Mycora: technogenic life. Fast-reproducing, fast-mutating, and endlessly voracious. In the year 2106, these microscopic machine/creatures have escaped their creators to populate the inner solar system with a wild, deadly ecology all their own, pushing the tattered remnants of humanity out into the cold and dark of the outer planets. Even huddled beneath the ice of Jupiter's moons, protected by a defensive system known as the Immunity, survivors face the constant risk of mycospores finding their way to the warmth and brightness inside the habitats, resulting in a calamitous "bloom." But the human race still has a trick or two up its sleeves; in a ship specially designed to penetrate the deadly Mycosystem, seven astronauts are about to embark on mankind's boldest venture yet--the perilous journey home to infected Earth! Yet it is in these remote conditions, against a virtually omnipotent foe, that we discover how human nature plays the greatest role in humanity's future. From the Paperback edition.