Apollo 11

Crew

Neil Armstrong (commander), Michael Collins (command module pilot), Edwin "Buzz" Aldrin (lunar module pilot)^[2]

Spacecraft

Command module Columbia, lunar module Eagle, launched on a Saturn V^[2][8]

Launch

July 16, 1969, 9:32 a.m. EDT, Pad 39A, Kennedy Space Center^[2][3]

Landing

July 20, 1969, 20:17:40 UT, Sea of Tranquility, at 0.67408° N, 23.47297° E^[3][4]

Time on the surface

21 hours, 36 minutes, with one moonwalk of about two and a half hours^[2][6]

Samples returned

21.55 kilograms of rock and soil^[3]

Splashdown

July 24, 1969, 16:50:35 UT, Pacific Ocean, after 195 hours, 18 minutes, 35 seconds^[2][3]

Background

The mission grew out of the Cold War contest in space. Shortly after the Soviet Union put Yuri Gagarin in orbit on April 12, 1961, Kennedy asked Vice President Lyndon Johnson to find a space effort that could deliver dramatic results.^[4] On May 25, 1961, he told a joint session of Congress that the country should land a person on the Moon and bring that person home.^[1][4] The Apollo program that followed cost $25.8 billion between 1960 and 1973, according to a tally by The Planetary Society, or about $309 billion in 2025 dollars.^[14] NASA's own account from the time said more than 300,000 people across industry, universities and government were working on it at its peak.^[8]

Launch and the trip out

More than a million spectators, among them Vice President Spiro Agnew and former President Johnson, saw the Saturn V lift off from Florida at 9:32 a.m. EDT on July 16, 1969.^[4][5] The stack weighed about six million pounds at liftoff.^[8] After a stay in Earth orbit, a burn of the rocket's third stage lasting 5 minutes and 48 seconds sent the spacecraft toward the Moon. Only one of four planned course corrections proved necessary.^[2] The crew entered lunar orbit on July 19.^[2]

The landing

Armstrong and Aldrin undocked in Eagle on July 20, leaving Collins alone aboard Columbia.^[5] The final descent burn lasted about 12 and a half minutes, and it was not routine.^[6] The guidance computer raised program alarms, codes 1202 and 1201, which the crew had not seen in training and which signaled that it was being asked to process too much data. Flight controllers judged the overload harmless and told the crew to continue each time.^[7][18] Radio contact with Eagle also kept dropping, so Mission Control at times spoke to the lander through Collins.^[7]

0:46 "A controlled fall" NASA's account of why landing was the hardest part of any Apollo mission: fuel for only one try.

Near the end, Armstrong saw the automatic approach heading for a crater the size of a football field littered with large rocks, and he took partial manual control to fly beyond it.^[2][8] Eagle landed roughly 6 kilometers from its planned point, about 400 meters west of a crater named West.^[4] The maneuvering used up propellant, and a low-fuel warning came on with about 5% left.^[6][7] Armstrong's onboard readings suggested very little margin, but analysis after the flight found about 45 seconds of fuel remained at touchdown.^[6] Eagle landed at 4:17 p.m. EDT.^[3][5] Armstrong then reported:^[7]

1:26 "The Eagle has landed" Fuel calls of 60, 30 and 20 seconds, then mission audio from Tranquility Base and Houston's reply.

“Houston, Tranquility Base here. The Eagle has landed.”Neil Armstrong

On the surface

The moonwalk began about six and a half hours after landing.^[6] Armstrong stepped off the ladder at 10:56 p.m. EDT on July 20, or 02:56 UT on July 21, and Aldrin joined him about 15 to 20 minutes later.^[2][3][6] NASA gives Armstrong's words as "one small step for a man, one giant leap for mankind"; the Smithsonian's timeline renders them without the "a."^[2][5] A television camera sent the scene to Earth.^[2] The Smithsonian estimates that 650 million people watched, while NASA's report of the time gave a Comsat estimate of 500 million.^[4][8]

0:27 600 million people watching NASA's film of the moonwalk as the world saw it.

Over about two and a half hours the two men gathered samples, and ranged no more than about 300 feet (90 meters) from the lander.^[2][3] They raised a 3-by-5-foot American flag held out by a horizontal rod, unveiled a plaque on a landing leg, and spoke for about two minutes with President Richard Nixon by a relayed telephone link.^[7][8] The plaque reads "Here Men From Planet Earth First Set Foot Upon The Moon July 1969 A.D. We Came In Peace For All Mankind."^[8]

1:04 The plaque on the ladder "They came in peace for all mankind": the plaque left on the lander's leg.

