"Timing has always been a key element in my life. I have been blessed to have been in the right place at the right time."

"Before deciding what to do about national space policy, Obama set up an outside review panel of space experts, headed up by my friend Norm Augustine, former head of Lockheed Martin and a former government official."

"I want to reach a new generation. That's why I am Twittering now. I have a BlackBerry, an iPhone and a Mac."

"Being first outside the spacecraft would bring much more responsibility, and I really wasn't looking for that."

"The much-hyped Ares 1-X was much ado about nothing."

"We must still think of ourselves as pioneers to understand the importance of space."

"I was motivated to improve the U.S. strategy of going back to the moon in 1985. That's a long time ago. Going back to the moon would be a great achievement for tourism adventure flights."

"There's a need for accepting responsibility - for a person's life and making choices that are not just ones for immediate short-term comfort. You need to make an investment, and the investment is in health and education."

"To move forward, what's required is a unified space agenda based on exploration, science, development, commerce, and security."

"When I was a little kid, we only knew about our nine planets. Since then, we've downgraded Pluto but have discovered that other solar systems and stars are common. So life is probably quite prevalent."

"I didn't start skiing until I was 50. My wife Lois taught me how to ski. I'm proficiently conservative."

"There's a historical milestone in the fact that our Apollo 11 landing on the moon took place a mere 66 years after the Wright Brothers' first flight."

"I think humans will reach Mars, and I would like to see it happen in my lifetime."

"I think both the space shuttle program and the International Space Station program have not really lived up to their expectations."

"There are always door openings. And gradually, it accumulates. The opportunities open up in front of you."

"If we can conquer space, we can conquer childhood hunger."

"I still say, 'Shoot for the moon; you might get there.'"

"There may be aliens in our Milky Way galaxy, and there are billions of other galaxies. The probability is almost certain that there is life somewhere in space."

"Globalisation means many other countries are asserting themselves and trying to take over leadership. Please don't ask Americans to let others assume the leadership of human exploration. We can do wonderful science on the Moon, and wonderful commercial things. Then we can pack up and move on to Mars."

"I was the first Navy, Marine or Air Force person who had been an astronaut to return back to the Air Force. I had certain expectations about what would be a reasonable and desirable position to be assigned to after my years of service."

"Computers allow us to squeeze the most out of everything, whether it's Google looking up things, so I guess that tends to make us a little lazy about reading books and doing things the hard way to understand how those things work."

"We can continue to try and clean up the gutters all over the world and spend all of our resources looking at just the dirty spots and trying to make them clean. Or we can lift our eyes up and look into the skies and move forward in an evolutionary way."

"As we reflect back upon the tragic loss of Challenger and her brave crew of heroes who were aboard that fateful day, I am reminded that they truly represented the best of us, as they climbed aloft on a plume of propellant gasses, reaching for the stars, to inspire us who were Earthbound."

"Maybe it was the challenge of flight, the opportunity to fly, the competition of summer camp and the inspiration and discipline of West Point. I think all of those things helped me to develop a dedication and inspired me to get ahead."

"If we go back to the moon, we're guaranteed second, maybe third place because while we are spending all that money, Russia has its eye on Mars. Landing people on the moon will be terribly consuming of resources we don't have. It sounds great - 'Let's go back. This time we're going to stay.' I don't know why you would want to stay on the moon."

"Bringing an asteroid back to Earth? What's that have to do with space exploration? If we were moving outward from there, and an asteroid is a good stopping point, then fine. But now it's turned into a whole planetary defense exercise at the cost of our outward exploration."

"I've led a life of such structured discipline and always had a goal in mind of knowing what I was doing, from West Point to the Air Force combat, MIT, looking for new things to study and get involved in. And then I got into the space program, and how disciplined can you get?"

"You need propellants to accelerate toward Mars, then to decelerate at Mars, again to re-accelerate from Mars to Earth, and finally to decelerate back at Earth. Accordingly, the mass of these required propellants, in short, drives our need for innovative launch vehicles."

"Whenever I gaze up at the moon, I feel like I'm on a time machine. I am back to that precious pinpoint of time, standing on the foreboding - yet beautiful - Sea of Tranquility. I could see our shining blue planet Earth poised in the darkness of space."

