Astronauts Neil Armstrong and Buzz Aldrin of NASA’s Apollo 11 mission almost died on the Moon after a small piece of equipment from their Eagle lunar module got damaged. Fortunately, Aldrin was able to come up with a very simple yet important solution to their problem.

Details of the tense moment on the Moon were revealed through Jonathan Mayo’s book “Titanic: Minute By Minute.” According to an excerpt from the book, the astronauts discovered the fatal error on the morning of July 21, 2969.

As Aldrin and Armstrong prepared to take a nap, the former curled up on the floor while the latter tried to sleep on the cover of the Eagle module’s ascent engine. At that moment, Aldrin saw a broken circuit breaker switch on the floor.

After scanning the module’s instrument panel, Aldrin discovered that the broken switch was for the ascent engine, the main component that will fly the Eagle back to the Columbia command module that was waiting in lunar orbit. They had no way of replacing the component since they had already discarded many of their tools and equipment in preparation for a lighter return trip to Columbia.

The astronauts immediately informed Mission Control regarded the problem. Astronaut Michael Collins, who was waiting in Columbia, was then notified by Mission Control regarding the status of Aldrin and Armstrong. At that moment, Collins thought his greatest fear was about to come true.

“My secret terror for the last six months has been leaving [Armstrong and Aldrin] on the Moon and returning to Earth alone,” he said according to USA Today Post.

Collins noted that he even trained in flying the Columbia alone in preparation for this type of grim moment.

Fortunately, Aldrin was able to come up with an ingenious way to activate the engine’s circuit breaker without the switch. Using a felt-tip pen with a chrome casing, Aldrin was able to engage the circuit breaker and activate the module’s engine.

At 5:54 pm on July 21, Armstrong and Aldrin lifted off from the Moon aboard the Eagle. The lunar module traveled for a couple of hours before finally docking with Columbia.

apollo 11 flag
Astronaut Aldrin posing with the American flag on the surface of the Moon in 1969. NASA