The Immortality Option — James P. Hogan

Titan, Saturn's largest moon, was frozen and lifeless...but only by some definitions!

Organic life had never evolved on its barren surface, but somehow Titan had become home to the Taloids, a race of self-aware robots who lived in competing city-states, grew houses and tools, tended their robotic herds, and worshipped a god called the Lifemaker.

When humans discovered the Taloids on Titan, they suspected that the robots' sentience had evolved by accident -- artificial intelligence gone wrong. But where was the ancient civilization that had spawned them? With no help from the Taloids -- who seemed to know nothing of their own origins -- Earth's finest scientists were stumped.

Then strange blocks of code were discovered in Titan's ancient computer banks. Neither Taloid digital DNA nor the operating system for Titan's robotic "ecology," the code had clearly lain undisturbed for eons. But now, with human help, it was beginning to activate at last...