By Neil F. Comins

Villard, 253 pages, $19.95 hardcover

The astrophysicist Neil F. Comins sounds confident that the age of space tourism is on the horizon. “Voyages to Mars, asteroids, comets, and the Jovian system — Jupiter and the bodies orbiting it — will all be feasible destinations in the coming half-century,” he writes. A round trip to any planet this side of Saturn will, “under ideal conditions,” take no more than five years of your life. For this starry-eyed prediction to come true, however, he wants us to banish any science-fiction illusions that these trips will be pleasure cruises. His original and sobering book — part fictional spaceship log, part nuts-and-bolts survival manual — warns of mundane dangers out there to mind and body far more serious than power-mad Klingons or homicidal computers.

For starters, any prolonged flight outside the atmosphere risks exposure of cells to sickening levels of radiation. The skin of a spaceship is not much safer. Space is littered with lithic debris, and a collision with a particle no bigger than a pebble could well be catastrophic. (Pockmarks from thousands of tiny impacts slowed the orbit of the Salyut 7 space station so much that it fell from the sky.) A state of microgravity for years will also take its toll on physical and psychic health. Between 3 and 13 percent of personnel on any space mission are likely to show signs of mental illness from claustrophobia, homesickness, chronic boredom and inactivity. The bacteria that causes tooth decay may grow faster in outer space, where dentists are scarce. Food will taste worse and be harder to digest.

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Landing after years of confinement in a titanium can won’t offer much relief either. Landslides and earthquakes will make a simple hike on some surfaces riskier than a trip to the Baghdad airport. “Walking around on Io will be like exploring a minefield,” Mr. Comins writes, referring to one of Jupiter’s 63 known moons. “Each step will bring you into contact with life-threatening geological conditions.”