Gas flow in near surface comet like porous structures: Application to 67P/Churyumov-Gerasimenko

Christou, Chariton; Dadzie, S. Kokou; Thomas, Nicolas; Marschall, Raphael; Hartogh, Paul; Jorda, Laurent; Kührt, Ekkehard; Wright, Ian; Rodrigo, Rafael (2018). Gas flow in near surface comet like porous structures: Application to 67P/Churyumov-Gerasimenko. Planetary and space science, 161, pp. 57-67. Elsevier 10.1016/j.pss.2018.06.009

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We performed an investigation of a comet like porous surface to study how sub-surface sublimation with subsequent flow through the porous medium can lead to higher gas temperatures at the surface. A higher gas temperature of the emitted gas at the surface layer, compared to the sublimation temperature, will lead to higher gas speeds as the gas expands into the vacuum thus altering the flow properties on larger scales (kilometres away from the surface). Unlike previous models that have used modelled artificial structures, we used Earth rock samples with a porosity in the range 24–92% obtained from X-ray mi cro computed tomography (micro-CT) scans with resolution of some μ m. Micro-CT scanning technology provides 3D images of the pore samples. The direct simulation Monte Carlo (DSMC) method for the rarefied gas dynamics is directly applied on the digital rock samples in an unstructured mesh to determine the gas densiti es, temperatures and speeds within the porous medium and a few centimetres above the surface. The thicknesses of the rock samples were comparable to the diurnal thermal skin depth (5 cm). H 2 O was assumed to be the outgassing species. We correlated the coma temperatures and other properties of the flow with the rock porosities. The results are discussed as an input to analysis of data from the Microwave Instrument on Rosetta Orbiter (MIRO) on the 67P/Churyumov- Gerasimenko

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Physics Institute > Space Research and Planetary Sciences
08 Faculty of Science > Physics Institute
08 Faculty of Science > Physics Institute > NCCR PlanetS

UniBE Contributor:

Thomas, Nicolas and Marschall, Raphael

Subjects:

500 Science > 520 Astronomy
600 Technology > 620 Engineering

ISSN:

0032-0633

Publisher:

Elsevier

Language:

English

Submitter:

Dora Ursula Zimmerer

Date Deposited:

04 Jul 2018 11:14

Last Modified:

22 Mar 2019 11:34

Publisher DOI:

10.1016/j.pss.2018.06.009

BORIS DOI:

10.7892/boris.118279

URI:

https://boris.unibe.ch/id/eprint/118279

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