Porosity of Cometary-Like Ice:Measurement and Modelling of Its Influence to the Elasticity
Abstract
Landing on a comet as intended at the Rosetta mission opens the possibility of direct measurement of seismic and elastic waves. This will provide us elasto-mechanical characteristics of the cometary material. In preparation of this cometary seismic experiment porous water ice was investigated by acoustic sounding. Porosity increases the compressibility and decreases the rigidity of the icy material. A hyperbolic influence of the porosity to the bulk modulus was found. This relation is different from that of porous stones where the bulk modulus decreases linearly up to critical porosity typically of the order of 0.5. For bigger porosity stones crumble whereas ice is still coherent. A quantitative model was developed to describe the compressibility of porous ice. The assumption is that any variation of the volume of the material is provided by a superposition of solid matrix and pore space variation. Both components contribute to the compressibility. The bulk modulus of the pore space, however, does not arise from any fluid or gas filling but contributes by its own pore space stiffness.
- Publication:
-
AAS/Division for Planetary Sciences Meeting Abstracts #28
- Pub Date:
- September 1996
- Bibcode:
- 1996DPS....28.0823M