Supernova: Book one in the Starlight galaxy series

After the near apoclypse of an astoid hitting her planet which she barely managed to escape by boarding the Salvation. Hex the Ionwing, Polestar the Novawing and Quasar the Solarwing find a piece of a long lost artifact which leads them to a unknown place abord the massive ship.
when they enroll in the Space Travel Agency as first years they face threats from not only outside the ship but inside as an unkown lifeform managed to board the ship camoflauged as one of the tribes will Hex and the other make it to the end of their first year