This is one of the Hugo finalists in the Best Novel category. It was published by William Morrow/Harper-Collins.

The moon breaks apart because of some unknown agency. Everyone watches with awe, but soon astrophysicists produce models that indicate the pieces will continue to break up and fall on the earth, eventually producing rings like Saturn’s. The rain of debris is expected to last about 10,000 years and wipe out life as we know it on Earth. Governments, advised by scientists, move to produce a Cloud Ark of habitats that will float in space, carrying and preserving the legacy of Earth, including genetic, cultural and technical data for the use of future pioneers.

This effort is some of the most thought-provoking of hard SF. Stephenson has set up a scenario and then follows out what happens, projecting ways that humans might cope with a catastrophe that will wipe out mankind. Who will be chosen to populate the Ark? What should they take with them? How will they sustain themselves for 10,000 years? How do they overcome engineering and tech problems along the way? Stephenson establishes a cast of main characters, some on Earth and some on the International Space Station (ISS), and shifts between, following the efforts from different points of view. This is written in a folksy, matter-of-fact style, and the author makes no effort to hurry it up. He gets technical. There’s human interest.

On the negative side, Stephenson uses an episodic structure, and the novel sort of eases along without much in the way of rising action, coming in at an extended 883 pages. The characterization and ending aren’t all they could have been. I also ended up with some major questions. If the Cloud Ark is inside the orbit of the moon, won’t it get nailed by the 10,000-year Hard Rain the same as Earth? Wouldn’t it be safer to just move to Mars? Or maybe underground? Space seems like a tough place to make it for 10,000 years.

Like The Martian, this would make a good film. Four stars.