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1. Sulfur Implantation into Water Ice with Propane: Implications for Organic Chemistry on the Surface of Europa

Author: Alexis Bouquet, Cíntia Aparecida Pires da Costa, Philippe Boduch, Hermann Rothard, Alicja Domaracka, Grégoire Danger, Isabelle Schmitz, Carlos Afonso, Philippe Schmitt-Kopplin, Vincent Hue, Tom A. Nordheim, Alexander Ruf, Fabrice Duvernay, Maryse Napoleoni, Nozair Khawaja, Frank Postberg, Thomas Javelle, Olivier Mousis, and Laura Isabel Tenelanda Osorio
Subjects: Astrochemistry, Radiation interactions (Ice), Europa, Galilean satellites, Astronomy, QB1-991
Abstract: We performed experiments of implantation of energetic sulfur ions (105 keV) into 2:1 water:propane ices at 80 K and analyzed the resulting refractory organic matter with ultrahigh-resolution mass spectrometry. Our goal was to characterize the organic matter processed in the surface conditions of Europa, where it would receive a heavy flux of energetic particles, including sulfur ions, and determine whether organosulfurs could be formed in these conditions, using the simplest alkane that can exist in solid form on Europa’s surface. We find that the produced organic matter contains a large variety of both aliphatic and aromatic compounds (several thousand unique formulae), including polycyclic aromatic hydrocarbons (PAHs), with masses up to 900 amu. A large number of aromatic hydrocarbons is found along with oxygenated, mostly aliphatic, compounds. Organosulfurs are found in both CHS and CHOS form, demonstrating they can be formed from any organic compound through sulfur implantation. These organosulfurs’ properties (aromaticity, mass) appear similar to the rest of the organic matter, albeit their low quantity does not allow for a thorough comparison. Our results have implications for the type of refractory organic matter that could be observed by the JUICE and Europa Clipper space missions and how the surface of Europa could generate complex organics, including PAHs and organosulfurs, that could then enrich the subsurface ocean. In particular, they indicate that a large diversity of organic matter, including organosulfurs, can be formed from simple precursors in a geologically short time frame under the ion flux that reaches Europa.
Published: 2024
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2. Early Stages of Galilean Moon Formation in a Water-depleted Environment

Author: Olivier Mousis, A. Schneeberger, Jonathan I. Lunine, Christopher R. Glein, Alexis Bouquet, and Steven D. Vance
Subjects: Galilean satellites, Natural satellites (Solar system), Natural satellite formation, Planetary system formation, Astrophysics, QB460-466
Abstract: A key feature of the Galilean satellite system is its monotonic decrease in bulk density with growing distance from Jupiter, indicating an ice mass fraction that is zero in the innermost moon Io and about half in the outer moons Ganymede and Callisto. Jupiter-formation models, and perhaps the Juno spacecraft water measurements, are consistent with the possibility that the Jovian system may have formed, at least partly, from ice-poor material. And yet, models of the formation of the Galilean satellites usually assume abundant water ice in the system. Here, we investigate the possibility that the Jovian circumplanetary disk was populated with ice-depleted chondritic minerals, including phyllosilicates. We show that the dehydration of such particles and the outward diffusion of the released water vapor allow condensation of significant amounts of ice in the formation region of Ganymede and Callisto in the Jovian circumplanetary disk. Our model predicts that Europa, Ganymede, and Callisto should have accreted little, if any, volatiles other than water ice, in contrast to the comet-like composition of Saturn’s moon Enceladus. This mechanism allows for the presence of ice-rich moons in water-depleted formation environments around exoplanets as well.
Published: 2023
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3. Cold Traps of Hypervolatiles in the Protosolar Nebula at the Origin of the Peculiar Composition of Comet C/2016 R2 (PanSTARRS)

Author: Olivier Mousis, Artyom Aguichine, Alexis Bouquet, Jonathan I Lunine, Grégoire Danger, Kathleen E. Mandt, and Adrienn Luspay-kuti
Subjects: Solar Physics
Abstract: Recent observations of the long-period comet C/2016 R2 (PanSTARRS; hereafter R2) indicate an unusually high N2/CO abundance ratio, typically larger than ∼0.05, and at least 2–3 times higher than the one measured in 67P/Churyumov–Gerasimenko. Another striking compositional feature of this comet is its heavy depletion in H2O (H2O/CO ∼ 0.32%), compared to other comets. Here we investigate the formation circumstances of a generic comet whose composition reproduces these two key features. We first envisage the possibility that this comet agglomerated from clathrates, but we find that such a scenario does not explain the observed low water abundance. We then alternatively investigate the possibility that the building blocks of R2 agglomerated from grains and pebbles made of pure condensates via the use of a disk model describing the radial transport of volatiles. We show that N2/CO ratios reproducing the value estimated in this comet can be found in grains condensed in the vicinity of the CO and N2 ice lines. Moreover, high CO/H2O ratios (>100 times the initial gas-phase value) can be found in grains condensed in the vicinity of the CO ice line. If the building blocks of a comet assembled from such grains, they should present N2/CO and CO/H2O ratios consistent with the measurements made in R2's coma. Our scenario indicates that R2 formed in a colder environment than the other comets that share more usual compositions. Our model also explains the unusual composition of the interstellar comet 2l/Borisov.
Published: 2021
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4. Organic chemistry on the surface of jovian icy satellites: formation of complex refractory organic matter by implantation of sulfur ions into water-alkanes ices

Author: Alexis Bouquet, Grégoire Danger, Laura Tenelanda-osorio, Philippe Boduch, Hermann Rothard, Julien Maillard, Isabelle Schmitz-Afonso, Carlos Afonso, Philippe Schmitt-Kopplin, Fabrice Duvernay, Cintia Pires da Costa, Lawry Honold, Physique des interactions ioniques et moléculaires (PIIM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Normandie Université (NU), and Université Paris Cité (UPCité)
Subjects: [SDU]Sciences of the Universe [physics]
Abstract: We present the results of the implantation of sulfur ions in ice samples (H2O:C3H8) in conditions relevant to Europa and other jovian satellites. The samples were prepared and irradiated at 80 K, and were thick enough to ensure the projectiles were implanted in the ice, allowing the sulfur projectiles to become part of the ensuing chemistry. The evolution of the samples was followed with Fourier Transform Infra-Red (FT-IR) spectroscopy, and the organic residues were analyzed off-site through Ultra High Resolution Mass Spectrometry (UHRMS). The UHRMS shows formation of a complex, diverse refractory organic matter, however no evidence of organosulfur formation has been found. Introduction: Energetic particles from Jupiter’s magnetosphere (electrons, protons, oxygen and sulfur ions) are likely to be a key driver of the chemical evolution of the icy satellite’s surface, especially Europa; they can alter organic matter deposited on the surface from the internal ocean. In the case of impinging ions, in addition to the stopping power and total energy of the projectile [1], their reactivity is a possible factor in the chemistry. Sulfur is abundant in Jupiter’s magnetosphere [3] due to Io’s volcanic activity, and highly reactive. Experiments with sulfur projectiles have been performed and have shown the efficient creation of sulfuric acid in water ice [4, 5]; previous experiments by our group with interstellar analogs showed it can become part of the organic chemistry triggered by irradiation and form organosulfurs [6]. Here, in temperature conditions relevant to Europa (80K), we investigate the composition of the organic residue generated by the irradiation of a water:propane ice by sulfur ions. Experiments We performed the experiments at the ARIBE low-energy line at the Grand Accélérateur National d’Ions Lourds (GANIL) in Caen, France. The projectiles were 105 keV S6+ and 105 keV Ar7+ (the latter to produce a reference sample with a non-reactive projectile). The samples were prepared at 80K on a ZnSe window from a 2:1 H2O:C3H8 gas mixture and irradiated at a fluence of approximately 1014 ions. To ensure the products would be abundant enough to be detected, cycles of deposition-irradiation were repeated up to 15 times. The finally obtained samples were slowly warmed up to 300K to sublimate the volatiles and leave the refractory organic residue. This residue was analyzed off-site using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). This FT-ICR-MS technique represents the highest mass resolving power (R > 106) and highest mass accuracy ( Results Infrared spectroscopy shows little difference to previous work on irradiation with electrons of similar ices [8], except for the early production of CO2 and modest abundance of CH4. No qualitative difference was seen between Ar-irradiated and S-irradiated samples in the IR. The results from the ESI or LDI FT-ICR-MS analysis show a very diverse, (3000 + annotations) refractory (average Double Bond Equivalent=14) organic matter (Figure 1). The residue features an insoluble phase. Heavy molecules (m/z>200) are common, showing that a fairly low dose is enough to form large molecules. No organosulfur could be identified, in stark contrast with our previous experiments [6]. Analysis of the soluble phase by ESI-FT-ICR shows that the oxygen-bearing products tend to be lighter. We discuss how our results compare to experiments using electrons ([8], and our own work). Figure 1: Annotations (spot size is a function of intensity) obtained with the LDI-FT-ICR analysis, showing number of carbon atoms vs double bond equivalent (DBE) and number of oxygen atoms. A large amount of the residue is oxygen poor and highly aromatic. Acknowledgements A.B. and G.D. acknowledge the CNRS program "Programme National de Planétologie" (P.N.P, INSU), G.D. acknowledges the “Programme de Physique et Chimie du Milieu Interstellaire” (P.C.M.I, INSU) and the “Centre National d’Etudes Spatiales” (C.N.E.S) (exobiology program). H.R., P.B. and C.P.dC. acknowledge funding from Région Normandie through RIN EMERGENT SCHINOBI. References [1] Teolis et al. JGR: Planets 122.10 (2017): 1996-2012.[2] von Steiger, R., Schwadron, N., Fisk, L., et al. 2000, JGR: Space Physics, 105, 27217[3] Paranicas, C., Cooper, J., Garrett, H., Johnson, R., & Sturner, S. 2009, Europa. University of Arizona Press, Tucson, 529[4] Ding et al. Icarus 226.1 (2013): 860-864.[5] Strazzulla, et al. Icarus 192.2 (2007): 623-628.[6] Ruf, et al. ApJL, 885(2), L40 (2019).[7] Ruf et al.(2017) PNAS 114(11), 2819-2824.[8] Hand, K. P., & Carlson, R. W. JGR: Planets, 117(E3). (2012)
Published: 2023

5. The role of phyllosilicates in shaping the Galilean moons' density gradient

Author: Olivier Mousis, Antoine Schneeberger, Jonathan Lunine, Christopher Glein, Alexis Bouquet, Steven Vance, Vassilissa Vinogradoff, Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Physique des interactions ioniques et moléculaires (PIIM), and Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU]Sciences of the Universe [physics]
Abstract: A key feature among the Galilean satellites is their monotonic decrease in density, indicating an ice fraction that is zero in the innermost moon Io, and about half in the outer moons Ganymede and Callisto. So far, there is no formation scenario that explains this gradient while considering the moons grew in a water-depleted circumplanetary disk. Here, we investigate the possibility that the jovian circumplanetary disk was fueled with ice-free chondritic minerals, including phyllosilicates. To do so, we use a standard one-dimensional gas-starved accretion disk model derived from the literature [1, 2] coupled with gas and solids transport modules [3, 4] to investigate the evolution of vapors released by the dehydration of phyllosilicates. We show that the dehydration of such particles and the outward diffusion of the released water vapor allows condensation of significant amounts of ice in the formation region of Ganymede and Callisto in the Jovian circumplanetary disk. This mechanism naturally explains the presence of ice-rich moons around a water-depleted Jupiter. [1] Canup, R.M., Ward, W.R. 2002. Formation of the Galilean Satellites: Conditions of Accretion. The Astronomical Journal 124, 3404–3423. doi:10.1086/344684 [2] Sasaki, T., Stewart, G.R., Ida, S. 2010. Origin of the Different Architectures of the Jovian and Saturnian Satellite Systems. The Astrophysical Journal 714, 1052–1064. doi:10.1088/0004-637X/714/2/1052 [3] Birnstiel, T., Klahr, H., Ercolano, B. 2012. A simple model for the evolution of the dust population in protoplanetary disks. Astronomy and Astrophysics 539. doi:10.1051/0004-6361/201118136 [4] Anderson, S.E., Mousis, O., Ronnet, T. 2021. Formation Conditions of Titan's and Enceladus's Building Blocks in Saturn's Circumplanetary Disk. The Planetary Science Journal 2. doi:10.3847/PSJ/abe0ba
Published: 2022

