Neil Armstrong had plenty on his mind — on the afternoon of July 20, 1969 — as he guided the Apollo 11 lunar module, known as “the Eagle,” over the barren, crater-pocked surface of the moon, anxiously searching for a place to land.
The stakes couldn’t be higher for the then-38-year-old mission commander and lunar module pilot Buzz Aldrin — and for the nation.
Minutes earlier, alarms from the landing radar computers had begun flashing on the control panels in front of the two astronauts, so Armstrong made the decision to switch off the computer and take manual control of the module.
The tiny, cramped spacecraft continued racing down toward the moon’s surface. Suddenly, another alarm light began flashing. Their fuel tank was beginning to run dry.
Looking back, landing on the moon wasn’t just our job, it was a historic opportunity to prove to the world America’s can-do spirit. I’m proud to serve the country that gave me this historic opportunity. Today belongs to you. We must hold the memory of #Apollo11 close. #Apollo50th— Buzz Aldrin (@TheRealBuzz) July 20, 2019
“At about a hundred feet [above the surface] there’s a light that comes,” Aldrin recalls in a just-released video interview he recorded at the Science Museum of London in 2016. “It’s the fuel quantity light and about that time Capsule Communicator Charlie Duke says [we’ve got] 60 seconds of fuel left.”
Armstrong heard the unwelcome news but remained focused on the controls while studying the moonscape unfolding beneath the cockpit window.
The Eagle had overshot the mission’s planned landing site by over three miles and terrain below was unfamiliar to Armstrong, filled with massive craters and boulders that would have made a successful landing impossible.
“Sixty seconds,” Aldrin recalls about what was racing through his mind during those tense moments. “We’d better ease down. But I don’t want to disturb Neil by saying: ‘Hurry up, hurry up!’ ”
Running out of fuel this close to the lunar surface would, in all likelihood, doom the two men, who had traveled nearly 240,000 miles away from their home planet.
Over the next 30 seconds, the two men descended 90 feet, which meant they had another half a minute worth of fuel in the module’s tank.
Seconds ticked before Armstrong finally located an open expanse of gray, dusty terrain on the moon’s Sea of Tranquility where he could safely land the Eagle.
“We touched down,” recalls Aldrin. “And I think the estimate, not because somebody put a dipstick in the fuel to see how much was left, but it was calculations and information on board, we probably had about 15 seconds of fuel left.”
So what exactly did the famously tight-lipped Armstrong think about those nail-biting final moments before he and Aldrin became the first two men to land on another planet?
The answer to that question came decades later.
According to astronaut Gene Cernan, Armstrong’s longtime friend — who became the last man to walk on the moon during the Apollo 17 mission in 1972 — Neil downplayed the idea about being concerned that the module’s fuel tank was about to run dry.
“I was with Neil once in Afghanistan and I remember walking into this room with him filled with a bunch of young Marines,” Cernan told PEOPLE during a 2016 interview, shortly before his death.
“I remember this tall kid with an M1 rifle slung over his shoulder approached and asked, ‘Mr. Armstrong, weren’t you nervous flying over the moon with all those rocks and craters, knowing that you only had a few seconds of fuel left?’ ”
Armstrong grinned at the young soldier.
“Well, young man,” Cernan recalled Armstrong saying, “Everyone knows that when the fuel gauge says empty, there’s always a gallon or two left at the bottom of the tank.”