NASA's Apollo program featured 17 unmanned and manned space missions. Astronauts made six successful lunar landings, including the first one--Apollo 11-- launched on this day in 1969.

"Mystery creates wonder," explained commander Neil Armstrong. "And wonder is the basis of man's desire to understand."

Four days later, with Michael Collins orbiting above in the command module, Neil Armstrong and Buzz Aldrin landed on the moon's surface. "Houston, Tranquility Base here. The Eagle has landed," announced Armstrong to the world.

As millions on Earth watched spellbound on live television, Armstrong, followed by Aldrin, stepped down the ladder onto the powdery Sea of Tranquility and said, "That's one small step for man, one giant leap for mankind."

The world listened in as President Nixon put in a long distance call to the moon. "Because of what you have done," he praised, "the heavens become a part of man's world."

The mission made good on President Kennedy's 1961 challenge to put a man on the moon "within ten years." Project Apollo included the efforts of over 400,000 people and 50,000 companies and universities. It took eight years of work, at a cost of $25 billion.

The astronauts gathered photographs and information about gravitational forces in space. They brought back lunar rocks which continue to profoundly influence the scientific world.

According to California geology professor Lee Silver, the samples, "showed more about the first third of the solar system history than we ever got about studying the earth. The moon turned out to be the best source of insight."

From a distance, there are no borders, only possibilities.