"This was my first serious foray into space art. Done in 1982, I worked closely with the Voyager spacecraft imaging team on it. It shows a crater on the polar region of Dione, Saturn's fourth major moon. The white streaks are fissures filled with fresh ice from beneath, and were caused by a cometary impact on the reverse side of the moon. Dione is composed of water ice, and the surface gravity is so low, you could throw a rock into orbit."