It has been a very long time since I even finished a novel, let alone finished it in three days. For that reason alone, I have to recommend Old Man's War, the Hugo Award finalist in 2006 by John Scalzi. To say it was influenced by Robert Heinlein's Starship Troopers would be a gross understatement since the novel is a virtual rewrite of the classic. However, if the plot is borrowed more-or-less intact, the universe envisioned by Scalzi is quite different. The galaxy is literally overflowing with life, while planets suitable to support it are rare. Thus competition is extreme among the various races seeking to claim some lebensraum for themselves. People of Earth are largely ignorant of life in the colonies, as indeed are most colonists. The real power lies in the hands of the Colonial Union and the Colonial Defense Force, the civilian and military branches of the authority responsible for administration of the colonies. Because they routinely engage in contact, both hostile and friendly (ok, mostly hostile), with the wider galactic community, the Union and the CDF have the most advanced technology. Earth is a backwater by comparison and the Union seems content to keep it that way.
They still need a steady supply of recruits, however, and they have a unique way of acquiring them. Humans who reach the age of 75 are allowed to sign up to the CDF, enticed with the implied, but not quite confirmed promise of a healthy, young body. After their tour, which may be from 2 to 10 years, they may muster out and settle down to live another lifetime as a colonist. They can never return to Earth, but for many, the trade-off is worth it.
Old Man's War was Scalzi's first novel and three more books in the same setting have been released, The Ghost Brigades, The Last Colony and Zoe's Tale. They promise to reveal more of the motivations of the Colonial Union, which seems to be more than it appears. I will definitely be looking for the rest of the series.
Moons of Minaria
16 hours ago