This is a good primer on the importance of Phosphorus [1].
Enceladus is surprisingly small (150 miles in diameter). It's too small for a rocky core. Instead it has a mushy or spongy core. But something inside is still generating heat. Some of this is from gravitational tides. It's not clear to me if that explains all of it however.
My understanding is that the heat is caused by the flexing of Enceladus orbiting Saturn, it's pull is so strong that slight differences in distance causes massive heat. Super cool!
Frasier Cain is a great journalist for everything space related, if you want to see more.
This discovery is from analyzing data that was captured during the Cassini missions in 2004. Imagine how much data we’re getting from JWST right now and what almost two decades of analysis will similarly yield from that. Absolutely stunning.
edit:
A follow up to this follow up found that it had calibration errors and reported 3ppb on Venus. The original study however had 20ppb. https://arxiv.org/abs/2211.09852
You can guess that they're overselling phosphorous as a landmark
Finding organic carbon everywhere used to seem very exciting - turns out that's just the fate of low-number metals in the universe. Who'da thunk such a thing.
Permanent. As Enceladus orbits Saturn, variances in the strength of the the gravity field causes Enceladus to contract and expand, building up heat and pressure. Since Enceladus is completely ocean covered by a thin layer of ice, the water blasts out of fissures in the surface. Some now think that some of Saturns rings have been generated over time by Enceladus ejecting water
and other matter as it orbits.
Enceladus is surprisingly small (150 miles in diameter). It's too small for a rocky core. Instead it has a mushy or spongy core. But something inside is still generating heat. Some of this is from gravitational tides. It's not clear to me if that explains all of it however.
[1]: https://www.youtube.com/watch?v=oPU9jeQbTOU