6. Origin of Molecular Oxygen in Comets: Current Knowledge and Perspectives

Author: Adrienn Luspay-kuti, Olivier Mousis, Jonathan I. Lunine, Yves Ellinger, Françoise Pauzat, Ujjwal Raut, Alexis Bouquet, Kathleen E. Mandt, Romain Maggiolo, Thomas Ronnet, Bastien Brugger, Ozge Ozgurel, and Stephen A. Fuselier
Subjects: Chemistry and Materials (General), Space Sciences (General)
Abstract: The Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) instrument onboard the Rosetta spacecraft has measured molecular oxygen (O2) in the coma of comet 67P/Churyumov-Gerasimenko (67P/C-G) in surprisingly high abundances. These measurements mark the first unequivocal detection of O2 in a cometary environment. The large relative abundance of O2 in 67P/C-G despite its high reactivity and low interstellar abundance poses a puzzle for its origin in comet 67P/C-G, and potentially other comets. Since its detection, there have been a number of hypotheses put forward to explain the production and origin of O2 in the comet. These hypotheses cover a wide range of possibilities from various in situ production mechanisms to protosolar nebula and primordial origins. Here, we review the O2 formation mechanisms from the literature, and provide a comprehensive summary of the current state of knowledge of the sources and origin of cometary O2.
Published: 2018
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7. Ceres: Astrobiological Target and Possible Ocean World

Author: Edward D. Young, Christopher H. House, Marc Neveu, Kelly E. Miller, Anton I. Ermakov, Amanda R. Hendrix, Lynnae C. Quick, Maria Cristina De Sanctis, Jennifer E.C. Scully, Michael T. Bland, Alexis Bouquet, Carol A. Raymond, Christopher T. Russell, Julie Castillo-Rogez, Thomas H. Prettyman, Brent Sherwood, Laboratoire d'Astrophysique de Marseille (LAM), and Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Solar System, Evolution, Chemical, 010504 meteorology & atmospheric sciences, Oceans and Seas, Water, 01 natural sciences, Agricultural and Biological Sciences (miscellaneous), Minor Planets, Astrobiology, [SDU]Sciences of the Universe [physics], Space and Planetary Science, Physics::Space Physics, Exobiology, 0103 physical sciences, Earth (chemistry), Astrophysics::Earth and Planetary Astrophysics, 010303 astronomy & astrophysics, Geology, 0105 earth and related environmental sciences
Abstract: International audience; Ceres, the most water-rich body in the inner solar system after Earth, has recently been recognized to have astrobiological importance. Chemical and physical measurements obtained by the Dawn mission enabled the quantification of key parameters, which helped to constrain the habitability of the inner solar system's only dwarf planet. The surface chemistry and internal structure of Ceres testify to a protracted history of reactions between liquid water, rock, and likely organic compounds. We review the clues on chemical composition, temperature, and prospects for long-term occurrence of liquid and chemical gradients. Comparisons with giant planet satellites indicate similarities both from a chemical evolution standpoint and in the physical mechanisms driving Ceres' internal evolution.
Published: 2020

8. Effect of the UV dose on the formation of complex organic molecules in astrophysical ices: irradiation of methanol ices at 20 K and 80 K

Author: Laura I Tenelanda-Osorio, Alexis Bouquet, Thomas Javelle, Olivier Mousis, Fabrice Duvernay, Grégoire Danger, Physique des interactions ioniques et moléculaires (PIIM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Institut Universitaire de France (IUF), Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.), ANR-16-CE29-0015,RAHIIA_SSOM,Analyses de résidus provenant d'analogues de glace interstellaire pour la compréhension de la formation de la matière organique du Système Solaire(2016), and ANR-12-JS08-0001,VAHIIA,Analyse de volatiles issus du réchauffement d'analogues de glaces interstellaires(2012)
Subjects: molecular processes, Space and Planetary Science, [CHIM.ANAL]Chemical Sciences/Analytical chemistry, [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], astrochemistry, [SDU]Sciences of the Universe [physics], ultraviolet: planetary systems, Astronomy and Astrophysics
Abstract: Methanol is a ubiquitous complex organic molecule (COM) in the interstellar medium, thought to be a precursor of larger COMs when it is submitted to different energetic processes, that can trigger chemical reactions in solid and gas phases. Using laboratory experiments, we report the characterization of the evolution of photoproducts generated by the UV irradiation of methanol ice at different UV doses and temperatures (20 and 80 K). We used gas chromatography coupled to mass spectrometry (GC-MS) to analyse the volatile organic compounds (VOCs) recovered during the warming of the photoprocessed methanol ice. We identified 21 molecules (with up to five carbon atoms, including alcohols, aldehydes, ketones, ester, and ethers) and followed their abundance as a function of the UV fluence and ice temperatures. With increasing UV fluence, an increase in the production of heavier COMs is observed, while species with 1 or 2 carbon atoms are depleted or do not increase. Species within a same chemical family show the same pattern of evolution, with heavier molecules present in smaller quantities. Ketones and esters are the chemical families that lead to more complex molecules and start forming at the earliest stages of irradiation. Their formation pathways are driven by radical recombinations with CO as the main building blocks. Aldehydes are formed before their alcohol counterparts, implying they do not form through alcohol dehydrogenation, but via radical recombination around HCO. Ethers seem to be the precursors of a large set of COMs, and alcohols present a steady profile throughout irradiation.
Published: 2022

9. An Exogenic Origin for the Volatiles Sampled by the LCROSS Impact

Author: Olivier Mousis, Kathleen Mandt, Dana M. Hurley, L. O. Magana, Adrienn Luspay-Kuti, Kurt D. Retherford, and Alexis Bouquet
Subjects: Outgassing, geography, Solar wind, geography.geographical_feature_category, Impact crater, Volcano, Asteroid, Micrometeoroid, Regolith, Astrobiology, Plume
Abstract: Returning humans to the Moon presents an unprecedented opportunity to determine the origin of volatiles stored in the permanently shaded regions (PSRs), which trace the history of lunar volcanic activity, solar wind surface chemistry, and volatile delivery to the Earth and Moon through impacts of comets, asteroids, and micrometeoroids. So far, the source of the volatiles sampled by the Lunar Crater Observation and Sensing Satellite (LCROSS) plume (1, 2) has remained undetermined. We show here that the source could not be volcanic outgassing and the composition is best explained by cometary impacts. Ruling out a volcanic source means that volatiles in the top 1–3 meters of the Cabeus PSR regolith may be younger than the latest volcanic outgassing event (~ 1 billion years ago; Gya) (3).
Published: 2021

10. Effect of the UV flux and temperature on the formation of complex organic molecules in astrophysical ices

Author: Olivier Mousis, Laura Isabel Tenelanda-Osorio, Grégoire Danger, Alexis Bouquet, Laboratoire d'Astrophysique de Marseille (LAM), and Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Materials science, [SDU]Sciences of the Universe [physics], Chemical physics, Flux (metabolism), Organic molecules
Abstract: I. Introduction Ices throughout the ISM are exposed to different energetic processes that trigger several reactions and change the com- position of the ice [1–3]. Particularly, ices in stars–forming regions can be subjected to the ultraviolet radiation that comes from the new born stars and triggers reactions in the ice. These ices are normally composed of H2O, CO, CO2, NH3 , methanol (CH3OH), and traces of other molecules. Irradiation–induced reactions in these ices are a source of complex organic molecules (COM) that might later feed the building blocks of planets or other bodies that are being formed. Methanol is one of the main constituents of interstel- lar ices, where its abundance can go up to 30% (with respect to water) [1, 3, 4]. With this in mind, we irradiated pure methanol ice deposited at 20 and 80 K, with UV radiation during different periods of time to evaluate the effect of fluence and temperature in the abundance of volatile COMs that formed. II. Methods All experiments were carried out in the VAHIIA set-up [5]. Briefly, the system consist of an ultrahigh vacuum chamber connected to a GC–MS through a pre–condensation loop. The latter consist of a stainless steel loop that is immersed in liquid nitrogen for the recovery of the volatile COMs coming from the vacuum chamber. This is connected to a custom–made group of valves that allows to recover volatile COMs for their injection in the GS–MS for identification. Species recovered were identified by comparing the chromatographic peak and mass spectra with the standard database, whose retention time and mass spectrum were obtained in the system under the same conditions as the experiments. Pure methanol was deposited in a copper plated surface attached to the tip of the cryostat in the chamber at 20 K. Six periods of time were used: 15 and 30 min, 1, 3, 8 and 24 h, for evaluating different UV fluence. Each experiment consists of five layers of 0.2 mbar of pure methanol ice each, one on top of the other. Each of these layers is irradiated during the period of time under evaluation, with a UV flux of ∼1e13 photons s−1 cm−2, using a flowing H2 microwave–discharge lamp. Layers have been verified to be opaque to the UV photons, ensuring the layer(s) underneath the one being irradiated are not affected further. Once five layers are irradiated, under the same conditions, the chamber is warmed up to ∼ 300 K and volatiles are recovered with the injection of Argon for transferring the sample to the pre–condensation loop. Each experiment consist of 5 layers having received the same irradiation dose to obtain a larger quantity of products, and facilitate their detection and identification with the GC-MS. In addition, experiments were carried out at 80 K to evaluate the effect of the temperature on the abundance of volatiles formed. In this case we evaluated 30 min, 1 h and 24 h of irradiation. III. Effect of fluence 23 molecules were identified after UV–irradiation of methanol ice. Figure 1 shows the absolute area under the total ion content curve of the molecules identified, as a function of the irradiation time. This quantity is a function of the abundance of the compound and is hereafter referred to as integrated TIC. Within functional groups, the same pattern is seen for molecules with different numbers of carbons. Aldehydes are the main functional group that forms. With the exception of formaldehyde, all of them have a similar increase up to 8h of irradiation and then even though the integrated TIC increases, the slope is smaller. Alcohols have a low yield and have a steady integrated TIC. Ethers are produced rapidly and reach high integrated TIC during the first 3-8 h but then, their formation is lower than its usage for the formation of more complex molecules and its integrated TIC drops. Dimethyl Ether (DME) has the highest integrated TIC throughout all experiments. Ketones are the main products with 4 and 5 carbons, and maintain a constant increase with the time of irradiation. Esters and ketones are the only two functional groups identified with up to 5 carbons in the chain. With the exception of methyl formate, esters have a similar pattern. During the first 3 h of irradiation the integrated TIC increases rapidly but between 3-8 h there is a recession. After, the increase is the highest. At 8 h of irradiation several molecules display an inflection point. Aldehydes’s rate of production decreases (the integrated TIC is lower than expected), while the integrated TIC of esters and ketones is higher. Special cases are formaldehyde, DME and dimetoxymethane, who fall under the detection threshold after 24 h of irradiation tends to zero, which indicates they are the main reactants to form the more complex molecules. Fig. 1. Integrated TIC of volatiles formed after UV–irradiation at 20 K. Aldehydes: blue, ethers: yellow, alcohol: black, ketones: green, esters: red. IV. Effect of temperature At 80 K there is a reduction in diversity and integrated TIC of products, and there is no common pattern to describe the functional groups as in section III. Propanol, DME and 1,3,5–trioxane are not identified at anytime. Aldehydes are identified only after 24 h of irradiation, except for isobutyraldeyde that appears at all times. Alcohols and Ethers have a lower yield. Ketones are still produced at all times with constant yield, which suggest an efficient mechanism of formation. References [1] S. Maity, R. I. Kaiser, and B. M. Jones, Physical Chemistry Chemical Physics, vol. 17,no. 5, pp. 3081–3114, 2015. [2] P. de Marcellus, C. Meinert, I. Myrgorodska, L. Nahon, T. Buhse, L. L. S.d’Hendecourt, and U. J. Meierhenrich, PNAS, vol. 112, no. 4, pp. 965–970, 2015. [3] D. Paardekooper, J.-B. Bossa, and H. Linnartz, Astronomy & Astrophysics, vol. 592, p. A67, 2016. [4] A. Bergantini, S. Góbi, M. J. Abplanalp, and R. I. Kaiser, The Astrophysical Journal, vol. 852, no. 2,p. 70, 2018. [5] N. Abou Mrad, F. Duvernay, P. Theulé, T. Chiavassa, and G. Danger, Analytical chemistry, vol. 86, no. 16, pp. 8391–8399, 2014
Published: 2021

