This is another book you can download for free from the Baen Free Library. It's almost twenty years old, and has not aged well. (No, gents, that global warming thing you were making fun of has not gone away.) It's still an entertaining read if you are an old-school sci-fi fan and have been to enough conventions to catch the references. By "old school" I mean old enough to have been reading sci-fi when this book first came out, in 1992, before people would get all snotty with you if you said "sci-fi" instead of "SF." If not (get off my lawn!), you'll probably find it a rather tedious polemic with lots of in-jokes you won't get.
I used to be a big fan of Larry Niven, having read most of his Known Space books, and I've also enjoyed several of his collaborations with Jerry Pournelle. But this book could almost have been a satire about SF's reputation for being the domain of geeky white dudes with cranky political opinions, except that Niven and Pournelle are so earnest about it. (I hardly mention Michael Flynn because, seriously, who the heck is he?) There's just something about science fiction authors that seems to turn a lot of them into axe-grinding hacks at a certain point. You know how Robert Heinlein's books, as he got older and crankier, even though they still had the old master's touch, would often go off the rails with the characters delivering sermons about libertarian philosophy or why it totally made sense for nubile, super-hot genius geek girls to want to bang chubby, aging science fiction authors? In Fallen Angels, we have a moderately interesting rescue mission followed by a chase story that is continuously derailed by the authors lashing out at various targets of ire. Admittedly, most of these are pretty easy targets (creationists, New Agers, politicians), but they also take a few shots at psychologists (all the soft sciences, really), the humanities, and fantasy authors. (Fantasy is elves and dragons and fairy shit, not awesome literature of awesomeness ringing with the authenticity of SCIENCE FICTION.) Also, environmentalists are stupid and will destroy the world.
So, the premise is that a new ice age is upon us. Boy, were those climate scientists wrong! See, while everyone was worried about global warming, it turns out that it was really all the pollution in the air causing the greenhouse effect which was all that was holding off the return of the glaciers. Once the Greens took over the world (well, they took over the United States, but in this book, the United States is the world), they enacted draconian environmental laws which turned the U.S. into a police state in which science fiction is outlawed, scientists get lynched, and the lack of air pollution has caused the Earth to cool and glaciers to render Canada uninhabitable except for Eskimos. (Yes, Eskimos show up in this book, with all the dog-sledding, igloo-building, wife-swapping cultural sensitivity you'd expect from a bunch of cranky white dudes writing a science fiction novel for other cranky white dudes.)
Just before the Greens shut down all space travel, the last shuttle went up to the orbiting space stations, which continue to be (barely) self-sufficient, having declared themselves independent of the crazies down on Earth. Two "Angels" from the space habitations are shot down while scooping nitrogen from the upper atmosphere. They crash on the ice, near where Worldcon is being held. Since science fiction is now outlawed (technically not outlawed, but under the Green regime, admitting to being a SF fan or a "technophile" is akin to admitting a fondness for recreational kitten torture), Worldcon is very much an underground affair. But fans find out about the "fallen Angels," and head off across the ice to save them before they are captured by government agents.
Naturally, they succeed, and then resolve to do whatever it takes to get the two angels (who at first can barely move in Earth's gravity, having lived all or most of their lives in free fall) back in orbit, which involves a tense chase across the U.S. being pursued by the USAF, the INS, and the Green police. (Yes, the Greens have their own police force -- in fact, Earth First! has its own police force) which is not without drama or humor, but also not without a bunch of detours to rant about environmentalism and attend more science fiction conventions (SF fandom functioning as a sort of Underground Railroad to smuggle SF authors, scientists, and fugitive spacemen across the country). There are many verses of filk songs and many, many in-jokes, including a lot of self-referential humor by the authors.
This book is an ode to space exploration and a big, wet sloppy kiss to fandom (SF fans save the day!). Unfortunately, there are so many SF fans saving the day that the cast of characters becomes large, confusing, and unnecessary. Most are thinly-veiled alter egos or composites of real people in fandom. (In fact, the authors auctioned off appearances in their novel for various charities, so some of the characters literally bought their way into this book.)
Also, as mentioned above, this book was written in 1991, when the Internet was, if not still in its infancy, just learning to walk. So the technology is painfully dated, even though it's supposed to be taking place some unspecified number of years in the future.
Now, I may have been a liiiiitle bit unfair in picking on the ridiculousness of the premise, since in the author's notes, they admit that this was as much satire as anything. But they assert that the science is real (which it is, for the most part -- I'll give them a good-faith "Okay, maybe" about the new ice age), and really, the constant uplifting of SF fandom, and space travel as the only important human accomplishment left to strive for, got tired. I mean, I'm all for making fun of creationists and woo-gazers and other anti-science types, but it's like listening to a friend who's very sincere but completely insane about a worthy cause: maybe you agree with most of his sentiments, but after a while you just want to say "Dude, give it a rest!"
Verdict: Despite all the snark above, I actually found this a fairly entertaining read, but then, I'm a cranky old white dude. If you believe FIAWOL, then you'll probably like this book, but if FIJAGH, go read something funnier that takes itself less seriously, like Bimbos of the Death Sun.