Ancient and present surface evolution processes in the Ash region of comet 67P/Churyumov-Gerasimenko

Bouquety, Axel; Jordá, L.; Groussin, O.; Séjourné, Antoine; Bouley, Sylvain; Costard, F.

doi:10.1051/0004-6361/202140516

Cited by 5 publications

(15 citation statements)

References 44 publications

(57 reference statements)

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“…The occurrence of outgassing events increases when the comet approaches the Sun because the solar insulation increases. At each perihelion passage, the comet loses material (Pätzold et al 2018), leading to the apparition of new morphological features or changes in existing ones (Groussin et al 2015b;El-Maarry et al 2017;Bouquety et al 2021).…”

Section: Cometary Environmentmentioning

confidence: 99%

“…Several of these morphologies can be identified as depressions. In order to select the most appropriated ones, which will become our baseline for the comparison with 67P, we list here the terrestrial and Martian permafrost depressions identified in the literature, and compare their characteristics with the two depressions studied in Bouquety et al (2021). Four main types of permafrost depressions exist on Earth and Mars (French 2007;Hargitai & Kereszturi 2015).…”

Section: Permafrost Depressions On Earth and Marsmentioning

confidence: 99%

“…1). These depressions are topographic hollows with an arched shape that has a size of meters to tens of meters, and a depth of several meters (Groussin et al 2015b;Pajola et al 2016;Vincent et al 2016;El-Maarry et al 2017;Hu et al 2017;Birch et al 2019;Bouquety et al 2021). Some of these depressions grew by several meters during perihelion approach; for example, depressions in the Hapi region grew and migrated by 11 m over 12 days (Birch et al 2019).…”

Section: Introductionmentioning

confidence: 99%

“…However, the origin of these depressions remains unclear, and two hypotheses are currently proposed. The first hypothesis is that they are located next to a cliff collapse and therefore correspond to a mass-wasting event (Pajola et al 2016;Vincent et al 2016;El-Maarry et al 2017), as demonstrated by new boulders at the feet of some cliffs (Vincent et al 2015;Bouquety et al 2021). The second hypothesis is that they result from the erosion of dust-covered terrains, with dust dragged away by outgassing (Keller et al 2015;Groussin et al 2015b;Shi et al 2016;Hu et al 2017;Birch et al 2019); this erosion process could be a transient event induced by the perihelion passage.…”

Section: Introductionmentioning

confidence: 99%

“…In a previous study (Bouquety et al 2021), we performed a comparative morphometrical analysis of two of these depressions that are located on a cliff edge in the Ash region. We found that these two depressions grew by several meters during perihelion passage, with two preferential growths: a first growth close to the cliff, associated with the apparition of new boulders at its foot, which we interpreted as triggered by a combination of water-ice sublimation and a landslide, and a second growth on the opposite side of the cliff, which we interpreted as controlled by water-ice sublimation alone.…”

Section: Introductionmentioning

confidence: 99%

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Evidence for thermokarst depressions on comet 67P/Churyumov-Gerasimenko: An interplanetary comparison

Bouquety

Groussin

Jordá

et al. 2022

A&A

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Aims. The nucleus of comet 67P/Churyumov-Gerasimenko (67P) is ice rich and shows evidence of morphologies driven by sublimation processes. In particular, the fine-particle deposits (FPD) that cover its surface reveal depressions of many tens of meters. A detailed analysis of these morphologies and of the properties of the fine-particle deposits could help to constrain the amount of water ice in the subsurface. The aim of this paper is to characterize these depressions and constrain their formation and evolution by a detailed quantitative study of their morphometry and thermal environment, and through a comparison with similar morphologies on Earth and Mars. Methods. To study the cometary depressions, we constructed a database of morphometrical parameters for 131 depressions on 67P, 50 alases on Earth, and 200 scalloped depressions on Mars. We measured these parameters manually with the ArcGIS software. We used the images of the Narrow Angle Camera for 67P (down to a resolution of 1 m pixel−1), of the USGC-Digital Orthophoto Quadrangle for the Earth (5 m pixel−1), and of the High Resolution Imaging Science Experiment for Mars (25 cm pixel−1). We also used the digital elevation models associated with these images. In addition, we performed a study of the thermal environment of each depression on 67P to estimate the maximum temperature, the total erosion, and the total energy received from the Sun during one revolution. The morphometrical and thermal environment parameters were then used together for a comparative study of the depressions on 67P, the Earth, and Mars. Results. Our results show that depressions on 67P are geological analogs to alases on Earth and scalloped depressions on Mars; we call them cometary thermokarst depressions. They have been formed by a thermokarst process (i.e., permafrost thawing that causes a subsidence) triggered by water-ice sublimation. The cometary thermokarst depressions on 67P are distributed throughout the nucleus, without preferential distribution for a particular hemisphere or region. They are exclusively located in the fine-particle deposit layer, which is a few meters thick and is thought to have to contain a volume fraction of water ice of about 50% for the subsidence to occur. The formation and evolution of the depressions is driven by the Sun; the side facing the dominant insulation is the preferential direction of erosion. Our results contribute to a better understanding of the periglacial system on comet 67P and of the erosion processes on the nucleus.

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Section: Cometary Environmentmentioning

confidence: 99%

Section: Permafrost Depressions On Earth and Marsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Evidence for thermokarst depressions on comet 67P/Churyumov-Gerasimenko: An interplanetary comparison

Bouquety

Groussin

Jordá

et al. 2022

A&A

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Preparation of the ExoMars Mission: Feasibility study and preliminary methods for generating stereoscopic data with the CLose-UP Imager CLUPI

Bouquety,

Fayon,

Koschny

et al. 2024

Advances in Space Research

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Thermal Balance and Water Ice Sublimation on the Surface of Hyperactive Comet 103P/Hartley 2

2022

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Hyperactive comets have attracted attention due to their high water production rate with an unclear mechanism, though some hypotheses have been proposed to explain it. Based on the thermal theories of the comet nuclei, this paper studied a comet surface thermal model considering the sublimation of H2O. In this paper, a method for solving the sublimation rate of water ice by infrared spectroscopy is proposed. The method adopts the assumption of subpixel temperature nonuniformity on the comet nucleus surface and uses the numerical solution of the Fredholm equation. We use the HRI‐IR spectrum (1.05–4.8 μm) data by EPOXI to analyze the pixel‐by‐pixel water sublimation rate of hyperactive comet 103P/Hartley 2. The results show that sublimation exists in most areas of the surface with or without surface roughness, and most of the water production rate (70%–90%) may come from the comet nucleus when Gauss random surface roughness is adopted. According to the sublimation law, it is estimated that the sublimation temperature of water ice on 103P is above 180 K. If the dust‐to‐ice volume ratio is 3:1, the sublimation temperature is about 200–210 K, which indicates that the water ice may sublimate underneath. This may explain why exposed water ice on the surface can hardly be observed while the active fraction of this comet is up to 100%.

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Ancient and present surface evolution processes in the Ash region of comet 67P/Churyumov-Gerasimenko

Cited by 5 publications

References 44 publications

Evidence for thermokarst depressions on comet 67P/Churyumov-Gerasimenko: An interplanetary comparison

Evidence for thermokarst depressions on comet 67P/Churyumov-Gerasimenko: An interplanetary comparison

Preparation of the ExoMars Mission: Feasibility study and preliminary methods for generating stereoscopic data with the CLose-UP Imager CLUPI

Thermal Balance and Water Ice Sublimation on the Surface of Hyperactive Comet 103P/Hartley 2

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