Knowledge of the past and an optimistic view of the present give you great opportunities.

History will remember the inhabitants of this century as the people who went from Kitty Hawk to the moon in 66 years, only to languish for the next 30 in low Earth orbit. At the core of the risk-free society is a self-indulgent failure of nerve.

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

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.

The decision to go to the moon is now appreciated and associated with President Kennedy's speech, but somebody else had told him it was a good idea. It turned out to be a good commitment, but it was a unique situation.

Mars is there, waiting to be reached.

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