How Apollo 11 got to the Moon and back
On this page
A Saturn V rocket stood about 110 metres tall on the launch pad. Eight days later, the only part of it that came home was a cone-shaped capsule less than 4 metres across. Apollo 11 worked by throwing pieces of the spacecraft away, one after another, as soon as each had done its job.
The crew and the two spacecraft
Apollo 11 carried three NASA astronauts:
- Neil Armstrong, commander
- Edwin "Buzz" Aldrin, lunar module pilot
- Michael Collins, command module pilot
On top of the rocket sat two spacecraft joined together. The command and service module, called Columbia, was the crew's home for the journey there and back. The capsule at the front held the astronauts; the service module behind it held the main engine, fuel, oxygen and power supplies. The lunar module, Eagle, was a light, spidery craft built only to work in space and on the Moon. It could never have survived a trip through Earth's atmosphere.
Only Armstrong and Aldrin went down to the surface. Collins stayed in orbit around the Moon in Columbia, which was their only way home.
The mission in seven stages
1. Launch (16 July 1969). The Saturn V lifted off from Kennedy Space Center in Florida. It had three stages. The first burned for under three minutes and lifted the rocket through the thickest part of the atmosphere. The second carried it most of the way to orbit, and the third finished the job. Each stage dropped away when its fuel was gone.
2. Leaving Earth orbit. The crew circled the Earth for about two and a half hours, checking their systems. Then the third stage fired again. This burn, called translunar injection, sped the spacecraft up enough to leave low orbit and coast towards the Moon. Soon afterwards Columbia separated, turned round and docked nose to nose with Eagle, pulling it free of the third stage. The joined craft then coasted for about three days.
3. Into lunar orbit. Arriving at the Moon, the spacecraft was moving too fast to stay there. The service module engine fired against the direction of travel to slow it down, and the Moon's gravity captured it into orbit.
4. The landing (20 July). Armstrong and Aldrin moved through the docking tunnel into Eagle, undocked and began the descent. Three things went wrong on the way down. The guidance computer flashed alarm codes 1201 and 1202, because it was being given more work than it could handle at once; Mission Control in Houston judged that it was safe to continue. The automatic guidance was steering towards a crater surrounded by large boulders, so Armstrong took partial manual control and flew on, looking for a clear spot. And by the time Eagle touched down, fuel in the descent stage was running low. They landed in the Sea of Tranquility, a flat plain of ancient lava, and Armstrong radioed: "Houston, Tranquility Base here. The Eagle has landed."
5. On the surface. A few hours later Armstrong climbed down the ladder and stepped onto the Moon. Aldrin followed about 20 minutes later. In roughly two and a half hours outside, they collected about 21.5 kg of rock and soil, set up a seismometer to detect moonquakes, put out a sheet of foil to catch particles from the solar wind, planted a US flag and took photographs. They also left a laser reflector. Scientists still bounce laser pulses off it to measure the distance to the Moon very precisely.
6. Leaving the Moon (21 July). The lunar module came apart in two. The lower descent stage stayed behind as a launch platform, and the upper ascent stage fired its own engine and climbed back to lunar orbit. It docked with Columbia, the crew and samples transferred, and the ascent stage was released. The service module engine then fired to send Columbia home.
7. Splashdown (24 July). Shortly before reaching Earth, the service module was cast off. Only the capsule, heat shield first, entered the atmosphere. Air resistance slowed it from a very high speed, the shield protected the crew from the heat, and parachutes opened for the last part of the fall. Columbia came down in the Pacific Ocean and the crew were picked up by the aircraft carrier USS Hornet. Because nobody could yet be certain that Moon samples carried no germs, the astronauts spent about three weeks in quarantine.
Timeline
Mission times are usually given in UTC (Coordinated Universal Time, which for everyday purposes is the same as GMT), so that everyone uses one clock.
| Event | Date and time (UTC) |
|---|---|
| Launch | 16 July 1969, 13:32 |
| Eagle lands | 20 July, 20:17 |
| Armstrong's first step | 21 July, 02:56 |
| Eagle lifts off from the Moon | 21 July, 17:54 |
| Splashdown | 24 July, 16:50 |
Armstrong's first step was late on 20 July by the clocks in Houston, but in the early hours of 21 July in UTC. That is why books give both dates.
Worked example: how long was Eagle on the Moon?
- It landed at 20:17 on 20 July and lifted off at 17:54 on 21 July.
- From 20:17 to midnight is 3 h 43 min.
- From midnight to 17:54 is 17 h 54 min.
- 3 h 43 min + 17 h 54 min = 20 h 97 min = 21 h 37 min.
So Eagle sat on the surface for about 21 and a half hours, but the moonwalk itself took only about two and a half of them.
Try the same method for the whole mission, from launch to splashdown. You should get about 8 days 3 hours.
Five common mix-ups
- "All three astronauts walked on the Moon." Collins never left lunar orbit.
- "The whole rocket went to the Moon." The first two stages fell away within minutes of launch. Our guide to how rockets work explains why dropping stages saves so much fuel.
- Swapping the names. Columbia was the command module. Eagle was the lunar module, the one that landed.
- "The flag was waving in the wind." A horizontal rod held the top edge of the flag out. It wobbled because the astronauts twisted the pole into the ground, and with no air to damp the movement, it took a while to stop.
- "Apollo 11 was the only Moon landing." Twelve astronauts walked on the Moon on six missions: Apollo 11, 12, 14, 15, 16 and 17. Apollo 13 had to turn back after an oxygen tank exploded, and the last moonwalk was on Apollo 17 in December 1972.
You can test yourself on the crew, the spacecraft and the dates with this Apollo 11 quiz on ModernScholar. To see what lies beyond the Moon, our planets of the Solar System table puts the key facts side by side.
Frequently asked questions
Why did Apollo 11 land in the Sea of Tranquility?
Planners wanted a flat, fairly smooth area near the Moon's equator, on the side facing Earth so that radio contact was never lost, and one that earlier robotic spacecraft had already photographed in detail.
Can you see the landing site through a telescope?
No. Even the largest telescopes on Earth cannot make out an object as small as a lunar module at that distance. NASA's Lunar Reconnaissance Orbiter, which circles the Moon, has photographed the Apollo sites from above, and the descent stages are visible in its images.
Sources and further reading
- Apollo 11 – NASA – NASA's mission page, with the crew, timeline, photographs and audio.
- Apollo 11 – Britannica – a concise encyclopedia account of the flight and landing.
- NASA History – NASA's history office, with archive material on the whole Apollo programme.
