Cleared to proceed to the moon, the astronauts fired the S-IVB engine again, increasing their velocity to 38,400 kilometers per hour. On 20 July, Sunday in the United States, Armstrong and Aldrin occupied and powered up the lunar module, Eagle, and deployed its landing legs. The two craft separated at 1:46 p.m. (KSC time). Collins fired the command module rockets to move about three kilometers away. Flying feet first, face down, Armstrong and Aldrin fired Eagle's descent engine at 3:08 p.m. Forty minutes later, as the command module emerged from behind the moon, Collins reported: "Everything is going just swimmingly." The two astronauts guided the Eagle into elliptical orbit. Armstrong throttled the engine at 4:05 p.m. to slow its descent.
As the moonscape came into clearer view, Armstrong saw they were approaching a crater almost as large as a football field. He took over manual control and steered toward a less formidable site. At Mission Control physicians noted his heart beat had increased from a normal 77 to 156. While Armstrong manipulated the control, Aldrin called out altitude readings: "750 feet, coming down at 23 degrees . . . 700 feet, 21 down . . . 400 feet, down at nine. . . . Got the shadow out there . . . 75 feet, things looking good . . . lights on . . . picking up some dust . . . 30 feet, 2 1/2 down . . . faint shadow . . . four forward . . . drifting to the right a little . . . contact light . . . O.K. Engine stop." As the probes beneath three of Eagle's four footpads touched the surface, a light flashed on the instrument panel. The world heard Armstrong's quiet message: "Houston. Tranquility Base here. Eagle has landed."42
Later the crew explained that at some distance from the surface, fine dust had blown up around the spacecraft and obscured their vision. They felt no sensation at the moment of landing, and set to work telling people on earth what they could see from Eagle's windows. At 6 p.m. Armstrong recommended that the walk on the moon should begin about 9 p.m., earlier than originally planned. Later than he proposed, but still five hours ahead of schedule, Armstrong opened the hatch and squeezed through it at 10:39 p.m. He wore 38 kilograms of equipment on his back, containing the portable life support and communications systems. On the moon, the weight amounted to only 6.3 kilograms. Wriggling through the hatch, Armstrong cautiously proceeded down the nine-step ladder. He paused at the second step to pull a ring to deploy a television camera, mounted to follow his movements as he climbed down. At 10:56 p.m. he planted his left foot on the moon. Then the words that were to take their place among the great phrases of history: "That's one small step for a man, one giant leap for mankind."43
At 1:54 p.m. 21 July, after 22 hours on the lunar surface, Aldrin fired the ascent stage engine. It functioned perfectly. They docked with the command module at 5:35 p.m. Collins touched off the main engine at 12:55 a.m. 22 July, while on the back side of the moon, and the astronauts headed for home. Because of stormy seas, they adjusted their course to a new landing area 434 kilometers from the original site. They splashed down in the Pacific at 12:50 p.m. 24 July. President Nixon greeted them on the aircraft carrier Hornet.44
The Apollo program had achieved its objective five months and ten days before the end of the decade.
One of the most perceptive writers of our time, Anne Morrow Lindbergh, probed the deeper meanings of these amazing engineering accomplishments. In Earthshine, she spoke of the "new sense of awe and mystery in the face of the vast marvels of the solar system," and the feeling of modesty before the laws of the universe that counterbalanced man's pride in his tremendous achievements. Many had remarked that mankind would never again look on the moon in the same way. She thought it more significant that people would never again look at earth in the same way. We would have a new sense of its richness and beauty. She concluded: "Man had to free himself from earth to perceive both its diminutive place in the solar system and its inestimable value as a life-fostering planet."45