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Voyage to Saturn
DECEMBER 2006
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By Bill Douthitt
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Images by NASA, Jet Propulsion Laboratory, and Space Science Institute
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As the Cassini probe reveals the secrets of the ringed giant, it is finding clues to the very beginnings of the solar system.
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Get a taste of what awaits you in print from this compelling excerpt.
The rain comes just once every thousand years, in torrents of liquid methane. The noxious air dims sunshine to an eternal orange twilight. The cold—290 degrees below zero Fahrenheit (minus 180°C)—is a lethal assault. And beyond the hazy sky looms the ringed planet Saturn.
Yet here on Saturn's outsize moon Titan is a world eerily like our own. "Titan is a Peter Pan world," says Tobias Owen of the University of Hawaii's Institute for Astronomy. "It's got all the materials and elements to develop into a planet like Earth," he says, "but it never had the chance to grow up." The dense atmosphere is filled with hydrocarbon smog, "like L.A. on a bad day," Owen says. The rare methane monsoons create sudden rivers that cut deep channels in Titan's low hills and run down to a great sandy plain. Like Earth, Titan may have geologic activity and volcanism—a slow, chilly version that erupts a lavalike mix of half-melted water and ammonia. Most tantalizing of all, Titan's gentle winds carry a rich brew of organic molecules, some reminiscent of compounds that provided the raw material for life on Earth.
Owen and his fellow planetary scientists are used to picturing Titan in their imaginations. Now they've visited, if only by remote control. For the past two-and-a-half years, a space probe called Cassini has hobnobbed with the moons and rings of Saturn and gazed down on the giant planet. Soon after arriving, Cassini even launched a second, smaller probe called Huygens, which touched down on Titan's surface.
The Titan encounter was a high point in what has amounted to a voyage back in time. From the exotic metallic hydrogen in its interior to the fine rubble of its rings, on moons that range from the icy oddball Phoebe to Enceladus, which spurts warm geysers, Saturn carries clues to how the solar system took shape 4.6 billion years ago and gave rise to life. The planet and its orbiting retinue, says planetary scientist Jeff Cuzzi of NASA's Ames Research Center, "connects us to solar system structure and evolution on the grandest scale."
Get the whole story in the pages of National Geographic magazine.
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