I've been to the Titanic in a yellow submarine and the North Pole in a Russian nuclear ice breaker.

Astronauts working for the government will always need to be either pilots or mission specialists. Those who want to be pilots should have military experience - ideally, a test pilot background.

On Apollo 11 in route to the Moon, I observed a light out the window that appeared to be moving alongside us. It was either the rocket we had separated from, or the 4 panels that moved away when we extracted the lander from the rocket and we were nose to nose with the two spacecraft. So in the close vicinity, moving away, were 4 panels. And i feel absolutely convinced that we were looking at the sun reflected off of one of these panels.

Some things just can't be described. And stepping onto the moon was one of them.

Computers allow us to squeeze the most out of everything, whether it's Google looking up things, so I guess that tends to make us a little lazy about reading books and doing things the hard way to understand how those things work.

Standing on the Moon looking back at Earth - this lovely place you just came from - you see all the colours, and you know what they represent. Having left the water planet, with all that water brings to Earth in terms of colour and abudance life, the absence of water and atmosphere on the desolate surface of the Moon gives rise to a stark contrast.

When we get there, if we don't find any life on Mars, from that point on there will be life on Mars because we'll bring it there, whether it's germs and leftover urine bags, whatever it is.