“Hey, Apollo – Houston, this is Apollo 10. Look, I know you ran some studies, but by golly, we can see Snoopy, and he isn’t too far away! He’s catching up with us. Can you talk to the FIDOS? He’s right down below us. We can occasionally see him tumbling end-over-end down below there, and he’s coming in closer each pass. That’s Snoopy’s descent stage. We can see him right down below us now, and he’s right – I thought he was a little out-of-plane, but now he’s looking more in-plane with us.” Tom Stafford Apollo 10
As the lunar module approached, Young saw it through his sextant at a distance of 259 kilometers. Stafford and Cernan got a radar lock on the command module shortly after the insertion burn and watched with interest as the instrument measured the dwindling gap between the vehicles and demonstrated the theories of orbital mechanics in actual practice. Cernan especially liked the steady communications that kept both crews aware of what was happening.
The abort system had two basic control modes, “attitude hold” and “automatic.” In automatic, the computer would take over the guidance and start looking for the command module, which was certainly not what the crew intended to do at that moment. While correcting for a minor yaw-rate-gyro disturbance, the astronauts accidentally switched the spacecraft to the automatic mode, resulting in frantic gyrations.
When Stafford and Cernan were ready for undocking they discovered the Lunar Module had slipped three and a half degrees out of line with the command module at the latching point, possibly due to loose mylar collecting on the docking ring…