Volume: 03, Issue: 02 01/26/2005 
This mosaic of three frames provides unprecedented detail of the high ridge area including the flow down into a major river channel from different sources. Image courtesy ESA/NASA/JPL/Univ. of Arizona.
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Huygens DISR image showing a bright linear feature where water ice may have been extruded onto the surface, and stubby dark channels possibly formed by 'springs' rather than 'rain' of liquid methane. Image courtesy ESA/NASA/JPL/Univ. of Arizona.
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Huygens DISR image of a dark plain area on Titan that indicates flow around bright 'islands'. The areas below and above the bright islands may be at different elevations. Image courtesy ESA/NASA/JPL/Univ. of Arizona.
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Other Articles in This Issue:
Opportunity Observes Unprecedented Mars Meteorite
Swift Captures the Birth of a Black Hole
Expedition 10 Crew Completes Spacewalk
Chat Live about Space Shuttle Columbia Tragedy

Huygens Probe Reveals Earth-like Qualities on Titan

On Jan. 14, 2005, the European Space Agency’s (ESA) Huygens probe made a historic descent to the surface of Saturn’s largest moon, Titan. The probe landed with a splat in the moon’s mud-like surface, beginning its discovery of features strikingly similar to those on Earth.

"We now have the key to understanding what shapes Titan's landscape," said Dr Martin Tomasko, Principal Investigator for Huygens’ Descent Imager-Spectral Radiometer (DISR). "Geological evidence for precipitation, erosion, mechanical abrasion, and other fluvial activity says that the physical processes shaping Titan are much the same as those shaping Earth."

Spectacular images captured by the DISR reveal that Titan has extraordinarily Earth-like meteorology and geology. Images have shown a complex network of narrow drainage channels running from brighter highlands to lower, flatter, dark regions. These channels merge into river systems running into lakebeds featuring offshore “islands” and “shoals” remarkably similar to those on Earth.

Data provided in part by the Gas Chromatograph and Mass Spectrometer (GCMS) and Surface Science Package (SSP) support Dr Tomasko's conclusions. Huygens data provides strong evidence for liquids flowing on Titan. However, the fluid involved is methane, a simple organic compound that can exist as a liquid or gas at Titan's sub-170°C temperatures, rather than water as on Earth. Titan's rivers and lakes appear dry at the moment, but rain may have occurred not long ago.

Deceleration and penetration data provided by the SSP indicate that the material beneath the surface's crust has the consistency of loose sand, possibly the result of methane rain falling on the surface over eons, or the wicking of liquids from below towards the surface.

Heat generated by Huygens warmed the soil beneath the probe, and both the GCMS and SSP detected bursts of methane gas boiled out of surface material. This reinforces methane's principal role in Titan's geology and atmospheric meteorology: forming clouds and precipitation that erodes and abrades the surface.

In addition, DISR surface images show small rounded pebbles in a dry riverbed. Spectra measurements are consistent with a composition of dirty water ice rather than silicate rocks. However, these materials are rock- solid at Titan's frigid temperatures.

Titan's soil appears to consist at least partly of precipitated deposits of the organic haze that shrouds the planet. This dark material settles out of the atmosphere. When washed off high elevations by methane rain, it concentrates at the bottom of the drainage channels and riverbeds, contributing to the dark areas seen in DISR images.

Stunning evidence based on finding atmospheric argon 40 indicates that Titan has experienced volcanic activity. The difference, however, is that Titan’s volcanoes seem to generate water ice and ammonia, unlike Earth’s lava-producing volcanoes.

"We are really extremely excited about these results,” said Jean-Pierre Lebreton, ESA's Huygens Project Scientist and Mission manager. “The scientists have worked tirelessly for the whole week because the data they have received from Huygens are so thrilling. This is only the beginning, these data will live for many years to come and they will keep the scientists very, very busy."

The Cassini-Huygens mission is a cooperation between NASA, ESA, and ASI, the Italian space agency. The Jet Propulsion Laboratory (JPL), a division of the California Institute of Technology in Pasadena, is managing the mission for NASA's Office of Space Science, Washington DC. JPL designed, developed and assembled the Cassini orbiter, while ESA operated the Huygens probe.

For more information on the Cassini-Huygens mission, visit the following websites:

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