November 1997

Learning from Venus

Venus Revealed: A New Look Below the Clouds of Our Mysterious Twin Planet

By Mark Dwortzan

In the 1960s, intent on demonstrating the superiority of our military-industrial complex to the Soviet Union, we funded the space program to reach the moon. In the 1970s and 1980s, we began to justify space expenditures by touting Teflon pans, super metal alloys, and miniaturized ro-botics. Now a new rationale for planetary exploration has emerged-environmentalism. The more we know about other worlds, say space enthusiasts, the better we can tackle the environmental dilemmas that beset our own planet.

So argues planetary scientist David Harry Grinspoon of the University of Colorado at Boulder, in Venus Re-vealed: A New Look Below the Clouds of Our Mysterious Twin Planet, the first book to explain the findings of the Magellan mission. Expertly guiding the reader beneath the clouds that have long hidden Venus from earthbound eyes, Grinspoon celebrates Magellan and other spacecraft voyages that have increased our understanding of our sister planet's geology, climate, and atmosphere. At the same time, he acknowledges that these insights may not play well with a taxpaying public facing declining schools, disintegrating inner cities, overpopulation, and many other social ills. So throughout the book, Grinspoon emphasizes how missions like Magellan may lead to practical solutions to problems here on earth, such as ozone depletion, global warming, and acid rain.

What's striking about Venus Re-vealed, besides some captivating Magellan photos of the Venusian landscape, is the author's informal style. It immediately comes across in the introduction, where he describes an exhilarating drive up California's Pacific Coast Highway to catch views of Voyager 2's Neptune encounter at the Jet Propulsion Laboratory in 1989. This journey sets the tone for the rest of the book, which Grinspoon delivers like a smart, irreverent travel companion on a long-awaited road trip.

And there's no excuse to drift off. If Grinspoon thinks you may be losing it during a discussion of a complex topic such as the relative motion of planets, he will pull the car to the side of the road, and bring you up to speed with an ex-planation section en-titled "Who Cares?" or a sports an-alogy (on the solar system track, "Venus is a runner on the inside lane"). At other times, he'll lighten the load with an amusing footnote or quirky subtitle.

Taking the reader on a fascinating historical tour of Venus as seen from the imagination, telescopes, and spacecraft, the author gradually brings the planet into focus. Before the invention of the telescope, stargazers noticed how Venus stood out in the night sky. It was not only the brightest object, but also a quixotic companion to the sun, putting in rotating nine-month appearances as evening or morning star. The eye-catching planet inspired reverence in many ancient cultures, becoming a symbol of birth, death, and resurrection, a beacon of fertility (with its appearances matching the human gestation period), and a goddess of love.

Starting in the 1600s, astronomers viewed Venus through the telescope, initially discovering its moonlike phases, and later detecting an atmosphere, leading to speculation that Venus was a "swamp world," with oceans, vegetation, and rain. But swathed in a global blanket of clouds, Venus refused to reveal its secrets through optical telescopes. To penetrate the cloud cover, twentieth century scientists turned to other instruments, such as ultraviolet detectors and radar.

From 1962 to 1994, an armada of 24 Soviet and American spacecraft missions radically altered our view of Venus. Their observations revealed a dimly lit planet largely devoid of water, with a 900 degrees Fah-renheit surface temperature, a 97 percent carbon dioxide atmosphere, and sulfuric acid clouds. By 1990, topographic maps, which were produced by radar pulses, and ground-based radar images yielded a fuzzy, incomplete picture of the surface.