To send humans back to the moon would not be advancing. It would be more than 50 years after the first moon landing when we got there, and we'd probably be welcomed by the Chinese. But we should return to the moon without astronauts and build, with robots, an international lunar base, so that we know how to build a base on Mars robotically.

We could have human intelligence in orbit around Mars, building things there.

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

All the Chinese have to do is fly around the Moon and back, and they'll appear to have won the return to the Moon with humans. They could put one person on the surface of the Moon for one day and he'd be a national hero.

I came to dedicate my life to opening space to the average person and crafting designs for new spaceships that could take us far from home. But since Apollo ended, such travels were only in our collective memory.

The best way to study Mars is with two hands, eyes and ears of a geologist, first at a moon orbiting Mars... and then on the surface.

I was not the commander, I was a junior person, so once both were outside, I followed my leader, because we (NASA) had not put together detailed jobs of people outside. I believe it could have been improved. But it was very successful for what it was.