11. On the distribution of volatiles in the Galilean moons’ primordial hydrospheres

Author: Laura Isabel Tenelanda-Osorio, Olivier Mousis, Alexis Bouquet, and Grégoire Danger
Published: 2021

12. Science Goals and Mission Objectives for the Future Exploration of Ice Giants Systems: a Horizon 2061 Perspective — Part I: From Science Questions to Measurement Requirements

Author: Marius Millot, Scott Bolton, Diego Turrini, J. Hunter Waite, Kate Craft, Sushil K. Atreya, Glenn S. Orton, Michel Blanc, J. Schmidt, Magali Deleuil, Tibor S. Balint, Kathleen Mandt, Thomas Ronnet, Elizabeth P. Turtle, Pierre Vernazza, Nicolas André, Olivier Mousis, Sean Hsu, Mark Hofstadter, Sébastien Charnoz, David H. Atkinson, Tom Spilker, Krista M. Soderlund, Kunio M. Sayanagi, Ravit Helled, Laurent Lamy, Jonathan I. Lunine, Léa Griton, Frank Postberg, Xianzhe Jia, Ricardo Hueso Alonso, Alexis Bouquet, Linda Spilker, Laboratoire d'Astrophysique de Marseille (LAM), and Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Engineering, [SDU]Sciences of the Universe [physics], Management science, business.industry, Perspective (graphical), business, Ice giant
Abstract: International audience; In this White Paper (part I) we present an analysis of our current knowledge of Ice Giant systems in the light of six key science questions about planetary systems formulated in the ``Planetary Exploration, Horizon 2061'' long-term foresight exercise. We formulate measurement requirements and favored destinations for each of these science questions.
Published: 2021

13. Science Goals and Mission Objectives for the Future Exploration of Ice Giants Systems: a Horizon 2061 Perspective — Part II: Mission scenarios

Author: Linda Spilker, Kunio M. Sayanagi, Nicolas André, Sushil K. Atreya, Kate Craft, Olivier Mousis, Mark Hofstadter, Leigh N. Fletcher, David H. Atkinson, Marius Millot, Tom Spilker, Ravit Helled, Kathleen Mandt, Léa Griton, Frank Postberg, Sean Hsu, Scott Bolton, Xianzhe Jia, Krista M. Soderlund, Juergen Schmidt, Pierre Vernazza, J. Hunter Waite, Laurent Lamy, Elizabeth P. Turtle, Jonathan I. Lunine, Sebastien Charnoz, M. Deleuil, Alexis Bouquet, Tibor S. Balint, Glenn S. Orton, Michel Blanc, Ricardo Hueso, Thomas Ronnet, Diego Turrini, Laboratoire d'Astrophysique de Marseille (LAM), and Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU]Sciences of the Universe [physics], business.industry, Political science, Environmental resource management, Perspective (graphical), business, GeneralLiterature_MISCELLANEOUS, Ice giant
Abstract: International audience; Starting from the six key science objectives for the exploration of planetary systems presented in part I of this White Paper, and from the corresponding measurement requirements for the future exploration of Ice Giants systems, we build a notional road map for a set of missions to these systems that will address most of these science objectives.
Published: 2021

14. Sulfur ion irradiation experiments simulating space weathering of Solar System body surfaces Organosulfur compound formation

Author: Philippe Schmitt-Kopplin, Philippe Boduch, Olivier Mousis, Grégoire Danger, Alexis Bouquet, and Alexander Ruf
Subjects: Physics, Refractory, Minor Planets, Asteroids: General, Comets: General, Methods: Laboratory: Molecular, Astrochemistry, Astrobiology [Solid State], 010504 meteorology & atmospheric sciences, chemistry.chemical_element, Astronomy and Astrophysics, Context (language use), Astrophysics, Photochemistry, 01 natural sciences, Space weathering, Sulfur, Ion, chemistry, 13. Climate action, Space and Planetary Science, 0103 physical sciences, Molecule, Irradiation, 010303 astronomy & astrophysics, Organosulfur compounds, 0105 earth and related environmental sciences
Abstract: Context. Sulfur (S) is of prime interest in the context of (astro)chemical evolution and habitability. However, the origin of S-bearing organic compounds in the Solar System is still not well constrained. Aims. We carried out laboratory experiments to test whether complex organosulfur compounds can be formed when surfaces of icy Solar System bodies are subject to high-energy S ions. Methods. Non-S-bearing organic residues, formed during the processing of astrophysical H2O:CH3OH:NH3-bearing ice analogs, were irradiated with 105 keV-S7+ ions at 10 K and analyzed by high-resolving FT-ICR-MS. The resulting data were comprehensively analyzed, including network analysis tools. Results. Out of several thousands of detected compounds, 16% contain at least one sulfur atom (organosulfur (CHNOS) compounds), as verified via isotopic fine structures. These residue-related organosulfur compounds are different from those formed during the S ion irradiation of ices at 10 K. Furthermore, insoluble, apolar material was formed during the sulfur irradiation of residues. Potential organosulfur precursors (CHNO molecules) were identified by means of molecular networks. Conclusions. This evidence of organosulfur compounds formed by sulfur irradiation of organic residues sheds new light onto the rich and complex scope of pristine organosulfur chemistry in the Solar System, presented in the context of current and future space missions. These results indicate that the space weathering of Solar System bodies may lead to the formation of organosulfur compounds.
Published: 2021

15. Limits on the contribution of early endogenous radiolysis to oxidation in carbonaceous chondrites’ parent bodies

Author: Kelly E. Miller, Alexis Bouquet, Christopher R. Glein, Olivier Mousis, Physique des interactions ioniques et moléculaires (PIIM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Southwest Research Institute [San Antonio] (SwRI), Laboratoire d'Astrophysique de Marseille (LAM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), and Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, Abundance (chemistry), Inorganic chemistry, chemistry.chemical_element, Astronomy and Astrophysics, Context (language use), Astrophysics, 010502 geochemistry & geophysics, 01 natural sciences, Sulfur, chemistry.chemical_compound, chemistry, Meteorite, 13. Climate action, Space and Planetary Science, Chondrite, 0103 physical sciences, Radiolysis, Sulfate, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, Earth (classical element), 0105 earth and related environmental sciences
Abstract: Context.Carbonaceous chondrites have undergone alteration in their parent bodies and display oxidized secondary phases, including sulfates in CI and CM chondrites. The cause of the formation of these sulfates is yet to be determined.Aims.This study investigates the potential of endogenous radiolysis of water (i.e., radiolysis caused by radionuclides present in the rock) on the parent bodies of carbonaceous chondrites. Radiolysis may have contributed to the enhanced degree of oxidation of CI and CM chondrites, and we also examined CV chondrites as a case with no measured sulfates.Methods.We quantified the oxidants produced by radiolysis and how much of the sulfur content could be oxidized to form sulfates by this method. The amount of oxidants was calculated using a radiolytic production model developed and used for Earth and planetary applications that takes into account relevant physical parameters (water-to-rock ratio, grain density) and composition (amount of radionuclides, sulfur content).Results.For CM and CI parent bodies, even using a very favorable set of assumptions, only slightly more than 1% of the available sulfur can be oxidized into sulfates by this process, significantly below the amount of sulfates observed in these chondrites.Conclusions.Endogenous radiolysis is unlikely to have significantly contributed to the abundance of sulfate in CI and CM meteorites. The hypothesis of oxidation of sulfur by large quantities of O2accreted with primitive ice, on the other hand, is quantitatively supported by measurements of O2in comet 67P/Churyumov-Gerasimenko.
Published: 2021

16. Cold Traps of Hypervolatiles in the Protosolar Nebula at the Origin of the Peculiar Composition of Comet C/2016 R2 (PanSTARRS)

Author: Kathleen Mandt, Olivier Mousis, Alexis Bouquet, Artyom Aguichine, A. Luspay-Kuti, Jonathan I. Lunine, Grégoire Danger, Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Physique des interactions ioniques et moléculaires (PIIM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Cornell University [New York], Aix Marseille Université (AMU), Johns Hopkins University (JHU), and Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES)
Subjects: Physics, Nebula, Solar System, 010504 meteorology & atmospheric sciences, Comet, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Astronomy and Astrophysics, Coma (optics), Astrophysics, Key features, 01 natural sciences, Geophysics, 13. Climate action, Space and Planetary Science, Interstellar comet, 0103 physical sciences, Earth and Planetary Sciences (miscellaneous), Composition (visual arts), Formation and evolution of the Solar System, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract: Recent observations of the long-period comet C/2016 R2 (PanSTARRS; hereafter R2) indicate an unusually high N2/CO abundance ratio, typically larger than ∼0.05, and at least 2–3 times higher than the one measured in 67P/Churyumov–Gerasimenko. Another striking compositional feature of this comet is its heavy depletion in H2O (H2O/CO ∼ 0.32%), compared to other comets. Here we investigate the formation circumstances of a generic comet whose composition reproduces these two key features. We first envisage the possibility that this comet agglomerated from clathrates, but we find that such a scenario does not explain the observed low water abundance. We then alternatively investigate the possibility that the building blocks of R2 agglomerated from grains and pebbles made of pure condensates via the use of a disk model describing the radial transport of volatiles. We show that N2/CO ratios reproducing the value estimated in this comet can be found in grains condensed in the vicinity of the CO and N2 ice lines. Moreover, high CO/H2O ratios (>100 times the initial gas-phase value) can be found in grains condensed in the vicinity of the CO ice line. If the building blocks of a comet assembled from such grains, they should present N2/CO and CO/H2O ratios consistent with the measurements made in R2’s coma. Our scenario indicates that R2 formed in a colder environment than the other comets that share more usual compositions. Our model also explains the unusual composition of the interstellar comet 2l/Borisov.
Published: 2021

