The Javelin Program (Time to Orbit: Unknown, #1)

When Dr Aspen Greaves signed up for the Javelin Program, humanity's first foray into colonising deep space, they expected to wake up to life in a thriving colony on a distant planet. Instead, they find themself five years away from their destination on a broken spaceship full of complex mysteries, dead astronauts, and a very unhelpful AI. Aspen wasn't trained for any of this. But if they can't keep themselves alive, get the ship in working order, and find out what went wrong by unravelling a chain of mysteries leading all the way back to distant Earth, then neither Aspen nor the five thousand sleeping passengers in their care will ever see a planet again.