It never hit me until years later that while landing on the moon is dangerous enough, the return to the command module relies on one switch and the engine performing perfectly as designed and planned. If the switch was somehow inoperative or the engine start a bust, the team was stuck on the moon forever.
When Apollo 11 landed on the Moon, as they were entering or exiting the lunar module, one of the astronauts broke off the toggle on the switch that fired the engines. When it was discovered, since they were live to the world the phrase “my watch stopped” was to be used as to not alarm the world. They discovered that there was enough of the guts of the switch left that they could turn it on and off using a ballpoint pen.
The switch panel was moved away from the door on Apollo 12 and later missions.
That is true. They went for simplicity. No fuel pumps or anything, two different components under pressure- hydrazine, and nitrogen tetroxide. When they mix they burn. No spark plug needed or ignitors. And it had to be throttle-able, supposedly the hardest nut to crack.
Problem is the stuff was so toxic and corrosive the engine had to be disassembled after firing. So while it was “tested” as a design, there was no way to test it again before launch. It had to work on the Moon for sure.
They kept having to shave pounds on the LEM during design so eventually made the pressure vessel itself out of thin aluminum out of acid etching or something like that. It had reinforced ribs but it was about as thick as a modern aluminum pop can in places, they could hear it making clinking or “oilcanning” noises when shut down and trying to rest on the Moon. They had to be mindful not to poke holes in the skin.of the spacecraft.
I was looking at the 16 launch from the moon. I think I read there might have been a millisecond delay in one of the pyrotechnics.
This might have been the real showstopper- maybe they got close on that one. What had to happen, the umbilicals, electrical connections, and the hardware securing the ascent and descent stages together had to fire cleanly and within a split second of each other. Because once the rocket fuel starts mixing, it’s going somewhere, the question is where.
It gets “caught up” and hangs, they are fooked. Starts a flat spin or flipping end over end or remains partially attached and floppin’ like a catfish and the end up dirty side up stuck on the moon.
All of the thin panel covers were all pranged up to hell on 16, they think maybe the millisecond delay caused a backpressure “pop” on the ascent stage. Charlie Duke said the whole thing dropped about 2” and he had an “oh shit” moment in the split second it took for the engine to launch. I think they were a red nether hair to havin’ something real bad happen on that launch.