In 1969, Neil Armstrong became the first human to walk on the moon. Those first steps were preceded by a fast-paced technological race between the Soviet Union and the USA. Here's how it all started.
The story of human spaceflight begins in the 1950s. It was a time when there were just two superpowers: the USA and the Soviet Union. And they gave the world a bitter arms race.
If you dominated in space, you could also dominate on Earth. That was the thinking.
And the Soviet Union was out in front. After all, there's little difference between a space rocket and an inter-continental ballistic missile.
John Glenn was one of the first American astronauts. Glenn was a fighter pilot during the second world war and in the Korean War. As a test pilot in 1957, he flew the first supersonic aircraft for the US air force.
But he wasn't so sure whether the US would win the space race against the Soviets.
"They had been launching rockets and ours had been blowing up too much on the launchpad," recalled Glenn later. "That was the background to what happened in 1957, when they sent up Sputnik."
The Americans were slower but more thorough
Sputnik was the first ever satellite.
As was discovered later, Sputnik wasn't a particularly elaborate piece of technology — it was a metal ball with a simple radio transmitter and receiver inside.
But the Soviet success shocked the world. And put pressure on the US government to counter this new threat from space.
"In 1957, Sputnik signaled the beginning of the space age, and the United States was behind," said US astronaut Neil Armstrong.
The USA's answer to Sputnik was a far more complex satellite called "Explorer 1."
But not only that, the then-president, Dwight D. Eisenhower, also established an American space agency, NASA.
A clear vision: Human spaceflight
America's goal was to send humans into space.
"We have one of the most challenging assignments that has ever been given to modern man," said Eisenhowever in a speech at the time.
"We will be developing and launching into space vehicles needed to obtain scientific data and to explore the solar system. We will be preparing for the day when manned flight goes into space," he said.
And the American engineers were sure they could do it, too. They had Wernher von Braun on their side.
Wernher von Braun was a aerospace engineer, who had built rockets for Nazi Germany. After the war, von Braun migrated to the US with about a hundred of his best experts and built an American missile program.
Read more: From Apollo 11 to the new space race
Politicians, like President Kennedy, and scientists considered Wernher von Braun an expert in rockets.
The American public saw von Braun as the ultimate expert. It was only later, in the 1970s, that people started to ask questions about von Braun's Nazi past and his involvement in war crimes.
But that wasn't an issue for von Braun in the 1950s.
His sole concern, and that of his team, was delivering better satellites than the Soviets. And they succeeded.
"We have produced more scientific knowledge with our smaller vehicles than the Russians have with their much larger ones," boasted von Braun during a press conference.
Skeptical test pilots
American test pilots at the time were less than enthusiastic about sending humans into space.
"They were trying to convince me how neat it would be to get into a capsule on top of a rocket," recalled US astronaut, Walter Schirra, later. "And I said: No way! Send the idiot who is sitting on a canon in the circus — and forget us! Then they tried to convince me: 'No, it will be alright — we'll put some monkeys and chimpanzees in first'. But I thought: Now I know I want out of here! So I really had a very negative opinion of it."
Schirra's objections did not hold long.
In 1959, Schirra become one of the first seven astronauts presented by NASA to the public for its Mercury Project.
They were full of optimism in front of the press.
And then the first Mercury rocket started, with a major fault.
"None of us has ever seen a missile launch," said Glenn, who was one of the original seven. "The booster launches and we see a big flame and we stand there watching it like this. And here these seven budding astronauts watching this go up to 27,000 feet and it blew. And it just looked like an atomic bomb over our heads. Then we were looked at each other and thought: We'll have to talk to the engineers tomorrow."
Chimpanzees or people
There was another shock sooner after that.
On April 12, 1961, cosmonaut Yuri Gagarin became the first person to orbit the Earth. And the Soviets were out in front again.
"We started launching monkeys and chimpanzees and then they launched Juri Gagarin," recalled Schirra later. "We were totally shocked by that."
Head start USSR (L-R): Valery Bykovsky, Valentina Tereshkova, and Yuri Gagarin were the first cosmonauts.
It was time for another strong political signal.
John F. Kennedy had been elected US President. And like Eisenhower before him, Kennedy was determined to take the technological lead from the Soviets.
In a speech, Kennedy said: "I believe that this nation should commit itself to achieving a goal, before this decade is out, of landing a man on the moon and returning him safely to the Earth."
Then, in another speech, he reiterated his determination: "We choose to go to the moon in this decade and do the other thing, not because they are easy, but because they are hard."
The Soviet lead shrinks
Kennedy could say that because the US had started to catch up.
When Alan Shepherd became the first American to orbit Earth on May 5, 1961, the gap between them and the Soviets had shrunk to less than a month.
The USA had switched to the fast lane.
In the next eight years, the USA launched almost twice as many space missions as the Soviets. However, America's good run was not all good. In 1967 a spacecraft exploded during a ground test and three astronauts died.
That threw the American space program back by 21 months.
But it didn't stop NASA from setting ever more ambitious goals — such as the first moon orbits in October and November 1968. It was the first time astronauts had seen the far side of the moon.
"On Apollo 8, we rotated the spacecraft and saw for the very first time the far site of the moon, only 60 miles below," said US astronaut James Lovell later. "And we were like three school kids looking into a candy store window. I kind of forgot the flight plan for a second as those ancient old craters slowly slipped by."
Edward H. White went on the first space walk in 1965 and died two years later on a test flight for Apollo 1
It was a short step from there to landing on the moon.
Apollo 11 was the first mission to land on lunar surface.
Astronaut Michael Collins stayed back in the orbiter when Buzz Aldrin and Neil Armstrong undocked from the Command Module in the landing vehicle, the Eagle.
"There are certain events in life, that you never forget and the lunar landing, and in particular, the last seconds leading up to the landing will never be forgotten," said Gene Kranz.
Kranz was the Flight Director at NASA's control center in Houston, Texas. While trying to land the capsule on the moon's surface, various computer alarms went off.
"As the crew took over, about two minutes prior to landing, searching for the landing site, we knew that we were using a lot more fuel than we had expected," recalled Kranz.
Things remained hectic, even after the successful landing and Armstrong and Aldrin had said those legendary words: "the Eagle has landed."
"No controller had a chance to absorb the emotion of that landing," Kranz recalled, "because we had to work for the next two hours — nonstop."
The moon landing was a world first. And so was the live coverage of the event on TV.
Public interest was huge. More than 2000 journalists were accredited at Cape Canaveral and Houston.
"Up until that moment, TV had always been a goal, but not a requirement," said Kranz.
And that everything would work in the deciding moment was far from certain.
"Once, we landed safely, the only thing that counted for us was to see the picture. What I felt at that moment was: 'The TV better work or else!' and if it doesn't they really will know who I am — because I will be the man who didn't bring you television on the moon."
But the technology delivered and millions of people across the world watched as Neil Armstrong became the first human to put a foot on the moon, and said those other legendary words:
"That's one small step for [a] man, one giant leap for mankind."