Gemini VIII has to abort

On 16 March 1966 Neil Armstrong and Dave Scott in Gemini VIII achieved a successful docking. Buzz Aldrin was in Mission Control:

I was in the Mission Control room in Houston on March 16, 1966, when Neil Armstrong and Dave Scott accomplished one of Project Gemini 5 main goals, orbital rendezvous and docking with an Agena target vehicle, during the Gemini VIII flight. I didn’t know Neil Armstrong that well – he was a civilian astronaut from the second group but he was highly thought of from his days as a NASA test pilot on the X‑15 rocket plane out at Edwards. For almost five hours, Arm‑strong and Scott maneuvered their spacecraft to match orbits with the Agena and finally rendezvoused above the Caribbean, as Dave Scott called out radar ranges and Neil slowed the spacecraft by “eyeball” judgment.

After about an hour of floating near the Agena (“station keeping”) Mission Control told them, “Go ahead and dock.” The spacecraft’s cylindrical neck eased into the open throat of the Agena’s docking adapter. Mechanical latches sprang out to connect the two vehicles.

“Flight,” Neil called to flight director Gene Kranz in Houston, “we are docked! It’s really a smoothie.”

The Mission Control room was loud with cheers and whistles among the usually quiet flight directors. Gemini had just passed a milestone. Orbital docking brought us one step closer to an LOR mission and a landing on the moon. Because the Agena was built to accept engine commands directly from the Gemini spacecraft, the mission plan next called for Neil and Dave to fire the Agena engine to change their orbit. But the docked Gemini‑Agena began rolling, slowly at first, and then with increasingly wilder gyrations.

“Neil,” Dave Scott said, “we’re in a bank.”

Armstrong didn’t have to be reminded. He struggled with his hand controllers to keep the cumbersome composite vehicle stable. He had to break away or the roll would become violent enough to damage the neck of the spacecraft where their parachute was stored. Neil fired the thrusters to undock, but the roll increased. The Gemini’s antennas would not stay in alignment, cutting off communication with the Earth station below, the tracking ship Coastal Sentry Quebec .

Finally, Scott got through. “We have serious problems here,” he announced. “We’re tumbling end over end up here.”

One of their RCS thrusters was stuck open, tossing the Gemini in an accelerating spin, which was now one revolution per second. Dave and Neil were having their vision blurred and they became dizzy.

Finally Armstrong broke the spin by completely shutting down the spacecraft’s orbital attitude and maneuver system and activating the separate reentry control thrusters. But this meant they would have to descend from orbit quickly because this thruster system could develop leaks once it had been fired.

The Mission Control room was on full alert. Around the country, NASA managers quickly consulted with each other then told Armstrong to go for an emergency retrofire with a descent trajectory into the western Pacific. Gemini VIII was above the Congo River when Gene Kranz and his flight controllers ordered the burn. The combined flame of the solid‑rocket retros and the control thrusters dazzled the two pilots as they slid through the starry night. For the next 15 minutes they stared anxiously out their windows hoping to see the Pacific Ocean through the bright orbital dawn ahead. They still didn’t know if their retrofire had been accurate and whether they would land in the ocean or in some remote jungle – or maybe in enemy territory in Indochina.

As the sun climbed above the Pacific, Gemini VIII descended by parachute several hundred miles southeast of Japan. A search aircraft from Okinawa spotted their parachute and dropped rescue frogmen, who struggled to attach a flotation collar to the spacecraft as it rolled in the nasty 15foot swells. Several hours later Neil and Dave were aboard the destroyer Mason , seasick but otherwise okay. Their flight had lasted less than 12 hours.

Docking meant nothing if the composite vehicle could not be controlled. Lunar Orbit Rendezvous during an Apollo mission would depend on a perfectly controlled flight of the composite command and service module and the lunar module. But our first attempt at this had failed dangerously. No one was cheering in Mission Control.

After intensive investigations engineers at McDonnell, the manufacturers of the Gemini spacecraft, decided that a control thruster had stuck in its firing position due to an electrical short circuit. They modified the circuit to prevent any possibility of the thruster firing with the switch off.