Mass, Density, Internal Structure and Mass Loss of the Nucleus 67P/Churyumov-Gerasimenko
Abstract
Cometary nuclei consist mostly of dust and water ice, but the internal structure of a comet nucleus were essentially unknown. Bulk properties such as mass, volume (size and shape), and particularly the density, must be known for constraining its internal structure. The radio science experiment RSI on the Rosetta spacecraft derived the mass and the gravity field of comet 67P/Churyumov-Gerasimenko at distances varying between 100 km and 10 km, and together with the current best estimates of the volume by the OSIRIS camera, the bulk density of the nucleus. A model of the internal structure is derived from the information of two shape models by comparing observed and theoretical gravity coefficients. The comet nucleus appears to be a body of low mass, low density and high porosity. Individual bulk densities of the two lobes were derived by a bimodal gravity field approach which are, however, not very different from the global bulk density. The currently still on-going second gravity field determination will reveal a statistically significant mass loss by the outgassing activity which peaked during the perihelion passage.
- Publication:
-
AAS/Division for Planetary Sciences Meeting Abstracts #48
- Pub Date:
- October 2016
- Bibcode:
- 2016DPS....4811627P