Wednesday, October 12, 2011

Surprisingly Earth-like features revealed on Saturn's moon

After meticulously stitching together images that were gathered over six years by a NASA spacecraft in orbit around Saturn, astronomers have created a global map of the surface of Titan, the ringed planet's largest moon, and it features some surprisingly Earth-like geological features.

An international team of astronomers, led by the University of Nantes in France, created the striking mosaic of Titan's surface using infrared images taken by the Visual and Infrared Mapping Spectrometer (VIMS) aboard NASA's Cassini spacecraft.

The global map and animations were presented Oct. 4 at the European Planetary Science Congress and the American Astronomical Society's Division of Planetary Science in Nantes, France.

The researchers used images that were taken during the Cassini mission's first 70 flybys of Titan. But, piecing together the map was an intricate and painstaking project because scientists had to comb through the pictures on a pixel-by-pixel basis to adjust illumination differences and other distortions caused by Titan's thick and hazy atmosphere, said Stéphane Le Mouélic, of the University of Nantes.

"As Cassini is orbiting Saturn and not Titan, we can observe Titan only once a month on average," Le Mouélic said in a statement. "The surface of Titan is therefore revealed year after year, as pieces of the puzzle are progressively put together. Deriving a final map with no seams is challenging due to the effects of the atmosphere — clouds, mist etc. — and due to the changing geometries of observation between each flyby."

Lifting the veil on Saturn's largest moon
Titan is the only moon known to be cloaked in a dense atmosphere, which is composed mainly of nitrogen. It also has clouds of methane and ethane, and ongoing research has presented increasing evidence for methane rain on the large, frigid moon.

Since Titan is veiled in an opaque atmosphere, its surface is difficult to study with visible light cameras, and only a few specific infrared wavelengths can penetrate the haze. Cassini's infrared instruments and radar signals provide an intriguing glimpse down to the surface of the frozen body, which, as the new global map reveals, has some interesting Earth-like features.

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