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13 results on '"PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS"'

1. Meteoroid Impacts as a Source of Bennu's Particle Ejection Events

Author

David Vokrouhlický, Stephen R. Schwartz, Michael C. Nolan, Jamie Molaro, William F. Bottke, A. Moorhead, Dante S. Lauretta, Carl Hergenrother, Harold C. Connolly, Kevin J. Walsh, Patrick Michel, Southwest Research Institute [Boulder] (SwRI), Joseph Louis LAGRANGE (LAGRANGE), 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), Lunar and Planetary Laboratory [Tucson] (LPL), and University of Arizona

Subjects
010504 meteorology & atmospheric sciences, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Noon, ejecta, 01 natural sciences, Astrobiology, Planetary Sciences: Solar System Objects, Impact crater, Geochemistry and Petrology, Impact Phenomena, Cratering, Comets, OSIRIS‐REx, Earth and Planetary Sciences (miscellaneous), impacts, meteoroids, Ejecta, Planetary Sciences: Solid Surface Planets, Research Articles, 0105 earth and related environmental sciences, Meteoroid, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Impact Phenomena, Dust, Debris, Asteroids, Surfaces, Exploration of the Activity of Asteroid (101955) Bennu, Tectonophysics, Geophysics, Atmosphere of the Moon, 13. Climate action, Space and Planetary Science, Asteroid, [SDU]Sciences of the Universe [physics], Local time, Comets: Dust Tails and Trails, Bennu, Planetary Sciences: Comets and Small Bodies, Other, Natural Hazards, Geology, Research Article
Abstract

Asteroid (101955) Bennu, a near‐Earth object with a primitive carbonaceous chondrite‐like composition, was observed by the Origins, Spectral Interpretation, Resource Identification, and Security‐Regolith Explorer (OSIRIS‐REx) spacecraft to undergo multiple particle ejection events near perihelion between December 2018 and February 2019. The three largest events observed during this period, which all occurred 3.5 to 6 hr after local noon, placed numerous particles, Key Points Meteoroids derived from comets strike Bennu near perihelion once every 2 weeks on average with an impact kinetic energy >7,000 JThey can explain the particle sizes (

Published
2020

2. Plasma Double Layers at the Boundary between Venus and the Solar Wind

Author

T. Dudok de Wit, Marc Pulupa, K. E. Korreck, Shannon Curry, Robert J. MacDowall, Katherine Goodrich, Michael L. Stevens, Peter Harvey, Jasper Halekas, John W. Bonnell, Davin Larson, Keith Goetz, M. McManus, Anthony W. Case, Justin C. Kasper, Stuart D. Bale, Roberto Livi, Phyllis Whittlesey, David M. Malaspina, Department of Astrophysical and Planetary Sciences [Boulder], University of Colorado [Boulder], Space Sciences Laboratory [Berkeley] (SSL), University of California [Berkeley], University of California-University of California, University of Iowa [Iowa City], 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, 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), School of Physics and Astronomy [Minneapolis], University of Minnesota [Twin Cities] (UMN), and University of Minnesota System-University of Minnesota System

Subjects
010504 meteorology & atmospheric sciences, Magnetosphere, Venus, 010502 geochemistry & geophysics, bow shock, 01 natural sciences, Solar Wind/Magnetosphere Interactions, Planetary Sciences: Solar System Objects, Magnetosheath, Kinetic Waves and Instabilities, Physics::Plasma Physics, Electric field, Parker Solar Probe Observations at Venus: VGA1‐2, Research Letter, Meteorology & Atmospheric Sciences, Magnetospheric Physics, Planetary Sciences: Solid Surface Planets, Planetary Sciences: Fluid Planets, 0105 earth and related environmental sciences, Physics, biology, solar wind interaction, Plasma, biology.organism_classification, Planetary Magnetospheres, magnetosheath, Research Letters, Computational physics, Interplanetary Physics, Solar wind, Geophysics, Magnetospheres, 13. Climate action, [SDU]Sciences of the Universe [physics], Physics::Space Physics, Space Plasma Physics, double layer, General Earth and Planetary Sciences, Electron temperature, Planetary Sciences: Comets and Small Bodies, kinetic physics, Astrophysical plasma, Planetary Bow Shocks, Space Sciences
Abstract

