Investigating the porosity of Enceladus

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 are based. We present an application of experimental equations - derived for the 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 the Earth and Mars for comparison. Our result for Enceladus is a minimum porosity of about 5 per cent at the centre of the body. For the total pore volume, we estimated 1.51 & BULL; 10(7) km(3) for Enceladus, 2.11 & BULL; 10(8) km(3) for the Earth and 1.62 & BULL; 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 & BULL; 10(9) km(2), while for the Earth this value is only 5.07 & BULL; 10(7) km(2).