Fear and worry are emotions that cloud the mind from being able to think clearly, to remember what the procedures are to deal with that emergency.

The energy varies with the square of the velocity, so if you need five times the velocity, that's 25 times the energy.

In my mind, public space travel will precede efforts toward exploration -- be it returning to the moon, going to Mars, visiting asteroids, or whatever seems appropriate. We've got millions and millions of people who want to go into space, who are willing to pay. When you figure in the payload potential of customers, everything changes.

It was challenging to understand what was necessary to successfully carry out all the training simulations that we, as crewmen, would experience, and make a very successful use of that training and education.

At the core of the risk-free society is a self-indulgent failure of nerve.

Returning to the Moon with NASA astronauts is not the best usage of our resources. Because OUR resources should be directed to outward, beyond-the-moon, to establishing habitation and laboratories on the surface of Mars that can be built, assembled, from the close-by moons of Mars.

As time goes by, I'm increasingly impressed by how very special and timely it was that we got the degree of national commitment needed to put people on the Moon. For the first time, this nation was united in trying to develop an interplanetary capability. We've been trying to repeat that situation ever since.