When were the LM and CSM fueled?
Around L-30 days, or starting June 16 for Apollo 11. LC-39 is basically evacuated for a week, because you have to fuel the SM, two stages of LM, and the S-IVB APS, and (as you note) a single chemical at a time. In his book, Jonathan Ward has a great diagram of the work platforms for working on the LM inside the SLA, as well as Polaroids of workers installing the insulation on the footpads and the commemorative plaque. That's why the ladder taping differs in pre-rollout photos.
In order to meet the Kennedy end-of-decade deadline, integration and rollout schedules during 1969 were greatly overlapped and -- in a sense -- compressed. Stacking for Apollos 12 and 13 were arranged such that if Apollo 11 failed to land, 12 (and possibly 13) could be rolled out and prepared at greatly accelerated schedules. Keep in mind the VAB could stack
four Saturn Vs simultaneously. Part of this was because there were originally going to be pads C and D at LC-39. But the real goal was to shift as much work as possible to the pad and the MSS so that a high bay in the VAB could be freed up to stack another Saturn V in case they needed to launch a new mission fast.
Once the tanks are loaded everyone treats it as a live bomb, carries a gas mask, and practices evacuation drills.
Jeff Quitney's YouTube channel had several excellent videos on procedures for handling hypergols. Sadly the Copyright Gods seem to have smitten his whole channel from existence. If only there were another way for him to share his vintage videos... (
cough, Vimeo,
cough). In addition to ASTP, there was a post-flight accident while safing the Apollo 15 command module. Even after the all-jets firing during the final descent, enough propellant remains in the CM hypergol tanks to cause severe injury. This is also why Texas residents were warned to stay away from
Columbia debris. Even a tiny amount of these chemicals can be injurious.
At this point we have to remember the Titans. The whole point of that system was to have "storable" propellants so that the missiles could be kept ready for launch at a moment's notice. That whole infrastructure was
stolen adapted to provide the safety protocols as well as the engineering. The Air Force had a whole program for extending hypergol storage -- piping, seals, valves, etc. And, of course, the specialized gas-sniffers you mention. This all fed into Apollo, and this is what allowed them to load the propellants so early. If you're thinking in terms of constraints, the constraint is, "When we are actively loading propellants, we have to evacuate the pad for a week." When you schedule that week depends on many factors, and storability skills learned from Titan gives you more flexibility.in scheduling. And yes, everyone who worked on the LUT or MSS after about June 22 had to be Propellant Hazards qualified.
Somewhere I have pictures of some friends jumping into the emergency chute from the top of the Ariane V gantry in Kourou during one of those drills.
Jonathan covers the escape chute and "rubber room" for LC-39 in some detail. Fireproof, shockproof, self-contained, food and water for 24 men for a day. He's the guy who probably knows more about Apollo launch preparations than anyone living today.
