Scardown — Elizabeth Bear

The year is 2062, and after years on the run, Jenny Casey is back in the Canadian armed forces. Those who were once her enemies are now her allies, and at fifty, she's been handpicked for the most important mission of her life -- a mission for which her artificially reconstructed body is perfectly suited. With the earth capable of sustaining life for just another century, Jenny -- as pilot of the starship Montreal -- must discover brave new worlds. And with time running out, she must succeed where others have failed.

Now Jenny is caught in a desperate battle where old resentments become bitter betrayals and justice takes the cruelest forms of vengeance. With the help of a brilliant AI, an ex--crime lord, and the man she loves, Jenny may just get her chance to save the world. If it doesn't come to an end first...