But that's exactly where NASA found an ingredient of plastic—the first time the chemical has been detected on another world.
The Cassini spacecraft found small amounts of propylene, a chemical used to make storage containers and other products, in the atmosphere of Saturn's largest moon Titan.
Titan is among the few bodies in the solar system with a significant atmosphere made up of hydrocarbons.
Cassini previously detected signs that propylene might be present in Titan's hazy atmosphere. But scientists weren't convinced until one of the spacecraft's instruments measured the heat coming from Saturn and its moons, and identified the chemical.
The finding appears Monday in the Astrophysical Journal Letters.