John Ortberg

What I look for when I see a piece of art for the first time is some kind of emotional, intellectual experience, that's a combination of both of those things and is informed by my knowledge and something new that I see the artist doing.

Supplying fuel for a Mars expedition from the lunar surface is often suggested, but it's hard to make it pay off - Moon bases are expensive, and just buying more rockets to launch fuel from Earth is relatively cheap.