The solar wind is slowed, deflected, and heated as it encounters Venus's induced magnetosphere. The importance of kinetic plasma processes to these interactions has not been examined in detail, due to a lack of constraining observations. In this study, kinetic‐scale electric field structures are identified in the Venusian magnetosheath, including plasma double layers. The double layers may be driven by currents or mixing of inhomogeneous plasmas near the edge of the magnetosheath. Estimated double‐layer spatial scales are consistent with those reported at Earth. Estimated potential drops are similar to electron temperature gradients across the bow shock. Many double layers are found in few high cadence data captures, suggesting that their amplitudes are high relative to other magnetosheath plasma waves. These are the first direct observations of plasma double layers beyond near‐Earth space, supporting the idea that kinetic plasma processes are active in many space plasma environments., Key Points Plasma double layers are detected near the Venusian bow shockMultiple double layers are identified in a small amount of burst dataKinetic processes may help mediate interaction between the solar wind and induced magnetospheres

Published
2020

3. The Near-Sun Dust Environment as Seen by Parker Solar Probe

Author

Malaspina, D., Szalay, J. R., Pokorny, P., Pusack, A., Page, B., Bale, S. D., Bonnell, J. W., Dudok de Wit, Thierry, Goetz, K., Goodrich, K., Harvey, P., Macdowall, R. J., Pulupa, M., and POTHIER, Nathalie

Subjects
[SDU] Sciences of the Universe [physics], PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS, IONOSPHERE, Rings and dust, Dust, Meteor-trail physics, PLANETARY SCIENCES: COMETS AND SMALL BODIES, PLANETARY SCIENCES: FLUID PLANETS
Abstract

Over the last two years, and six near-Sun encounter orbits, the Parker Solar Probe spacecraft has provided the first in-situ observations of interplanetary dust closer than ~0.3 AU from the Sun. Dust is detected by the FIELDS instrument via impact ionization and subsequent perturbations to the plasma environment close to the spacecraft. FIELDS observations yield count rates, impact amplitudes, and impact directionality information. Interpreting these data to arrive at new understanding of dust dynamics of the inner heliosphere requires combining state-of-the-art modeling and theory with detailed FIELDS instrument knowledge. In this talk, we describe recent results related to the near-Sun dust environment, including: bounding the location and rate of beta-meteoroid production, the interaction of debris streams with near-Sun dust, the density of near-circular dust near the Sun, hints of dust sublimation close to the Sun, and the effects of instrument operation on dust impact detection. The Parker Solar Probe FIELDS data provide an in-situ window into stellar processing of dust in the near-Sun plasma environment, and we are beginning to understand what we see.

Published
2020

4. Voltage Waveforms Associated with Dust Impacts on Parker Solar Probe

Author

Gasque, L. C., Bale, S., Bowen, T. A., Dudok de Wit, Thierry, Goetz, K., Malaspina, D., Page, B., Szalay, J. R., and POTHIER, Nathalie

Subjects
[SDU] Sciences of the Universe [physics], PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS, IONOSPHERE, Rings and dust, Dust, Meteor-trail physics, PLANETARY SCIENCES: COMETS AND SMALL BODIES, PLANETARY SCIENCES: FLUID PLANETS
Abstract

Since its first solar encounter in November 2018, data returned by the Parker Solar Probe (PSP) has advanced our understanding of the Sun and near-Sun environment. In particular, the PSP/FIELDS instrument suite, which measures electric and magnetic fields in the vicinity of the spacecraft, can detect changes in spacecraft floating potential from plasma clouds generated by interplanetary dust impacts, allowing in-situ measurements of the near-Sun dust environment. Early findings on the statistics of these dust impacts are reported in e.g. Page et al. 2020, Szalay et al. 2020, Bale et al. 2020, and Malaspina et al. 2020. However, little work has been done yet to examine the Time Domain Sampler (TDS) waveforms of individual dust impacts on PSP, which are available from PSP's first two solar encounters. In this study, we examine these TDS waveforms, comparing them to models of spacecraft charging due to dust impacts and attempting to identify different populations of dust based on the waveforms. Additionally, we examine timescales evident in the waveforms as related to timescales in spacecraft charging physics in the near-Sun environment. This work has implications for future modeling efforts of dust impacts on spacecraft and spacecraft charging, as well as further understanding the heliospheric dust environment.

