Unless we are able to commit to a permanent growing settlement [on Mars], then I don't think just going there with humans and coming back is worth doing. The expense of planning to come back is like the people who left Europe to come to America and then to turn around and go back to Europe, it really doesn't make any sense at all.

The final frontier may be human relationships, one person to another.

There are a lot of reasons for not doing something. And if humanity had come up with all the reasons for not doing something we wouldn't have spread across the Earth the way we have. There's a curiosity, and I would submit that that curiosity will put human beings on the surface 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.

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.

Human rights problems will always exist for years to come, but maybe they'll lessen somewhat.

Nobody ever asks who was the seventh person on the Moon. The only thing they know is who's number one and who's number two. Does anybody know who the last man was?