The Saturn V rocket lifted off at an almost frighteningly slow speed at 09:32 local time (13:32 UTC) from Launch Complex 39A at the Kennedy Space Center, on the eastern coast of Florida. Every second, 13 tonnes of fuel were pumped into the five engines and burned; each of them produced 7500 kilonewtons of thrust. Twelve seconds later, the launcher cleared the launch tower. At 111 metres tall and weighing almost 3000 tonnes at launch, it was the most powerful rocket ever to have been built. Its lift-off was accompanied by a tremendous rumbling noise, the like of which had never been heard before from any human-made machine. Around one million people watched the launch from the local area. Atop the three-stage launcher was the Apollo 11 Command Module, Columbia, with the astronauts Neil Alden Armstrong, Edwin Eugene Aldrin and Michael Collins. They were scheduled to reach the Moon three days later. On the night of 20–21 July 1969, Neil Armstrong and Buzz Aldrin became the first human beings to set foot on the surface of the Moon. A thousand-year-old dream had come true!
Thousands of tonnes of fuel
The first stage burned for two-and-a-half minutes, carrying the launcher up to an altitude of 61 kilometres. From there, it sped towards space at a speed of 8000 kilometres per hour. Two thousand tonnes of fuel had now been burned, the stage separated and fell into the Atlantic Ocean, 560 kilometres west of the launch site. The second stage burned for another six minutes, before it too separated and fell into the sea, this time 4000 kilometres from Florida. The first burn of the third stage placed the Command Module, Service Module and Lunar Module in Earth orbit at an altitude of approximately 185 kilometres. There, the spacecraft orbited the planet for three hours at a speed of seven kilometres per second (25,000 kilometres per hour). Meanwhile, control of the spacecraft was transferred from Kennedy Space Center to Ground Control in Houston, Texas, for the remainder of the mission.
From Earth to the Moon in three days
At 16:22 UTC (17:22 CET), after one-and-a-half orbits of Earth, the spacecraft began its journey to the Moon. The Saturn IVB upper stage accelerated it to the required escape velocity of 11.2 kilometres per second. The most difficult manoeuvre on the journey to Earth’s satellite took place half an hour after injection into lunar transfer orbit. This was the separation of the Command and Service Module (CSM) from the third stage, followed by a 180-degree turn and the docking of the tip of the Command Module with the Lunar Module, so that it could be extracted from the third stage. After this, the now-connected components were again rotated by 180 degrees. Michael Collins, who was in charge of the manoeuvre, completed it without problems. The astronauts now had almost 400,000 kilometres left to travel.
The expended upper stage flew on its own trajectory past the Moon; it is still in orbit around the Sun. Telescopes on Earth have been able to use the reflection curves to detect the titanium oxide in the white paint and thus observe it on several occasions.
Time was short – NASA speeds up the pace and the risk
How was the Apollo 11 crew selected? Who decided which astronauts would be the first to fly to the Moon? And who determined who would be the first person to set foot on Earth's satellite? In one sense, the choice of Neil Armstrong, Buzz Aldrin and Michael Collins for the Apollo 11 mission was down to a lucky coincidence. Armstrong and Aldrin were the reserve crew for the Apollo 8 mission, which completed the very first journey to the Moon with a human crew at Christmas in 1968 and took the famous photograph of Earth appearing over the Moon's horizon – Earthrise.
The third substitute astronaut was originally Fred Haise, but Armstrong successfully petitioned Deke Slayton, the Assistant Director of Flight Crew Operations at NASA, for Michael Collins to take Haise's place. Collins had already proven his skills on Gemini 10. On 10 January 1969, Armstrong, Aldrin and Collins were presented to the public as the crew of Apollo 11. At this point, however, the Lunar Module had not even been tested, so it was by no means certain that Apollo 11 would land humans on the Moon.
But time was running out. NASA feared that the Soviet Union would soon be able to send the first cosmonauts to the Moon. The state of play was unclear following the surprise death of the Russian rocket engineer Sergei Korolev on 14 January 1966. In addition, there was President John F Kennedy's announcement on 25 May 1961, which committed the US to the goal of "… before this decade is out, landing a man on the Moon and returning him safely to the Earth." So, NASA was in a hurry – which increased the risk. The Apollo 6 and 7 missions, which took place in 1968, were unmanned test flights in Earth orbit. Apollo 8 in December 1968 marked the first time that the Saturn V rocket had been used, flying directly to the Moon with astronauts on board. In early 1969, NASA tested the completed Lunar Module in Earth orbit with Apollo 9. Apollo 10 in May 1969 was a dress rehearsal, with the Lunar Module descending to approximately 15 kilometres above the surface of the Moon. After all of this had gone smoothly, NASA was ready to attempt a landing with Apollo 11.
