The first human beings to land on Mars should not come back to Earth. They should be the beginning of a build-up of a colony/settlement, I call it a 'permanence'.

America's can-do spirit cast a warm glow across nations and cultures, generating more goodwill and support for our country's ideals and causes than had otherwise been possible.

I grew up in a country that I thought was special. And it was.

Any observations from the Moon or a sense of realising this or that about the greater meaning of things wasn't as influential for me as the experience of coming back and dealing with being a person who's been to the Moon.

By venturing into space, we improve life for everyone here on Earth - scientific advances and innovations that come from this kind of research create products we use in our daily lives.

I don't think we're going to build a 50-person spacecraft or a 100-person spacecraft.

Exploring Mars is a far different venture from Apollo expeditions to the moon; it necessitates leaving our home planet on lengthy missions with a constrained return capability.