One Giant Leap by Heather Kaczynski

When Cassandra Gupta was chosen to be the youngest member of a top-secret mission to the far reaches of the universe she knew to expect the unexpected. But nothing could have prepared her for the catastrophic events that would occur once she left Earth.

Cassie and the rest of the crew have found themselves in the middle of a conflict between two alien civilizations hell-bent on destroying each other . . . and anyone else who gets in their way. What was supposed to be a reconnaissance mission soon becomes a fight for their lives. But Cassie knows that it isn’t enough to simply survive. The war is coming to Earth, and only she has the information that can possibly stop the devastation it will bring. With humanity’s fate in the balance, Cassie must decide who she can trust and who she is willing to sacrifice in order to complete her mission.