Armstrong, Aldrin, Collins – three exceptional people
Neil Armstrong was selected as the mission commander. He had also held this position on the Gemini mission in March 1966, when two spacecraft were docked together in space for the first time. That mission had almost ended in disaster, as the Gemini capsule began to tumble, but Armstrong brought the situation under control. He was seen as modest, almost introverted, but also extremely professional, exceptionally skilled, quick-thinking and a good team member. These were all qualities that NASA believed made him ideally suited to the command of Apollo 11. It was also clear that he, the commander and also a civilian, should be the first to set foot on the Moon. Edwin 'Buzz' Aldrin, the Lunar Module pilot, was known as more of a hothead – ambitious, an enthusiastic astronaut and no less capable than Armstrong. Other astronauts nicknamed him 'Dr Rendezvous'. While studying for a doctorate at the Massachusetts Institute of Technology in Boston, he wrote his thesis on the docking manoeuvre between two spacecraft, which had been carried out for the first time in the mid-1960s. Finally, Michael Collins, born in Rome, had performed a spacewalk as part of Gemini 10, and was considered to have a very even temperament. He also had an artistic streak – he designed the mission badge for Apollo 11, with an eagle landing on the Moon and holding an olive branch in its talons – a sign of peaceful intentions. All three were the same age – born in 1930 – and had gained experience as pilots in wartime and as former fighter jet test pilots in the US Air Force or Navy.
For three days, the Apollo mission flew without incident towards the Moon, whose gravitational field captured the capsule as planned. It was on a 'free-return trajectory'. This meant that after reaching the Moon, its gravity would allow the Command and Service Module to return to Earth, even in the event that its engine failed to fire. But everything went according to plan: At 17:21 CET on 19 July, the mission entered lunar orbit. Just 20 hours later, now on 20 July, Armstrong and Aldrin crawled from the 'Columbia' Command Module into the 'Eagle' Lunar Module and undocked from the Command and Service Module at 18:44. After further system tests and visual checks by Michael Collins – who watched the 'Eagle' rotating from the windows of the 'Columbia' – Neil Armstrong initiated the landing process with the words "The eagle has wings!"
Computer errors, boulders and manual control
The following quarter of an hour made space history. Armstrong and Aldrin – both standing and looking at the Moon out of the small triangular windows – soon realised, as they approached the surface while travelling from east to west, towards the volcanic plain of Mare Tranquillitatis, that they had passed the landmarks explored by for Apollo 10 several seconds too early. They were going to land several kilometres too far to the west. Five minutes after the engines had been ignited, while they were still 1800 metres above the Moon, the low-power yet robust on-board computer registered the famous 1201 and 1202 alarms, which did not strike Armstrong as particularly worrying. Mission control quickly issued a recommendation to ignore these alarms, which indicated the computer could no longer process the incoming data quickly enough.
Neil Armstrong took manual control of the Lunar Module. He saw a funnel-shaped crater with steep inner walls and metre-sized boulders around its edge at the intended landing site. Immediately, he realised that this place would be too dangerous for a landing and steered the Lunar Module over it. At the same time, he received the announcement via the Capsule Communicator (CapCom), astronaut Charles Duke, in Houston: "60 seconds!" The tank of the Lunar Module descent stage only had enough fuel for one more minute. Half a minute later: "30 seconds!" The mission was on the verge of being aborted. The Lunar Module was only three metres above the surface, and it was not certain that it would have been possible to abort without crashing onto the lunar surface. Neil Armstrong kept his cool and landed with enough fuel for only another 20 seconds. Buzz Aldrin called out “Contact light!” to Houston. Three seconds later the two astronauts shut down the engine, which had been whipping up dust.
The Eagle has landed, and Houston takes a deep breath
Twenty endless seconds later, the control centre was immensely relieved to receive Neil Armstrong's message: "Houston, Tranquillity Base here. The Eagle has landed." CapCom Duke replied, "Roger, Tranquillity. We copy you on the ground. You got a bunch of guys about to turn blue. We’re breathing again. Thanks a lot." It was Sunday, 20 July 1969 at 20:17 UTC (21:17 CET and mid-afternoon in the USA). Humans had landed on the Moon.
Shortly after midnight, German time – 21 July had already begun there, while the Moon landings took place in the evening of 20 July, US time, this being the best time for broadcasts – the astronauts in the Eagle began preparing the exit to the Moon. The hatch was opened at 03:38 CET. Neil Armstrong mounted the ladder at 03:51, climbed down it and, at 03:56:20 CET on 21 July 1969 stepped on the Moon and uttered the famous words, "That's one small step for man, one giant leap for mankind." Buzz Aldrin followed him 20 minutes later. For just over two hours, the first two men on the Moon explored the vast wasteland, collected 21.5 kilograms of moon rocks and samples of lunar dust, carried out the experiments that they had brought with them, and planted a United States flag. US President Richard Nixon congratulated them via a telephone connection from the White House in Washington D. C., transmitted via Houston.
Meanwhile, Michael Collins orbited the Moon 18 times, awaiting the return of his fellow astronauts. On 21 July at 18:54 CET, the upper part of the Lunar Module began its journey back to the Command and Service Module in lunar orbit. It docked with the CSM and then separated again after Armstrong and Aldrin had transferred to the Command Module. The Lunar Module crashed onto the Moon. Three days later, the astronauts splashed down safely in the Pacific Ocean and were picked up by helicopters from the aircraft carrier USS Hornet. As it was necessary to make sure that the astronauts had not brought any lunar microbes back to Earth, they had to undergo two weeks of quarantine.
The experiments and the descent stage of the Lunar Module remained on the Moon. A plaque on the landing leg beneath the exit ladder was unveiled by the two astronauts. It reads: “Here men from the planet Earth first set foot upon the Moon, July 1969, A. D. "We came in peace for all mankind."
Further information about the anniversary of the first Moon landing can be found on DLR's dedicated website.