Investigating the porosity of Enceladus

TL;DR

This study estimates Enceladus's interior porosity using Earth-derived equations, revealing a minimum porosity of about 5% and comparing pore volumes with Earth and Mars to understand its geophysical properties.

Contribution

It applies experimental Earth-based porosity equations to icy moons, providing new estimates for Enceladus's porosity and pore surface area, and compares these with terrestrial planets.

Findings

Enceladus has a minimum interior porosity of about 5%.

Estimated pore volume of Enceladus is 1.51*10^7 km^3.

Pore surface area on Enceladus is significantly larger relative to its surface area.

Abstract

The interior of Enceladus, a medium sized icy moon of Saturn hosts hydrothermal activity and exhibits tidal heating and related geyser-like activity. There are major disagreements in the existing literature on the porosity of the interior, due to the different theoretical assumptions on which porosity related calculations were based. We present an application of experimental equations - derived for Earth - for icy planetary objects and Enceladus in particular. We chose a set of boundary values for our initial parameters from measured porosity values of chondrite samples as references, and calculated the porosity related values of Enceladus using various approaches. We present a comprehensive investigation of the effects of using these different porosity calculation methods on icy moons. With our most realistic approach we also calculated the same values for Earth and Mars for comparison. Our result for Enceladus is a minimum porosity of about 5\% at the centre of the body. For the total pore volume we estimated $1.51*10^7 km^3$ for Enceladus, $2.11*10^8 km^3$ for Earth and $1.62*10^8 km^3$ for Mars. Using the same method, we estimated the total pore surface area. From this we derived that the pore surface under a given $1 km^2$ area of the surface on Enceladus is about $1.37*10^9 km^2$, while for Earth this value is only $5.07*10^7 km^2$.