"The pilgrims on the Mayflower landed at Plymouth Rock. To my knowledge, they didn't wait around for a return trip to Europe. You settle some place with a purpose. If you don't want to do that, stay home. You avoid an awful lot of risks by not venturing outward."

"There's no doubt who was a leader in space after the Apollo Program. Nobody came close to us. And our education system, in science, technology, engineering and math, was at the top of the world. It's no longer there. We're descending rather rapidly."

"NASA's been one of the most successful public investments in motivating students to do well and achieve all they can achieve, and it's sad that we are turning the program in a direction where it will reduce the amount of motivation it provides to young people."

"By refocusing our space program on Mars for America's future, we can restore the sense of wonder and adventure in space exploration that we knew in the summer of 1969. We won the moon race; now it's time for us to live and work on Mars, first on its moons and then on its surface."

"I think the American Dream used to be achieving one's goals in your field of choice - and from that, all other things would follow. Now, I think the dream has morphed into the pursuit of money: Accumulate enough of it, and the rest will follow."

"What are you going to do with astronauts who first reach the surface of Mars and then turn around and rocket back home-ward? What are they going to do, write their memoirs? Would they go again? Having them repeat the voyage, in my view, is dim-witted. Why don't they stay there on Mars?"

"Just as Mars - a desert planet - gives us insights into global climate change on Earth, the promise awaits for bringing back to life portions of the Red Planet through the application of Earth Science to its similar chemistry, possibly reawakening its life-bearing potential."

"The purpose of going to Mars is for humans to first begin to occupy, permanently, another planet in the solar system. The astronauts or pilgrims, whatever you might call them, are going to be very historically unique human beings."

"When you go to Mars, you need to have made the decision that you're there permanently. The more people we have there, the more it can become a sustaining environment. Except for very rare exceptions, the people who go to Mars shouldn't be coming back. Once you get on the surface, you're there."

"We need to begin thinking about building permanence on the Red Planet, not just have voyagers do some experiments, plant a flag and claim success. Having them go there, repeat this, in my view, is dim-witted. Why not stay there?"

"I'm convinced that sending people to Mars is so expensive that if you go once and bring the people back and then go again and bring the people back, we're eventually going to run out of money. But what if we send people the first time and they don't come back? What if they stay there?"

"The leader of an Earth organization who makes a commitment to history - of humans living on Earth, to begin permanent settlement/occupation of not the moon, but of another planet - this leader will have a legacy for history that will supersede Columbus, Genghis Khan or almost any recognized leader."

"Any observations from the Moon or a sense of realising this or that about the greater meaning of things wasn't as influential for me as the experience of coming back and dealing with being a person who's been to the Moon."

"I'm urging NASA to foster the development of what I call 'runway landers.' No, that's not the name of a high stakes gambler from Vegas. It's a type of spacecraft that flies to orbit like the retiring Shuttles but then glides to a landing like an airplane on a runway. Just like the Shuttles do."

"As we begin to have landings on the moon, we can alternate those with vertical launch of similar crew modules on similar launch vehicles for vertical-launch tourism in space, if you want to call it that... adventure travel."

"Mars, we know, was once wet and warm. Was it home to life? And what can living and learning to work on its rust-colored surface teach us about the future of our own planet, Earth? Answering those mysteries may hold the key to our future."

"Over the years, I think I've matured in my spiritual evolution and development to understand a bit more than the narrow religious thinking - to move beyond that through a sort of perfection of the grandiose nature of the universe, and how perfect it is it in its sense and how satisfied we should all be in our place in that."

"I think the people who experienced the Apollo missions came away from that experience wondering to themselves, 'When can we get a chance to experience spaceflight?' I've heard that many, many times: that people got into a new career field hoping that they would be able to experience spaceflight."

"When we can demonstrate that we can take off horizontally and put something into orbit, then we can begin to talk about increasing the amount of payload. But to say, 'I'm going to do that and put people into orbit' is a real leap."

"Does it make sense for the U.S. to expend hundreds of billions of dollars to mount a new Apollo-style program to return to the moon? Or have we blazed that trail? Shouldn't we help other nations achieve this goal with their own resources but with our help?"