Gravity Versus Gravity

A sci fi thriller with space for adventure, mystery and romance.
Two comets return to earth after three centuries as binary comets. Earth was lucky then as they passed by at a distance. Not this time.
The comets rage their fury in a desert on their journey towards the sun when they cause a zero-gravity event. On their return journey to their dark abyss, they'll cause another zero-gravity event. And, the second event is not in an isolated place.
Only one man can avert the catastrophe. But someone has to believe him first.