Study Suggests Titan May Hold Keys For Exotic Brand Of Life

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Titan, a Geologically Dynamic World Pasadena CA (JPL) Sep 09, 2005 Synthetic aperture radar images (shown above- see larger image) obtained in February 2005 show that Titan's surface is modified by fluid flows and wind-driven deposits. Previous synthetic aperture radar images have shown features that may be cryovolcanic in origin, such as long flows and linear features that may have formed by tectonic processes.

The latest data argue that Titan has a young and dynamic surface that is modified by all four major geologic processes: volcanism, tectonism, erosion, and impact cratering. All surfaces of solid bodies are shaped by these four processes, and Cassini-Huygens is revealing how each has contributed to the Titan we see today.

The data show a variety of surface drainage patterns that include twisting channels 1 to 2 kilometers-wide (0.6 to 1.2 miles) and up to 200-kilometers-long (124 miles). There is a well-developed drainage pattern associated with a large (450-kilometer, or 280 mile-diameter) basin that has eroded part of the basin's rim on the lower right of the image. These patters are in much larger scales than those imaged by the Huygens probe.

The most surprising new features revealed in the synthetic aperture images are dark lineated streaks, dubbed "cat scratches", which are seen in patches throughout the whole radar swath image.

The "scratches" are interpreted as linear/longitudinal dunes formed by wind transport. Radar images of terrestrial dunes, such as snow dunes in Antarctica, show remarkably similar patterns. Individual "scratches" are 500 meters to 1 kilometer (1,640 feet to 0.6 miles) across and spaced by 1 to 2 kilometer intervals (0.6 to 1.2-mile), straight or undulated, and oriented roughly east-west, suggesting a direction of prevalent winds.

Boulder CO (SPX) Sep 09, 2005
Saturn's moon Titan has long been a place of interest to astrobiologists, primarily because of its apparent similarities to the early Earth at the time life first started. A thick atmosphere composed primarily of nitrogen and abundant organic molecules (the ingredients of life as we know it) are among the important similarities between these two otherwise dissimilar planetary bodies.

Scientists have considered it very unlikely that Titan hosts life today, primarily because it is so cold (-289 degrees Fahrenheit, or -178 Celsius) that the chemical reactions necessary for life would proceed too slowly. Yet previously published data, along with new discoveries about extreme organisms on Earth, raise the prospect that some habitable locales may indeed exist on Titan.

In a paper being presented at the Division for Planetary Sciences 2005 Meeting this week, a team of researchers from Southwest Research Institute (SwRI) and Washington State University say that several key requirements for life now appear to be present on Titan, including liquid reservoirs, organic molecules and ample energy sources.

Methane clouds and surface characteristics strongly imply the presence of an active global methane cycle analogous to Earth's hydrological cycle. It is unknown whether life can exist in liquid methane, although some such chemical schemes have been postulated. Further, abundant hints of ice volcanism suggest that reservoirs of liquid water mixed with ammonia may exist close to the surface.

"One promising location for habitability may be hot springs in contact with hydrocarbon reservoirs," says lead author David H. Grinspoon, a staff scientist in the SwRI Space Science and Engineering Division. "There is no shortage of energy sources [food] because energy-rich hydrocarbons are constantly being manufactured in the upper atmosphere, by the action of sunlight on methane, and falling to the surface."

In particular, the team suggests that acetylene, which is abundant, could be used by organisms, in reaction with hydrogen gas, to release vast amounts of energy that could be used to power metabolism. Such a biosphere would be, at least indirectly, solar-powered.

"The energy released could even be used by organisms to heat their surroundings, helping them to create their own liquid croenvironments," says Grinspoon. "In environments that are energy-rich but liquid-poor, like the near-surface of Titan, natural selection may favor organisms that use their metabolic heat to melt their own watering holes."

The team says these ideas are quite speculative but useful in that they force researchers to question the definition and universal needs of life, and to consider the possibility that life might evolve in very different environments.

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Dragon Storms And Tiger Stripes: Scientists Stunned By New Saturn Data

Cambridge, England (AFP) Sep 05 2005
New data sent back by the Cassini space probe has left scientists beguiled by Saturn's seething clouds of gas, the beauty and unexpected turbulence of its rings and the diversity of its moons, a conference heard on Monday.

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