Published
2020

5. Comparing Electron Energetics and UV Brightness in Jupiter's Northern Polar Region During Juno Perijove 5

Author

Fran Bagenal, G. R. Gladstone, Steven Levin, Barry Mauk, Thomas K. Greathouse, Vincent Hue, P. Louarn, R. J. Wilson, Michelle F. Thomsen, Jamey Szalay, John E. P. Connerney, Robert Ebert, Masafumi Imai, P. W. Valek, George Clark, William S. Kurth, Frederic Allegrini, David J. McComas, Scott Bolton, Chris Paranicas, Southwest Research Institute [San Antonio] (SwRI), Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], NASA Goddard Space Flight Center (GSFC), Department of Nuclear Engineering, Kyoto University, ECLIPSE 2015, 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), University of Iowa [Iowa City], Institut de recherche en astrophysique et planétologie (IRAP), 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), Institut de Recherche pour le Développement (IRD)-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)-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), Johns Hopkins University Applied Physics Laboratory [Laurel, MD] (APL), Princeton University, Institut de médecine moléculaire de Rangueil (I2MR), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées- Institut Fédératif de Recherche Bio-médicale Institution (IFR150)-Institut National de la Santé et de la Recherche Médicale (INSERM), School of Social and Community Medicine [Bristol], University of Bristol [Bristol], Louarn, Philippe, Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), 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 Fédératif de Recherche Bio-médicale Institution (IFR150)-Institut National de la Santé et de la Recherche Médicale (INSERM), Kyoto University [Kyoto], 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), and Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-IFR150-Institut National de la Santé et de la Recherche Médicale (INSERM)

Subjects
Juno, Brightness, Jupiter's aurora, 010504 meteorology & atmospheric sciences, polar auroral region, Astrophysics::High Energy Astrophysical Phenomena, Energy flux, Electron, Astrophysics, [SDU.ASTR] Sciences of the Universe [physics]/Astrophysics [astro-ph], 7. Clean energy, 01 natural sciences, Jupiter, [SDU] Sciences of the Universe [physics], Planetary Sciences: Solar System Objects, Flux (metallurgy), Altitude, Aurorae, 0103 physical sciences, Research Letter, Magnetospheric Physics, 010303 astronomy & astrophysics, Planetary Sciences: Fluid Planets, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Physics, electron energy flux, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Energetics, Planetary Magnetospheres, Energetic Particles: Precipitating, Polar Regions, Research Letters, polar UV emissions, Geophysics, Magnetospheres, precipitating electrons, 13. Climate action, [SDU]Sciences of the Universe [physics], Physics::Space Physics, General Earth and Planetary Sciences, Polar, Space Sciences
Abstract

We compare electron and UV observations mapping to the same location in Jupiter's northern polar region, poleward of the main aurora, during Juno perijove 5. Simultaneous peaks in UV brightness and electron energy flux are identified when observations map to the same location at the same time. The downward energy flux during these simultaneous observations was not sufficient to generate the observed UV brightness; the upward energy flux was. We propose that the primary acceleration region is below Juno's altitude, from which the more intense upward electrons originate. For the complete interval, the UV brightness peaked at ~240 kilorayleigh (kR); the downward and upward energy fluxes peaked at 60 and 700 mW/m2, respectively. Increased downward energy fluxes are associated with increased contributions from tens of keV electrons. These observations provide evidence that bidirectional electron beams with broad energy distributions can produce tens to hundreds of kilorayleigh polar UV emissions., Key Points Simultaneous peaks are observed in electron energy flux and UV brightness when they map to same location in Jupiter's polar region at the same timeUpward greater than downward electron energy fluxes are observed, suggesting that primary acceleration region may be below ~1.5 jovian radiiDownward energy fluxes able to produce tens to hundreds of kilorayleigh polar UV emissions are identified; increases in energy flux due to tens of keV electrons

Published
2019

6. Methanol Near-Infrared Bands as a Probe of Irradiated Ices in Space

Author

Urso, R. G., Baklouti, D., Brunetto, R., Djouadi, Z., Institut d'astrophysique spatiale (IAS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Brunetto, Rosario

