Seeds of Gaia

Revenge is heading to Earth at the speed of light.The Gaia probes left a dying Earth millennia ago in a bold effort to spread life to a lifeless universe. Unfortunately, not all of those worlds were uninhabited... The aliens watched their world die to swarms of nanite terraformers, but with their last breath they launched a terrible, unstoppable weapon to kill those who'd stolen their home. Patrol Captain Sam Avalon is the first human to encounter it, a missile the size of an asteroid, tearing through anything in its path, destined to impact Earth in four years and leave nothing but ashes.
Together with the mysterious government operative Priscilla and the cyborg soldier Telia Proctor, they do their best to unite old enemies in a desperate attempt to save the cradle of humanity from the sins of their fathers.