Chapter 8 of 10

The Broken Switch and the Felt-Tip Pen

Using a felt-tip marker to engage the broken Engine Arm circuit breaker (GET 123:20:43)

Told in Eagle’s imagined voice · the events are real · source

AS11-40-5927 (20 July 1969) --- Astronaut Edwin E.
EagleThe moonwalk was over, my hatch was locked, and then Buzz looked down at the dusty floor—and spotted a tiny black plastic knob.
NASA
01While turning around inside my tight cabin, one of the crew's bulky life-support backpacks had brushed against Panel 16 and snapped the knob right off a critical switch.
Of all the hundreds of switches on my walls, that broken one was the 'Engine Arm' circuit breaker—the master switch that unlocks my liftoff rocket.
02Without pushing that recessed metal stem inward to close the electrical circuit, the valves to my ascent engine could never open. Neil and Buzz would be stranded on the Moon.
AS11-40-5902 (20 July 1969) --- Astronaut Edwin E.
EaglePoking a metal tool into the hole was too dangerous—a single spark inside my pure-oxygen cabin could short out the power or start a fire.
NASA/JSC
03While the astronauts tried to rest, engineers in Houston tested backup wiring paths—until Buzz reached into the shoulder pocket of his spacesuit and pulled out an ordinary plastic felt-tip pen.
Two hours before liftoff, Buzz pressed the plastic tail of his felt-tip pen straight into the broken slot—and the breaker clicked solidly into place.
04Electricity surged safely to the ascent engine circuits. A multi-billion-dollar moonship was ready to fly again because of a humble pocket pen.

The big idea

When a backpack snapped the plastic knob off the Engine Arm circuit breaker, Buzz Aldrin used the non-conductive plastic end of a felt-tip pen to push the recessed switch in without causing an electrical short.

Think about it

Why was it critical that Buzz used a plastic pen rather than a metal screwdriver or pocketknife to push the broken circuit breaker in?

In this chapter: Panel 16 Engine Arm circuit breaker and a plastic Duro felt-tip marker

Sources: Main record

Machine illustration: AI-made. Photos: NASA Image and Video Library, credited on each picture.

Chapter 8 of 10

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