Subjects
[SDU] Sciences of the Universe [physics], PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS, [SDU]Sciences of the Universe [physics], 6270 Pluto and satellites, 6224 Kuiper belt objects, 5455 Origin and evolution, PLANETARY SCIENCES: SOLID SURFACE PLANETS, 6040 Origin and evolution, PLANETARY SCIENCES: COMETS AND SMALL BODIES
Abstract

International audience; Cosmic rays, solar ions and UV photons induce changes in both the structure and composition of frozen volatiles trapped in solar system small bodies such as comets, Kuiper-belt objects (KBOs) and trans-neptunian objects (TNOs). Recently, Stern et al. 2019 reported about the presence of methanol and water ice on the surface of (486958) 2014 MU69 revealed by the New Horizons space probe. Both species were identified also in other small bodies, such as (55638) 2002 VE95 and the centaur 5145 Pholus. Laboratory experiments that simulate the interaction between cosmic rays and frozen volatiles have shown that when carbon-bearing species are bombarded with keV-MeV ions, energetic processing determines the formation of both volatiles (such as CO, CO2, H2CO, etc.) and refractory species that may account for the visible and near-infrared reddening observed in various solar system small bodies. Here we present laboratory experiments performed to contribute in the interpretation of observations of methanol-rich bodies. Frozen samples containing water and methanol were deposited at temperatures that are close to those measured on 2014 MU69 and other TNOs. After the deposition, frozen volatiles were bombarded with 40 keV protons between a few and hundreds eV/molecule. Samples were analysed in the near-infrared range, where methanol exhibit an intense band at 2.27 microns and minor feature at 2.34 microns (4400 and 4280 cm-1, respectively). The analysis revealed a different sensitivity to ion irradiation of the two features. In particular, we show that the ratio between the band areas evolves with increasing irradiation doses. We suggest that it could be used as a probe to discern between pristine and processed ices, as well as to establish upper limits for the 2.34 microns band when only the 2.27 microns band is observed.

Published
2019

7. Probing Jovian broadband kilometric radio sources tied to the ultraviolet main auroral oval with Juno

Author

Masafumi Imai, Corentin Louis, G. Randall Gladstone, John E. P. Connerney, Thomas K. Greathouse, Scott Bolton, William S. Kurth, Philippe Zarka, Department of Physics and Astronomy [Iowa City], University of Iowa [Iowa City], Southwest Research Institute [San Antonio] (SwRI), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Unité Scientifique de la Station de Nançay (USN), Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), 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)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), NASA Goddard Space Flight Center (GSFC), 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), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), 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, and Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO)

Subjects
Juno, Brightness, 010504 meteorology & atmospheric sciences, Field line, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Magnetic dip, 010502 geochemistry & geophysics, medicine.disease_cause, 01 natural sciences, Jovian, Jupiter, Juno‐UVS, Planetary Sciences: Solar System Objects, Radio Emissions, medicine, Research Letter, Magnetospheric Physics, Ionosphere, Planetary Sciences: Solid Surface Planets, Planetary Sciences: Fluid Planets, 0105 earth and related environmental sciences, Auroral Phenomena, Physics, Solar Physics, Astrophysics, and Astronomy, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Jovian ultraviolet auroras, Astronomy, Auroral Ionosphere, Planetary Magnetospheres, Research Letters, Magnetic field, Geophysics, Magnetospheres, Waves, General Earth and Planetary Sciences, Polar, broadband kilometric radiation, Planetary Sciences: Comets and Small Bodies, Ultraviolet Emissions, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Space Sciences, Ultraviolet
Abstract

Observations of Jovian broadband kilometric (bKOM) radiation and ultraviolet (UV) auroras were acquired with the Waves and Juno‐UVS instruments for ∼2 hr over the northern and southern polar regions during Juno's perijoves 4, 5, and 6 passes (PJ4, PJ5, and PJ6). During all six time periods, Juno traversed auroral magnetic field lines connecting to the UV main auroral ovals, matching the estimates of bKOM radio source footprints. The localized bKOM radio sources for the PJ4 north pass map to magnetic field lines having distances of 10 to 12 Jovian radii (R J) at the magnetic equator, whereas the extended bKOM radio sources for the other events map to field lines extending to 20–61 R J. We found the peak bKOM intensities during Juno's potential radio source crossings show positive, negative, and no correlations with the UV main oval brightness and color ratio. Only the positive correlations suggest wave‐particle energy transport., Key Points First simultaneous observations of Jovian broadband kilometric radio source footprints and ultraviolet auroras were carried out using JunoJovian broadband kilometric radio source footprints correspond to the UV main oval locationsLink of Jovian radio intensity during Juno's near‐source crossing with both brightness and color ratio of the UV main oval was investigated

