To colonize the "surface" of Jupiter, humans have a machine that can transform an earth animal (including humans) into an animal similar to one of the Jovian natives (& back)! But every human sent out of research "dome" into the wild has vanished. Story is about resolving the mystery of these vanishings.
Fact sheet.First published: Astounding, November 1944.
Listed in "William G Contento's Top Ten Most Reprinted Stories".
Note: Why is this post so short?