17. Science Goals and Mission Objectives for the Future Exploration of Ice Giants Systems: A Horizon 2061 Perspective

Author: J. Schmidt, Olivier Mousis, Sébastien Charnoz, Ravit Helled, Krista M. Soderlund, Olivier Witasse, Pierre Vernazza, Elizabeth P. Turtle, Nicolas André, Jonathan I. Lunine, Alexis Bouquet, L. Lamy, Corentin Louis, Magali Deleuil, Kathleen L. Craft, Kathleen Mandt, Léa Griton, Ricardo Hueso, Thomas Ronnet, Michel Blanc, Diego Turrini, University of Zurich, Blanc, Michel, Laboratoire d'Astrophysique de Marseille (LAM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), and Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Solar System, 010504 meteorology & atmospheric sciences, 530 Physics, Computer science, 7. Clean energy, 01 natural sciences, Space exploration, Astrobiology, law.invention, Jupiter, Orbiter, 1912 Space and Planetary Science, Planet, Neptune, law, 0103 physical sciences, 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Uranus, Astronomy and Astrophysics, [SDU]Sciences of the Universe [physics], 13. Climate action, Space and Planetary Science, 10231 Institute for Computational Science, 3103 Astronomy and Astrophysics, Ice giant
Abstract: The comparative study of planetary systems is a unique source of new scientific insight: following the six “key science questions” of the “Planetary Exploration, Horizon 2061” long-term foresight exercise, it can reveal to us the diversity of their objects (Question 1) and of their architectures (Question 2), help us better understand their origins (Question 3) and how they work (Question 4), find and characterize habitable worlds (Question 5), and ultimately, search for alien life (Question 6). But a huge “knowledge gap” exists which limits the applicability of this approach in the solar system itself: two of its secondary planetary systems, the ice giant systems of Uranus and Neptune, remain poorly explored. Starting from an analysis of our current limited knowledge of solar system ice giants and their systems in the light of these six key science questions, we show that a long-term plan for the space exploration of ice giants and their systems will greatly contribute to answer these questions. To do so, we identify the key measurements needed to address each of these questions, the destinations to choose (Uranus, Neptune, Triton or a subset of them), the combinations of space platform(s) and the types of flight sequences needed. We then examine the different launch windows available until 2061, using a Jupiter fly-by, to send a mission to Uranus or Neptune, and find that: (1) an optimized choice of platforms and flight sequences makes it possible to address a broad range of the key science questions with one mission at one of the planets. Combining an atmospheric entry probe with an orbiter tour starting on a high-inclination, low periapse orbit, followed by a sequence of lower inclination orbits (or the other way around) appears to be an optimal choice. (2) a combination of two missions to each of the ice giant systems, to be flown in parallel or in sequence, will address five out of the six key questions and establish the prerequisites to address the sixth one: searching for life at one of the most promising Ice Giant moons. (3) The 2032 Jupiter fly-by window, which offers a unique opportunity to implement this plan, should be considered in priority; if this window cannot be met, using the 2036 Jupiter fly-by window to send a mission to Uranus first, and then the 2045 window for a mission to Neptune, will allow one to achieve the same objectives; as a back-up option, one should consider an orbiter + probe mission to one of the planets and a close fly-by of the other planet to deliver a probe into its atmosphere, using the opportunity of a future mission on its way to Kuiper Belt Objects or the interstellar medium; (4) based on the examination of the habitability of the different moons by the first two missions, a third one can be properly designed to search for life at the most promising moon, likely Triton, or one of the active moons of Uranus. Thus, by 2061 the first two missions of this plan can be implemented and a third mission focusing on the search for life can be designed. Given that such a plan may be out of reach of a single national agency, international collaboration is the most promising way to implement it.
Published: 2020

18. Science Goals and Mission Objectives for the Future Exploration of Ice Giants Systems - A Horizon 2061 Perspective

Author: Michel Blanc, Kathleen Mandt, Olivier Mousis, Nicolas Andre, Alexis Bouquet, Sebastien Charnoz, Kate Craft, Magali Deleuil, Lea Griton, Ravit Helled, Ricardo Hueso, Laurent Lamy, Jonathan Lunine, Thomas Ronnet, Juergen Schmidt, Krista Soderlund, Diego Turrini, Elizabeth Turtle, Pierre Vernazza, and Olivier Witasse
Abstract: The comparative study of the different planetary systems accessible to our observations is a unique source of new scientific insight: it can reveal to us the diversity of these systems and of the objects within them, help us better understand their origins and how they work, find and characterize habitable worlds, and ultimately, search for alien life in our galactic neighborhood. But, in the solar system itself, two of its secondary planetary systems, the ice giant systems, as well as their two main objects, Uranus and Neptune, remain poorly explored. We will present an analysis of our current limited knowledge of these systems in the light of six key science questions about planetary systems formulated in the “Planetary Exploration, Horizon 2061” long-term foresight exercise: (Q1) What is the diversity of planetary systems objects? (Q2) What is the diversity of their architectures? (Q3) What do we know of their origins and formation scenarios? (Q4) How do they work? (Q5) Do they host potential habitats? (Q6) Where and how to search for life? We will show that a long-term plan for the space exploration of ice giants and their systems, complemented by the combination of Earth and space-based observations, will provide major contributions to answers to these six questions. In order to do so, we identify the measurements that must be performed in priority to address each of these questions, the destinations to choose (Uranus, Neptune, Triton or a subset of them), and the combinations of space platform(s) (orbiter, atmospheric entry probe(s), lander…) and of flight sequences needed. Based on this analysis, we look at the different launch windows available until 2061, using a Jupiter fly-by, to send a mission to Uranus or Neptune and find that: (1) a single mission to one of the Ice giants, combining an atmospheric entry probe and an orbiter tour starting on a high-inclination, low-periapse orbit, followed by a sequence of lower- inclination orbits, at least at one of the planets, will make it possible to address a broad range of these key questions; (2) a combination of two well-designed missions to each of the ice giant systems, to be flown in parallel or in sequence, will make it possible to address five out of the six key questions, and to establish the prerequisites for addressing the sixth one. The 2032 Jupiter fly-by window offers a unique opportunity to achieve this goal; (3) if this window cannot be met, using the 2036 Jupiter fly-by window to send a mission to Uranus first, and then the 2045 window for a mission to Neptune, will achieve the same goals. As a back-up option, the feasibility of sending an orbiter + probe mission to one of the planets and using the opportunity of a mission on its way to the interstellar medium to execute a close fly-by of the other planet and deliver a probe into its atmosphere should be studied carefully; (4) based on the expected science return of the first two missions, a third mission focusing on the search for life at a promising moon, namely Triton based on our current knowledge, or perhaps one of the active moons of Uranus after due characterization, can be properly designed. By the 2061 horizon, the first two missions of this plan can be implemented and the design of a third mission focusing on the search for life can be consolidated. Given the likelihood that such a plan may be out of reach of a single national agency, international collaboration is the most promising way to implement it.
Published: 2020

19. Formation of complex organosulfur compounds by sulfur implantation in astrophysical ice analogs – implications for the chemical evolution of the surface of icy objects

Author: Alexander Ruf, Alexis Bouquet, Olivier Mousis, Louis D'Hendecourt, Philippe Schmitt-Kopplin, R. G. Urso, Fabrice Duvernay, Grégoire Danger, Vassilissa Vinogradoff, Philippe Boduch, and Rosario Brunetto
Subjects: Moons of Jupiter, Solar wind, Solar System, Materials science, chemistry, 13. Climate action, Infrared, chemistry.chemical_element, Irradiation, Radiation chemistry, Sulfur, Jovian, Astrobiology
Abstract: Irradiation of ices is a ubiquitous cause of chemical evolution of the surface of icy bodies of the solar system, due to solar UVs, solar wind particles, and magnetospheric particles. Sulfur is present in the solar wind and, in large quantities, in the jovian magnetosphere; in addition of acting as a projectile and inducing radiation chemistry, it is reactive and may be incorporated into the compounds produced. This may be a factor in increasing the chemical complexity of the surface of KBOs, TNOs, and jovian moons.We have performed implantation of 105 keV sulfur ions into a water-methanol-ammonia ice at the Grand Accélérateur National d’Ions Lourds (GANIL) in Caen, France. Similar samples were also irradiated with argon (non-reactive projectiles). The samples were monitored in the infrared during the implantation process. The organic residues left after heating and sublimating the volatiles were then analyzed with Very High Resolution Mass Spectrometry (VHRMS). The infrared spectra of the argon-irradiated and sulfur-irradiated samples are qualitatively the same, but VHRMS shows the residue of the sulfur-irradiated sample contains more than a thousand of CHNOS formulas that are not present in the argon-irradiated sample. This indicates an active and rich sulfur chemistry induced by the implantation. The compounds formed are mostly aliphatic and can reach masses up to 700 amus. We discuss the implications for icy objects of the solar system and other ongoing experiments to explore the chemistry induced by sulfur implantation on the surface of the jovian moons.
Published: 2020

20. Cassini INMS constraints on the composition and latitudinal fractionation of Saturn ring rain material

Author: Christopher R. Glein, Brian Magee, B. Bolton, Rebecca Perryman, Kelly E. Miller, Matthew M. Hedman, J. H. Waite, Alexis Bouquet, T. Brockwell, Mark E. Perry, Laboratoire d'Astrophysique de Marseille (LAM), and Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Atmospheres, 010504 meteorology & atmospheric sciences, Rings of Saturn, Organic chemistry, Astrophysics, Ring (chemistry), Mass spectrometry, 01 natural sciences, Spectral line, Ion, Cosmochemistry, Atmosphere, Saturn, 0103 physical sciences, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Physics, Astronomy and Astrophysics, Space and Planetary Science, composition, [SDU]Sciences of the Universe [physics], Physics::Space Physics, Astrophysics::Earth and Planetary Astrophysics, rings
Abstract: International audience; During Cassini's Grand Finale, the spacecraft flew between Saturn's upper atmosphere and its innermost ring, the D ring. Throughout these final orbits, Cassini encountered material flowing from the D ring into Saturn's atmosphere. Here, we present a compositional analysis of this material using data collected by Cassini's Ion Neutral Mass Spectrometer. We confirm the identification of CH4, CO2, CO, N2, H2O, NH3, and organics in the ring material, and provide upper limits for organic compounds of interest. The H/C, O/C, N/C, and S/C ratios of ring material are constrained using three different kinds of model spectra: automated fits, hand fits of inorganics + hydrocarbons, and hand fits of inorganics + organics with priority given to O-, N-, and S-bearing organics. Additionally, we compare data from the final plunge to earlier orbits, and find that ring material can be divided into gas and dust constituents, with CO2 at the volatility boundary between the two phases. At increasing distance above the equatorial plane, the gas/dust molar ratio increases.
Published: 2020

21. Expected effect of atomic oxygen of Europa's exosphere on the MAss Spectrometer for Planetary EXploration

Author: Ryan C. Blase, Alexis Bouquet, J. Hunter Waite, Tim Brockwell, Laboratoire d'Astrophysique de Marseille (LAM), and Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Materials science, 010504 meteorology & atmospheric sciences, medicine.disease_cause, 01 natural sciences, Antechamber, Astrobiology, Jupiter, symbols.namesake, Sputtering, 0103 physical sciences, medicine, MASPEX, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Spectrometer, Photodissociation, Astronomy and Astrophysics, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Van Allen radiation belt, symbols, Atomic oxygen, Europa, Ultraviolet, Exosphere
Abstract: International audience; The future Europa Clipper NASA mission to Europa will carry the MAss Spectrometer for Planetary EXploration (MASPEX), which will analyze the compounds making up Europa's exosphere, and plumes, if present. Europa's exosphere is likely to feature abundant atomic oxygen, a product of sputtering of Europa's surface by energetic particles from Jupiter's radiation belts, or photolysis of oxygen-bearing molecules in the exosphere. Due to its very high reactivity, this atomic oxygen could induce chemical processes within MASPEX. These processes could involve materials composing the instrument, or other compounds from Europa's exosphere. In both cases, the possible effect on the instrument's measurements is a concern. In this work we first review previous relevant experiments on the effect of atomic oxygen on several candidate metals and conclude that stainless steel with a gold coating is the most satisfactory choice for MASPEX's antechamber walls, and alumina for the impact plate. We then perform simulations of adsorption/desorption processes within the instrument's antechamber to bound the effect of atomic oxygen on other compounds from Europa's exosphere. We find that the accumulation of atomic oxygen during a flyby would lead to a reduction of the apparent abundance of water by as much as 0.125% (Δ[H2O]/[H2O] = -1.25 × 10-3). Evaluating the exact extent of this effect during data post-processing would require constraining the atomic oxygen abundance, which would have to be achieved with other instruments, such as the ultraviolet spectrometer.
Published: 2020

