Gateway   by Frederick Pohl

An alien race has left a space-base—the Gateway, a converted asteroid—in the vicinity of the Solar System complete with ships, which humans have worked out how to fly but not control their far destinations, though they can reliably return after the destination has been reached. The protagonist is a poorly miner who wins a lottery giving him the means to travel to and live on the base, and thereby volunteer for missions with the prospect of a very lucrative reward: to fly in one of the ships in the hope of discovering something wonderful about the vanished alien species, but with the real possibility that the ship might not return to base before supplies run out.

The book alternates chapter-by-chapter: half are spent on the space-base being too afraid to actually volunteer for any mission, and the interleaved chapters are a retrospective examination of the man's state of mind by an Earth-based robot psychologist. The whole is an exploration of the interactions, sexual and otherwise, of the protagonist with various interesting people he meets on the base and with whom he shares missions. The final reveal is that in his last mission the crew find themselves under the skin of a black hole, and the man sacrifices the lives of his nine companions to escape, eventually to live a life of luxury back on Earth with the rewards gleaned from providing valuable scientific data on the black hole.

The alternation of chapters and the psychology bit in particular I found tedious, and only marginally helped the development of the story. But the book is riveting because it looks at space exploration from such a different perspective to any other SF work. It is almost certainly never going to become a realistic future, but it does bring out how dangerous the deep space environment is going to be when mankind does start to explore in earnest.