The Ophuichi Hotline was John Varley's first, and probably best, novel. He arrived on the SF scene in the 1970s fizzing with ideas, and produced a host of excellent short stories before embarking on The Ophuichi Hotline . It's part of his continuing future history, the Eight Worlds sequence, in which first contact with other intelligences had not proved to be a very productive time for the human race, as they were barred from Earth for their crimes against the planet. The humans survive in the Solar System primarily by means of adapting technology downloaded from the eponymous Hotline, a one-way communications link with a distant galaxy which pours out huge amounts of data, much of it indecipherable, but which contains enough technological gems as to be worth mining constantly.
Trouble is, there is a price to pay, and the bill is coming due.
One of the main impacts that Varley's novel has is that he kills his heroine, Lilo, a number of times in the course of the book. Each time she is replaced by a clone, activated with the most recent mindtape made of her predecessor.