New constraints on the chemical composition and outgassing of 67P/Churyumov-Gerasimenko

Herny, Clémence; Mousis, O.; Marschall, Raphael; Thomas, N.; Rubin, Martin; Pinzón-Rodríguez, O.; Wright, I. P.

doi:10.1016/j.pss.2021.105194

Cited by 11 publications

(23 citation statements)

References 103 publications

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“…The overproduction occurred because the modelled southern hemisphere lacked a dust mantle, which led to an extreme erosion of 17 m with both H 2 O and CO 2 exposed at the surface. Herny et al (2021) acknowledged that neither ice expo-sure nor level of erosion were consistent with the observed nucleus. Because of the scaling they introduced, the resulting abundances and northern CO 2 sublimation front depth must be considered highly uncertain.…”

Section: Introductionmentioning

confidence: 82%

“…No conclusion was drawn regarding the depth below the surface where CO 2 is located. Herny et al (2021) used thermophysical modelling to reproduce the CO 2 /H 2 O, CO/H 2 O, and CO/CO 2 abundance ratios observed by ROSINA. Unfortunately, their model produced 5 times more water vapour than observed, therefore they scaled down all modelled production rates by that factor.…”

Section: Introductionmentioning

confidence: 99%

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Modelling the water and carbon dioxide production rates of Comet 67P/Churyumov–Gerasimenko

Davidsson

Samarasinha

Farnocchia

et al. 2021

Monthly Notices of the Royal Astronomical Society

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The European Space Agency Rosetta/Philae mission to Comet 67P/Churyumov–Gerasimenko in 2014–2016 is the most complete and diverse investigation of a comet carried out thus far. Yet, many physical and chemical properties of the comet remain uncertain or unknown, and cometary activity is still not a well-understood phenomenon. We here attempt to place constraints on the nucleus abundances and sublimation front depths of H2O and CO2 ice, and to reconstruct how the nucleus evolved throughout the perihelion passage. We employ the thermophysical modelling code ‘Numerical Icy Minor Body evolUtion Simulator’, or nimbus, to search for conditions under which the observed H2O and CO2 production rates are simultaneously reproduced before and after perihelion. We find that the refractories to water–ice mass ratio of relatively pristine nucleus material is μ ≈ 1, that airfall material has μ ≈ 2, and that the molar abundance of CO2 relative H2O is near 30 per cent. The dust mantle thickness is typically $\lesssim 2\, \mathrm{cm}$. The average CO2 sublimation front depths near aphelion were $\sim 3.8\, \mathrm{m}$ and $\sim 1.9\, \mathrm{m}$ on the northern and southern hemispheres, respectively, but varied substantially with time. We propose that airfall material is subjected to substantial fragmentation and pulverization due to thermal fatigue during the aphelion passage. Sub-surface compaction of material due to CO2 activity near perihelion seems to have reduced the diffusivity in a measurable way.

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Section: Introductionmentioning

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Modelling the water and carbon dioxide production rates of Comet 67P/Churyumov–Gerasimenko

Davidsson

Samarasinha

Farnocchia

et al. 2021

Monthly Notices of the Royal Astronomical Society

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“…The Rosetta spacecraft, as part of a mission launched and operated by the European Space Agency (ESA), helped uncover a great store of new knowledge about 67P, such as its gas and dust composition (e.g. Herny et al 2021;Longobardo et al 2020;Pestoni et al 2021), nucleus surface (e.g. Feller et al 2019) and temporal evolution (e.g.…”

Section: Introductionmentioning

confidence: 99%

High D/H ratios in water and alkanes in comet 67P/Churyumov-Gerasimenko measured with Rosetta/ROSINA DFMS

