My vision is for a fully reusable rocket transport system between Earth and Mars that is able to re-fuel on Mars - this is very important - so you don't have to carry the return fuel when you go there.
It would take six months to get to Mars if you go there slowly, with optimal energy cost. Then it would take eighteen months for the planets to realign. Then it would take six months to get back, though I can see getting the travel time down to three months pretty quickly if America has the will.
Land on Mars, a round-trip ticket - half a million dollars. It can be done.
I personally think going to Mars, if it takes two years or two and a half years, that's doable. Certainly, the first people who go there, that's going to be a big motivator, being first getting to Mars.
My view is that we should go back to the moon, build up the infrastructure to make flights there commonplace - be comfortable with it - then use that infrastructure to expand and go to Mars.
I can only think of one experience which might exceed in interest a few hours spent under water, and that would be a journey to Mars.
Human beings are fragile things, and for the period of time it takes to get them to Mars and back, you have dangerous radiation from the sun and the galaxy. We have to think about issues like that.
President Bush's proposal to focus our resources on sending humans to Mars is intriguing, but it is not the most compelling reason that Americans ought to focus our interest on the Red Planet.
The life expectancy of people going to Mars may be decreased by the higher level of radiation that they receive.
Can you imagine, in 2030, taking a space cruise on the very ship that carried the first human beings to Mars? I can't believe that people wouldn't line up for that possibility.
Is a one-way trip to Mars ever really seriously going to happen? Surely that's morally reprehensible. However old people are, however much they say they want to go on a one-way mission, people should be thinking about the possibility of returning.
Imagine we could accelerate continuously at 1 g-what we're comfortable with on good old terra firma-to the midpoint of our voyage, and decelerate continuously at 1 g until we arrive at our destination. It would take a day to get to Mars, a week and a half to Pluto, a year to the Oort Cloud, and a few years to the nearest stars.
If we're going to go farther from Earth, to Mars or somewhere else someday, we have to have a good understanding of the psychological impact on people. And not only psychologically, but how it affects their cognition. We're doing a lot of research on my cognitive abilities.
Britain should definitely be part of a Mars mission.
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.
I believe the biggest impediment we have right now with going to Mars is public commitment. More people need to see themselves as a part of space travel; we need to see more inclusiveness.
We do need different types of propulsion to get to Mars. I wrote one of the first Ph.D. theses on that in the 1960s.
