How Gemini Spacecraft Achieved The First-Ever Space Docking in 1966

Docking a spacecraft to another spacecraft in the weightless environment of space was only studied in theories and science fiction until when Gemini did the impossible in the 1960s. On March 16, 1966, at 11:41 a.m. EDT (1641 GMT), NASA astronauts Neil Armstrong and David Scott were launched into space aboard the Gemini spacecraft atop Titan II for the Gemini 8 mission.

Three hours before this launch, NASA launched the uncrewed Agena upper stage atop an Atlas booster from nearby Complex 14 separately, hoping to attempt the first-ever docking in space. After the Gemini 8 crew were launched into orbit from Cape Canaveral’s Complex 19, they began to pursue the Agena target vehicle.

NASA planned the Gemini 8 mission to be a three-day mission. The crew was expected to rendezvous with the Agena-D target vehicle and perform four docking tests during that mission. NASA planned the mission based on the success of the Gemini 6 and Gemini 7 missions, whose crews achieved the first rendezvous between two manned spacecraft in December 1965.

During the Gemini 8 mission, Scott was also instructed to conduct a spacewalk following the first American EVA conducted by Gemini 4 astronaut Edward White in June 1965.

How Gemini Spacecraft Docked With Agena

The beautiful view from Gemini 8, just 2 feet (0.6 m) from an Agena target vehicle, before achieving the first space docking on March 16, 1966. (Image credit: NASA)

 It took Neil Armstrong and David Scott about 6 hours, five orbits, and nine rendezvous maneuvers to cover the distance and dock with the Agena target vehicle at 5:14 p.m. EDT (2214 GMT). The successful docking of the two separate spacecraft was celebrated across the globe.

“Flight, we are docked!” reported Armstrong, seconds after piloting the Gemini capsule to a dock with an unmanned target vehicle. “It’s really a smoothie.”

Scott also shared his personal experience with the first docking.

“All was quiet as we felt first contact, then a firm clunk and capture as the docking latches joined the two vehicles,” Scott wrote in “Two Sides of the Moon,” his 2004 memoir with cosmonaut Alexei Leonov. “Docking seemed like a piece of cake, as easy as parking a car in an open garage.”

Challenges Encountered By The Astronauts After Docking Gemini Spacecraft to Target Vehicle

After making the historic docking, Scott realized that the “8-ball” on Armstrong’s section of the spacecraft was indicating that their spacecraft was rolling slowly.

“Our first instinct was that the Agena, which had suffered problems in the past, was ‘going wild,'” Scott revealed.

After the Gemini spacecraft docked with the Agena spacecraft, the crew switched engines and began to use the target’s engine to pilot both capsules. They did this to conserve Gemini’s fuel supply. However, when they noticed that they were rolling, the crew went into action and disabled the Agena control system hoping to stop the motion.

But, it worked only for a short period after which the capsule continued to roll and even increased its intensity. Scott revealed that the intensity of the rolling reached a point where the astronauts started to rotate on all three axes.

Mission Control had previously advised the crew to undock from the target in case of any strange anomaly in space. Hence, Armstrong took this advice into action and immediately called to be undocked from Agena. The pilot of the mission pulled away from the target vehicle. After that, both Armstrong and Scott worked to restore the smooth movement of their spacecraft.

“Immediately, it was obvious that the problem was not the Agena’s,” Armstrong explained. “It was ours.”

Another Trouble Loading

Neil Armstrong and David Scott recovered from the Pacific Ocean after splashing down in March 1966. (Image credit: NASA)

At that moment, the crew noticed that one of Gemini 8’s orbit attitude and maneuver system (OAMS) thrusters had encountered a short circuit and was stuck on firing. When the crew moved the craft into the range to establish communication with ground control, they were already in a serious situation.

“We have serious problems here,” Scott radioed to Mission Control. “We’re tumbling end over end up here.”

The tumbling made the crew get dizzy as the craft was about to surpass a rate of one revolution per second.

“I could tell when I looked above me to the controls for the rocket engine that things were getting blurry,” Armstrong described. “I knew we were going to have to do something quickly to make sure that we could work on the problem without losing our vision or our consciousness.”

Armstrong revealed that the only option he had at that moment was to disable the OAMS thrusters and change to use the re-entry control system.

“We both knew that if this didn’t work, we were dead,” Scott recalled.

Immediately, Armstrong reached over his head and switched on the thrusters at the front end of the Gemini capsule. In no time, the spacecraft returned to its control once again.

After the mission, engineers later discovered that the number 8 OAMS thruster was the actual cause of the entire issue.

In conclusion, NASA and other space agencies learned a lot from the first historic docking in space. Today, agencies use the technique to safely send astronauts and supplies to the International Space Station. In the future, we should be expecting companies like SpaceX to dock two spacecraft for on-orbit refueling and other complex tasks.

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