Helliconia Spring

Helliconia follows an eccentric orbit around a double-star system with a twenty-six-hundred-year cycle of very long seasons. As spring slowly breaks the brutally long winter, humans emerge from hiding and a long sequence of civilization and growth begins to repeat again, unbeknownst to the participants but watched by an orbiting satellite station, Avernus, created by Earth some centuries ago. Humans free themselves from slavery to the aboriginal Phagors, and religion and science flower and expand.