"One small step for man, one giant leap for mankind" could have turned out dramatically different had it not been for astronaut Buzz Aldrin鈥檚 ingenuity in averting disaster with a simple felt-tip pen.
Following the Apollo 11 historic July 20, 1969, moonwalk, Aldrin and Neil Armstrong were preparing to return to command from their lunar module when they discovered that a 1-inch engine arm circuit breaker switch had broken off the instrument panel.
In his book, Magnificent Desolation: The Long Journey Home from the Moon, Aldrin recalls spotting something on the floor of the lunar module that didn鈥檛 belong there.
鈥淚 looked closer and jolted a bit,鈥 he writes. 鈥淭here on the dust on the floor on the right side of the cabin, lay a circuit breaker switch that had broken off.鈥
Wondering where the switch had come from, he looked at the rows of breakers on the instrument panel. Then he 鈥済ulped hard.鈥
鈥淭he broken switch had snapped off from the engine-arm circuit breaker, the one vital breaker needed to send electrical power to the ascent engine that would lift Neil and me off the moon,鈥 he writes.
Somehow, he or Armstrong must have accidentally bumped the switch in the cramped space with their cumbersome backpacks. 鈥淩egardless of how the circuit breaker switch had broken off, the circuit breaker had to be pushed back in again for the ascent engine to ignite to get us back home,鈥 he writes.
The broken switch was reported to Mission Control, but after a fretful night trying to get some sleep, Houston had not figured out a solution the next morning.
鈥淎fter examining it more closely, I thought that if I could find something in the LM to push into the circuit, it might hold,鈥 Aldrin writes. 鈥淏ut since it was electrical, I decided not to put my finger in, or use anything that had metal on the end. I had a felt-tipped pen in the shoulder pocket of my suit that might do the job.
鈥淎fter moving the countdown procedure up by a couple of hours in case it didn't work, I inserted the pen into the small opening where the circuit breaker switch should have been, and pushed it in; sure enough, the circuit breaker held. We were going to get off the moon, after all. To this day I still have the broken circuit breaker switch and the felt-tipped pen I used to ignite our engines.鈥
If the engine arm circuit breaker remained open, Armstrong and Aldrin likely would have been stuck, says NASA Chief Historian William Barry.
鈥淗ad the felt-tip pen not worked, I鈥檓 certain that Mission Control and the crew would have worked hard to find other ways to close the circuit so that the ascent engine could be fired,鈥 he says. 鈥淏ut this was a serious situation鈥攅nough that on subsequent lunar modules a guard was installed over those circuit breakers to prevent a similar problem.鈥
Barry says that during the Apollo program, Mission Control and the astronauts ran thousands of simulations, and the simulation team was 鈥渜uite devious鈥 about coming up with problems for them to work through.
鈥淚鈥檓 not aware that this specific scenario was simulated, but the in-depth systems knowledge learned in those hours in the simulators鈥攁nd the techniques developed for astronauts and ground crews to work through problems鈥攚ould have served them well if further work was needed to fix the broken 鈥榚ngine arm鈥 circuit breaker,鈥 he says.
Many of those simulations, Barry notes, involved maneuvering the command module to complete the rendezvous in case of a problem with the lunar module ascent stage getting into the right orbit.
鈥淎s is typical of simulator training, the crews would have practiced the launch and docking maneuver many times鈥攁nd usually while having to deal with some simulated failure,鈥 he says. 鈥淔lying the actual mission was (usually) much easier than the dozens of times they would have practiced this particular maneuver in the simulator.鈥
But, Barry says, the command module couldn鈥檛 solve the problem if the lunar module wasn鈥檛 able to get off the surface. 鈥淪o a failure of the ascent engine would have been a critical problem,鈥 he says.
