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Apollo 11
Apollo 11 Mission to Earth's Moon

Mission Type: Orbiter, Sample Return
Launch Vehicle: Saturn V
Launch Site: Kennedy Space Center, Launch Complex 39A, Florida, United States
NASA Center: Johnson Space Center, Langley Research Center
Spacecraft Mass: 28,801 kg (63,495 lbs.)
Spacecraft Instruments: Passive Seismic Experiment
Lunar Field Geology
Laser Ranging Retroreflector
Solar Wind Composition
Cosmic-Ray Detection (helmets)
Lunar Surface Close-Up (camera)
Lunar Sample Analysis

NASA History Office
National Space Science Data Center

On 25 May 1961, six weeks after Soviet Cosmonaut Yuri Gagarin became the first person to fly into space and just 20 days after Alan Shephard became the first American to do so, President Kennedy declared a national goal of landing a man on the moon and returning him safely to Earth by the end of the decade. A little more than eight years later, that feat was accomplished.

Apollo 11 Commander Neil A. Armstrong and Edwin E. "Buzz" Aldrin Jr., pilot of the lunar module "Eagle," landed in Mare Tranquilitatis (the Sea of Tranquility) on 20 July 1969, while Michael Collins continued orbiting the moon in the command module "Columbia."

Descent to the Moon

The lunar module was very different from the command module, which would have to withstand the heat and stress of re-entry into Earth's atmosphere. Walls as thin as a couple of sheets of printer paper were all that shielded the astronauts from the vacuum of space as they descended to the lunar surface. The floor of the crew compartment which the two men shared measured about 36 by 55 inches (91 by 140 cm). And since chairs were omitted to keep the weight down, the astronauts stood during both descent and ascent. They used harnesses augmented by handholds, arm rests and Velcro strips on the soles of their shoes to keep from bouncing around the cabin.

This first human landing on the moon did not go smoothly. The descent was punctuated by a series of alarms caused by radar-tracking problems and computer overload. Armstrong overrode the automatic landing system when the astronauts saw that it was taking them to a dangerously rocky region. Dust which the rocket engine blasted off the ground obscured their view and the fuel gauge read disturbingly low, but they touched down safely at 20:17 UT (4:17 p.m. EDT). Armstrong, with his heart racing at 150 beats per minutes instead of his usual 60, coolly radioed the message, "Houston, Tranquility Base here. The Eagle has landed."

The astronauts immediately prepared the spacecraft to lift off and return to orbit. They needed to be ready to leave quickly if one of the lunar module's footpads began to sink into the dust, a fuel tank on the ascent stage appeared damaged, or some other emergency presented itself.

One small step

Armstrong stepped onto the lunar surface at 02:56 on 21 July UT (10:56 p.m. on 20 July EDT) with the words, "That's one small step for (a) man, one giant leap for mankind." Aldrin followed 19 minutes later.

They deployed the Early Apollo Scientific Experiment Package (EASEP) and other instruments, unfurled a sheet of aluminum foil to trap solar-wind particles, took photographs and collected 21.55 kg (47.51 pounds) of lunar rock and soil, which included three minerals never seen before. They walked a total distance of about 250 meters (about 820 feet) and returned to Eagle, closing the latch at 5:11 UT.

Meanwhile, a drama was playing out in lunar orbit. The Soviet Union's Luna 15, a robotic spacecraft launched three days before Apollo 11, was that country's second attempt (following a failed launch the previous month) at a sample-return mission from the moon. The Soviet spacecraft entered lunar orbit on 17 July, two days before Apollo 11 arrived. Though the American mission would be first to land people on the moon, the Soviet mission might have been first to bring lunar samples back to Earth.

But Luna 15 remained in lunar orbit for four days while its controllers checked the onboard systems and performed two orbital maneuvers. When it fired its main retro-rocket to begin its landing, at 15:47 on 21 July, the American astronauts had completed their moon walk but would not begin their journey home for another two hours.

Four minutes into its descent, about 3 kilometers (less than 2 miles) above the lunar surface, the Soviet spacecraft stopped transmitting. It is thought to have crashed into the side of a mountain in Mare Crisium.

Return to Earth

Armstrong and Aldrin lifted off from the moon at 17:54 UT on 21 July after 21 hours, 36 minutes on the lunar surface. The descent stage which had powered their soft landing served as a launch platform for the ascent stage that returned them to orbit. After they docked with Columbia and transferred into its crew compartment, they jettisoned Eagle into lunar orbit. It is assumed to have crashed into the lunar surface during the following one to four months.

Columbia splashed down in the Pacific Ocean on 24 July 1969 at 16:50:35 UT (12:50:35 p.m. EDT) after a mission elapsed time of 195 hrs, 18 mins, 35 secs. The splashdown point was 400 miles SSW of Wake Island and 24 km (15 mi) from the recovery ship USS Hornet. The primary mission goal of landing astronauts on the moon and returning them to Earth had been achieved.

This had been the second space flight for each of the three astronauts. Armstrong, a civilian, had flown on Gemini 8; Aldrin was a USAF Colonel who had flown on Gemini 12; and Collins was a USAF Lt. Colonel who had flown on Gemini 10. The backup crew for Apollo 11 was Jim Lovell, Fred Haise, and William Anders. Command module Columbia is on display at the National Air and Space Museum in Washington, D.C.

Key Dates
16 Jul 1969:  Launch
19 Jul 1969:  Lunar Orbit Insertion
20 Jul 1969:  Lunar Landing
21 Jul 1969:  Lunar Surface Departure
24 Jul 1969:  Recovery on Earth
Status: Successful
Fast Facts
Apollo 11 Facts First time humans walked on the moon.

First words spoken from the surface of another world: "Houston, Tranquility Base here. The Eagle has landed."

A plaque on the descent stage (which also served as launch platform for the ascent stage and remains on the lunar surface) reads: "Here men from the planet Earth first set foot on the moon July 1969, A.D. We came in peace for all mankind."

To make the lander as light as possible, it contained no seats. The astronauts stood while descending to the lunar surface and returning to the orbiting command module.

The command module was named "Columbia" after "Columbiad," the canon that launched the moonship in Jules Verne's novel, From the Earth to the moon.
Science & Technology Features
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During the Apollo program, McKay gave the first men to walk on the moon training in geology. Read More...
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Last Updated: 5 Sep 2013