Return from Armageddon

In this tale of one possible future, the people of Earth have finally united under one flag and have formed a one-world government with the capital situated in what was formerly known as Las Vegas. Although religious and political strife have been squelched under the iron rule of the Federation of United Countries and United Peoples, a new threat looms. An armada of spaceships appears near Jupiter with the apparent intention of invading the troubled planet.
Brilliant engineer Becky Johnson designs a planetary defense system under the direction of General Max Berger, chief military officer of the Federation. The system is nearly ready to be activated when things begin to go awry.