Another of the Baen ebook giveaways; this is [a:Niven|12534|Larry Niven|http://d202m5krfqbpi5.cloudfront.net/authors/1182720933p2/12534.jpg]'s, [a:Pournelle|39099|Jerry Pournelle|http://d202m5krfqbpi5.cloudfront.net/authors/1216417671p2/39099.jpg]'s and [a:Flynn|126502|Michael Flynn|http://d202m5krfqbpi5.cloudfront.net/authors/1282631351p2/126502.jpg]'s dystopian future-America novel where the Greens have won and dominated, at least, the north American political landscape. As a result, any anthropogenic global warming that there was is abruptly halted and instead a new ice-age sweeps down across the American landscape. While science is not banned outright, there is now the concept of appropriate science and inappropriate science. Inappropriate science is a large catch-all for anything deemed polluting, or wasteful, and means that NASA has been completely closed down ‒ stranding a community of astronauts on the space station. With no hope of a return home or any supply runs they are managing to become self-sufficient and, in order to top up their own gas supplies, have started scooping up gasses from the Earth's outer atmosphere (fuelling even more the hatred of the off-worlders by the green Earthers who view this as stealing more of Earth's resources). It's on one of these runs that the two spacemen, the fallen angels of the title, crash to Earth and the race is on to both avoid the authorities and see if they can even return to the space station.
Strangely, as well as making most branches of science illegal, the government has also cracked down on science fiction: both authors and fans are having to operate on the fringes of society. Presumably as science fiction glorifies the now banned sciences it's been included as well, but this device is what makes this novel. The fallen angels come down the day before the annual science-fiction convention, so a rag-tag group of sci-fi fans decide to jump in a van and go rescue them. The novel makes much of the complete cultural disconnect between the two angels, for whom space represents their quite functional, hand-to-mouth existence, and the sci-fi fans, for whom space represents some kind of romantic ideal. This disconnect, and the authors' clear understanding and enjoyment of fandom culture, also provides much of the humour of the book ‒ the angels clearly think the fans are mad throughout the whole novel, yet somehow the fans' optimism, and problem solving, keeps managing to get things done.
Much is written of the politics of this novel in other comments and it's clear that Niven, Pournelle and Flynn are writing from a libertarian, anti-AGW platform. That said, if you can bring yourself to see past that, science fiction at its core is supposed to be about 'what ifs'. The 'what if' of this novel, that the green movement took power and reversed the warming that was holding back the next ice age, is an interesting idea and is artfully told with a fair amount of humour and barely any of the political grand-standing that some of the other reviewers had suggested. What I found slightly more annoying was the heavy name dropping throughout the story, some of whom (like [a:RMS|318269|Richard M. Stallman|http://d202m5krfqbpi5.cloudfront.net/authors/1308056730p2/318269.jpg]) are foreshadowed as part of the latter story, and are then never mentioned again, and some annoying overuse of PoV switching in some of the later chapters that made those sections somewhat confusing to read.