Is This How Astronauts Feel All The Time?
Let me explain. The book begins on Earth, an Earth that is kept tightly shut off from the rest of the universe by the Colonial Union. The CU allows the citizens of certain countries to become colonists, and allows anyone over the age of 75 to enlist in its defense forces.
But no-one else is allowed off-world. No-one. Not even to visit. And the CU doesn't share its technology, instead using it to keep those on Earth firmly under control.
As I lay in bed reading last night, identifying with the people of Scalzi's Earth, I was overcome with intense claustrophobia. The idea that there was a whole universe out there, within reach, that I was being kept from, being kept prisoner on this planet, was unbearable. There was a tinge of agoraphobia too, that there was something unspeakably large in the sky, over me, pushing me down, holding me down ...
Then it occurred to me that this is might be what astronauts feel all the time, especially those that have made it into orbit. Or maybe it's worse for those astronauts who are fully trained but will never get into orbit. There's only a few shuttle flights left before the Space Shuttle program is decommissioned in 2010, where they'll be flying at a reduced rate until the Orion spacecraft is ready to replace them (scheduled to be ready 2014, so probably 2018).
Update: the rest of the book is much more Boy's Own Adventure than the grittier, drier, "Forever War" by Joe Haldeman. I couldn't help but compare them while reading Scalzi's debut, but that didn't stop me enjoying it at all. Just started reading the follow-up, "Ghost Brigades".