Published
2019

8. Infrared Spectra of Dark Asteroid Ryugu and Carbonaceous Chondrites

Author

Matsuoka, M., Nakamura, T., Hiroi, T., Kitazato, K., Senshu, H., Iwata, T., Abe, M., Amano, K., Kobayashi, S., Osawa, T., Ohtake, M., Matsuura, S., Arai, T., Komatsu, M., Nakato, A., Nakauchi, Y., Pilorget, C., Brunetto, R., Poulet, F., Riu, L., Domingue, D. L., Vilas, F., Takir, D., Palomba, E., Galiano, A., Milliken, R., Perna, D., Barucci, M. A., Bibring, J. P., Institut d'astrophysique spatiale (IAS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Brunetto, Rosario

Subjects
[SDU] Sciences of the Universe [physics], 6207 Comparative planetology, PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS, [SDU]Sciences of the Universe [physics], 6045 Physics and chemistry of materials, PLANETARY SCIENCES: SOLID SURFACE PLANETS, PLANETARY SCIENCES: COMETS AND SMALL BODIES, 5410 Composition, 6008 Composition
Abstract

International audience; Near-infrared Spectrometer (NIRS3) onboard Hayabusa2 successfully obtained reflectance spectra of the C-type near-Earth asteroid Ryugu over a wavelength range of 1.8-3.2 µm. It was observed that Ryugu exhibits very low albedo (less than 0.02 at 2.0 μm), a slightly positive spectral slope, and an ubiquitous weak OH absorption band at 2.72 μm. These properties are nearly homogeneous across the asteroid surface. However, data of regions near the equator with ~40 m spatial resolution (~20 km altitude) exhibit variations in the 2.0-μm albedo that are possibly associated with geomorphological features. Reflectance values are higher near crater rims and lower in crater centers. Future updates to the photometric correction may change these apparent associations, but it is also observed that spectra of several flat areas without any obvious geomorphological features show relatively high reflectance (e.g., near 270, 300, and 350 degrees longitude, close to the equatorial ridge). If verified, the brighter areas could indicate surface materials that (a) are relatively carbon-poor, (b) have different physical properties, such as smaller grain size and/or decreased porosity, and/or (c) exhibit different forms/degrees of space weathering. Comparing spectra of carbonaceous chondrites with those of Ryugu shows that no meteorites are an ideal spectral match to Ryugu at all wavelengths. However, spectra of shocked or heated carbonaceous chondrites are most similar with their low albedo and weak, narrow OH absorption feature at 2.72 μm. Future lab analyses of samples returned from Ryugu will provide additional information on the mineralogical and chemical properties of Ryugu and how these relate to its spectral characteristics. Acknowledgements: We appreciate support from the National Institute of Polar Research for providing carbonaceous chondrites, the Japan Society for the Promotion of Science (JSPS) Core-to-Core Program "International Network of Planetary Sciences", the NASA Hayabusa2 Participating Scientist Program (NNX16AL34G), and the Solar System Exploration Research Virtual Institute 2016 (SSERVI16) Cooperative Agreement (NNH16ZDA001N) SSERVI-TREX.

Published
2019

9. Hayabusa2/NIRS3 spectral observations of asteroid (162173) Ryugu

Author

Brunetto, R., Kitazato, K., Iwata, T., Abe, M., Ohtake, M., Matsuura, S., Arai, T., Nakauchi, Y., Nakamura, T., Matsuoka, M., Senshu, H., Hirata, N., Hiroi, T., Pilorget, C., Poulet, F., Riu, L., Domingue, D. L., Takir, D., Palomba, E., Milliken, R., Perna, D., Barucci, M. A., Bibring, J. P., Watanabe, S., 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), Department of Environmental and Materials Engineering, Nagoya Institute, Graduate School of Science and Engineering, Tokyo Metropolitan University [Tokyo] (TMU), RIKEN Nishina Center for Accelerator-Based Science [Wako] (RIKEN RNC), RIKEN - Institute of Physical and Chemical Research [Japon] (RIKEN), Tsukuba Space Center (TKSC), Japan Aerospace Exploration Agency [Tokyo] (JAXA), Brown University, Division of Geological and Planetary Sciences [Pasadena], California Institute of Technology (CALTECH), Istituto di Astrofisica e Planetologia Spaziali - INAF (IAPS), Istituto Nazionale di Astrofisica (INAF), Jet Propulsion Laboratory (JPL), California Institute of Technology (CALTECH)-NASA, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), 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)-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), Tokyo Metropolitan University [Tokyo], RIKEN Nishina Center (for Accelerator-Based Science), NASA-California Institute of Technology (CALTECH), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, and 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)

