That`s Why I Have To Go

On the Orion, Chako determines that virus-like nanomachines have entered Adam's body and changed the nanomachines already there into malignant ones, and they probably entered through the scrape on his hand. They decide to head directly for the nearest sub-terraforming machine. After passing through a forest, they reach an ancient, crumbling city. They stop by a large building that they hope is a hospital, but the medicines they find had already decomposed long ago. Chako estimates them to be five hundred to a thousand years old, the same age as Adam's ruins. When Howard finds writing on a medicine bottle that's the same as writing they saw in the ruins, they realize that Adam's people had come from this planet, which raises the question of why he was in a spaceship on the island.