102 hours and 45 minutes. Scroll and follow the Saturn V rocket from Florida, stage by stage, until the lunar module Eagle stands on the Moon.
Five F-1 engines ignite almost nine seconds before launch. Clamps hold the rocket down until all five are at full thrust, and only then does it let go. 2,900 tonnes barely move at first. It takes just over ten seconds to clear the 120-metre tower.
After 83 seconds comes Max Q, when the air presses hardest against the hull. The white collar is condensation where the rocket breaks the sound barrier.
After two and a half minutes the first stage’s more than 2,000 tonnes of kerosene and liquid oxygen are gone. Eight small retro-rockets pull the S-IC back, while four small rockets on the interstage nudge the rest forward so the fuel in the S-II settles against the tank bottoms. Then five J-2 engines running on liquid hydrogen ignite. Their flame is almost invisible.
Thirty seconds after separation the interstage ring drops away, a five-metre skirt that is only dead weight now. Shortly after, the launch escape tower fires itself off the top of the command module. It could have pulled the crew free if something had gone wrong near the ground. This high up, Columbia manages on its own.
The second stage drops away and the third stage, the S-IVB, fires for the first time. Two and a half minutes later Apollo 11 is in a nearly circular orbit around Earth. The rocket now lies flat. Speed is the only thing keeping it up there.
For one and a half orbits the crew checks every system. Then the S-IVB fires again, for five minutes and 47 seconds. Speed rises to 10.8 km/s, close to escape velocity. The manoeuvre is called translunar injection. The path is chosen so the spacecraft would swing around the Moon and fall back towards Earth if the engines went quiet.
The lunar module Eagle has been folded up under four panels on top of the third stage. Collins separates Columbia, moves ahead a little, turns the spacecraft 180 degrees and docks its nose to Eagle’s roof. Then he pulls the lander out. The empty third stage is sent off into an orbit around the Sun.
For the rest of the way the engine is mostly off. Earth’s gravity slows the spacecraft the whole time, from 10.8 km/s to under 1 km/s. After just over 61 hours the Moon’s gravity takes over and speed rises again. So the Sun won’t roast one side, the spacecraft rotates three times an hour.
The path takes Apollo 11 around the far side of the Moon, where the radio goes silent. There, out of contact with Houston, the main engine fires for six minutes and brakes the spacecraft into lunar orbit. On Earth they only learn it worked when the signal returns on the other side, to the second.
The Eagle has wings
Armstrong and Aldrin crawl through the tunnel into Eagle. The lander separates from Columbia and slowly turns once in front of Collins’s window so he can see that all four legs are deployed. Collins stays in orbit, alone. A short burn then lowers Eagle’s orbit to 15 km above the surface.
The descent engine fires. Eagle first flies legs-first with the engine as a brake. The computer raises alarms 1202 and 1201: it is overloaded but keeps up with what matters, and Houston answers that they are go. Near the ground Armstrong sees the computer steering towards a crater full of boulders. He takes over and flies past it.
The Eagle has landed
One of the long probes under the footpads touches the surface and the Contact light comes on. Armstrong shuts down the engine. There is fuel left for about 45 seconds. Then he says: Houston, Tranquility Base here. The Eagle has landed.
Armstrong climbs down the ladder and puts his left foot in the dust: That’s one small step for man, one giant leap for mankind.
Around 600 million people are watching live. After two and a half hours outside, both are back in Eagle. On 24 July all three splash down in the Pacific.