Campbell, Jack (Naval officer). Doomed Earth #2

"Lieutenant Selene Genji is hurled into the past to try and save a world that doesn't want her, in this action-packed adventure from New York Times bestselling author Jack Campbell. Earth was destroyed on June 12th, 2180. Lieutenant Selene Genji watched it happen. And only she can prevent it. Hurled forty years into the past, into a time before the Universal War began, Genji can only guess what to do to change the events that led to the death of all humanity. She has no way of knowing the long-term impacts of her actions and can only depend on her instincts. But many of the people she's trying to save want Genji dead. Her creation was an experiment: a fusing of human and alien DNA. To them, she's a monster who can't be trusted, a tool of the aliens who have just made first contact. Fortunately, she has an unshakeable ally in Lieutenant Kayl Owen, who has risked everything to help her mission. Declared a traitor to humanity by Earth Guard, Owen is determined to help Genji save the Earth. Even if he dies trying"--