Heechee

Gateway – a portal to the secrets and riches of the universe – an asteroid serving as a spaceport for a thousand alien ships. No one knows what their creators looked like or where they went. But the ships still work, and each is programmed for faster-than-light travel to a distant location somewhere in the uncharted universe. Just hop on. You can't steer them, yet volunteers still line up to head into the unknown aboard these vessels.