Issue |
A&A
Volume 683, March 2024
|
|
---|---|---|
Article Number | A245 | |
Number of page(s) | 13 | |
Section | Planets and planetary systems | |
DOI | https://doi.org/10.1051/0004-6361/202348684 | |
Published online | 28 March 2024 |
Upper limit of the solar wind protons backscattering efficiency from Comet 67P/Churyumov-Gerasimenko
1
Swedish Institute of Space Physics,
981 92
Kiruna,
Sweden
e-mail: romain.canu-blot@irf.se
2
Department of Physics, Umeå University,
907 36
Umeå,
Sweden
Received:
21
November
2023
Accepted:
20
January
2024
Context. Solar wind ions backscattering is a fundamental plasma-surface interaction process that may occur on all celestial bodies exposed to the solar wind and lacking a significant atmosphere or magnetosphere. Yet, observations have been limited to the regolith-covered Moon and Phobos, one of the Martian moons.
Aims. We aim to expand our knowledge of the process to include comets by investigating the backscattering of solar wind protons from the surface of comet 67P/Churyumov-Gerasimenko.
Methods. We used one of the ion spectrometers on board ESA’s Rosetta spacecraft to search for evidence of backscattered solar wind protons from the cometary surface. The signal of interest was expected to be very weak and several statistical treatments of the data were essential to eliminate any influence from background noise and instrumental effects. Due to limited knowledge of the signal location within the observed parameter space, we conducted a statistical analysis to identify the most probable conditions for detecting the signal.
Results. No significant solar wind backscattered protons were ever observed by the instrument. The statement applies to the large spectrum of observation conditions. An upper limit of the backscattered proton flux is given, as well as an upper limit of the backscattering efficiency of 9 × 10−4.
Conclusions. The surface of comet 67P/Churyumov-Gerasimenko distinguishes itself as a notably weak reflector of solar wind protons, with its backscattering efficiency, at most, as large as the lowest observed backscattering efficiency from the lunar regolith.
Key words: plasmas / scattering / methods: statistical / space vehicles: instruments / comets: general / comets: individual: 67P/Churyumov-Gerasimenko
© The Authors 2024
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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