Half Life — Hal Clement

In about two hundred years, the human race on Earth is perhaps facing extinction due to the rapid evolution of disease. A crew of young men and women travel to the moons of Saturn, to Titan, to investigate the biochemistry of the pre-life conditions there in the slim hope of discovering something that might save Earth. The whole story runs at high-speed, as they race to find answers across the surface of an alien landscape with death close behind . . . and gaining.