Careers, like rockets, don't always take off on time. The trick is to always keep the engine running.

Once you get into space, you can really unleash a lot of creativity, but the launch itself? I have been through all of the creative ways, and believe me, chemical rockets are the best.

I've always been interested in the idea of space exploration. When I was younger it was just a dream, but the theory of rockets being able to travel through space was very much alive. I found it very exciting.

The years of space flight since the orbiting of Sputnik I back in 1957 had produced many fascinating results, but they had also brought a realization of the many problems that surrounded the use of rockets for space flight.

It seems that 'rocket scientist' is a job category that's here for the long haul, like 'mortician.' But all this activity masks an important point: rockets are not a terribly efficient way to lift things into space.

Space travel is the only technology that is more dangerous and more expensive now than it was in its first year. Fifty years after Yuri Gagarin, the space shuttle ended up being more dangerous and more expensive to fly than those first throwaway rockets, even though large portions of it were reusable. It's absurd.

Reusable rockets promise much easier testing because you should usually get them back, and you can debug as you go rather than having to get everything perfect the first time.

Whether solid rockets are more or less likely to fail than liquid-fuel rockets is debatable. More serious, though, is that when they do fail, it's usually violent and spectacular.

Rocket scientists agree that we have about reached the limit of our ability to travel in space using chemical rockets. To achieve anything near the speed of light we will need a new energy source and a new propellant. Nuclear fission is not an option.

I'm never going to go to Mars, but I've helped inspire, thank goodness, the people who built the rockets and sent our photographic equipment off to Mars.

Growing up in the '60s and early '70s, with the space flight and the Apollo program, I always loved planes. I always loved rockets and I always loved space travel.

One of the things that we can say with confidence is that we will have much lighter, much stronger materials, and this will reduce the cost of air flight, and the cost of rockets.

Rocket science is tough, and rockets have a way of failing.

Sometimes people wonder why aeroplanes are so cheap and rockets are so expensive. Even the most superficial comparison shows one obvious difference: aeroplane engines use outside air to burn their fuel, while rockets have to carry their own oxidisers along.

I certainly remember building model rockets. It was fun to watch the rocket blast into the air, suspenseful to wonder if the parachute would open to bring the rocket safely back.

The rockets and the satellites, spaceships that we're creating now, we're pollinating the universe.

As a kid, I was obsessed with space. Well, I was obsessed with nuclear science too, to a point, but before that, I was obsessed with space, and I was really excited about, you know, being an astronaut and designing rockets, which was something that was always exciting to me.

The revolutionary breakthrough will come with rockets that are fully and rapidly reusable. We will never conquer Mars unless we do that. It'll be too expensive. The American colonies would never have been pioneered if the ships that crossed the ocean hadn't been reusable.

Rockets are cool. There's no getting around that.

Some ways of using our thinking are really inspiring. There are people who use their thinking to race cars. People use their thinking to build rockets to the moon. It's all just a use of your thinking.

I was quiet, a loner. I was one of those children where, if you put me in a room and gave me some crayons and a pencils, you wouldn't hear from me for nine straight hours. And I was always drawing racing cars and rockets and spaceships and planes, things that were very fast that would take me away.

The odds of me coming into the rocket business, not knowing anything about rockets, not having ever built anything, I mean, I would have to be insane if I thought the odds were in my favor.

I think the whole Rockets organization has done amazing things.

As when astronaut Mike Mulhane was asked by a NASA psychiatrist what epitaph he'd like to have on his gravestone, Mulhane answered, "A loving husband and devoted father," though in reality, he jokes in "Riding Rockets," "I would have sold my wife and children into slavery for a ride into space.