Part of the difficulty with arriving at a satisfactory theory for the Star stems from a compartmentalized approach.
Here is a simple analogy. Imagine a planetary rover lands on the north pole of a planet, and the humans controlling it wish to drive to the south pole.
Kepler rejected the idea that the enormous scale of the cosmos suggested that mankind is less important than in the cozier Aristotelian-Ptolemaic model.
A planet needs more than location in a habitable zone. It needs the right ingredients, and salt has a surprising role.
Enceladus is an especially fascinating case. Nearly 100 geysers of water ice are currently jetting out of its south pole at supersonic speed.