Apollo 11

On July 20, 1969, two people stepped onto the surface of the Moon for the first time in history. Apollo 11 was the United States spaceflight that got them there and brought them home.

Quick facts

• Launch: July 16, 1969, 9:32 a.m. EDT (13:32 UTC) from Launch Pad 39A, Kennedy Space Center, atop a Saturn V rocket (vehicle AS-506).
• Crew: Neil Armstrong (commander), Michael Collins (command module pilot), and Edwin “Buzz” Aldrin Jr. (lunar module pilot).
• Spacecraft: the command/service module Columbia (CSM-107) and the lunar module Eagle (LM-5). A lunar module is the small lander that carries astronauts down to the surface.
• Moon landing: July 20, 1969, 4:17:43 p.m. EDT, in the Sea of Tranquility.
• First step on the Moon: about 109 hours and 24 minutes into the flight.
• Moonwalk (EVA, or extravehicular activity — time spent outside the spacecraft): about 2 hours 32 minutes, ranging up to about 300 feet from the lander.
• Time on the surface: about 21 hours 36 minutes. Samples returned: about 21.5 kg (47.5 lb) of Moon rock and soil.
• Splashdown: July 24, 1969, in the Pacific Ocean, about 13 miles from the recovery ship USS Hornet. Total mission: 195 hours 18 minutes 35 seconds (about 8 days).

How the mission worked

Apollo 11 used a plan called lunar-orbit rendezvous, meaning the spacecraft split into pieces near the Moon and reunited afterward. The three-stage Saturn V — 363 feet (about 110 m) tall and weighing roughly 3,000 tonnes — did the heavy lifting. A “stage” is a self-contained rocket section that fires, then drops away once empty. The first stage (S-IC) and its five F-1 engines produced about 7.5 million pounds of thrust to climb off the pad. The second stage (S-II) pushed toward space, and the third stage (S-IVB) first placed the craft in orbit around Earth, then re-fired for trans-lunar injection — the burn that aimed it at the Moon.

Once on its way, Columbia turned around, docked with Eagle, and pulled it free for the coast to the Moon. In lunar orbit, Armstrong and Aldrin climbed into Eagle and undocked, leaving Collins alone in Columbia. Eagle‘s descent engine lowered the lander to a gentle touchdown. To leave, Eagle‘s ascent stage fired, using the descent stage below it as a launch pad, and rose to re-dock with Columbia. The crew transferred back, dropped Eagle, and burned the engine for trans-Earth injection. Near home, only the cone-shaped command module re-entered the atmosphere, deploying parachutes for an ocean splashdown.

Why it matters

Apollo 11 was the first time humans set foot on another world. It fulfilled the goal President John F. Kennedy set in 1961 — to land people on the Moon and return them safely before the decade’s end — and, during the Cold War Space Race, it showed decisive U.S. capability over the Soviet Union. Scientifically, the roughly 21.5 kg of returned samples were the first Moon material ever studied directly, reshaping ideas about how the Moon formed. The mission also proved the entire approach — Saturn V, command/service module, lunar module, and lunar-orbit rendezvous — that enabled five more landings through Apollo 17. Watched live by an estimated 600 million people, it became one of the most shared events in human history. The crew left a plaque reading “We came in peace for all mankind” and set up science gear, including a laser retroreflector — a mirror that bounces laser beams back to Earth — still used today to measure the Earth-Moon distance.

Notable hardware

• Saturn V (AS-506): the 363-foot, three-stage rocket built under Wernher von Braun at NASA’s Marshall center — still the most powerful rocket flown operationally to the Moon.
• Command/Service Module Columbia: the “mothership” Collins flew solo in lunar orbit; its command module was the only part to return to Earth and is now displayed at the Smithsonian National Air and Space Museum.
• Lunar Module Eagle: the two-stage lander that touched down in the Sea of Tranquility and carried Armstrong and Aldrin back to orbit.
• F-1 engine: five of these kerosene/oxygen engines powered the Saturn V’s first stage, together making about 7.5 million pounds of thrust.

A close call on the way down

The descent was not routine. Eagle‘s guidance computer flashed “1202” and “1201” alarms — it was overloaded but correctly dropping low-priority tasks — and mission control judged them safe and pressed on. Armstrong took manual control to steer past a boulder-strewn area, touching down with only seconds of fuel margin and about four miles beyond the original target. As he became the first person to walk on the Moon, he said, “That’s one small step for man, one giant leap for mankind.”