A comparison of multiple Rosetta data sets and 3D model calculations of 67P/Churyumov-Gerasimenko coma around equinox (May 2015)

Marschall, Raphael; Rezac, Ladislav; Kappel, David; Su, C. C.; Gerig, Selina-Barbara; Rubin, Martin; Pinzón-Rodríguez, O.; Marshall, David; Liao, Ying; Herny, Clémence; Arnold, G.; Christou, Chariton; Dadzie, S. Kokou; Groussin, O.; Hartogh, P.; Jordá, L.; Kührt, Ekkehard; Mottola, S.; Mousis, O.; Preusker, Frank; Scholten, F.; Theologou, P.; Wu, Jong-Shinn; Altwegg, Kathrin; Rodrigo, R.; Thomas, N.

doi:10.1016/j.icarus.2019.02.008

Cited by 21 publications

(24 citation statements)

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“…In this work, we have used the modeling approach (and in particular our DRAG3D model for the dust coma) described in detail in Marschall et al [16]. This approach has been successfully applied for the analysis and interpretation of multiple Rosetta instruments, in particular ROSINA, MIRO (Microwave Instrument for the Rosetta Orbiter), VIRTIS (Visible and Infrared Thermal Imaging Spectrometer), and OSIRIS [16][17][18][19]. While in previous work we have applied this approach to specific epochs of the Rosetta mission, we have employed it here to cover the entire mission period to study longer-term processes.…”

Section: Methodsmentioning

confidence: 99%

The Dust-to-Gas Ratio, Size Distribution, and Dust Fall-Back Fraction of Comet 67P/Churyumov-Gerasimenko: Inferences From Linking the Optical and Dynamical Properties of the Inner Comae

et al. 2020

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In this work, we present results that simultaneously constrain the dust size distribution, dust-togas ratio, fraction of dust re-deposition, and total mass production rates for comet 67P/Churyumov-Gerasimenko. We use a 3D Direct Simulation Monte Carlo (DSMC) gas dynamics code to simulate the inner gas coma of the comet for the duration of the Rosetta mission. The gas model is constrained by ROSINA/COPS data. Further, we simulate for different epochs the inner dust coma using a 3D dust dynamics code including gas drag and the nucleus' gravity. Using advanced dust scattering properties these results are used to produce synthetic images that can be compared to the OSIRIS data set. These simulations allow us to constrain the properties of the dust coma and the total gas and dust production rates. We determined a total volatile mass loss of (6.1 ± 1.5) • 10 9 kg during the 2015 apparition. Further, we found that power-laws with q = 3.7 +0.57 −0.078 are consistent with the data. This results in a total of 5.1 +6.0 −4.9 •10 9 kg of dust being ejected from the nucleus surface, of which 4.4 +4.9 −4.2 • 10 9 kg escape to space and 6.8 +11 −6.8 • 10 8 kg (or an equivalent of 14 +22 −14 cm over the smooth regions) is re-deposited on the surface. This leads to a dust-togas ratio of 0.73 +1.3 −0.70 for the escaping material and 0.84 +1.6 −0.81 for the ejected material. We have further found that the smallest dust size must be strictly smaller than ∼ 30µm and nominally even smaller than ∼ 12µm.

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Section: Methodsmentioning

confidence: 99%

The Dust-to-Gas Ratio, Size Distribution, and Dust Fall-Back Fraction of Comet 67P/Churyumov-Gerasimenko: Inferences From Linking the Optical and Dynamical Properties of the Inner Comae

et al. 2020

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“…Furthermore, it has been shown (Liao 2017) that lateral expansion will smooth out source inhomogeneities on scales up to the mean free path and hence the COPS data cannot be used to infer surface source distributions accurately. MIRO can make up for this deficiency, in principle (Marschall et al 2019), but the inversion of the measured lines is far more complicated than in a bound atmosphere application and is compromised by the relatively broad beam width. One important aspect that might yet be resolved is the temperature of the gas at source which may be higher than the free sublimation temperature as a result of interaction between the gas and the surface layer(s).…”

Section: Innermost Gas and Dust Comae Properties And Surface Relationmentioning

confidence: 99%

“…It is necessary to use these data sets together to constrain models (e.g. Marschall et al 2019;Tenishev et al 2016) of the surface activity distribution. However, from the work so far, it is not obvious that a satisfactory unique solution can be obtained even for optimum cases.…”

