Against infinity

1983 · Book · Gregory Benford

On the poisonous, icy surface of Ganymede (one of the moons of Jupiter), a man and a boy are on a deadly hunt. Their prey is the Aleph-- an unknowable alien artifact that roamed and ruled Ganymede for countless millennia. The Aleph haunts men's dreams and destroys all efforts to terraform Ganymede into an habitable planet. by Gregory Benford