• Leah Sacks

Revisiting Research

Hello all, my lab is welcoming new students as the semester starts, so this post is intended to be a bit of an introduction to myself and what I work on. I’m about 2 years into my PhD working with Catherine Neish. My focus in on fracturing on small icy bodies. Specifically I’m studying Saturn’s moon Tethys. Tethys has a diameter of about 1000 km and is made almost entirely of ice. I’m trying to understand the origin of the fractures, rift zones, and other linear surface features that we see on small moons like Tethys. An image of Tethys is shown below! Courtesy of the Cassini ISS Instrument Team.

These surface features are somewhat of a mystery. Most of these outer moons are small enough and cold enough that they are considered inactive, yet we see this evidence of tectonic forces. Most commonly, these features are explained as the results of ocean freeze out. When these small bodies form, the heat of formation creates a subsurface ocean covered with an icy crust. As the moon cools down, either over time or because its orbit circularized or both, the ice crust thickens, pressurizing the ocean. The water in turns puts stresses on the ice crust, resulting in the observed fractures, features, and rifts. However, there is less commonality across the different moons that would be expected for the same process operating the same way on each moon. On Tethys, we see that there are preferred orientations to the features that we see across the surface, and we cannot explain why there is a large rift oriented SSW-NNE. We theorize that some outside factor must be affecting the formation of these features, to concentrate them in these ways.

My research is focused on exploring the formation of these features on Tethys. I am working on mapping these features and comparing them to similar features on Charon. The two moons both have similar features, but their rift zones have different appearances. This comparison is intended to draw out the factors that may result in different appearances, and thus may be affecting their formation process. I am also exploring the relationship between craters and fractures. And inexplicable fracture on Tethys has led us to hypothesize that craters may have affected some of the fracture formation. Therefore I’m exploring the relationship between the two sets of features. Finally, I’m exploring the parameters that have affected the formation of Tethys and Charon from a more quantitative approach using a numerical model. Code written for use on Europa and Enceladus will be used to explore Tethys and Charon. The two moons have had different fracture histories and I hope to understand what is unique about each moon that has made them look as they do today.

I’m currently working on my preparing for my comprehensive exam and writing my proposal.

That’s all for today’s blog post as we have many people who have to introduce themselves, but hopefully this has given a good overview of what I work on.

5 views0 comments

Recent Posts

See All