt of Gemini 6A was on December 12, 1965 at 9:54AM EST. All went well right up to ignition—in fact the engines did ignite, 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 that there was no upwards motion, causing it to abort the launch. At this point mission rules dictated that the crew should eject from the spacecraft, as the rocket would explode on impact with the pad if it had lifted off by even an inch (2.54 cm).

Schirra elected not to eject as neither he nor Stafford had detected any upwards motion, and the ejection seats were seen as a last resort. In an early test of the system involving a dummy, the hatch had failed to blow off and the dummy's head was rammed into the side of the spacecraft. Also all ejection seats cause a dangerous compression of the spine as these were designed to carry the astronauts as quickly as possible (with the goal of evacuating the astronauts a couple of hundred meters away from an exploding rocket).

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 the ones that were harder to pull out on future missions, 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 get lower 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

The third attempt to launch Gemini Spacecraft Number 6 (second attempt for the 6A mission) was successful on December 15. 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 mile orbit.

The plan called for the rendezvous to take place on the fourth orbit of Gemini 6A. 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 2 hours and 18 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 miles).

The radar on Gemini 6A first made contact with Gemini 7 at 3 hours and 15 minutes when they were 434 kilometers, (270 miles) 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 5 hours and 4 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 fuel on Gemini 6A, giving plenty of fuel for some fly arounds. During the next 270 minutes the crews moved as close as 1 foot, (30 centimetres), 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 10 miles, (16 kilometers). This ensured that there wouldn't be any accidental collisions in the night.

A Christmas surprise

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

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. The Smithsonian Institution claims these were the first musical instruments played in space and keeps the instruments on display.

Reentry

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

Insignia

Walter Schirra explained the patch in his book All We Did Was Fly to the Moon:

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

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

Splashdown (spacecraft landing)

References

External links

NASA Gemini 6 press kit for cancelled mission - Oct 20, 1965

NASA Gemini 7/Gemini 6 press kit - Nov 29, 1965

Gemini 6 Mission Report (PDF) - October 1965 cancelled mission

Gemini 6/Agena target vehicle 5002 systems test evaluation (PDF) December 1965

On The Shoulders of Titans: A History of Project Gemini

Spaceflight Mission Patches

http://www.collectspace.com/news/news-092703a.html

Category:1965 in spaceflight Category:1965 in the United States Category:Gemini mission Category:Human spaceflights