Titan

Planetary Data

Atmospheric Data

*Including ethane, diacetylene, methylacetylene, cyanoacetylene, acetylene, propane

The absence of ammonia and the presence of methane, although they should have a similar half life, indicates a source for methane on Titan. Clathrates (methane incorporated into ice), comets and a Fischer Tropsch like synthesis are suggestions for the abundance of methane.

At the surface temperature (~94K) water ice does not sublimate, so the atmosphere is nearly free of water vapor. Scattered variable clouds punctuate an overall haze in Titan's atmosphere. These clouds are probably composed of methane, ethane or other simple organics. Other more complex chemicals in small quantities must produce the orange color as seen from space.

The October 2004 Cassini flyby photographed bright, high clouds at Titan's south pole, but they do not appear to be methane, as had been expected. This discovery has baffled scientists, and studies are currently underway to determine the composition of the clouds and decide whether our understanding of Titan's atmosphere needs to be revised.19 Observations by Cassini of the atmosphere made in 2004 suggest that Titan is a "super rotator", like Venus, with an atmosphere that rotates much faster than its surface.

Geological Data

It is possible that areas of Titan's surface may be coated in a tar-like layer of organic precipitate called tholin, but this has not been confirmed. The presence of argon 40 was also discovered in the atmosphere, evidence of cryovolcanism producing a "lava" of water ice and ammonia.17 Later, a methane-spewing volcano was spotted in close-up images, and Titanian volcanism is now believed to be a significant source of the methane in the atmosphere; previously hypothesized methane oceans now appear to be virtually absent. However, according to the New York Times, the Cassini-Huygens team has since concluded that data from July 2006 observations of the northern polar region provide "definitive evidence for the presence of lakes on the surface of Titan."

The Huygens probe landed just off the easternmost tip of a bright region now called Adiri, and photographed pale hills with dark 'rivers' running down to a dark plain. Current understanding is that the hills (also referred to as highlands) are composed mainly of water ice. Dark organic compounds, created in the upper atmosphere by the ultraviolet radiation of the Sun, may rain from Titan's atmosphere. They are washed down the hills with the methane rain and are deposited on the plains over geological time scales.

There is evidence of erosion at the base of the rocks, indicating possible fluvial activity. The surface is darker than originally expected, consisting of a mixture of water and hydrocarbon ice. It is believed that the 'soil' visible in the images is precipitation from the hydrocarbon haze above.

A mountain range measuring 150km long (93 miles), 30km (19 miles) wide and 1.5km (1 mile) high was discovered by Cassini in 2006. This range lies in the southern hemisphere and is thought to be composed of icy material and covered in methane snow. The movement of tectonic plates, perhaps influenced by a nearby impact basin, could have opened a gap that the mountain's material upwelled through. Evidence of volcanic activity from the latest Cassini mission suggests that temperatures are probably much higher in hotbeds, enough for liquid water to exist. Argon 40 detection in the atmosphere indicates that volcanoes spew plumes of water and ammonia -- Cryovolcanism.

Orbital Data

Saturnian Moon

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