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Titan's Strange Prospects
San Francisco (SPX) Oct 15, 2004 On Jan. 14, 2005, the Huygens probe will plow into the orange atmosphere of Saturn's moon, Titan, becoming the first spacecraft to attempt to land on a moon in our solar system since the Soviet Union's Luna 24 touched down on Earth's moon in 1976. Though scientists hope that Huygens will survive the plunge, it will be flying blind through hydrocarbon haze and methane clouds to a surface that could consist of seven-kilometer-high ice mountains and liquid methane seas. That's the picture that emerges from a series of articles - half of them by University of California, Berkeley, researchers - published in the journal Geophysical Research Letters last month and detailing what scientists know to date about the surface, atmosphere and magnetic field of Titan. This view sets the stage for an analysis of new data soon to arrive from the Cassini spacecraft and Huygens probe. "These (journal) papers really give a state-of-the-art picture of Titan, before Cassini goes into orbit around Saturn and the Huygens probe goes into Titan's atmosphere," said Imke de Pater, a professor of astronomy at UC Berkeley who wrote the introductory paper in the series and co-authored four of the nine papers. The papers came out of a meeting De Pater hosted last November at UC Berkeley to discuss what has been gleaned to date about the moon from optical, infrared and radar telescopes, including the Hubble Space Telescope and the twin Keck Telescopes in Hawaii. Scientists expect the current sketchy picture of Titan's surface, totally obscured by clouds and haze, will much improve when the Cassini spacecraft, which is carrying the Huygens probe, starts an intense observation of Titan later this month. While on-board infrared imaging cameras can pierce the cloud cover, however, they can only reveal bright and dark spots on the surface, which are difficult to interpret. What Huygens will encounter at Titan's surface will remain a mystery until the probe plops into an ocean or parachutes to solid ground. "Based upon their spectral characteristics, the bright areas imaged by various Earth-bound telescopes and the Hubble Space Telescope could be a mixture of rock and water ice," de Pater said. Such a mixture appears relatively bright in comparison with substances like tar and liquid hydrocarbons, which absorb essentially all sunlight at these wavelengths and hence appear very dark. "The dark areas could contain liquid hydrocarbons," she said. "But they're all still a mystery." Some scientists have suggested that one large bright area, Xanadu, is a mountain of rock and water ice that stands out because runoff (hydrocarbon rain) has washed off the dark hydrocarbon particles. UC Berkeley graduate student J. Taylor Perron and de Pater concluded in one of the papers that such an ice continent, primarily composed of water ice, could be no higher than 3 to 7 kilometers - that is, at most, 23,000 feet, about the height of Mt. Aconcagua in Argentina. That is even more impressive on a globe less than half the diameter of Earth.
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