22. Cassini finds molecular hydrogen in the Enceladus plume: Evidence for hydrothermal processes

Author: Mark E. Perry, Scott Bolton, Tim Brockwell, Ben Teolis, J. Grimes, Christopher R. Glein, Greg Miller, Alexis Bouquet, Jonathan I. Lunine, Rebecca Perryman, J. Hunter Waite, Brian Magee, and Kelly E. Miller
Subjects: Multidisciplinary, 010504 meteorology & atmospheric sciences, 01 natural sciences, Hydrothermal circulation, Plume, Astrobiology, Chemical energy, Saturn, 0103 physical sciences, Chemical equilibrium, Enceladus, 010303 astronomy & astrophysics, Chemical composition, Geology, 0105 earth and related environmental sciences, Hydrothermal vent
Abstract: Hydrothermal processes on Enceladus Saturn's moon Enceladus has a subsurface ocean covered by a layer of ice. Some liquid escapes into space through cracks in the ice, which is the source of one of Saturn's rings. In October 2015, the Cassini spacecraft flew directly through the plume of escaping material and sampled its chemical composition. Waite et al. found that the plume contains molecular hydrogen, H 2 , a sign that the water in Enceladus' ocean is reacting with rocks through hydrothermal processes (see the Perspective by Seewald). This drives the ocean out of chemical equilibrium, in a similar way to water around Earth's hydrothermal vents, potentially providing a source of chemical energy. Science , this issue p. 155 ; see also p. 132
Published: 2017

23. Organosulfur Compounds Formed by Sulfur Ion Bombardment of Astrophysical Ice Analogs: Implications for Moons, Comets, and Kuiper Belt Objects

Author: Olivier Mousis, R. G. Urso, Alexander Ruf, Louis Le Sergeant d'Hendecourt, Philippe Boduch, Alexis Bouquet, Rosario Brunetto, Grégoire Danger, Vassilissa Vinogradoff, Fabrice Duvernay, Philippe Schmitt-Kopplin, FRA, DEU, Physique des interactions ioniques et moléculaires (PIIM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Centre de recherche sur les Ions, les MAtériaux et la Photonique (CIMAP - UMR 6252), Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Caen Normandie (UNICAEN), Normandie Université (NU), Helmholtz-Zentrum München (HZM), Technische Universität Munchen - Université Technique de Munich [Munich, Allemagne] (TUM), Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Aix Marseille Université (AMU), Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU), Research Unit Analytical BioGeoChemistry (BGC), Ce travail a bénéficié d'une aide du gouvernement français au titre du ProgrammeInvestissements d’Avenir, Initiative d’Excellence d’Aix-Marseille Université - A*MIDEX, Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Matériaux Avancés (IRMA), Normandie Université (NU)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU)-Institut national des sciences appliquées Rouen Normandie (INSA Rouen Normandie), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Rouen Normandie (UNIROUEN), Institut National des Sciences Appliquées (INSA)-Normandie Université (NU)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Helmholtz Zentrum München = German Research Center for Environmental Health, Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), ANR-16-CE29-0015,RAHIIA_SSOM,Analyses de résidus provenant d'analogues de glace interstellaire pour la compréhension de la formation de la matière organique du Système Solaire(2016), and Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES)
Subjects: Physics, Astrochemistry, 010504 meteorology & atmospheric sciences, Hydrogen, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], chemistry.chemical_element, Astronomy and Astrophysics, Atomic mass unit, 01 natural sciences, Sulfur, Astrobiology, chemistry, 13. Climate action, Space and Planetary Science, [CHIM.ANAL]Chemical Sciences/Analytical chemistry, 0103 physical sciences, Trans-Neptunian object, 010303 astronomy & astrophysics, Organosulfur compounds, Carbon, Refractory (planetary science), ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract: Carbon, hydrogen, nitrogen, oxygen, and sulfur are the main elements involved in the solid-phase chemistry of various astrophysical environments. Among these elements, sulfur chemistry is probably the least well understood. We investigated whether sulfur ion bombardment within simple astrophysical ice analogs (originating from H2O:CH3OH:NH3, 2:1:1) could trigger the formation of complex organosulfur molecules. Over 1100 organosulfur (CHNOS) molecular formulas (12% of all assigned signals) were detected in resulting refractory residues within a broad mass range (from 100 to 900 amu, atomic mass unit). This finding indicates a diverse, rich and active sulfur chemistry that could be relevant for Kuiper Belt objects (KBO) ices, triggered by high-energy ion implantation. The putative presence of organosulfur compounds within KBO ices or on other icy bodies might influence our view on the search of habitability and biosignatures.
Published: 2019

24. How Adsorption Affects the Gas-Ice Partitioning of Organics Erupted from Enceladus

Author: Alexis Bouquet, Christopher R. Glein, J. Hunter Waite, Laboratoire d'Astrophysique de Marseille (LAM), and Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, Adsorption, Space and Planetary Science, [SDU]Sciences of the Universe [physics], planets and satellites: oceans, astrobiology, Astronomy and Astrophysics, Enceladus, planets and satellites: individual: Enceladus, Astrobiology
Abstract: International audience; We study the effect of adsorption of volatile organic compounds (VOCs) in Enceladus’ geysers, both onto the ice grains ejected in the plumes, and onto the ice walls of the cracks connecting Enceladus’ internal ocean to its surface. We use a model of adsorption/desorption based on the Polanyi-Wiegner equation and experimental values of binding energies (energy of desorption E des) of the adsorbed compounds to water ice. We find that under conditions expected at Enceladus, the process of adsorption tends to ensure that the VOCs with the highest binding energy are over-represented on the ice surface, even if their abundance is comparatively lower than those of other compounds. We find that VOCs with E des ≤ 0.5 eV are insignificantly affected by adsorption while compounds with E des ≥ 0.7 eV are readily retained on the surface and compete to occupy most of the adsorption sites. We also deduce that ice grains falling back onto the surface are likely to retain most of the molecules adsorbed on their surface. The implication is that remote observation or sampling of the ice in the cracks or of the surface around it would show a mixture of VOCs that would not be representative of the gas phase of the plumes, with the high E des VOCs dominating the adsorbed phase.
Published: 2019

25. Origin of Molecular Oxygen in Comets: Current Knowledge and Perspectives

Author: Jonathan I. Lunine, Stephen A. Fuselier, Ozge Ozgurel, Y. Ellinger, Kathleen Mandt, F. Pauzat, Ujjwal Raut, B. Brugger, Olivier Mousis, Thomas Ronnet, Alexis Bouquet, Romain Maggiolo, Adrienn Luspay-Kuti, Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de chimie théorique (LCT), and Institut de Chimie du CNRS (INC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, Nebula, 010504 meteorology & atmospheric sciences, Ice, Comet, Astronomy and Astrophysics, Astrobiology, 01 natural sciences, Article, law.invention, Molecular oxygen, Orbiter, Planetary science, [SDU]Sciences of the Universe [physics], Space and Planetary Science, law, Abundance (ecology), Radiolysis, 0103 physical sciences, Comets, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract: International audience; The Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) instrument onboard the Rosetta spacecraft has measured molecular oxygen (O2) in the coma of comet 67P/Churyumov-Gerasimenko (67P/C-G) in surprisingly high abundances. These measurements mark the first unequivocal detection of O2 in a cometary environment. The large relative abundance of O2 in 67P/C-G despite its high reactivity and low interstellar abundance poses a puzzle for its origin in comet 67P/C-G, and potentially other comets. Since its detection, there have been a number of hypotheses put forward to explain the production and origin of O2 in the comet. These hypotheses cover a wide range of possibilities from various in situ production mechanisms to protosolar nebula and primordial origins. Here, we review the O2 formation mechanisms from the literature, and provide a comprehensive summary of the current state of knowledge of the sources and origin of cometary O2.
Published: 2018

26. Appendix

Author: Paul-Alexis Bouquet
Published: 2018

27. Synthesis of Molecular Oxygen via Irradiation of Ice Grains in the Protosolar Nebula

Author: Grégoire Danger, Peter Wurz, Thomas Ronnet, Jonathan I. Lunine, O. Mousis, Romain Maggiolo, Alexis Bouquet, and Aix Marseille Université (AMU)
Subjects: 010504 meteorology & atmospheric sciences, Abundance (chemistry), 530 Physics, Comet, FOS: Physical sciences, Cosmic ray, Astrophysics, 01 natural sciences, 0103 physical sciences, Irradiation, 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Earth and Planetary Astrophysics (astro-ph.EP), Physics, Nebula, Molecular cloud, 520 Astronomy, Astronomy and Astrophysics, 620 Engineering, [SDU]Sciences of the Universe [physics], 13. Climate action, Space and Planetary Science, Radiolysis, Order of magnitude, Astrophysics - Earth and Planetary Astrophysics
Abstract: Molecular oxygen has been detected in the coma of comet 67P/Churyumov--Gerasimenko with a mean abundance of 3.80 $\pm$ 0.85\% by the ROSINA mass spectrometer on board the Rosetta spacecraft. To account for the presence of this species in comet 67P/Churyumov--Gerasimenko, it has been shown that the radiolysis of ice grains precursors of comets is a viable mechanism in low-density environments, such as molecular clouds. Here, we investigate the alternative possibility that the icy grains present in the midplane of the protosolar nebula were irradiated during their vertical transport between the midplane and the upper layers over a large number of cycles, as a result of turbulent mixing. Consequently, these grains spent a non-negligible fraction of their lifetime in the disk's upper regions, where the irradiation by cosmic rays was strong. To do so, we used a coupled disk-transport-irradiation model to calculate the time evolution of the molecular oxygen abundance radiolytically produced in ice grains. Our computations show that, even if a significant fraction of the icy particles have followed a back and forth cycle towards the upper layers of the disk over 10 million of years, a timespan far exceeding the formation timescale of comet 67P/Churyumov--Gerasimenko, the amount of produced molecular oxygen is at least two orders of magnitude lower than the Rosetta observations. We conclude that the most likely scenario remains the formation of molecular oxygen in low-density environments, such as the presolar cloud, prior to the genesis of the protosolar nebula., Accepted for publication in The Astrophysical Journal
Published: 2018

28. The Role of Clathrate Formation in Europa’s Ocean Composition

Author: J. Hunter Waite, Olivier Mousis, Christopher R. Glein, Alexis Bouquet, Grégoire Danger, Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), and Aix Marseille Université (AMU)
Subjects: planets and satellites: individual: Europa, Physics, [SDU]Sciences of the Universe [physics], Space and Planetary Science, Clathrate hydrate, astrobiology, planets and satellites: composition, Astronomy and Astrophysics, Composition (language), planets and satellites: interiors, methods: numerical, Astrobiology
Abstract: International audience; We use a thermodynamic statistical model to evaluate how the composition of Europa’s internal ocean may have been affected by clathrate hydrate formation. Assuming an input of the observed O2 and CO2 from the surface into a mildly acidic ocean (pH < 6), and considering the possibility of contributions by reduced (with CH4 and H2S) or oxidized (CO2-bearing) hydrothermal fluids, we calculate the fractional occupancies in clathrate and deduce the effect on the ocean’s composition. The structure of the clathrate formed, and therefore its density and composition is influenced by the relative amount of O2 compared to the other compounds present. We also include a mixture of noble gases—argon, krypton, and xenon—based on cometary abundances measured at comet 67P and find that the Ar/Kr ratio can be affected by almost two orders of magnitude. In most cases, the formed clathrate is likely to become part of the icy crust, with guest molecules possibly accessible to future in situ measurements by the Europa Clipper and JUICE missions.
Published: 2019

