• Leah Sacks

Inception of Impactors is Important

This post is just a little summary of a recent paper and some thoughts on how it will impact my research.

I decided to read the recent paper "Regional Impact Crater Mapping and Analysis on Saturn's Moon Dione and the Relation to Source Impactors" by Ferguson et al., 2022. This study was intended to examine several open questions regarding crater populations among Saturn's moon. There is a debate over what population of asteroids or other objects are the source for observed craters. Suggestions include the present day heliocentric objects observed at Jupiter and suggested to have created the surfaces observed on Europa and Ganymede or heliocentric comets suggested to have created the surface seen on Triton. In previous work, the author suggested the possible influence of a planetocentric set of impactors. In other words, objects orbiting Saturn may have impacted the moons, rather than objects orbiting the sun. From this information, the authors also address questions regarding the age of Saturn's inner moons.

The authors selected the highest resolution, well-lit areas of Dione and mapped craters within those areas. From these craters, they collected data such as morphology and long axis orientation (for non-circular) craters. When compared against production functions for the afore mentioned populations, the results do not match either function particularly well (see below). The authors instead propose that similar to previous work on Tethys, some of the craters on the body are from a set of impactors orbiting Saturn. From visual observations, and by comparing the observed production function against observations from Tethys (see below), the authors also concluded that Dione has a younger surface age than Tethys, and that it has been resurfaced, likely multiple times.

Figure 9, Ferguson et al., 2022

Figure 10, Ferguson et al., 2022

For my own work, I have been looking a little bit at crater clusters on Tethys and this information, as well as the earlier paper referenced within the paper, will directly influence my thoughts about the possible impactor sources and the dynamics of the Tethys-Saturn system. Additionally, I have upcoming work looking at circumstances surrounding resurfacing on icy moons. Dione has clearly been resurfaced, while Tethys has not. My modeling of some fo the factors that may have influenced these situations may be able to look at the circumstances that allow Dione to be resurfaced while Tethys remains untouched.

That's all for now, here is a link to the paper:

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