Nemesis - Bill Napier

CIA listening posts have detected evidence of an extraordinary operation by cosmonauts of the resurgent and aggressive Russian regime - a plan to deflect a giant asteroid into a collision course with the United States. The result would be unimaginable devastation, and the West's top astrophysicists are secretly assembled to try and find a way of averting total disaster. But the key to finding the asteroid is a suprising one - its course was predicted in an obscure Renaissance manuscript, the only copy of which has now gone mysteriously missing...