Second Chance — David D. Levine

Chaz Eades is on the mission of a lifetime -- the first to an alien solar system far beyond our own -- and it's a one-way trip. When he learns that contact with Earth has been lost, he wants to help reestablish communication. But the commander insists on science first and contact later, the crew is inexplicably hostile, and Chaz finds himself painfully isolated. Soon he realizes that there's a secret at the heart of the crew's troubles that is much larger than any he could have imagined. All bets are off, and he's not at all prepared for the mission he faces now: survival.