The Huygens Probe - Titan's Atmosphere
The Huygens space probe has revealed a significant amount of information about the atmosphere of Titan, Saturn’s largest moon. To measure the chemical content of Titan’s atmosphere, the Huygens probe utilized a gas chromatograph and mass spectrometer. The mass spectrometer found the molecular masses of gases in the atmosphere and the gas chromatograph was able to further separate the isotopes of these molecules. The Huygens Atmospheric Structure Instrument (HASI) was able to measure the physical and electrical content of Titan’s atmosphere.
The findings from these instruments showed that Titan’s atmosphere is composed of 98.4% nitrogen. The remaining atmosphere is primarily composed of methane, ethane, and argon with trace amounts of other elements and hydrogen compounds. Methane and ethane gas in Titan’s atmosphere give it a substantial greenhouse effect, although its temperature is still only 93 K. Because Titan’s atmosphere does not contain any trace amounts of noble gases, its atmosphere is most likely the product of out gassing from inside of Titan. If out gassing had not been occurring on Titan, then Titan’s atmosphere would not have methane in it -- all the methane would have been converted into hydrocarbons within 50 million years.
Titan’s atmospheric pressure has been found to be 1.5 times that of Earth. Visible light cannot escape the atmosphere of Titan due to a layer of smog in Titan’s lower atmosphere that is caused by negative ions. These negative ions are caused by Titan not having its own magnetosphere and being exposed to solar wind when it is outside of Saturn’s magnetosphere. The negative ions, being heavier than other elements, sink lower into the atmosphere and help form the orange smog that makes it impossible to see Titan’s surface. The solar wind also contributes to a loss in Titan’s atmosphere that could eventually destroy it if Titan did not have out gassing occurring to replace the atmosphere being lost.