Saturn Rukh

Five carefully selected people, each with the chance to earn $1 billion. The catch? They have to descend into Saturn's upper atmosphere and establish a factory that will produce meta, the fuel that powers interplanetary flight. With only enough meta to get them to Saturn, failure will cost them their lives. And all too soon the crew becomes marooned on the back of what they dub a Rukh, a 4-kilometer-long creature that swims in Saturn's upper atmosphere and has two brains, male and female. This engaging book by physicist Robert L. Forward evokes the sense of wonder of old-time science fiction.