29. Scientific rationale for Saturn's in situ exploration

Author: J. Poncy, C. Briois, D. Gautier, Jean-Pierre Lebreton, Andrew Morse, T. R. Spilker, Alexis Bouquet, K. Reh, T. Kostiuk, W. D Geppertt, Pgj Irwin, Ricardo Hueso, J. M. Petit, Carl D. Murray, David H. Atkinson, Matthew S. Tiscareno, Scott Bolton, Ravit Helled, Agustín Sánchez-Lavega, Matthew M. Hedman, S. Guerlet, A. Coustenis, Peter Wurz, James O'Donoghue, Kathrin Altwegg, D Lebleu, François-Xavier Schmider, Mohamad Ali-Dib, Georg Fischer, Nadine Nettelmann, Thibault Cavalié, Amy Simon, Aymeric Spiga, Michel Blanc, Olivia Venot, G. S. Orton, Tristan Guillot, Sushil K. Atreya, Miriam Rengel, O. Mousis, N. André, R. Moreno, J. H. Waite, Philippe Rousselot, Emmanuel Lellouch, Leigh N. Fletcher, Ioannis A. Daglis, Bernard Marty, Jonathan I. Lunine, Régis Courtin, Thierry Fouchet, Univers, Transport, Interfaces, Nanostructures, Atmosphère et environnement, Molécules ( UTINAM ), Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Franche-Comté ( UFC ), University of Leicester, Physikalisches Institut [Bern], Universität Bern [Bern], ASP 2016, Laboratoire d'Astrophysique de Bordeaux [Pessac] ( LAB ), Université de Bordeaux ( UB ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Bordeaux ( UB ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire d'études spatiales et d'instrumentation en astrophysique ( LESIA ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire de Paris-Université Paris Diderot - Paris 7 ( UPD7 ) -Centre National de la Recherche Scientifique ( CNRS ), Service de parasitologie - mycologie [CHU Pitié-Salpétrière], Assistance publique - Hôpitaux de Paris (AP-HP)-CHU Pitié-Salpêtrière [APHP], Tel Aviv University [Tel Aviv], Department of Atmospheric, Oceanic and Planetary Physics [Oxford] ( AOPP ), University of Oxford [Oxford], Centre de Recherches Pétrographiques et Géochimiques ( CRPG ), Université de Lorraine ( UL ) -Centre National de la Recherche Scientifique ( CNRS ), Le Collège d'études mondiales/FMSH, Fondation Maison des sciences de l'homme, K.U.Leuven, Centre for Medical Imaging, University College London, London, United Kingdom, Space Science Division [San Antonio], Southwest Research Institute [San Antonio] ( SwRI ), Jet Propulsion Laboratory ( JPL ), NASA-California Institute of Technology ( CALTECH ), Université Claude Bernard Lyon 1 ( UCBL ), Université de Lyon, Institut Lumière Matière [Villeurbanne] ( ILM ), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique ( CNRS ), Géomatériaux et Modèles Géotechniques ( IFSTTAR/GERS/GMG ), Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux ( IFSTTAR ) -PRES Université Nantes Angers Le Mans ( UNAM ), National Observatory of Athens ( NOA ), Department of Physics [Stockholm], Stockholm University, Stockholm University Astrobiology Centre, Joseph Louis LAGRANGE ( LAGRANGE ), Université Nice Sophia Antipolis ( UNS ), Université Côte d'Azur ( UCA ) -Université Côte d'Azur ( UCA ) -Observatoire de la Côte d'Azur, Université Côte d'Azur ( UCA ) -Centre National de la Recherche Scientifique ( CNRS ), University of Idaho [Moscow, USA], Departamento de Fisica Aplicada [Bilbao], Universidad del Pais Vasco / Euskal Herriko Unibertsitatea ( UPV/EHU ), Department of Astronomy [Ithaca], Cornell University, Max-Planck-Institut für Sonnensystemforschung ( MPS ), Université Pierre et Marie Curie - Paris 6 ( UPMC ), Laboratoire de Météorologie Dynamique (UMR 8539) ( LMD ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -École polytechnique ( X ) -École des Ponts ParisTech ( ENPC ) -Centre National de la Recherche Scientifique ( CNRS ) -Département des Géosciences - ENS Paris, École normale supérieure - Paris ( ENS Paris ) -École normale supérieure - Paris ( ENS Paris ), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] ( LSCE ), Université de Versailles Saint-Quentin-en-Yvelines ( UVSQ ) -Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Paris-Saclay-Centre National de la Recherche Scientifique ( CNRS ), Amélioration génétique et adaptation des plantes méditerranéennes et tropicales ( UMR AGAP ), Institut national de la recherche agronomique [Montpellier] ( INRA Montpellier ) -Centre international d'études supérieures en sciences agronomiques ( Montpellier SupAgro ) -Centre de Coopération Internationale en Recherche Agronomique pour le Développement ( CIRAD ) -Institut national d’études supérieures agronomiques de Montpellier ( Montpellier SupAgro ), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace ( LPC2E ), Institut national des sciences de l'Univers ( INSU - CNRS ) -Université d'Orléans ( UO ) -Centre National de la Recherche Scientifique ( CNRS ), NASA Goddard Space Flight Center ( GSFC ), Univers, Transport, Interfaces, Nanostructures, Atmosphère et environnement, Molécules (UMR 6213) (UTINAM), Université de Franche-Comté (UFC)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Department of Atmospheric, Oceanic and Planetary Physics [Oxford] (AOPP), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Sonnensystemforschung (MPS), Max-Planck-Gesellschaft, The Open University [Milton Keynes] (OU), Institut für Physik [Rostock], Universität Rostock, Centre de Recherches Pétrographiques et Géochimiques (CRPG), Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Catholic University of Leuven - Katholieke Universiteit Leuven (KU Leuven), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Southwest Research Institute [San Antonio] (SwRI), NASA Goddard Space Flight Center (GSFC), University of Michigan [Ann Arbor], University of Michigan System, Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), National Observatory of Athens (NOA), Austrian Academy of Sciences (OeAW), Joseph Louis LAGRANGE (LAGRANGE), Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Universidad del Pais Vasco / Euskal Herriko Unibertsitatea [Espagne] (UPV/EHU), Queen Mary University of London (QMUL), Department of Physics and Astronomy [Leicester], Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris)-École normale supérieure - Paris (ENS Paris), Center for Radiophysics and Space Research [Ithaca] (CRSR), Thales Alenia Space [Cannes], Thales Alenia Space, Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), California Institute of Technology (CALTECH)-NASA, Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Cornell University [New York], École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Centre National d’Études Spatiales [Paris] (CNES), University of Oxford, Universität Bern [Bern] (UNIBE), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Tel Aviv University (TAU), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Thales Alenia Space [Toulouse] (TAS), THALES [France], Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Assistance publique - Hôpitaux de Paris (AP-HP) (APHP)-CHU Pitié-Salpêtrière [APHP], Fondation Maison des sciences de l'homme (FMSH), Université Claude Bernard Lyon 1 (UCBL), Institut Lumière Matière [Villeurbanne] (ILM), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Géomatériaux et Modèles Géotechniques (IFSTTAR/GERS/GMG), Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-PRES Université Nantes Angers Le Mans (UNAM), Université Pierre et Marie Curie - Paris 6 (UPMC), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), and Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Exploration of Saturn, Solar System, 010504 meteorology & atmospheric sciences, [ PHYS.ASTR ] Physics [physics]/Astrophysics [astro-ph], Galileo Probe, Entry probe, FOS: Physical sciences, 7. Clean energy, 01 natural sciences, Astrobiology, Solar system formation, Jupiter, Giant planet formation, Planet, Saturn, 0103 physical sciences, Elemental and isotopic composition, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Physics, Earth and Planetary Astrophysics (astro-ph.EP), Giant planet, In situ measurements, Astronomy, Astronomy and Astrophysics, 13. Climate action, Space and Planetary Science, Physics::Space Physics, Saturn atmosphere, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Ice giant, Astrophysics - Earth and Planetary Astrophysics
Abstract: Remote sensing observations meet some limitations when used to study the bulk atmospheric composition of the giant planets of our solar system. A remarkable example of the superiority of in situ probe measurements is illustrated by the exploration of Jupiter, where key measurements such as the determination of the noble gases abundances and the precise measurement of the helium mixing ratio have only been made available through in situ measurements by the Galileo probe. This paper describes the main scientific goals to be addressed by the future in situ exploration of Saturn placing the Galileo probe exploration of Jupiter in a broader context and before the future probe exploration of the more remote ice giants. In situ exploration of Saturn's atmosphere addresses two broad themes that are discussed throughout this paper: first, the formation history of our solar system and second, the processes at play in planetary atmospheres. In this context, we detail the reasons why measurements of Saturn's bulk elemental and isotopic composition would place important constraints on the volatile reservoirs in the protosolar nebula. We also show that the in situ measurement of CO (or any other disequilibrium species that is depleted by reaction with water) in Saturn's upper troposphere would constrain its bulk O/H ratio. We highlight the key measurements required to distinguish competing theories to shed light on giant planet formation as a common process in planetary systems with potential applications to most extrasolar systems. In situ measurements of Saturn's stratospheric and tropospheric dynamics, chemistry and cloud-forming processes will provide access to phenomena unreachable to remote sensing studies. Different mission architectures are envisaged, which would benefit from strong international collaborations., Comment: Submitted to Planetary and Space Science
Published: 2016

30. Limits on the Contribution of Endogenic Radiolysis to the Presence of Molecular Oxygen in Comet 67P/Churyumov–Gerasimenko

Author: Ozge Ozgurel, B. D. Teolis, J. Hunter Waite, Alexis Bouquet, Y. Ellinger, Georgios Nicolaou, Thomas Ronnet, Olivier Mousis, F. Pauzat, UTSA Department of Physics and Astronomy [San Antonio], The University of Texas at San Antonio (UTSA), Space Science and Engineering Division [San Antonio], Southwest Research Institute [San Antonio] (SwRI), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Swedish Institute of Space Physics [Kiruna] (IRF), Mullard Space Science Laboratory (MSSL), University College of London [London] (UCL), Laboratoire de chimie théorique (LCT), and Institut de Chimie du CNRS (INC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [PHYS]Physics [physics], Physics, Radionuclide, Astrochemistry, 010504 meteorology & atmospheric sciences, Analytical chemistry, Astronomy and Astrophysics, Radiation, 01 natural sciences, Mantle (geology), Space and Planetary Science, Comet nucleus, 0103 physical sciences, Radiolysis, [CHIM]Chemical Sciences, Molecular oxygen, 010303 astronomy & astrophysics, Order of magnitude, 0105 earth and related environmental sciences
Abstract: Radiolytic production has been proposed as a potential source for the molecular oxygen observed in comet 67P/Churyumov–Gerasimenko. Radiolysis can be exogenic or endogenic, the latter due to radionuclides present in the dust constitutive of the comet nucleus. We investigated the possibility of forming a significant amount of molecular oxygen through endogenic radiolysis. We applied a model of radiolytic production, developed for an Earth rock–water mixture, and improved it to account for the effect of the size of a radionuclide-bearing grain on the net radiation deposited in its ice mantle. We calculated the possible production of molecular oxygen considering the available experimental values of radiolytic yields. We found that endogenic radiolysis cannot account for the totality of the 3.8% (relative to water) O2 abundance derived from the ROSINA observations, with an end member case of our model producing at most a 1% abundance. By contrast, we predict H2O2 production leads to an abundance up to two orders of magnitude above observed values.
Published: 2018

