"It's time to open the space frontier to citizen explorers."

"The biggest benefit of Apollo was the inspiration it gave to a growing generation to get into science and aerospace."

"Walking around on the moon was significantly easier than we'd thought it would be. There weren't any balance problems, so you weren't tumbling over."

"I know: If you're looking down at Earth, you're looking through an atmosphere that has a bit of haze in many places and not just occasional clouds."

"My favourite thing to do on this planet is to scuba dive."

"I've been to the Titanic in a yellow submarine and the North Pole in a Russian nuclear ice breaker."

"America's can-do spirit cast a warm glow across nations and cultures, generating more goodwill and support for our country's ideals and causes than had otherwise been possible."

"Because of his military service, Dad was buried in Arlington National Cemetery."

"Retain the vision for space exploration. If we turn our backs on the vision again, we're going to have to live in a secondary position in human space flight for the rest of the century."

"It was interesting to think that the very first liquid ever poured on the Moon, and the first food eaten there, were communion elements."

"The life expectancy of people going to Mars may be decreased by the higher level of radiation that they receive."

"Going to Mars would evolve humankind into a two-planet species."

"Exploring Mars is a far different venture from Apollo expeditions to the moon; it necessitates leaving our home planet on lengthy missions with a constrained return capability."

"I suggest that going to Mars means permanence on the planet - a mission by which we are building up a confidence level to become a two-planet species."

"We need the next generation to be motivated and to push technological boundaries, to seek out new innovations."

"The way I see it, commercial interests should manage a lunar base while NASA gets on with the really important task of flying to Mars."

"Pascal Lee is a true pioneer of Mars exploration."

"Space architectures capable of supporting a permanent human presence on Mars are extraordinarily complex, with many different interdependent systems."

"The way I see it, what is going to come out of the moon activities is a respect for U.S. leadership."

"America can take man to the moon, and America can take men to Mars - and beyond."

"Mars has been flown by, orbited, smacked into, radar inspected, and rocketed onto, as well as bounced upon, rolled over, shoveled, drilled into, baked, and even laser blasted."

"What's aero braking? That's a way to use the gravity and upper atmosphere of Earth to sling shot a ship out either deeper into space, or slow it down to be 'captured' by Earth's gravity."

"Do we really need these big, gigantic, heavy rockets? What if we launch a rocket that's empty, and its sole purpose is to act as a source of fuel on the Moon? Who should build that? Well, I think the U.S. should build that."

"We had this whole big beautiful place for discovery, and all we could think to do with it was wipe out everything that made it worth discovering."