Pre-accretional irradiation of comet 67P/Churyumov-Gerasimenko constituents
Abstract
Comets are thought to have largely preserved the primordial material from which they formed. Therefore, cometary studies provide important clues about the processes involved in the formation of the Solar System. During the last weeks of ESA's Rosetta mission, the COSIMA (COmetary Secondary Ion Mass Analyser) instrument performed a series of measurements, which involved long-term sputtering of dust particles captured from comet 67P/Churyumov-Gerasimenko. These post-sputtering analyses revealed the subsurface composition of 8 particles, which we compare here with surfaces composition measured on 59 un-sputtered particle fragments for 9 elements. We found that the analysed surfaces are strongly depleted in metals, such as Mg and Fe, compared to solar abundances, while the subsurface material is consistent with solar values. Because the dust captured by COSIMA fragmented upon impact with the collection targets, this metal depletion cannot reside exclusively on the outer surface of the bulk particles. Instead, these depletion layers must coat the surface of smaller, unfragmented mineral subunits. Such depletion layers, which are often called 'rims', are common at the surface of small regolith dust particles found on airless bodies in our solar system and are attributed to space weathering. We suggest that these mineral cometary subunits experienced pre-accretional solar wind irradiation in the inner regions of the solar nebula during the early stages of Solar System formation. The small irradiated dust constituents must then have been transported to the outer regions of the solar nebula, where they mixed with ices to form the nucleus of the comet.
Related
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BibTeX
@misc{sansberro2026preaccretional,
title = {{Pre-accretional irradiation of comet 67P/Churyumov-Gerasimenko constituents}},
author = {Inès Sansberro and Nicolas Fray and Hervé Cottin and Cécile Engrand and Donia Baklouti and Christelle Briois and Anaïs Bardyn and Henning Fischer and Klaus Hornung and John Paquette and Jouni Ryno and Olivier J Stenzel and Laurent Thirkell and Martin Hilchenbach},
howpublished = {HAL},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.32724},
eprint = {2609.32724},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05780445v1},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Pre-accretional irradiation of comet 67P/Churyumov-Gerasimenko constituents
AU - Inès Sansberro
AU - Nicolas Fray
AU - Hervé Cottin
AU - Cécile Engrand
AU - Donia Baklouti
AU - Christelle Briois
AU - Anaïs Bardyn
AU - Henning Fischer
AU - Klaus Hornung
AU - John Paquette
AU - Jouni Ryno
AU - Olivier J Stenzel
AU - Laurent Thirkell
AU - Martin Hilchenbach
PY - 2026
DA - 2026/09/26
PB - HAL
DO - 10.48550/arxiv.2609.32724
UR - https://hal.science/hal-05780445v1
AB - Comets are thought to have largely preserved the primordial material from which they formed. Therefore, cometary studies provide important clues about the processes involved in the formation of the Solar System. During the last weeks of ESA's Rosetta mission, the COSIMA (COmetary Secondary Ion Mass Analyser) instrument performed a series of measurements, which involved long-term sputtering of dust particles captured from comet 67P/Churyumov-Gerasimenko. These post-sputtering analyses revealed the subsurface composition of 8 particles, which we compare here with surfaces composition measured on 59 un-sputtered particle fragments for 9 elements. We found that the analysed surfaces are strongly depleted in metals, such as Mg and Fe, compared to solar abundances, while the subsurface material is consistent with solar values. Because the dust captured by COSIMA fragmented upon impact with the collection targets, this metal depletion cannot reside exclusively on the outer surface of the bulk particles. Instead, these depletion layers must coat the surface of smaller, unfragmented mineral subunits. Such depletion layers, which are often called 'rims', are common at the surface of small regolith dust particles found on airless bodies in our solar system and are attributed to space weathering. We suggest that these mineral cometary subunits experienced pre-accretional solar wind irradiation in the inner regions of the solar nebula during the early stages of Solar System formation. The small irradiated dust constituents must then have been transported to the outer regions of the solar nebula, where they mixed with ices to form the nucleus of the comet.
ER -