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How did Voyager 1 help identify nitrogen as Titan’s main atmospheric gas?
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Titan
Titan, moon of Saturn, photographed by Voyager 2 on August 25, 1981, at a distance of 907,000 km (564,000 miles). Green and violet images were combined to make this photograph, which shows the extended atmosphere of the satellite.
During the 1980 flyby of Voyager 1, scientists were able to identify nitrogen as the primary component of Titan’s atmosphere by analyzing radio wave refraction and infrared data.1
While earlier observations had detected methane, Voyager 1’s measurements of radio wave bending revealed that methane accounted for only a small percentage of the total atmospheric molecules. By comparing infrared and radio data, researchers determined that the atmosphere’s constituent particles had a mean molecular weight of 28.6 atomic mass units. Because molecular nitrogen has a mean molecular weight of 28, it was identified as the most plausible major constituent, potentially alongside smaller amounts of argon.1