Geologists investigate Titan river formation
March 26, 2008 -- SF State Assistant Professor of Geology Leonard Sklar and colleagues from Wheaton College in Massachusetts are beginning a three-year project to duplicate and analyze the minus 180 degrees Celsius environment of Titan, Saturn's largest moon. They hope to discover what similarities may exist between the geological evolution of Titan’s networks of river channels and those on Earth. NASA is funding the study, which could challenge or confirm existing Earth-based assumptions about how planets function.
Images sent from the Huygens probe launched by NASA's Cassini spacecraft, have revealed that Titan has an Earth-like landscape complete with dunes, lakes, seas, volcanic mountains and frozen networks of river channels. "Titan is a unique place to study Earth-like erosion processes, but under radically different conditions,” said Sklar, whose research focuses on the formation of canyons and river channels. "The ‘rock’ on Titan is made of water-ice, and the liquid that falls from the sky and flows through the rivers is liquid methane."
Titan beyond Saturn's rings. Credit: NASA
Sklar and his colleagues want to understand the liquid methane cycle on the surface of Titan and the resistance of ice rock to erosion caused by sediment moving in the fluid methane. While the study will eventually involve precise measurement of the erosion, the focus right now is on simply duplicating the kind of rock ice found on Titan.
"It's not your basic ice-tray variety that often contains impurities, which cause cracks and bubbles that weaken it," Sklar said. "It's much more dense." He and SF State Geoscience graduate students Beth Zygielbaum and Peter Polito are currently trying to replicate Titan's rock ice in a chest freezer. To get the temperature in their freezer as cold as Titan's, they are using liquid nitrogen, rather than the more combustible liquid methane that rains on Titan.
In later phases of the study the investigators plan to quantify the resistance or strength of rock ice by recreating the process of erosion. "One question we will investigate is whether it depends upon how cold it is," Sklar said. The scientists plan to measure the effect of temperatures on resistance to erosion of ice rock at various temperatures leading up to the temperature extremes on Titan.
Researchers also plan to control rates of water-ice erosion under cryogenic conditions to study the role of variable ice-sediment grain size and concentrations. An investigation into the effects of contaminants that might occur in Titan's water ice bedrock is also planned. These phases of study conclude in April 2010.
Work will be conducted at the geomorphology experimental laboratory, part of the University of California, Berkeley's Field Station in Richmond, Calif., which Sklar currently manages and utilized while obtaining his Ph.D. in Earth and Planetary Science at the University of California, Berkeley.
Sklar's collaborator from Wheaton is Geoffrey Collins, an astronomer whose body of research includes the study of terrain and tectonics of such extraterrestrial satellites as Europa and Ganymede.
The SF State team received $130,800 in funding from NASA for the first phase of its study and hopes the discoveries they make will encourage further funding to continue its investigation. Sklar said the findings could reveal as much about Earth as it does about the moon of a distant planet.
"Titan's atmosphere is one and half times as dense as Earth's, mostly nitrogen and methane and other trace gasses similar to what scientists believe Earth's early atmosphere was like," he said. "By looking at Titan, we could learn about the conditions under which life might have begun on Earth."
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