Objectives

The augmented target docking adapter or the ATDA had been designed and built by McDonnell, the manufacturers of the Gemini spacecraft. It was basically a short cylinder with a docking cone on the front. It had all the systems that the Gemini would need for rendezvous but lacked a propulsion unit. It was built using already tested equipment and launched using the Atlas-SLV3 rocket.

Launch Attempts

The first radar readings were when they were 240 km away and they had a solid lock at 222 km. Their first sight came 3 hours and 20 minutes into the mission when they were 93 km way. They noted that they could see the flashing lights on the ATDA designed to aid identification from a distance. This made them hope that the launch shroud had in fact been jettisoned and that the telemetry was wrong.

As they got closer they found that in fact the shroud had half come off. Stafford described "It looks like an angry alligator out here rotating around". He asked if maybe he could use the spacecraft to open the 'jaws' but the ground decided against it.

The reason for the laynards was soon discovered. Douglas built the shroud, but Lockheed attached it to the rocket, while McDonnell built the ATDA. A Douglas engineer had made a practise run with the McDonnell crew but didn't give them instructions on the final procedures which involved the laynards. The McDonnell crew had the Douglas instructions for this procedure which said, "See blueprint", but there was no blueprint. So the McDonnell technicians decided to tape down the loose laynards as it seemed like the sensible thing to do.

The crew then did some planned rendezvous practice that involved them moving away from the ATDA by firing their thrusters and then practising approaching from below the target. They then got some much needed food and rest.

Cernan found the going tough. Every movement that he made caused a reaction, and even though there were handholds installed on the spacecraft after the comments of Ed White after his EVA on Gemini 4, Cernan found it hard to control himself. Even the umbilical was annoying and hard to control.

He finally reached the rear of the spacecraft and began to check and prepare the AMU. This took longer than planned due to lack of hand and foot holds. He was unable to get any leverage which made it hard to turn valves or basically anything that involved moving. All this was made worse when after sunset, his faceplate fogged up.

At this point Cernan decided that there was alot of risk in continuing the EVA. He couldn't see very well and had found that he could not move very well. He would have to disconnect himself from the umbilical that attach him to the Gemini (though would still be attached by a longer thinner lead), after he had connected himself to the AMU. But when he had finished with the AMU he would somehow have to take the thing off with one hand, while the other held onto the spacecraft. So he decided to cancel the rest of the EVA, with Stafford and Mission Control concurring.

He managed to move himself back to the cockpit and Stafford held onto he legs to give a rest. After trying to remove a mirror mounted to the side of the spacecraft, his suit cooling system overheated and his faceplate fogged up completely, meaning he couldn't see. He and Stafford managed to get the hatch closed and repressurised. Cernan had spent 128 minutes outside the spacecraft.

As well as the rendezvous and EVA, the other major objective of the mission was to carry out seven experiments. The only medical experiment was M-5, which measured the astronauts reactions to stress by measuring the intake and output of fluids before, during and after the flight.

S-10 had hoped to retrieve a Micrometeorite Collector from the ATDA, though this failed after they were unable to dock with it. They were able to image it though during there close approaches. Instead they were able to recover the collector from the Gemini spacecraft (S-12). D-12 also failed as it was an investigation of controlling the AMU.

The last experiment was D-14 which was UHF/VHF Polarization. This was an extendable antenna mounted on the adapter section at the rear of the spacecraft. It was hoped to obtain information about communication through the ionosphere. Six trials of this were performed but the antenna was broken by Cernan during his EVA.