Cassini mission press kit by NASA
= Cassini mission press kit by NASA
{c}
https://science.nasa.gov/wp-content/uploads/2023/09/cassini.pdf
The background discussion of Saturn states helium-to-molecular-hydrogen ratios and relates upper-atmosphere <helium> depletion to settling <helium> and additional <heat>. It is evidence for keeping He/H distinct from its reciprocal, not a current precision composition measurement.