How Apollo 11 almost got stuck on the Moon

In 1961, President Kennedy set the United States a two-part challenge that charged the country with a) landing a man on the Moon before the end of the decade and b) returning him safely to Earth.

While Apollo 11 successfully achieved the first part of that challenge when it touched down in the Sea of Tranquility in July 1969, what is less known is how close it came to failing to achieve the second part.

With their historic walk on the Moon complete, Neil Armstrong and Buzz Aldrin returned to lunar module Eagle and prepared to settle down for the night.

There were no beds, bunks or even seats in the lunar module in order to save weight, and so the astronauts instead slept on hammocks of sorts strung across the cabin. That particular night, Aldrin settled on the floor with Armstrong stretched out across the ascent engine cover above him.

It was at this point that Aldrin noticed something lying on the floor. He peered closely at it, and realised with a sinking feeling that it was a circuit breaker switch which had somehow broken off the instrument panel.

It wasn’t just any circuit breaker either. It was the most important one of all: the switch used to send electrical power to the ascent engine needed for Aldrin and Armstrong to get off the surface of the Moon, rendezvous with Mike Collins in the command module and return to Earth. With it broken, they were stuck.

Buzz Aldrin in lunar module Eagle | Credit: NASA

The lunar module was a very cramped space when both astronauts were wearing their fully pressurised suits, and so at some point either when they were leaving or returning, one of Armstrong and Aldrin must have bumped into the instrument panel and broken the switch off. Without it, they would struggle to close the circuit and light the engine.

Aldrin reported the problem to Mission Control and it was decided that the astronauts should continue with their planned rest/sleep period while Houston tried to come up with a work-around.

When ‘morning’ came, however, a solution was still not forthcoming.

Aldrin then began to formulate a plan in his head. He figured that if he could find something the right size and shape to jam into the circuit to close it, it might hold long enough for them to fire the ascent engine and get off the surface. He quickly ruled out using his finger, or anything capped with metal owing to all the electricity surging behind the instrument panel, and soon settled on a felt-tipped pen that he had in the shoulder pocket of his suit.

Lo and behold, the fix worked. Aldrin jammed the pen into the opening where the switch should have been and not long later Eagle successfully lifted off from the Moon’s surface, ensuring that President Kennedy’s 1961 pledge would be successfully completed. NASA made a note to install a cover over the circuit breaker to prevent a potentially disastrous recurrence on future missions.

The pen and the broken circuit breaker switch are currently on display at the Museum of Flight in Seattle.

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