Section: Innermost Gas and Dust Comae Properties And Surface Relationmentioning

confidence: 99%

“…While single point measurements of the gas density and composition by the ROSINA instrument provided a constraint on the gas flow field and composition, the non-uniqueness of the results when extending them to 3 dimensions around the nucleus has been shown to be extreme. Incorporation of other data (from the MIRO experiment for example) has been shown to be difficult because of the non-LTE nature of the flow (Marschall et al 2019). The observations of VIRTIS-M were of insufficient resolution to provide meaningful constraints.…”

Section: The Coma Swarmmentioning

confidence: 99%

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Towards New Comet Missions

et al. 2019

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The Rosetta observations have greatly advanced our knowledge of the cometary nucleus and its immediate environment. However, constraints on the mission (both planned and unplanned), the only partially successful Philae lander, and other instrumental issues have inevitably resulted in open questions. Surprising results from the many successful Rosetta observations have also opened new questions, unimagined when Rosetta was first planned. We discuss these and introduce several mission concepts that might address these issues. It is apparent that a sample return mission as originally conceived in the 1980s during the genesis of Rosetta would provide many answers but it is arguable whether it is technically feasible even with today's technology and knowledge. Less ambitious mission concepts are described to address the suggested main outstanding scientific goals.

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“…Coma models have been previously used to fit the ROSINA data (see Bieler et al 2015b;Fougere et al 2016), while Läuter et al (2019) applied an inverse coma model to study the spatial distribution of gas sources from ROSINA DFMS/COPS measurements. Marschall et al (2019) proposed a comparison of the ROSINA, MIRO, Visible InfraRed Thermal Imaging Spectrometer (VIRTIS) and Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) observations from May 2015 and an insolation-driven model constrained by MIRO's measurements. Most of these models focused on the dominant species, H 2 O, and showed that a purely insolation driven model could not reproduce all coma measurements, leading to potentially heterogeneous activity depending on the regions.…”

Section: Introductionmentioning

confidence: 99%

Investigating the Rosetta/RTOF observations of comet 67P/Churyumov-Gerasimenko using a comet nucleus model: influence of dust mantle and trapped CO

Hoang

Garnier

Lasue

et al. 2020

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Context. Cometary outgassing is induced by the sublimation of ices and the ejection of dust originating from the nucleus. Therefore measuring the composition and dynamics of the cometary gas provides information concerning the interior composition of the body. Nevertheless, the bulk composition differs from the coma composition, and numerical models are required to simulate the main physical processes induced by the illumination of the icy body. Aims. The objectives of this study are to bring new constraints on the interior composition of the nucleus of comet 67P/Churyumov-Gerasimenko (hereafter 67P) by comparing the results of a thermophysical model applied to the nucleus of 67P and the coma measurements made by the Reflectron-type Time-Of-Flight (RTOF) mass spectrometer. This last is one of the three instruments of the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA), used during the Rosetta mission. Methods. Using a thermophysical model of the comet nucleus, we studied the evolution of the stratigraphy (position of the sublimation and crystallisation fronts), the temperature of the surface and subsurface, and the dynamics and spatial distribution of the volatiles (H2O, CO2 and CO). We compared them with the in situ measurements from ROSINA/RTOF and an inverse coma model. Results. We observed the evolution of the surface and near surface temperature, and the deepening of sublimation fronts. The thickness of the dust layer covering the surface strongly influences the H2O outgassing but not the more volatiles species. The CO outgassing is highly sensitive to the initial CO/H2O ratio, as well as to the presence of trapped CO in the amorphous ice. Conclusions. The study of the influence of the initial parameters on the computed volatile fluxes and the comparison with ROSINA/RTOF measurements provide a range of values for an initial dust mantle thickness and a range of values for the volatile ratio. These imply the presence of trapped CO. Nevertheless, further studies are required to reproduce the strong change of behaviour observed in RTOF measurements between September 2014 and February 2015.

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A comparison of multiple Rosetta data sets and 3D model calculations of 67P/Churyumov-Gerasimenko coma around equinox (May 2015)

Cited by 21 publications

References 48 publications

The Dust-to-Gas Ratio, Size Distribution, and Dust Fall-Back Fraction of Comet 67P/Churyumov-Gerasimenko: Inferences From Linking the Optical and Dynamical Properties of the Inner Comae

The Dust-to-Gas Ratio, Size Distribution, and Dust Fall-Back Fraction of Comet 67P/Churyumov-Gerasimenko: Inferences From Linking the Optical and Dynamical Properties of the Inner Comae

Towards New Comet Missions

Investigating the Rosetta/RTOF observations of comet 67P/Churyumov-Gerasimenko using a comet nucleus model: influence of dust mantle and trapped CO

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