The Mass Loss of Comet 67P/Churyumov-Gerasimenko and Implications
Abstract
The Rosetta Radio Science Investigations experiment (RSI) determined the mass and the degree and order two gravity field of the nucleus of comet 67P/Churyumov-Gerasimenko after arrival in summer 2014 and again before the ultimate end of the mission in fall 2016. The comparison of the two mass values revealed a substantial mass loss by gas and dust of about 10 million tons. The low bulk density of 537 kg/m3 and reasonable assumptions of the compact dust material density implies a high porosity of about 75% and a high dust-to-ice mass ratio of the nucleus body. The ROSINA and MIRO gas observations, however, integrated over the mission time reveal a mass loss by the gas alone which does not allow a high dust-to-ice mass ratio for the material in space beyond a certain distance from the nucleus where the material does no longer fall back to the nucleus. The dust-to-ice mass ratio must be smaller than 1 in order to agree with the total mass loss determined by RSI. Only a small amount of the lifted mass at an active spot on the surface reaches space. Most of the dust mass falls back and is redistributed on the surface.
- Publication:
-
42nd COSPAR Scientific Assembly
- Pub Date:
- July 2018
- Bibcode:
- 2018cosp...42E2545P