Müller

Altwegg

Berthelier

et al. 2022

A&A

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Context. Isotopic abundances in comets are key to understanding and reconstructing the history and origin of material in the Solar System. Data for deuterium-to-hydrogen (D/H) ratios in water are available for several comets. However, no long-term studies of the D/H ratio in water of a comet during its passage around the Sun have been reported thus far. Linear alkanes are important organic molecules that have been found on several Solar System bodies, including comets. To date, the processes of their deuteration are still poorly understood, only the upper limits of isotopic ratios for D/H and 13C/12C in linear alkanes are currently available. Aims. The aim of this work is to carry out a detailed analysis of the D/H ratio in water as a function of cometary activity and spacecraft location above the nucleus. In addition, a first determination of the D/H and 13C/12C ratios in the first four linear alkanes, namely, methane (CH4), ethane (C2H6), propane (C3H8), and butane (C4H10) in the coma of 67P/Churyumov-Gerasimenko is provided. Methods. We analysed in situ measurements from the Rosetta/ROSINA Double Focusing Mass Spectrometer (DFMS). Results. The D/H ratio from HDO/H2O and the 16O/17O ratio from H216O/H217O did not change during 67P’s passage around the Sun between 2014 and 2016. All D/H ratio measurements were compatible within 1σ, with the mean value of 5.01 × 10−4 and its relative variation of 2.0%. This suggests that the D/H ratio in 67P’s coma is independent of heliocentric distance, level of cometary activity, or spacecraft location with respect to the nucleus. Additionally, the 16O/17O ratio could be determined with a higher accuracy than previously possible, yielding a value of 2347 with a relative variation of 2.3%. For the alkanes, the D/H ratio is between 4.1 and 4.8 times higher than in H2O, while the 13C/12C ratio is compatible, within the uncertainties, with the available data for other Solar System objects. The relatively high D/H ratio in alkanes is in line with results for other cometary organic molecules and it suggests that these organics may be inherited from the presolar molecular cloud from which the Solar System formed.

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“…However, using a range of published values, a size can be estimated. Additionally, assuming a spherical nucleus and uniform (homogeneous) distribution of material (Preusker et al 2015;Pätzold et al 2016;Herny et al 2018), as well as the understanding that organic molecules detected in comet comae must be present in the nuclear ice (e.g., Charnley et al 2002;Rodgers and Charnley, 2002), the amount of GLA and EG in each comet can be reasonably estimated. Other uncertainties arise from estimates of the amount of water in and the particular density of each comet.…”

Section: Calculating Delivery Amounts Of Sugar Moleculesmentioning

confidence: 99%

Cometary Glycolaldehyde as a Source of pre-RNA Molecules

2020

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Over 200 molecules have been detected in multiple extraterrestrial environments, including glycolaldehyde (C 2 (H 2 O) 2 , GLA), a two-carbon sugar precursor that has been detected in regions of the interstellar medium. Its recent in situ detection on the nucleus of comet 67P/Churyumov-Gerasimenko and through remote observations in the comae of others provides tantalizing evidence that it is common on most (if not all) comets. Impact experiments conducted at the Experimental Impact Laboratory at NASA's Johnson Space Center have shown that samples of GLA and GLA mixed with montmorillonite clays can survive impact delivery in the pressure range of 4.5 to 25 GPa. Extrapolated to amounts of GLA observed on individual comets and assuming a monotonic impact rate in the first billion years of Solar System history, these experimental results show that up to 10 23 kg of cometary GLA could have survived impact delivery, with substantial amounts of threose, erythrose, glycolic acid, and ethylene glycol also produced or delivered. Importantly, independent of the profile of the impact flux in the early Solar System, comet delivery of GLA would have provided (and may continue to provide) a reservoir of starting material for the formose reaction (to form ribose) and the Strecker reaction (to form amino acids). Thus, comets may have been important delivery vehicles for starting molecules necessary for life as we know it.

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New constraints on the chemical composition and outgassing of 67P/Churyumov-Gerasimenko

Cited by 11 publications

References 103 publications

Modelling the water and carbon dioxide production rates of Comet 67P/Churyumov–Gerasimenko

Modelling the water and carbon dioxide production rates of Comet 67P/Churyumov–Gerasimenko

High D/H ratios in water and alkanes in comet 67P/Churyumov-Gerasimenko measured with Rosetta/ROSINA DFMS

Cometary Glycolaldehyde as a Source of pre-RNA Molecules

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