-Betzaida Aponte-Hernandez 

This LPI is about Rhea! Good, because we don't get to see Rhea very often.

One thing that disturbs planetary scientists is the concept of regelation. All icy bodies are deeply influenced by it, but regelation has only recently been studied in such a context. As probes are lined up for the outer solar system, post-grads are tasked with studying long ignored physics until they become an expert.  

Rhea is Saturn's second largest moon, but it's down a weight class from Titan, Triton, Luna, & the Galilean moons. It compares better with certain KBO's like Pluto, or Uranus's two largest moons, Oberon and Titania.

• Ever wanted to see a geological map of Rhea? Timestamp at 1:50. The focus will be obvious a minute later.
• At 5:10 concrete proof that sometimes speakers hand draw their slides seconds before starting their presentation.
• Slide at 10:00. In the slides preceding she is setting up a D value for Rhea. In this slide, she is comparing her D value to other D values other people made for other smallish ice-worlds. They vary a lot, because the ice of each world is different. This is one of the most interesting things to me. Ice-minerals, salinity, composition, internal heat. Look at how big a difference between Titania & Oberon even though they are both of similar size and moons of Uranus.

Here's the trick. Usually when we see a complex crater on an ice-world we think big impact. Maybe something that even punched all the way through. Then a simple crater would mean a smaller impact that displaced the source ice. However that doesn't always work. Sometimes it appears that a crater should have been big and complex, but relaxed into a simple crater. Often simple ice-craters look like a portion of their volume was injected instead of ejected like a rock-crater would be.

It's interesting because regelation works on even the coldest of ices, but seems to be effected by composition and salinity even when temperature is out of the equation. Water-ice is a hard mineral when cold enough, but regelation remains a thing. Imagine now, impact basins with stony and metallic debris. How deep can they sink into Rhea before the debris collects at a certain depth? What about Oberon? Our speaker has now put Rhea on that data-point map.