War! A series of diplomatic crises precipitate a limited nuclear war on Earth. Missile defenses block access to space. Nothing goes up and nothing comes down. The people of the various space stations, the moon base, and a space colony whose construction had just begun must find a way to survive until the war is over. The ultimate survival test.
This was a really interesting look at near-future space innovation, brought about by the direst of emergencies -- a war starts on the ground, and suddenly no one who's currently in space can get down to the planet, and no one on the planet can send them any supplies. Stranded in space, the scientists, engineers, and military contemplate a near-certain death, then decide that they're going to figure out a way to stay alive, and start making it happen, through a series of innovations and repurposing existing systems.
I enjoyed this book because it's a plausible scenario for how we might get to a future like you read about in many farther-future sci-fi books, where people have worked out how to create self-sustaining orbital and moon habitats, and how to communicate, shield, and all those other things you need to do in space.
In places, it was a little dry, due to all the hard science that was being related, but the whole thing was very exciting, and I liked the inclusion of an evil general as an antagonist. Since the book left off with one plot arc concluded, but the question of their overall survival hanging, I will be interested to see if there are more books coming after this one!