This note contains spoilers for the book.

By Larry Niven and Brenda Cooper; I'm listing it under Cooper since, to me, the acknowledgements structure and content make it pretty clear it's her book, with some assistance from Larry. The commercial advantages of publishing it with Larry's name first are probably quite large.

I think this is very good. It has interesting technology, and good gosh-wow engineering (building a habitable moon with matter-antimatter annihilation space tugs by crashing rocks together, with waits of a thousand years now and then for things to settle down (made more bearable by good cryonic suspension; in fact the nano they introduce at freezing, which activates at wakeup, rather rejuvenates you), and individual and societal human problems.

It seems that the Council of Humanity fled Earth to avoid some not-very-detailed AI and nanotech disaster (that hadn't really hit when they left; but they must have been right since Earth went silent partway through their trip). They had a design problem in the Buzzard ramscoop field, though, and have to limp to a star-system with gas giants and not much else to do repairs. To do those repairs they have to build a habitable planetoid, terraform it, introduce an ecology to support a human population, and populate it with people—they need the extra people to build and run the antimatter generator and other things. And then they have to go on towards their original destination, where they hope to meet up with the other ships of the fleet, but they don't actually know if any of them got there (they did message back about the scoop field problem, and the ships not yet launched were fixed). They may be the last humans in the universe. And they'll be, at best, a bit late arriving, what with having to use 60,000 years of elapsed time to make their repairs.

They're also fairly dependent on an AI for running the ship, and in the course of the story he gets forked to make another AI named Vassal to help the Selenites. But, remember, AI is one of the principal things they're running from. Makes for a bit of cognitive dissonance.

And they don't have room to take the population they've planted on Selene with them. And Selene won't be stable for more than a few hundred years without highly advanced technology. And they plan to leave the population on it behind.

Still, all in all it's a fairly cheerful and upbeat book, and it ends with a better solution than that.

Meanwhile, all the major characters have personal problems going on, including Rachel who is having to grow up while becoming a major player in all this. This part is also very well done—I found the range of problems interesting and the distribution not too abusive of the characters.