American Scientist

Entering Space: Creating a Space-faring Civilization. Robert Zubrin. 305 pp. Tarcher/Putnam, $24.95.

Robert Zubrin is big on the long view of space exploration. But his credentials—a top-drawer space engineer and author of the best-selling The Case for Mars—give him enough reign to take us on a stepladder to the stars.

Zubrin also is president of the Mars Society, a group of scientists and engineers intent on the human exploration and colonization of Mars as quickly and efficiently as possible. From Mars to the stars, Zubrin has done his homework once again, his many equations in the book may leave lay readers reeling.

Although lunar colonies likely will pop up in the next century, Mars is a much greater bounty than the moon, writes Zubrin, a former senior engineer at Martin Marietta (now Lockheed Martin) in Denver. Mars contains large quantities of water, carbon, nitrogen, hydrogen and oxygen, all readily accessible. "For our generation and many that will follow, Mars is the New World," he writes.

Zubrin says Mars could be returned to its warm-wet climate of the past by human dumping of perfluorcarbons into the atmosphere, warming the planet and causing huge outgassing of carbon dioxide from its surface. The result—a runaway greenhouse effect—would allow for the growth of plants that could produce enough oxygen to make the atmosphere breathable by human beings in 1,000 years or sooner.

"Humanity's home, humanity's environment, is not the Earth—it is the solar system," he writes in his latest book, Entering Space. "We have done well for ourselves so far, by taking over the Earth and changing it for our own interests." Given humanity's ravaging of the planet and its resources, environmentalists and others will no doubt find this statement offensive.

Zubrin, however, sails merrily through the solar system, explaining how the abundant pre-biotic conditions of Titan, one of Saturn's many moons, might be the next stop for humans. If its abundance of carbon, hydrogen, nitrogen and oxygen were combined with heat and light from fusion reactors, "a sizable agricultural base could be created within a protected biosphere of Titan."

But he also believes the colonization of an outer-planet moon like Titan is nothing more than a "way station" to the stellar world. Zubrin believes that the next logical hop is to the Oort Cloud, a behemoth, spherical envelope encircling our solar system and containing trillions of "iceteroids" rich in water, carbon and nitrogen. And from "this archipelago of cosmic islands" lie the stars.

The nearest star, Alpha Centauri, is 4.3 light-years distant. It would take the Voyager spacecraft—launched in 1977 and rocketing along at 87,000 miles per hour—79,000 years to reach it.

Is an Alpha Centauri journey an impossible achievement for humans? No, says Zubrin. Antimatter—which violently explodes on contact with matter—was created during the Big Bang and has been re-created on a small scale in earthly labs. A manned spacecraft powered by antimatter explosions could travel at 90 percent the speed of light, reaching Alpha Centauri in just five years, by Zubrin's calculations.

The founder of Pioneer Astronautics, Zubrin takes the reader from today's Space Shuttle missions to future rocket planes leading to lunar observatories, orbital industries and the mining of asteroids. He winds up with interstellar travel—the ultimate space-engineering challenge—and the high probability of someday encountering other intelligent societies in the universe.

Entering Space is a good read for space enthusiasts, written by an engineer whose mind and heart lie light-years away.—Jim Scott, Boulder, Colorado