Thirty-five years ago, on July 20, 1969, humans first set foot on another world. U.S. Apollo 11 astronaut Neil Armstrong descended from a landing craft named "Eagle" to become the first person to step on the moon, a momentous event he eloquently consecrated.

"That's one small step for man, one giant leap for mankind," he said.

For many, it was the high point of a U.S. space program that was fueled by political adrenaline to compete with the Soviet Union.

The first moon landing was the culmination of eight years of the Apollo program, a dramatic demonstration of U.S. engineering prowess initiated by President John Kennedy in a 1961 speech before Congress.

"I believe that this nation should commit itself to achieving the goal before this decade is out of landing a man on the moon and returning him safely to the Earth," President Kennedy said.

Coming at the height of the Cold War, President Kennedy's remarks were a bid to assert American technical superiority over the Soviet Union, which had already launched the first satellite into Earth orbit and the first spacecraft to the moon, and was soon to beat the United States again with the first human to circle Earth.

But by 1969, the tide of space competition would turn as Neil Armstrong, Buzz Aldrin, and Michael Collins entered the Apollo 11 command module Columbia atop a gigantic Saturn V rocket.

An estimated one million people gathered along beaches and roads near the coastal Florida launch site and technicians engaged in frantic last-minute activity. But high off the ground atop the rocket, Buzz Aldrin felt a sense of solitude moments before entering the crew cabin.

"The most memorable thing that I can recall about that particular day was the opportunity to stand alone by myself out there and look at the rocket and the quietness and see the sun come up and to realize that in a very few moments, we were going to be departing in a great roar and off for a momentous event," he recalls.

Four days after takeoff, while in radio silence on the far side of the moon, the Eagle lander separated from the Apollo 11 command module. Once back in contact with mission controllers in Houston, Neil Armstrong confirmed the maneuver saying, "The 'Eagle' has wings."

But upon descent, he saw that the automatic guidance system was directing them toward large boulders. Mr. Armstrong took manual control and accelerated to a smoother area aptly named "The Sea of Tranquility" with just 20 seconds of landing fuel left.

"Houston, 'Tranquility Base' here. The 'Eagle' has landed," Armstrong said.

Six-and-a-half hours later, the two astronauts climbed out of the lander to begin several experiments and collect moon rock and soil. Neil Armstrong described the scene.

"It has a stark beauty all its own," he said. "It's like much of the high desert of the United States. It's different, but it's very pretty out here."

During their two-and-a-half hour moonwalk, the crewmen planted the U.S. flag in the soil and received a phone call from President Richard Nixon, who paid tribute to what he called their immense feat.

"Because of what you have done, the heavens have become a part of man's world. For one priceless moment in the whole history of man, all the people on this Earth are truly one, one in their pride in what you have done," the president said.

Roughly 21.5 hours after descent, astronauts Armstrong and Aldrin fired their ascent rockets and rejoined Michael Collins aboard the orbiting "Columbia" command module for the flight home, establishing forever what Mr. Armstrong has called Apollo 11's lasting legacy.

"The important achievement of Apollo was a demonstration that humanity is not forever chained to this planet, and our visions go rather further than that and our opportunities are unlimited," he said.