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After a nearly seven-year journey and a descent through the hazy atmosphere of Saturn's largest moon, the Huygens spacecraft has sent back streams of data and the first ever close-up pictures of Titan. The images indicate that the moon's chilly surface texture resembles wet sand or clay with a thin crust and is composed of both frozen water and hydrocarbons.
The Huygens probe, released from the Cassini spacecraft on December 24, entered Titan's atmosphere on January 14 and landed safely on the ground two hours and 32 minutes later. "The ride was bumpier than we thought it would be," remarks Martin Tomasko, a principal investigator for the Descent Imager/Spectral Radiometer on board Huygens. The spacecraft landed in the Titanian mud after its parachute slowed it to a speed of 50 meters a second in the upper atmosphere as it tilted between 10 and 20 degrees. Coming out of the haze, about 30 kilometers above the surface, the spacecraft righted itself, tilting just three degrees and slowing to a speed of around five meters a second. The picture above is a composite of 30 images, which together cover an area 30 kilometers wide, taken at altitudes between 13 and eight kilometers as the probe approached the surface. The team is still analyzing data to determine the exact path Huygens took, although they have already narrowed the possibilities. They expect to reconstruct the trajectory to within one kilometer.
Huygens sent back more than 474 megabits of data, including 350 images, in its first several hours on Titan. Collected samples from the atmosphere indicate there is a uniform mix of methane and nitrogen in the moon's stratosphere, with the amount of methane increasing as the probe approached the surface. Pictures of the moon's surface show a landscape that could have been carved by erosion, with channels and shoreline features, which suggests that seas of liquid methane and ethane could persist. Further details of the data received from Huygens are expected to be released later in the week.
