Simple-minded, Heinlein-esque, medium-future interplanetary power-struggle from the author of Dragon's Egg and Starquake. In the 21st century, Mars, after a brief independence under Communist Russians, is reconquered by UN forces under General Alexander Armstrong. Alexander returns to Earth and soon, heading his own religious cult, becomes supreme dictator of the planet. His scientist twin brother Gus stays on Mars as governor. So when the ever-more paranoid and megalomaniac Alexander orders all space colonies abandoned, interplanetary war seems likely. Deterred from invading Mars by missiles the Martians no longer have (they used them all to destroy an earlier nuclear strike), Alexander arranges that, if he dies, an asteroid will blow the Earth to bits. On Mars, meanwhile, Gus discovers an ancient alien-robot civilization; the robots agree to help terraform Mars for human occupation. A sophomoric rehash of standard notions, with cartoon characters and strained plotting, though the accurate, informative Marsology helps.