The surface distributions of the production of the major volatile species, H₂O, CO₂, CO and O₂, from the nucleus of comet 67P/Churyumov-Gerasimenko throughout the Rosetta Mission as measured by the ROSINA double focusing mass spectrometer

Combi, Michael; Shou, Yinsi; Fougere, Nicolas; Tenishev, Valeriy; Altwegg, Kathrin; Rubin, Martin; Bockelée-Morvan, Dominique; Capaccioni, Fabrizio; Cheng, Yu-Chi; Fink, Uwe; Gombosi, Tamas; Hansen, Kenneth C.; Huang, Zhenguang; Marshall, David; Toth, Gabor (2020). The surface distributions of the production of the major volatile species, H₂O, CO₂, CO and O₂, from the nucleus of comet 67P/Churyumov-Gerasimenko throughout the Rosetta Mission as measured by the ROSINA double focusing mass spectrometer. Icarus, 335, p. 113421. Elsevier 10.1016/j.icarus.2019.113421

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The Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) suite of instruments operated throughout the over two years of the Rosetta mission operations in the vicinity of comet 67P/Churyumov-Gerasimenko. It measured gas densities and composition throughout the comet's atmosphere, or coma. Here we present two-years' worth of measurements of the relative densities of the four major volatile species in the coma of the comet, H₂O, CO₂, CO and O₂, by one of the ROSINA sub-systems called the Double Focusing Mass Spectrometer (DFMS). The absolute total gas densities were provided by the Comet Pressure Sensor (COPS), another ROSINA sub-system. DFMS is a very high mass resolution and high sensitivity mass spectrometer able to resolve at a tiny fraction of an atomic mass unit. We have analyzed the combined DFMS and COPS measurements using an inversion scheme based on spherical harmonics that solves for the distribution of potential surface activity of each species as the comet rotates, changing solar illumination, over short time intervals and as the comet changes distance from the sun and orientation of its spin axis over long time intervals. We also use the surface boundary conditions derived from the inversion scheme to simulate the whole coma with our fully kinetic Direct Simulation Monte Carlo model and calculate the production rates of the four major species throughout the mission. We compare the derived production rates with revised remote sensing observations by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) as well as with published observations from the Microwave Instrument for the Rosetta Orbiter (MIRO). Finally we use the variation of the surface production of the major species to calculate the total mass loss over the mission and, for different estimates of the dust/gas ratio, calculate the variation of surface loss all over the nucleus.

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

UniBE Contributor:

Altwegg, Kathrin and Rubin, Martin

Subjects:

500 Science > 520 Astronomy
600 Technology > 620 Engineering

ISSN:

0019-1035

Publisher:

Elsevier

Language:

English

Submitter:

Dora Ursula Zimmerer

Date Deposited:

04 Feb 2020 14:17

Last Modified:

17 Feb 2020 07:23

Publisher DOI:

10.1016/j.icarus.2019.113421

BORIS DOI:

10.7892/boris.139317

URI:

https://boris.unibe.ch/id/eprint/139317

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