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Apollo 11


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

Key Dates

Launch​: July 16, 1969

Lunar Orbit Insertion: July 19, 1969

Lunar Landing: July 20, 1969

Lunar Surface Departure: July 21, 1969

Recovery on Earth: July 24, 1969


On May 25, 1961, six weeks after Soviet Cosmonaut Yuri Gagarin became the first person to fly into space and just 20 days after Alan Shepard 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 July 20, 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 that the two men shared measured about 36 by 55 inches (91 by 140 centimeters). 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.

The 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.
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. The fuel gauge read disturbingly low and dust, which the rocket engine blasted off the ground, obscured their view. But they touched down safely at 20:17 UT (4:17 p.m. EDT). Armstrong, with his heart racing at 150 beats per minute 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 arose.

One Giant Leap...

Armstrong stepped onto the lunar surface at 02:56 UT on July 21 (10:56 p.m. EDT on 20 July) 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 47.51 pounds (21.55 kilograms) of lunar rock and soil, which included three minerals never seen before. They walked a total distance of about 820 feet (about 250 meters) 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 July 17, 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 UT on July 21, the American astronauts had completed their moonwalk but would not begin their journey home for another two hours.

Four minutes into its descent, less than 2 miles (about 3 kilometers) 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 July 21 after 21 hours, 36 minutes on the lunar surface. The descent stage that 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 July 24, 1969 at 16:50:35 UT (12:50:35 p.m. EDT) after a mission elapsed time of 195 hours, 18 minutes, 35 seconds. The splashdown point was 400 miles SSW of Wake Island and 15 miles (24 kilometers) 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.

- Credit: NASA

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