The first four days of the Apollo 11 trip to the Moon went as planned, but just twenty minutes before landing the atmosphere became tense when the crew encountered a number of problems.
It was July 20, 1969, and because the world was following the progress of the spacecraft, it briefly lost radio contact with the mission control in Houston.
When the Eagle's lunar module was in the middle of its flight, Edwin "Buzz" Aldrin and the mission commander Neil Armstrong, an alarm bell began ringing.
The eagle disembarked two hours earlier from the main part of the ship, Columbia command module, where the third crewman Michael Collins remained in orbit.
It was an uneasy moment for Armstrong, a brilliant test pilot and an aviation engineer, but a man with famous words.
"Read us about the alarm program 1202," he delegates to the mission control.
They were ordered to go on. Houston realizes that the on-board computer is experiencing overflow, but all systems are working.
Below them, the Moon's craters fall quickly. Too soon, he realizes Armstrong: at this rate, they will cross the airstrip by a few miles.
Switches to manual control and begins to plot a new landing site from the illuminator. But there is a problem with finding the perfect place and it will be tight.
"Rocky enough," says Aldrin.
Aldrin still tells him about speed and computer readings. "It goes nicely," he says.
"Right over this crater," says Armstrong.
Meanwhile, the fuel is running out quickly.
Houston continues to announce the number of remaining seconds to "Bingo Fuel Call" – the point at which the Eagle will have 20 seconds to land or interrupt his mission.
It's been 30 seconds to Bingo.
Armstrong, calling for all his experience, is silent as he concentrates.
The module rests on the ground. "Contact light," says Aldrin, which means one of the leg foot sensors has landed. Engines are turned off.
– Houston, the Tranquility base here. The eagle landed – announces Armstrong.
"We're copying you on the ground. You have a group of guys who will soon become blue. We breathe again. Many thanks, says Charlie Duke, CapCom communicator or capsule on the ground.
A Nazi rocket man
History records that the number of people who worked on the Apollo program was 400,000. But the two figures are superior to their contributions.
In 1961, President John F. Kennedy called on his vice president Lyndon Johnson to defeat the Soviets in space.
"We are in a strategic space race with the Russians and we lose," Kennedy wrote in the magazine a year ago. "If a man circulates the Earth this year, his name will be Ivan."
Johnson reaches the godfather of NASA's space program: Wernher von Braun.
The Nazi former card-carrying was the inventor of the V-2 missiles, which fell to London during World War II.
At the end of the war, he surrendered to Americans who brought him and one hundred of his best engineers to Alabama as part of the secret Paperclip operation.
Von Braun told Johnson that while the US was far behind, they could defeat the Russians when it came to placing men on the moon, if they immediately began working on a giant support rocket.
Kennedy will turn to Congress in the same year, famous for committing a "landed man on the moon and safe return to Earth" by the end of the decade.
Eight years later, Richard Nixon was president when the goal was achieved.
In the case of a tragedy, he prepared the following remarks: "Fate decided that people who went to the moon to explore it in peace would stay on the moon to rest in peace."
But extraordinary national efforts have paid off.
Everything happened quickly, thanks to the check on the mission from Congress. In the period from October 1968 to May 1969. Four preparatory missions to Apollo were launched. Armstrong was elected in December 1968. On the eleventh commander.
A month after the start, Armstrong told Aldrin that he would pull the rank and be the first to set foot on the surface of the moon.
"I was silent for a few days, all the time fighting not to be angry with Neil," Aldrin recalled later in his memoirs.
"After all, he was a commander and as such a boss."
A huge jump
When the monstrous rocket designed by Von Braun took off with the Apollo 11 capsule at the summit on Wednesday, July 16, 1969, a million people came to the beach in front of Cape Canaveral to see.
But many doubted whether they would be able to land on the moon at the first attempt. Armstrong confided in 1999: "My premonition was that we had a 90% chance – or better – a safe return and a 50% chance of a successful landing."
For those in America, the final descent will take place on Sunday evening.
There was night in Europe, but they were all glued to televisions, though they could only hear the static of radio communication until Armstrong set up his black and white camera before the first step.
His grandmother advised him not to do it if he felt dangerous; he agreed, according to the book Rocket Men Craig Nelson.
As he descended to the foot of the ladder, he noticed that Eagle's footsteps had sunk in the ground just an inch or two, and the surface looked very fine-grained. "It's almost like a powder," he recalled.
Then on the radio: "Okay. I'm going to go down with LM now. "A break, then immortal words:" This is one small step for a man; one big leap for humanity. "
According to Armstrong, the line was not written. "I thought about it after landing," he said in an oral record recorded by NASA in 2001.
One problem: without an indeterminate article ("man") there was no grammatical correctness. Armstrong said he wanted to say it, but he agreed it was inaudible.
What does the Moon look like at close quarters?
Its color varies depending on the angle of the sun: from brown to gray to black like coal. And the lower level of gravity requires a habit.
"I started running a little and felt like I was moving in slow motion in a lazy leg, often with two feet floating in the air," wrote Aldrin in a book in 2009.
In two and a half hours, Armstrong picks up piles and heaps of lunar rocks and takes pictures. Aldrin installs a seismometer and two other scientific instruments.
They set up the US flag and leave a lot of items, including a medal honored with the first man in space, the Russian Yuri Gagarin.
With 857 black and white photos and 550 color, only four show Armstrong. Most of them are Aldrin. "It's much more photogenic than me," he joked in 2001.
Before they started to go, the astronauts were dusty. In the cockpit, "it smelled like a wet ash in my fireplace," said Armstrong.
Collins has been waiting in orbit for the last 22 hours.
"My secret terror for the last six months has left them on the moon and returned alone to Earth," he wrote later.
"If they can not get up from the surface or collide with it, I'm not going to commit suicide; I'll go home immediately, but I will be a marked man for my whole life and I know it. "
Fortunately, the lunar module engine worked, returned from Columbia and the trio began a long journey home.
At the end, deprived of additional modules and fuel, the capsule weighs only 12,250 pounds, or 0.2% of the take-off weight of the fully loaded Saturn V rocket.
July 24 enters the atmosphere, becoming a sphere of fire in the sky for a moment, then deploys three parachutes and falls safely to the Pacific.
The United States sent an aircraft carrier to retrieve it. Nixon was on board.
Elite divers extract men who are healthy, but unpleasant after the journey, to take them by helicopter to the ship.
There they are quarantined over fear at the time when they can be contaminated with extraterrestrial microorganisms.
At the first press conference, three weeks later, reporters asked three men, now global heroes, would they ever consider returning to the moon.
"At the Moon Reception Laboratory, we had very little time to meditate," Armstrong said, always.
None of them will ever come back to the cosmos.
After six more missions, the Apollo program was completed in 1972.
It was not until Donald Trump came to the office that the United States decided to return to the Moon as part of the Artemis program, named after the sister of the Apollo twins.
© Agence France-Presse