Saturday 21 January 2012

Buzz Aldrin Nearly Stranded Apollo 11 On The Moon

Well I never knew Buzz Aldrin nearly stranded the crew of Apollo 11 on the surface of the Moon!! Reading the text (transcribed radio conversations) the implication of what is being said is so frightening, I don't know how they kept calm... if that switch was knackered, they were stranded on the Moon forever!
112:56:28 Aldrin: Houston, Tranquility. Do you have a way of showing the configuration of the engine arm circuit breaker? Over. (Pause) The reason I'm asking is because the end of it appears to be broken off. I think we can push it back in again. I'm not sure we could pull it out if we pushed it in, though. Over.
112:56:56 McCandless: Roger. We copy. Stand by please. (Long Pause)
[With space limited in the cabin, a person wearing a PLSS has ample opportunity to hit a circuit breaker without being aware of it. The engine arm circuit breaker is seventh from the left in second row of Panel 16, which is on Buzz's side. Because Neil was never on that side of the spacecraft, it has to have been Buzz who hit it.]
[Aldrin - "There weren't guards over any of the circuit breakers. One got pushed in and one got broken off. So I must have pushed one in and broke one off (with his PLSS prior to doffing)."] 
112:57:23 McCandless: Tranquility Base, this is Houston. Our telemetry shows the engine arm circuit breaker in the Open position at the present time. We want you to leave it open until it is nominally scheduled to be pushed in; which is later on. Over.
112:57:41 Aldrin: Roger. Copy.
[Comm Break. As shown on Surface checklist page Sur-20 this circuit breaker was put in the 'open' position after powerdown and is supposed to remain open until about two and a half hours before launch, as indicated on Sur-45 and Sur-47. According to the Apollo 11 Mission Report, "The engine arm circuit breaker was successfully closed when it was required for ascent, but loss of the knob would not allow manual opening of the breaker."] 
[In his book, Men from Earth Buzz elaborates, "We discovered during a long checklist recitation that the ascent engine's arming circuit breaker was broken off on the panel. The little plastic pin (or knob) simply wasn't there. This circuit would send electrical power to the engine that would lift us off the moon...We looked around for something to punch in this circuit breaker. Luckily, a felt-tipped pen fit into the slot."] 
[To prevent a recurrence of this problem, NASA decided that guards would be placed over the breakers for future flights. Furthermore, additional checks of the circuit breaker configuration were added to the checklist. Buzz will close the circuit breaker at some point after the rest period and, at 123:20:43, about an hour before lift-off, Houston will tell the crew that telemetry indicates that the circuit breaker is in its proper, closed position.]

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