The science was modest by the standard of later flights, because weight limits and the short excursion ruled out the fuller instrument package.^[6] Aldrin set out a seismometer and a laser reflector south of the lander, along with a foil collector for the solar wind that stayed out for 77 minutes.^[6][7] The seismometer began returning data right away and was sensitive enough to detect the astronauts' footsteps.^[8] They also hammered in two core tubes, which went only 8 to 9 inches into the compacted soil, and took about 100 color photographs.^[6] They left behind medallions honoring three Apollo 1 astronauts and two cosmonauts, and a silicon disk of goodwill messages from 73 countries.^[2]

Departure and return

During the moonwalk preparations Aldrin had accidentally broken the circuit breaker that armed the ascent engine, and the crew pushed it in with a felt-tip pen.^[7] Rest was poor. Armstrong lay on the engine cover and Aldrin on the floor, in their suits and in a cold cabin, and Armstrong did not sleep at all.^[6][17] The ascent stage lifted off at 1:54 p.m. EDT on July 21 and docked with Columbia at 128 hours, 3 minutes into the flight, after which Eagle was cast off and left in lunar orbit.^[2][5] An engine burn just before midnight Eastern time sent the ship home.^[5]

Weather shifted the splashdown point by about 250 miles.^[2] Columbia came down in the Pacific on July 24 at 13°19' N, 169°9' W, about 24 kilometers from the recovery ship USS Hornet, where Nixon greeted the crew.^[3][9]

Quarantine and homecoming

Because no one could yet rule out harmful lunar microbes, the crew spent 21 days in quarantine, counted from first exposure to lunar material, mostly at the Lunar Receiving Laboratory in Houston.^[9] A flight surgeon checked them daily, and they wrote their reports and held debriefings there, with Armstrong marking his 39th birthday inside.^[9] Doctors found no sign of infection and the three walked out on the evening of Aug. 10, 1969.^[9][11] Later crews, from Apollo 15 on, did not go through quarantine.^[11]

On Aug. 13 they rode in parades in New York, before an estimated four million people, and Chicago, then went to a state dinner in Los Angeles, where Nixon presented each with the Presidential Medal of Freedom.^[9][10] Houston held its own parade on Aug. 16.^[10] A world tour followed.^[5]

1:23 "We did it, we humans" Recollection of the world tour after the flight: every country said "we did it."

Science and legacy

NASA's figures for the haul vary with rounding, from 21.55 kilograms to about 49 pounds.^[3][9] A later study sorted 73 of the mission's basalts into five groups dating from roughly 3.9 to 3.6 billion years ago, evidence of several separate lava flows at the site.^[13] The laser reflector has outlasted everything else from the flight: a 2004 NASA account called it the only lunar experiment running continuously since Apollo. Timing laser pulses to it has fixed the Earth-Moon distance to about 2 centimeters, shown the Moon is slowly moving away, pointed to a fluid core, and supported Albert Einstein's theory of gravity.^[12]

Apollo 11 was one of 15 Apollo missions.^[4] Apollo 17 made the program's last landing in December 1972, by which time 12 people had walked on the Moon.^[15] Columbia now belongs to the Smithsonian's National Air and Space Museum, which features it in its Destination Moon exhibition along with Armstrong's spacesuit.^[4] Eagle's descent stage remains at Tranquility Base, and images from NASA's Lunar Reconnaissance Orbiter have since shown the site from orbit.^[16] NASA is now planning a permanent Moon Base near the lunar South Pole, with the outpost phase set to start in 2032.^[19]

Timeline

1. May 25, 1961 President Kennedy sets the goal of a crewed lunar landing before Congress.^[1][4]
2. July 16, 1969 Apollo 11 lifts off at 13:32 UT.^[3]
3. July 19, 1969 The spacecraft enters lunar orbit.^[2]
4. July 20, 1969 Eagle lands at 20:17:40 UT.^[3]
5. July 21, 1969 Armstrong steps onto the Moon at 02:56:15 UT; the hatch closes after the moonwalk at 05:11:13 UT.^[3]
6. July 21, 1969 Eagle leaves the Moon at 17:54 UT.^[5]
7. July 24, 1969 Columbia splashes down at 16:50:35 UT.^[3]
8. Aug. 10, 1969 The crew leaves quarantine.^[9]
9. Aug. 13, 1969 Parades in New York and Chicago, and a state dinner in Los Angeles.^[10]
10. Dec. 1972 Apollo 17 makes the program's last lunar landing.^[15]