On July 20, 1969, mankind set foot on another celestial body. The Apollo 11 lunar module landed on the Sea of Tranquility. Hours later, Neil Armstrong descended the ladder and stepped onto the lunar landscape and into history.

The landing validated a Kennedy promise to put a man on the moon before the end of the decade. (In fact, we would do it twice: Apollo 12 would return to Earth's satellite that November.)

It culminated centuries of dreaming by the human race.

But the landings were about more than reaching the moon and owning up to Kennedy's pledge. In fact it probably had more to do with the hard realities of politics and the Cold War than with science.

And it certainly showed that our manned space flight program could overcome so many obstacles.

During the 1960s, the United States was locked in a symbolic "space race" with the Soviet Union. The race was really about technological superiority, both celestial and terrestrial. The moon happened to be a convenient target for such lofty and nationalistic ambitions.

Russia had always seemed to be a step or two ahead of the Americans. The U.S.S.R. was the first to put a satellite, a man and a woman in space (the latter more than 20 years before the United States would accomplish the feat); the first to have a man orbit the earth and the first to conduct a space walk.

Further complicating America's resolve to catch the Russians was the disastrous Apollo 1 fire of January 1967. A blaze broke out in th ecommand module during a ground test, killing three astronauts. It set America's manned space program back by more than a year.

But the tide turned in 1968. America's Apollo program was able to arise from the ashes and soar into space. On Christmas of that year, Apollo 8 became the first manned vehicle to leave the Earth's orbit and fly around the moon.

In the spring of 1969, the Russians suffered their own launching pad disaster which effectively put them out of the moon race.

Now Kennedy's promise was the real driving force, and the end of the decade was looming.

On July 16, 1969, Apollo 11 lifted off from Cape Kennedy in Florida and began the four-day trip to the moon. On board with Armstrong were Col. Buzz Aldrin and Lt. Col. Michael Collins.

Apollo 11's lunar module, the Eagle, touched down on the moon at about 3:40 p.m. CDT on Sunday, July 20. At approximately 9:56 p.m., Armstrong completed the trip by uttering the words, "That's one small step for man, one giant leap for mankind." (In Armstong's excitement, he actually misspoke the sentence. He intended to say, "That's one small step for a man ...") Aldrin joined him on the surface a few moments later.

The ascent stage of the lunar module roared off the surface the next day, and the command module Columbia returned to earth, splashing down in the South Pacific on July 24.

Kennedy's words had been realized, even if a final turn of the political screw pushed his memory into the background. The initial plans called for the crew of the Columbia to be plucked from the sea by the U.S.S. John F. Kennedy. But President Richard Nixon, who had no desire to remind the public of his old foe's motivating role in the epochal feat, changed the assignment and instead ordered the U.S.S. Hornet to the scene for the splashdown.