Subjects
PLANETARY SCIENCES: COMETS AND SMALL BODIESDE: 6205 Asteroids, PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], PLANETARY SCIENCES: SOLAR SYSTEM OBJECTSDE: 6207 Comparative planetology, 6040 Origin and evolution, PLANETARY SCIENCES: COMETS AND SMALL BODIESDE: 6055 Surfaces
Abstract

International audience; On 27 June 2018, JAXA's Hayabusa2 spacecraft arrived at a distance of 20 km from its target 162173 Ryugu, a sub-km sized asteroid in the near-Earth space, and began its 1.5-year asteroid proximity operation. We have performed near-infrared (1.8-3.2 µm) spectroscopic observations of Ryugu using the NIRS3 instrument onboard Hayabusa2 to begin characterizing and mapping the surface composition. The initial data, obtained by NIRS3 at a spatial resolution of about 35 m, show a very dark surface with little spectral variations across the surface. At this stage, the lack of a significant 2.7-µm feature illustrates that the spectra of Ryugu are different from those of phyllosilicate-rich carbonaceous chondrites. We will present the results of the analysis of the NIRS3 data, including the high-resolution data to be obtained during the first descent operations.

Published
2018

10. Enrichment of heavy nitrogen in Titan's HC3N detected using ALMA

Author

Cordiner, M., Nixon, C. A., Charnley, S. B., Teanby, N. A., Molter, E. M., Kisiel, Z., Vuitton, V., NASA Goddard Space Flight Center (GSFC), School of Earth Sciences [Bristol], University of Bristol [Bristol], Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), and Vuitton, Véronique

Subjects
[PHYS.ASTR.EP] Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS, 5210 Planetary atmospheres, PLANETARY SCIENCES: FLUID PLANETSDE: 6281 Titan, [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], and hazes, clouds, PLANETARY SCIENCES: ASTROBIOLOGYDE: 5749 Origin and evolution, PLANETARY SCIENCES: ASTROBIOLOGYDE: 5215 Origin of life
Abstract

International audience; Trace isotopic ratios contain unique information on the chemical histories of atmospheric gases. From the combined efforts of previous ground and space-based sub-mm and infrared observations, Titan's atmospheric HCN has been found to be substantially enriched in 15N compared with the bulk N2 reservoir. This is theorized to occur as a consequence of isotope-selective photodissociation of N2 in the upper atmosphere, giving rise to an enhanced abundance of atomic 15N that subsequently becomes incorporated into HCN. Here, we present the first maps of cyanoacetylene isotopologues in Titan's atmosphere, including H13CCCN and HCCC15N, detected in the 0.9 mm band using the Atacama Large Millimeter/submillimeter array (ALMA) around the time of Titan's (southern winter) solstice in May 2017 (see Figure 1). The HC3N emission is found to be strongly enhanced over the south pole (by a factor of 5.7 compared to the north pole), consistent with rapid photochemical loss of HC3N from the summer hemisphere combined with production and transport to the winter pole since the previous (2015) ALMA observations. The H13CCCN/HCCC15N flux ratio is consistent with an HC3N/HCCC15N ratio of 67 ± 14, which is significantly enriched in 15N compared with the main molecular nitrogen reservoir (which has a 14N/15N ratio of 167). This confirms the importance of photochemistry in determining the nitrogen isotopic ratio in Titan's organic inventory. In this presentation I will discuss the impact of these results on our understanding of the origin of Titan's N2, the evolution of its atmospheric 14N/15N ratio, and on our knowledge of the detailed photochemical processes occurring in nitrogen-rich planetary atmospheres.

