Zero Jumper - Patrick Mulholland - Bog

The Earth has been destroyed, and Juno is the last human alive. Using the Zero Jump engine, she must travel back in time to re-write history. But for now, Juno is trapped in the far future, along with her A.I companion Io. But Juno has not gone unnoticed. Alone and hunted she must track down an energy source powerful enough to send them home, before the human race finally becomes extinct.