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Titan was discovered in the spring of 1655 by the Dutch astronomer Christiaan Huygens. It is one of the first moons to be discovered in the solar system and is the second largest (second only to Jupiter's moon Ganymede). The first hint that it might have an atmosphere stemmed from observations of the moon by the Catalan astronomer Jose Comas Sola in 1908. Before 1980, Titan was known to be the only moon in the solar system having substantial atmosphere. Its reddish color, unique among Saturn's moons suggested that the chemistry of its atmosphere might be producing colored compounds.
On November 12 1980, the Voyager-1 spacecraft passed within 4,350 miles (7,000 km) of Titan, its instruments showing that the body's atmosphere is denser than that of Earth and that Titan's surface may be at least partially covered by liquid (methane or ethane). This denser atmosphere on Titan, which is composed of methane, nitrogen, and hydrocarbons, but lacks molecular oxygen, has retained conditions much like those that probably existed on all of the planets soon after they formed. The chemical reactions evolving in Titan's atmosphere today may be giving rise to some of the organic molecules that are thought to have been the precursors to life on Earth.
The Hunt for New Molecules
Based on observations of astronomers at ground-based observatories, one of the Huygens Probe's missions is to hunt for new molecules. The molecule acetonitrile (CH3CN) was recently discovered by French astronomers. Its presence is predicted by photochemical models and has significant implications for those who look at Titan as an "Earth before life." The presence of Argon in the Saturnian moon's atmosphere is also the subject of continuing research, since it would provide important consequences for the aerothemodynamic heat fluxes that Huygens will experience during entry.
Super-rotating Atmosphere
Like Venus, the zonal circulation of Titan's atmosphere is super-rotating. Knowledge of these zonal winds is important to the design of the Huygens Probe mission, since a large uncertainty in their magnitude complicates communications between the Huygens and the Orbiter.
For the latest developments and news on the mission visit:
NASA - National Aeronautics and Space Administration
ESA - European Space Agency
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