Published
2018

11. Chemistry, mineralogy, and grain properties at Namib and High dunes, Bagnold dune field, Gale crater, Mars: A synthesis of Curiosity rover observations

Author

Victoria E. Hamilton, Albert S. Yen, Pamela G. Conrad, R. Gellert, D. W. Ming, Ashwin R. Vasavada, Mathieu G.A. Lapotre, Scott K. Rowland, Abigail A. Fraeman, Roger C. Wiens, David F. Blake, Kenneth S. Edgett, Jeffrey R. Johnson, C. D. O'Connell-Cooper, P.-Y. Meslin, D. T. Vaniman, Danika Wellington, Ryan C. Sullivan, Michelle E. Minitti, Kirsten L. Siebach, Nathaniel Stein, Agnes Cousin, Sylvestre Maurice, Robert T. Downs, Nathan T. Bridges, Cherie N. Achilles, Stephen Kuhn, Craig Hardgrove, Lucy M. Thompson, Travis Gabriel, Paul R. Mahaffy, M. L. Litvak, Susanne Schröder, R. V. Morris, J. M. Morookian, Raymond E. Arvidson, Bethany L. Ehlmann, Patrick Pinet, Brad Sutter, M. McHenry, Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), 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), and Services communs OMP (UMS 831)

Subjects
010504 meteorology & atmospheric sciences, Namib, 01 natural sciences, Planetary Sciences: Solar System Objects, Earth and Planetary Sciences (miscellaneous), 010303 astronomy & astrophysics, Research Articles, Martian, grain size, Mars Science Laboratory, Investigations of the Bagnold Dune Field, Gale crater, Mars Exploration Program, Mineralogy, Physical Properties of Materials, Grain size, Planetary Mineralogy and Petrology, Chemistry, Geophysics, volatiles, Aeolian processes, Erosion and Weathering, dust, Geology, Composition, Research Article, Dunes, Surface Materials and Properties, Bedform, Mars, engineering.material, Planetary Geochemistry, amorphous phase, Geochemistry and Petrology, 0103 physical sciences, Rover, Plagioclase, MSL, Planetary Sciences: Solid Surface Planets, Mineralogy and Petrology, 0105 earth and related environmental sciences, Olivine, Mars soils, Bagnold, Geochemistry, sand dunes, Curiosity, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Rocknest, engineering
Abstract

The Mars Science Laboratory Curiosity rover performed coordinated measurements to examine the textures and compositions of aeolian sands in the active Bagnold dune field. The Bagnold sands are rounded to subrounded, very fine to medium sized (~45–500 μm) with ≥6 distinct grain colors. In contrast to sands examined by Curiosity in a dust‐covered, inactive bedform called Rocknest and soils at other landing sites, Bagnold sands are darker, less red, better sorted, have fewer silt‐sized or smaller grains, and show no evidence for cohesion. Nevertheless, Bagnold mineralogy and Rocknest mineralogy are similar with plagioclase, olivine, and pyroxenes in similar proportions comprising >90% of crystalline phases, along with a substantial amorphous component (35% ± 15%). Yet Bagnold and Rocknest bulk chemistry differ. Bagnold sands are Si enriched relative to other soils at Gale crater, and H2O, S, and Cl are lower relative to all previously measured Martian soils and most Gale crater rocks. Mg, Ni, Fe, and Mn are enriched in the coarse‐sieved fraction of Bagnold sands, corroborated by visible/near‐infrared spectra that suggest enrichment of olivine. Collectively, patterns in major element chemistry and volatile release data indicate two distinctive volatile reservoirs in Martian soils: (1) amorphous components in the sand‐sized fraction (represented by Bagnold) that are Si‐enriched, hydroxylated alteration products and/or H2O‐ or OH‐bearing impact or volcanic glasses and (2) amorphous components in the fine fraction (, Key Points Because of ongoing aeolian activity, the Bagnold dunes consist of well‐sorted sands and lack the finer grains typical of Martian soilsDune sands are chemically distinct with elevated Si, Mg, and Ni and lower H2O, S, and Cl relative to all previously measured Martian finesTwo distinct, water‐/OH‐bearing amorphous components are identified: Fe‐, S‐, and Cl‐rich material in dust and Si‐rich material in the sands