31. Methane clathrates in the solar system

Author: Yuri Aikawa, Mohamad Ali-Dib, Wolf D. Geppert, Alexis Bouquet, Eric Chassefière, Jack H. Waite, Sylvain Picaud, Jean Luc Charlou, Nils G. Holm, Philippe Rousselot, Olivier Mousis, Laboratoire d'Astrophysique de Marseille (LAM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Univers, Transport, Interfaces, Nanostructures, Atmosphère et environnement, Molécules (UMR 6213) (UTINAM), Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Géosciences Paris Sud (GEOPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Department of Geological Sciences [Stockholm], Stockholm University, Space Science and Engineering Division [San Antonio], Southwest Research Institute [San Antonio] (SwRI), The University of Texas at San Antonio (UTSA), Department of Physics [Stockholm], Stockholm University Astrobiology Centre, Department of Earth and Planetary Sciences [Kobe], Kobe University, Unité de recherche Géosciences Marines (Ifremer) (GM), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), and Géosciences Marines (GM)
Subjects: Solar System, Materials science, 010504 meteorology & atmospheric sciences, Extraterrestrial Environment, FOS: Physical sciences, Planets, Permafrost, 01 natural sciences, Methane, Astrobiology, Atmosphere, chemistry.chemical_compound, Planet, 0103 physical sciences, Cryosphere, 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Martian, Earth and Planetary Astrophysics (astro-ph.EP), Mars Exploration Program, Agricultural and Biological Sciences (miscellaneous), chemistry, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Crystallization, Astrophysics - Earth and Planetary Astrophysics
Abstract: We review the reservoirs of methane clathrates that may exist in the different bodies of the Solar System. Methane was formed in the interstellar medium prior to having been embedded in the protosolar nebula gas phase. This molecule was subsequently trapped in clathrates that formed from crystalline water ice during the cooling of the disk and incorporated in this form into the building blocks of comets, icy bodies, and giant planets. Methane clathrates may play an important role in the evolution of planetary atmospheres. On Earth, the production of methane in clathrates is essentially biological, and these compounds are mostly found in permafrost regions or in the sediments of continental shelves. On Mars, methane would more likely derive from hydrothermal reactions with olivine-rich material. If they do exist, martian methane clathrates would be stable only at depth in the cryosphere and sporadically release some methane into the atmosphere via mechanisms that remain to be determined. In the case of Titan, most of its methane probably originates from the protosolar nebula, where it would have been trapped in the clathrates agglomerated by the satellite's building blocks. Methane clathrates are still believed to play an important role in the present state of Titan. Their presence is invoked in the satellite's subsurface as a means of replenishing its atmosphere with methane via outgassing episodes. The internal oceans of Enceladus and Europa also provide appropriate thermodynamic conditions that allow formation of methane clathrates. In turn, these clathrates might influence the composition of these liquid reservoirs. Finally, comets and Kuiper Belt Objects might have formed from the agglomeration of clathrates and pure ices in the nebula. The methane observed in comets would then result from the destabilization of clathrate layers in the nuclei concurrent with their approach to perihelion. Thermodynamic equilibrium calculations show that methane-rich clathrate layers may exist on Pluto as well. Key Words: Methane clathrate-Protosolar nebula-Terrestrial planets-Outer Solar System. Astrobiology 15, 308-326.
Published: 2015

32. Possible evidence for a methane source in Enceladus' ocean

Author: J. Hunter Waite, Olivier Mousis, Sylvain Picaud, Alexis Bouquet, Laboratoire d'Astrophysique de Marseille (LAM), and Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Clathrate hydrate, Trapping, 01 natural sciences, Hydrothermal circulation, Methane, Plume, Astrobiology, chemistry.chemical_compound, Geophysics, chemistry, 13. Climate action, 0103 physical sciences, Subglacial lake, General Earth and Planetary Sciences, Polar, 14. Life underwater, Enceladus, 010303 astronomy & astrophysics, Geology, 0105 earth and related environmental sciences
Abstract: International audience; The internal ocean of Enceladus can be expected to present conditions favorable to the trapping of volatiles in clathrates. This process could influence the eventual composition of the ocean and therefore of the plumes emitted by the south polar region. Here we used a statistical thermodynamic model to assess which species detected in the plumes by the Cassini-Ion and Neutral Mass Spectrometer experiment are trapped in clathrates. We treated Enceladus' internal ocean as a terrestrial subglacial lake with a mixture of dissolved volatiles indicated by plume gas measurements. We find that the conditions for clathrate formation are met in this ocean, except above 20km or in hypothetical hot spots. The formation of multiple guest clathrates depletes methane below plume levels, suggesting that clathrates eventually dissociate (releasing methane) in the fissure that connects the ocean to the surface or that another mechanism (such as hydrothermal reactions) is compensating by adding methane into the ocean.
Published: 2015

33. Alternative Energy: Production of H 2 by Radiolysis of Water in the Rocky Cores of Icy Bodies

Author: Danielle Y. Wyrick, Alexis Bouquet, Christopher R. Glein, and J. Hunter Waite
Subjects: Physics, 010504 meteorology & atmospheric sciences, Hydrogen, chemistry.chemical_element, Astronomy and Astrophysics, 01 natural sciences, Oberon, Outer core, Astrobiology, Pluto, Chemical energy, chemistry, Space and Planetary Science, 0103 physical sciences, Radiolysis, Enceladus, Porosity, 010303 astronomy & astrophysics, computer, 0105 earth and related environmental sciences, computer.programming_language
Abstract: We applied a model of radiolysis in earthly rock–water mixtures to several known or suspected ocean worlds: Enceladus, Ceres, Europa, Titania, Oberon, Pluto, and Charon. In this model, radiation emitted by the long-lived radionuclides (40K, 232Th, 235U, and 238U) contained in the ordinary chondrite-like rocks is partly absorbed by the water permeating the material of each body's core. The physical and chemical processes that follow release molecular hydrogen (H2), which is a molecule of astrobiological interest. We compared the calculated production of H2 by radiolysis in each body's core to published estimates of production by serpentinization. This study presents production calculations over 4.5 Gyr for several values of rock porosity. We found that radiolysis can produce H2 quantities equivalent to a few percent of what is estimated from serpentinization. Higher porosity, which is unlikely at the scale of a body's entire core but possible just under the seafloor, can increase radiolytic production by almost an order of magnitude. The products of water radiolysis also include several oxidants, allowing for production of life-sustaining sulfates. Though previously unrecognized in this capacity, radiolysis in an ocean world's outer core could be a fundamental agent in generating the chemical energy that could support life.
Published: 2017

34. Instrumental Methods for Professional and Amateur Collaborations in Planetary Astronomy

Author: A. Leroy, Sylvain Bouley, John H. Rogers, Paolo Tanga, J. Guarro-Flo, Emmanuel Jehin, Gianluca Masi, C. Buil, Ricardo Hueso, H. B. Hammel, M. Vanhuysse, C. Pellier, A. S. Rajpurohit, P. Drossart, David Baratoux, G. S. Orton, Alice Decock, N. Esseiva, Anny Chantal Levasseur-Regourd, J. M. Gómez-Forrellad, C. Rinner, Georg Fischer, F. Meyer, A. Klotz, Jean Lecacheux, M. Ali Dib, T. Boehm, E. Frappa, F. Colas, Alain Maury, Françoise Roques, Philippe Rousselot, Vincent Boudon, J. P. Beaulieu, Alexandre Santerne, Santiago Pérez-Hoyos, Benoit Carry, R. W. Schmude, A. Wesley, B. Tregon, Thomas Widemann, Leigh N. Fletcher, Brigitte Zanda, Agustín Sánchez-Lavega, W. Beisker, M. Delcroix, Bruno Sicardy, F. Kugel, O. Mousis, D. Herald, S. Foglia, J. M. Petit, Jeremie Vaubaillon, L. Maquet, Mirel Birlan, A. Delsanti, L. Buzzi, Jean-Luc Dauvergne, Jean-Pierre Lebreton, Alexis Bouquet, Univers, Transport, Interfaces, Nanostructures, Atmosphère et environnement, Molécules (UMR 6213) (UTINAM), Université de Franche-Comté (UFC)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Escuela Tecnica Superior de Ingenieria Bilbao, Institut d'Astrophysique de Paris (IAP), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Géosciences Paris Sud (GEOPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE), Centre National de la Recherche Scientifique (CNRS)-Université de Lille-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Observatoire de Haute-Provence (OHP), Institut Pythéas (OSU PYTHEAS), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Centre National de la Recherche Scientifique (CNRS), International Occultation Timing Association European Section (IOTA ES), International Occultation Timing Association European Section, Centre National d'Études Spatiales [Toulouse] (CNES), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, Euraster, Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Universidad del Pais Vasco / Euskal Herriko Unibertsitatea [Espagne] (UPV/EHU), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Cosmologie, Astrophysique Stellaire & Solaire, de Planétologie et de Mécanique des Fluides (CASSIOPEE), Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS), Department of Earth and Planetary Sciences [Piscataway], Rutgers, The State University of New Jersey [New Brunswick] (RU), Rutgers University System (Rutgers)-Rutgers University System (Rutgers), Dynamique terrestre et planétaire (DTP), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Laboratoire Astrophysique de Toulouse-Tarbes (LATT), Centre National de la Recherche Scientifique (CNRS)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Laboratoire Interdisciplinaire Carnot de Bourgogne (LICB), Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS), Institut du Porc, Société Astronomique de France (SAF), Association AstroQueyras, Canberra Astronomical Society, Institut d'Astrophysique et de Géophysique [Liège], Université de Liège, Observatoire Chante-Perdrix, Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), European Southern Observatory (ESO), Departamento de Fı'sica Aplicada I, Association des Utilisateurs de Détecteurs Electroniques (AUDE), Association des Utilisateurs de Détecteurs Electroniques, Association T60, Observatoire Midi-Pyrénées, Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées, Chercheur indépendant, Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), PSL Research University (PSL)-PSL Research University (PSL)-Université de Lille-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut UTINAM (Univers, transport, interfaces, nanostructures, atmosphère et environnement, molécules) (Besançon), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), Departamento de Fisica Aplicada [Bilbao], Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), European Space Astronomy Centre (ESAC), Agence Spatiale Européenne = European Space Agency (ESA), Institut de recherche en astrophysique et planétologie (IRAP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France, Observatoire Castanet, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Association of Universities for Research in Astronomy (AURA), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centro de Astrofísica da Universidade do Porto (CAUP), Universidade do Porto = University of Porto, Joseph Louis LAGRANGE (LAGRANGE), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de recherche pour le développement [IRD] : UR206-Centre National de la Recherche Scientifique (CNRS), Laboratoire Interdisciplinaire Carnot de Bourgogne (ICB), Osservatorio Astronomico Schiaparelli, Association Française d'Astronomie - Ciel et Espace (AFA), Association Française d'Astronomie, Département d'astrophysique, Géophysique et Océanographie (AGO), Space Research Institute of Austrian Academy of Sciences (IWF), Austrian Academy of Sciences (OeAW), Department of Atmospheric, Oceanic and Planetary Physics [Oxford] (AOPP), University of Oxford, Astronomical Research Institute [Ashmore], Fundació Privada Observatori Esteve Duran, Astronomical Ring for Access to Spectroscopy (ARAS), International Occultation Timing Association (IOTA), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), L'Uranoscope de l'Ile de France, Observatoire de Gretz-Armainvilliers, Department of Physics [Roma Tor Vergata], Università degli Studi di Roma Tor Vergata [Roma], San Pedro de Atacama Celestial Explorations (SPACE), San Pedro de Atacama Celestial Explorations, Observatoire Oukaimeden, JUPOS - Database for Object Positions on Jupiter, British Astronomical Association (BAA), Gordon State College, Laboratoire Ondes et Matière d'Aquitaine (LOMA), Université de Bordeaux (UB)-Centre National de la Recherche Scientifique (CNRS), OverSky, Univers, Transport, Interfaces, Nanostructures, Atmosphère et environnement, Molécules ( UTINAM ), Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Franche-Comté ( UFC ), Universidad del Pais Vasco / Euskal Herriko Unibertsitatea ( UPV/EHU ), Institut d'Astrophysique de Paris ( IAP ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Institut de Mécanique Céleste et de Calcul des Ephémérides ( IMCCE ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire de Paris-Université de Lille-Centre National de la Recherche Scientifique ( CNRS ), Géosciences Paris Sud ( GEOPS ), Université Paris-Sud - Paris 11 ( UP11 ) -Centre National de la Recherche Scientifique ( CNRS ), European Space Astronomy Center ( ESAC ), European Space Agency ( ESA ), Institut de recherche en astrophysique et planétologie ( IRAP ), Université Paul Sabatier - Toulouse 3 ( UPS ) -Observatoire Midi-Pyrénées ( OMP ) -Centre National de la Recherche Scientifique ( CNRS ), Société Astronomique de France ( SAF ), International Occultation Timing Association European Section ( IOTA ES ), Observatoire Midi-Pyrénées ( OMP ), Laboratoire d'études spatiales et d'instrumentation en astrophysique ( LESIA ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire de Paris-Université Paris Diderot - Paris 7 ( UPD7 ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire d'Astrophysique de Marseille ( LAM ), Aix Marseille Université ( AMU ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National d'Etudes Spatiales ( CNES ) -Centre National de la Recherche Scientifique ( CNRS ), Association of Universities for Research in Astronomy ( AURA ), IMPEC - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales ( LATMOS ), Université de Versailles Saint-Quentin-en-Yvelines ( UVSQ ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Versailles Saint-Quentin-en-Yvelines ( UVSQ ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), Jet Propulsion Laboratory ( JPL ), NASA-California Institute of Technology ( CALTECH ), Centro de Astrofísica da Universidade do Porto ( CAUP ), Universidade do Porto [Porto], Joseph Louis LAGRANGE ( LAGRANGE ), Université Nice Sophia Antipolis ( UNS ), Université Côte d'Azur ( UCA ) -Université Côte d'Azur ( UCA ) -Observatoire de la Côte d'Azur, Université Côte d'Azur ( UCA ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire de Minéralogie et Cosmochimie du Museum (LMCM), UMR 7202 ( LMCM ), Muséum National d'Histoire Naturelle ( MNHN ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire Interdisciplinaire Carnot de Bourgogne ( LICB ), Université de Bourgogne ( UB ) -Centre National de la Recherche Scientifique ( CNRS ), Observatoire Midi-Pyrénées and Association T60, Association Française d'Astronomie - Ciel et Espace ( AFA ), Département d'astrophysique, Géophysique et Océanographie ( AGO ), Space Research Institute of Austrian Academy of Sciences ( IWF ), Austrian Academy of Sciences ( OeAW ), Department of Atmospheric, Oceanic and Planetary Physics [Oxford] ( AOPP ), University of Oxford [Oxford], Astronomical Research Institute {Ashmore], Astronomical Ring for Access to Spectroscopy ( ARAS ), Astronomical Ring for Access to Spectroscopy, International Occultation Timing Association ( IOTA ), International Occultation Timing Association, Laboratoire de Physique et Chimie de l'Environnement et de l'Espace ( LPC2E ), Institut national des sciences de l'Univers ( INSU - CNRS ) -Université d'Orléans ( UO ) -Centre National de la Recherche Scientifique ( CNRS ), Department of Physics [Roma], San Pedro de Atacama Celestial Explorations ( SPACE ), British Astronomical Association ( BAA ), University System of Georgia ( USG ), Laboratoire Ondes et Matière d'Aquitaine ( LOMA ), Université de Bordeaux ( UB ) -Centre National de la Recherche Scientifique ( CNRS ), Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), European Space Agency (ESA), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Universidade do Porto, Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de recherche pour le développement [IRD] : UR206-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Engineering, [PHYS.ASTR.IM]Physics [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], 010504 meteorology & atmospheric sciences, [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], FOS: Physical sciences, Planetary Astronomy, 01 natural sciences, Imaging, Photometry, Physics::Popular Physics, Planet, 0103 physical sciences, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, Spectroscopy, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Earth and Planetary Astrophysics (astro-ph.EP), Professional-amateur collaborations, business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, [ SDU.ASTR.IM ] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Astronomy and Astrophysics, [ SDU.ASTR.EP ] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Data science, Exoplanet, Physics::History of Physics, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Planetary science, [ PHYS.ASTR.EP ] Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Space and Planetary Science, Asteroid, Physics::Space Physics, Astrophysics::Earth and Planetary Astrophysics, [ PHYS.ASTR.IM ] Physics [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Interplanetary spaceflight, business, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Instrumentation and Methods for Astrophysics, Amateur, Astrophysics - Earth and Planetary Astrophysics
Abstract: Amateur contributions to professional publications have increased exponentially over the last decades in the field of Planetary Astronomy. Here we review the different domains of the field in which collaborations between professional and amateur astronomers are effective and regularly lead to scientific publications. We discuss the instruments, detectors, softwares and methodologies typically used by amateur astronomers to collect the scientific data in the different domains of interest. Amateur contributions to the monitoring of planets and interplanetary matter, characterization of asteroids and comets, as well as the determination of the physical properties of Kuiper Belt Objects and exoplanets are discussed., 123 pages, Accepted for publication in Experimental Astronomy
Published: 2013

