Regional study of Europa's photometry

TL;DR

This study analyzes Europa's surface photometry using images from Voyager and New Horizons, revealing diverse microphysical states and evidence of recent activity like cryovolcanism through detailed photometric modeling.

Contribution

It applies a Bayesian Hapke model to a large image dataset, uncovering new insights into Europa's surface microphysics and recent geological activity.

Findings

Most areas show bright backscattering consistent with space-weathered grains.

Identification of bright, forward-scattering areas suggests recent cryovolcanic deposits.

Surface photometry is more diverse than previously understood.

Abstract

The surface of Europa is geologically young and shows signs of current activity. Studying it from a photometric point of view gives us insight on its physical state. We used a collection of 57 images from Voyager's Imaging Science System and New Horizons' LOng Range Reconnaissance Imager for which we corrected the geometric metadata and projected every pixel to compute photometric information (reflectance and geometry of observation). We studied 20 areas scattered across the surface of Europa and estimated their photometric behavior using the Hapke radiative transfer model and a Bayesian framework in order to estimate their microphysical state. We have found that most of them were consistent with the bright backscattering behavior of Europa, already observed at a global scale, indicating the presence of grains maturated by space weathering. However, we have identified very bright areas showing a narrow forward scattering possibly indicating the presence of fresh deposits that could be attributed to recent cryovolcanism or jets. Overall, we showed that the photometry of Europa's surface is more diverse than previously thought and so is its microphysical state.