Spaceship Enterprise

Kenneth Silber from the April 1997 issue

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The moon's ample supply of helium-3, long touted by space buffs as a potential fuel for advanced fusion reactors, is duly noted, as are the even larger supplies of the substance in the atmospheres of all of the giant outer planets. Jupiter and Saturn present particularly daunting prospects for exploitation, Lewis acknowledges, since their powerful gravitational fields would require any departing vehicle to have an extremely high escape velocity. However, with a flourish of untrammeled technological optimism, he points out that souped-up helium-3 rockets just might do the trick.

Even some of the dangers posed by extraterrestrial objects might turn out to be opportunities. Lewis points out that near-Earth asteroids (some of which are easier to get to than the moon) could be mined to reduce their mass, thus minimizing the threat of a cataclysmic collision. The asteroidal material then could be converted into solar-power satellites that would collect and transmit energy for Earth. Moreover, Lewis notes, some near-Earth asteroids also pass in the vicinity of Mars and the Main Belt; these bodies, suitably hollowed-out, someday may serve as the "traveling hotels" of the solar system.

Lacking in Mining the Sky, but present in abundance in The Case for Mars, is a clear set of priorities for practical action. Lewis provides little concrete advice on how to bridge the chasm between the present state of space exploration and the bountiful future he envisions. By contrast, Zubrin and Wagner provide not only a detailed program for going to Mars but also a critique of competing objectives. In particular, the Mars enthusiasts seek to shoot down the moon as a goal for human colonization; the satellite, they note, is relatively impoverished in water and other resources needed for survival (a point still valid despite the recent detection of ice on the moon).

The Case for Mars and Mining the Sky both draw a sharp contrast between a brilliant space-faring future and a bleak existence if humanity remains Earth-bound. Both make reference to the dictum of H.G. Wells that "the choice is the Universe -- or nothing." However, the books differ notably in their discussion of that choice.

Mining the Sky contends that the notion that natural resources are running out is a myth -- but one that's all too true if Earth is the only source considered; Lewis even hazards a prediction of global collapse into subsistence agriculture around 2030 unless the riches of space are tapped. The Case for Mars, ultimately, is based more on the need for a frontier than on any shortage of terrestrial minerals. Zubrin and Wagner warn that Earth is slipping into a malaise of bureaucracy, cultural homogeneity, and diminished technological progress. Mars, they argue, would give rise to a dynamic new branch of human civilization, one whose entrepreneurial energies would reinvigorate Earth society as well.

Eventually, Mars, the asteroids, and the rest of the solar system may have been explored and settled. What then? Mining the Sky ends with a call for humanity to expand throughout the entire galaxy, creating a population of countless quintillions; Lewis's sheer maximalism may discomfit even some space enthusiasts. In The Case for Mars, Zubrin and Wagner proclaim that our distant descendants on a multitude of worlds, even with all their advanced capabilities, will still marvel at the boldness of those who began the great push into space. Science fiction has long been filled with such entertaining and inspiring visions. These two books show they might be affordable, too.