Old Man's War

John Perry does two things on his seventy-fifth birthday: he visits his wife's grave, and he enlists. The Colonial Defense Forces want recruits of retirement age, for the skills of decades of living; they leave Earth for good, serve two years in combat and, if they survive, get a homestead on a hard-won planet. Scalzi's first novel; Tor published it in hardcover in 2005, with cover art by John Harris.