MELBOURNE, Fla. – As the Eagle descended toward the Sea of Tranquility, Buzz Aldrin saw something he had never seen before: the shadow of the lunar module cast in front of them on the moon's cratered surface.

"That was new, not something we saw in the simulator," he recalled on the eve of today's 50th anniversary of the historic Saturn V launch that carried him, Neil Armstrong and Michael Collins on a 238,000-mile journey to the moon.

"I saw dust creating a haze, not particles, but a haze that went out, dust the engine was picking up. The light turns on, I said 'contact light,' 'engine stop,'" Aldrin said in a question-and-answer email sent to FLORIDA TODAY late Monday.

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The Eagle had landed. It was 4:17 p.m. EDT, July 20,1969. Neil Armstrong radioed, "Houston, Tranquility Base here. The Eagle has landed." Mission control erupted in celebration, and a controller remarked, "You got a bunch of guys about to turn blue; we're breathing again."

Armstrong and Aldrin had become the first humans ever to land on another galactic body. Collins waited for them, circling the moon in the command module, Columbia.

"Neil remembers we shook hands, and I recall putting my hand on his shoulder and we smiled," Aldrin said.

The Apollo 11 mission, which bore the hope of a nation and the fascination of the world, had launched four days earlier, on July 16, 1969, from Launch Complex 39A at Kennedy Space Center, the NASA facility renamed for the slain president who had set America on the goal of landing man on the moon and returning him safely before the decade was out.

By some estimates, more than a million people gathered along the Space Coast shoreline to watch the rumbling Saturn V lift into the heavens that July morning. Video from 1969 shows campers filling the beaches and people packed elbow-to-elbow in the parking lots.

In Aldrin's memoir, "Magnificent Desolation," he wrote, "Elevated 300 feet in the air on an upper platform of Kennedy Space Center’s Launch Pad 39-A, I stood alone on the grating of the towering gantry.

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"A few yards away, loaded with more than 2,000 tons of liquid oxygen and hydrogen propellant, the giant Saturn V rocket also stood, primed for liftoff as the countdown progressed. Large shards of frost were already falling off its outer skin from the super-chilled liquid oxygen within.

"Hours earlier my Apollo 11 crewmates, Neil Armstrong and Michael Collins, and I had enjoyed a predawn steak-and-eggs breakfast – an astronaut tradition – and had gone through an elaborate suiting-up with NASA’s equipment team helping us get into our pressurized suits, helmets, gloves, and boots."

The launch, Aldrin recalled in the email Q&A to FLORIDA TODAY, went smoothly.

"We had all seen preparations for a launch go down to seconds, then have to start over – and so I think we were relieved when the launch went ahead," he said.

"Launch was almost imperceptibly smooth through the early abort modes, and nothing unexpected happened. We knew we were accelerating, but the launch was so smooth compared to Gemini launches that we did not know the instant of leaving the ground.

"We only knew it from the instruments and voice communications, which confirmed lift-off. We saw our rate of climb, altitude changing, but were comfortable in our seats. We sort of looked at each other and thought, ‘We must be on our way … what’s next?’"

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What was next was a journey that would accomplish what years earlier had seemed impossible. The crew had been training intensely. Some 400,000 people – NASA employees, contractors around the nation – had worked long hours, staying late, solving one engineering puzzle after another, to make it a reality.

"It was a privilege to have been able to undertake the first manned mission to the lunar surface, an honor to have worked with so many good and dedicated people, and to have left our footprints there," Aldrin said. "Even now, sometimes, I marvel that we went to the moon."

When Armstrong stepped off the ladder onto the moon's surface, followed by Aldrin (who joked that he was "being careful not to lock the door behind me"), both men, Aldrin said, were struck by the moon's beauty. It was Aldrin who spoke the two words that have become a poetic descriptor for what they saw: Magnificent Desolation.

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"I guess I said that because it was magnificent … we had gotten there, and it looked pretty desolate," Aldrin said. "But it was magnificent desolation."

Once on the surface, Aldrin said they did not think about the immensity of what they were doing. They focused on the job, on talking back to Mission Control, on the experiments, particularly making sure they were level and pointing toward the sun. He said that wasn't as easy as it sounds, noting that a leveling device on the moon can be tricky and doesn't work right away.

Looking back 50 years on what was accomplished, on what he was part of, Aldrin acknowledged Apollo 11 means many things to many people, as evidenced by the multitude of commemorations around the nation.

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Aldrin hosted the Apollo XI 50th Anniversary Gala at the Ronald Reagan Library in California over the weekend, an event attended by many astronauts. It raised funds in support of Aldrin's Human Spaceflight Institute. Aldrin, who lives in Satellite Beach, is 89, and Collins is 88. Armstrong died in 2012.

"To me, it was the dream we had all signed up to chase, what we had imagined, worked and trained for, the apex of national service to a country we unabashedly loved, the height of aviation and exploration," Aldrin said.

Although sometimes, he has a fleeting sense that "the three of us missed 'the big event,'" he said. He admits people might smile upon hearing him say that.

"But while we were out there on the moon, the world was growing closer together right here," Aldrin said. "Hundreds of millions saw their own reflection in our visors, efforts, risk with purpose, doing what had not been done before."

Aldrin said he'd like to see "the next generation to buckle up, get back to the moon, and get on to a permanent presence on Mars.” And he hopes Americans truly appreciate what they accomplished together 50 years ago this month.

"It all felt like, that is what America is, what we can do, when we are united in purpose," Aldrin said. "Apollo showed that this nation, this America, can do whatever is required, when destiny calls on us to unify, and step up.

"It was an honor to be a part of Apollo. That was how I felt in 1969, how I still feel. … This is a blessed nation, truly blessed, and we are all lucky to be part of it. I hope we never forget how lucky we are to be Americans.”

Follow Mara Bellaby on Twitter: @MBellaby