35. PITS FORMATION FROM VOLATILE OUTGASSING ON 67P/CHURYUMOV–GERASIMENKO

Author: Pierre Vernazza, Nicolas Thomas, J. S. Kargel, A.-T. Auger, Philippe Lamy, Alexis Bouquet, Laurent Jorda, Aurélie Guilbert-Lepoutre, Olivier Mousis, B. Brugger, Holger Sierks, Univers, Transport, Interfaces, Nanostructures, Atmosphère et environnement, Molécules (UMR 6213) (UTINAM), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), and Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)
Subjects: Earth and Planetary Astrophysics (astro-ph.EP), Physics, Solar System, 010504 meteorology & atmospheric sciences, Clathrate hydrate, FOS: Physical sciences, Mineralogy, Astronomy and Astrophysics, 01 natural sciences, Mantle (geology), law.invention, Outgassing, 13. Climate action, Space and Planetary Science, law, 0103 physical sciences, Amorphous ice, Sublimation (phase transition), Crystallization, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Porosity, 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, Astrophysics - Earth and Planetary Astrophysics, 0105 earth and related environmental sciences
Abstract: We investigate the thermal evolution of comet 67P/Churyumov-Gerasimenko's subsurface in the Seth_01 region, where active pits have been observed by the ESA/Rosetta mission. Our simulations show that clathrate destabilization and amorphous ice crystallization can occur at depths corresponding to those of the observed pits in a timescale shorter than 67P/Churyumov-Gerasimenko's lifetime in the comet's activity zone in the inner solar system. Sublimation of crystalline ice down to such depths is possible only in the absence of a dust mantle, which requires the presence of dust grains in the matrix small enough to be dragged out by gas from the pores. Our results are consistent with both pits formation via sinkholes or subsequent to outbursts, the dominant process depending on the status of the subsurface porosity. A sealed dust mantle would favor episodic and disruptive outgassing as a result of an increasing gas pressure in the pores, while a high porosity should allow the formation of large voids in the subsurface due to the continuous escape of volatiles. We finally conclude that the subsurface of 67P/Churyumov-Gerasimenko is not uniform at a spatial scale of 100-200~m., Accepted for publication in The Astrophysical Journal Letters
Published: 2015

36. Plume and surface feature structure and compositional effects on Europa's global exosphere: Preliminary Europa mission predictions

Author: Alexis Bouquet, B. D. Teolis, Danielle Y. Wyrick, J. H. Waite, and Brian Magee
Subjects: 010504 meteorology & atmospheric sciences, Ices, Abundances, atmospheres, 01 natural sciences, Jovian, Astrobiology, Jupiter, Atmospheres, dynamics, Volcanism, 0103 physical sciences, Diffusion (business), Ejecta, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Astronomy and Astrophysics, Satellites, atmospheres, Regolith, Jupiter, satellites, Plume, Space and Planetary Science, Polar, Europa, Geology, Satellites, composition, Exosphere
Abstract: A Europa plume source, if present, may produce a global exosphere with complex spatial structure and temporal variability in its density and composition. To investigate this interaction we have integrated a water plume source containing multiple organic and nitrile species into a Europan Monte Carlo exosphere model, considering the effect of Europa's gravity in returning plume ejecta to the surface, and the subsequent spreading of adsorbed and exospheric material by thermal desorption and re-sputtering across the entire body. We consider sputtered, radiolytic and potential plume sources, together with surface adsorption, regolith diffusion, polar cold trapping, and re-sputtering of adsorbed materials, and examine the spatial distribution and temporal evolution of the exospheric density and composition. These models provide a predictive basis for telescopic observations (e.g. HST, JWST) and planned missions to the Jovian system by NASA and ESA. We apply spacecraft trajectories to our model to explore possible exospheric compositions which may be encountered along proposed flybys of Europa to inform the spatial and temporal relationship of spacecraft measurements to surface and plume source compositions. For the present preliminary study, we have considered four cases: Case A: an equatorial flyby through a sputtered only exosphere (no plumes), Case B: a flyby over a localized sputtered ‘macula’ terrain enriched in non-ice species, Case C: a south polar plume with an Enceladus-like composition, equatorial flyby, and Case D: a south polar plume, flyby directly through the plume.
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37. Organosulfur Compounds Formed by Sulfur Ion Bombardment of Astrophysical Ice Analogs: Implications for Moons, Comets, and Kuiper Belt Objects.

Author: Alexander Ruf, Alexis Bouquet, Philippe Boduch, Philippe Schmitt-Kopplin, Vassilissa Vinogradoff, Fabrice Duvernay, Riccardo Giovanni Urso, Rosario Brunetto, Louis Le Sergeant d’Hendecourt, Olivier Mousis, and Grégoire Danger
Published: 2019
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38. The Role of Clathrate Formation in Europa’s Ocean Composition.

Author: Alexis Bouquet, Olivier Mousis, Christopher R. Glein, Grégoire Danger, and J. Hunter Waite
Subjects: *METHANE hydrates, *CHURYUMOV-Gerasimenko comet, *CLATHRATE compounds, *OCEAN, *GAS hydrates, *NOBLE gases, *STATISTICAL models, *MAGNITUDE (Mathematics)
Abstract: We use a thermodynamic statistical model to evaluate how the composition of Europa’s internal ocean may have been affected by clathrate hydrate formation. Assuming an input of the observed O2 and CO2 from the surface into a mildly acidic ocean (pH < 6), and considering the possibility of contributions by reduced (with CH4 and H2S) or oxidized (CO2-bearing) hydrothermal fluids, we calculate the fractional occupancies in clathrate and deduce the effect on the ocean’s composition. The structure of the clathrate formed, and therefore its density and composition is influenced by the relative amount of O2 compared to the other compounds present. We also include a mixture of noble gases—argon, krypton, and xenon—based on cometary abundances measured at comet 67P and find that the Ar/Kr ratio can be affected by almost two orders of magnitude. In most cases, the formed clathrate is likely to become part of the icy crust, with guest molecules possibly accessible to future in situ measurements by the Europa Clipper and JUICE missions. [ABSTRACT FROM AUTHOR]
Published: 2019
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39. Limits on the Contribution of Endogenic Radiolysis to the Presence of Molecular Oxygen in Comet 67P/Churyumov–Gerasimenko.

Author: Alexis Bouquet, Olivier Mousis, Benjamin Teolis, Georgios Nicolaou, Ozge Ozgurel, Francoise Pauzat, Yves Ellinger, Thomas Ronnet, and J. Hunter Waite Jr
Subjects: *RADIOLYSIS, *OXYGEN, *RADIOISOTOPES, *COSMIC abundances, *CHURYUMOV-Gerasimenko comet
Abstract: Radiolytic production has been proposed as a potential source for the molecular oxygen observed in comet 67P/Churyumov–Gerasimenko. Radiolysis can be exogenic or endogenic, the latter due to radionuclides present in the dust constitutive of the comet nucleus. We investigated the possibility of forming a significant amount of molecular oxygen through endogenic radiolysis. We applied a model of radiolytic production, developed for an Earth rock–water mixture, and improved it to account for the effect of the size of a radionuclide-bearing grain on the net radiation deposited in its ice mantle. We calculated the possible production of molecular oxygen considering the available experimental values of radiolytic yields. We found that endogenic radiolysis cannot account for the totality of the 3.8% (relative to water) O2 abundance derived from the ROSINA observations, with an end member case of our model producing at most a 1% abundance. By contrast, we predict H2O2 production leads to an abundance up to two orders of magnitude above observed values. [ABSTRACT FROM AUTHOR]
Published: 2018
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40. Alternative Energy: Production of H2 by Radiolysis of Water in the Rocky Cores of Icy Bodies.

Author: Alexis Bouquet, Christopher R. Glein, Danielle Wyrick, and J. Hunter Waite
Published: 2017
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