21 quotes from the Apollo 11 astronauts on everything from walking on the moon to the future of spaceflight

"One truth I have discovered for sure: When you believe that all things are possible and you are willing to work hard to accomplish your goals, you can achieve the next 'impossible' dream. No dream is too high!"

Source: "No Dream is Too High: Life Lessons From a Man Who Walked on the Moon"

"Your mind is like a parachute: If it isn't open, it doesn't work."

Source: "No Dream is Too High: Life Lessons From a Man Who Walked on the Moon"

"I think we're going to the moon because it's in the nature of the human being to face challenges. It's by the nature of his deep inner soul … we're required to do these things just as salmon swim upstream."

Source: Internet Archive

"We are off! And do we know it, not just because the world is yelling 'Liftoff' in our ears, but because the seats of our pants tell us so! Trust your instruments, not your body, the modern pilot is always told, but this beast is best felt. Shake, rattle and roll!"

Source: "Carrying the Fire: An Astronaut's Journeys"

"There's a tremendously satisfying freedom associated with weightlessness. It's challenging in the absence of traction or leverage, and it requires thoughtful readjustment. I found the experience of weightlessness to be one of the most fun and enjoyable, challenging and rewarding, experiences of spaceflight. Returning to Earth brings with it a great sense of heaviness, and a need for careful movement. In some ways it's not too different from returning from a rocking ocean ship."

Source: Scholastic

"Houston, Tranquility Base here. The Eagle has landed."

Source: NASA

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

Source: NASA

"I thought, well, when I step off it's just going to be a little step — a step from there down to there — but then I thought about all those 400,000 people who had given me the opportunity to make that step and thought it's going to be a big something for all those folks and, indeed for a lot of others that weren't even involved in the project, so it was kind of a simple correlation."

Source: CBS News

"Pilots take no special joy in walking: pilots like flying. Pilots generally take pride in a good landing, not in getting out of the vehicle."

Source: "In the Shadow of the Moon"

"Magnificent desolation."

Source: "Magnificent Desolation: The Long Journey Home from the Moon"

"It's an interesting place to be. I recommend it."

Source: CBS News

"I really believe that if the political leaders of the world could see their planet from a distance of, let's say 100,000 miles, their outlook would be fundamentally changed. The all-important border would be invisible, that noisy argument suddenly silenced."

Source: Michael Collins on Twitter

"I am alone now, truly alone, and absolutely isolated from any known life. I am it. If a count were taken, the score would be three billion plus two over on the other side of the moon, and one plus God knows what on this side."

Source: "Carrying the Fire: An Astronaut's Journeys"

"From the distance of the moon, Earth was four times the size of a full moon seen from Earth. It was a brilliant jewel in the black velvet sky. Yet it was still at a great distance, considering the challenges of the voyage home."

Source: Scholastic

"As the senior crew member, it was appropriate for [Armstrong] to be the first. But after years and years of being asked to speak to a group of people and then be introduced as the second man on the moon, it does get a little frustrating. Is it really necessary to point out to the crowd that somebody else was first when we all went through the same training, we all landed at the same time and all contributed? But for the rest of my life I'll always be identified as the second man to walk on the moon. [Laughs.]"

Source: National Geographic

"Everyone who's been in space would, I'm sure, welcome the opportunity for a return to the exhilarating experiences there. For me, a flight in a shuttle, though most satisfying, would be anticlimactic after my flight to the moon."

Source: Scholastic

"I am, and ever will be, a white-socks, pocket-protector, nerdy engineer — born under the second law of thermodynamics, steeped in the steam tables, in love with free-body diagrams, transformed by Laplace, and propelled by compressible flow."

Source: National Academy of Engineering

"I see more moon missions as delaying Mars, which is a much more interesting place to go."

Source: United Press International

"Oh, I am quite certain that we will have such bases in our lifetime, somewhat like the Antarctic stations and similar scientific outposts — continually manned. Although, certainly there is the problem of the environment, the vacuum, the high and low temperatures of day and night. Still, in all, in many ways, it's more hospitable than Antarctica might be."

Source: BBC interview via Business Insider

"The urge to explore has propelled evolution since the first water creatures reconnoitered the land. Like all living systems, cultures cannot remain static; they evolve or decline. They explore or expire."

Source: Albuquerque Tribune