John Varley's recent fiction has repeatedly conjured up the spirit of Heinlein. In some cases, such as The Golden Globe, Heinlein's ghost faces pointed questions; in others, such as Red Thunder, Varley's intent seems to be primarily to offer tribute. This story of four young people and a defrocked astronaut going to Mars in a homemade spaceship, a few days ahead of the Chinese, re-creates many aspects of the first Heinlein juvenile, Rocket Ship Galileo.

But it's also quite a different book. Rocket Ship Galileo was technologically as realistic as Heinlein could make it; we may flinch at a reaction drive ejecting radioactive metal vapor into the atmosphere, but Freeman Dyson was still advocating nuclear pulse engines in the early 1960s. The Galileo's engineering was an intentionally conservative projection from the technology of 1945. Varley's spacedrive is frankly magical; it violates the law of conservation of mass/energy. In effect, Varley says that the only way the United States can get to Mars first is in a fairy tale.

The actual trip to Mars sorts late and is surprisingly unexciting; even the thwarted Chinese are mostly friendly. Most of the story is about the preparations; there are hints of legal obstacles and covert interference, but they never become a real threat. Varley makes it clear that the project costs huge amounts of money-and then reveals that the eccentric genius who invented the space drive has enough wealth from patents to fund the project. This is typical of this novel. and the main reason it's fun rather than compelling. There isn't much real conflict or real doubt. Varley's a skilled writer, and many Prometheus readers will likely enjoy Red Thunder, as I did. But Varley avoids any content that might have made it more than entertainment—and that's the least Heinleinian thing abut it.