Published
2017

12. Raman spectra of Martian glass analogues: A tool to approximate their chemical composition

Author

Claudia Romano, Donald B. Dingwell, Werner Ertel-Ingrisch, Alessandro Vona, Daniel R. Neuville, Kai-Uwe Hess, S. Kolzenburg, Magdalena Oryaëlle Chevrel, Danilo Di Genova, Università degli Studi Roma Tre, Ludwig-Maximilians-Universität München (LMU), Institut de Physique du Globe de Paris (IPGP), Centre National de la Recherche Scientifique (CNRS)-Université de La Réunion (UR)-Université Paris Diderot - Paris 7 (UPD7)-IPG PARIS-Institut national des sciences de l'Univers (INSU - CNRS), Dipartimento di Scienze Geologiche [Roma TRE], Department of Earth and Environmental Sciences [Munich], Università degli studi di Torino (UNITO), Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS), Università degli Studi Roma Tre = Roma Tre University (ROMA TRE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne (UCA)-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Università degli studi di Torino = University of Turin (UNITO), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Di Genova, Danilo, Kolzenburg, Stephan, Vona, Alessandro, Chevrel, Magdalena Oryaëlle, Hess, Kai Uwe, Neuville, Daniel R., Ertel Ingrisch, Werner, Romano, Claudia, and Dingwell, Donald B.

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Planetary Volcanism, Oceanography, 010502 geochemistry & geophysics, 01 natural sciences, Microanalysis, Peralkaline rock, remote sensing, Planetary Sciences: Solar System Objects, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, Earth and Planetary Sciences (miscellaneous), Chemical composition, Experimental Volcanism, Research Articles, Water Science and Technology, Melt inclusions, Martian, Ecology, Remote Sensing and Disasters, Forestry, Mars Exploration Program, Mar, Geophysics, Raman spectroscopy, symbols, Planetary Sciences: Comets and Small Bodies, Chemical analysis, Glasses, Mars, Remote sensing, Volcanology, Geochemistry and Petrology, Space and Planetary Science, Geology, Research Article, glasse, Soil Science, Mineralogy, Aquatic Science, glasses, symbols.namesake, volcanology, Volcanism, [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology, Remote Sensing of Volcanoes, Geophysic, Planetary Sciences: Solid Surface Planets, 0105 earth and related environmental sciences, Spectrometer, Paleontology, Tectonophysics, 13. Climate action, Earth-Surface Processe, chemical analysis, chemical analysi, Natural Hazards
Abstract

Raman spectrometers will form a key component of the analytical suite of future planetary rovers intended to investigate geological processes on Mars. In order to expand the applicability of these spectrometers and use them as analytical tools for the investigation of silicate glasses, a database correlating Raman spectra to glass composition is crucial. Here we investigate the effect of the chemical composition of reduced silicate glasses on their Raman spectra. A range of compositions was generated in a diffusion experiment between two distinct, iron‐rich end‐members (a basalt and a peralkaline rhyolite), which are representative of the anticipated compositions of Martian rocks. Our results show that for silica‐poor (depolymerized) compositions the band intensity increases dramatically in the regions between 550–780 cm−1 and 820–980 cm−1. On the other hand, Raman spectra regions between 250–550 cm−1 and 1000–1250 cm−1 are well developed in silica‐rich (highly polymerized) systems. Further, spectral intensity increases at ~965 cm−1 related to the high iron content of these glasses (~7–17 wt % of FeOtot). Based on the acquired Raman spectra and an ideal mixing equation between the two end‐members we present an empirical parameterization that enables the estimation of the chemical compositions of silicate glasses within this range. The model is validated using external samples for which chemical composition and Raman spectra were characterized independently. Applications of this model range from microanalysis of dry and hydrous silicate glasses (e.g., melt inclusions) to in situ field investigations and studies under extreme conditions such as extraterrestrial (i.e., Mars) and submarine volcanic environments., Key Points Raman spectra of glasses are presented for a large range of chemical compositions, analogous to Martian compositionsSpectral intensities are parameterized to derive a model for estimation of the glass composition from Raman spectraThis enables in situ estimations of glass compositions in extraterrestrial or submarine volcanic settings

Published
2016

13. Spectral properties of Titan's impact craters imply chemical weathering of its surface

Author

Jason W. Barnes, S. Le Mouélic, Philip D. Nicholson, Robert H. Brown, Michael Malaska, Jason M. Soderblom, R. L. Kirk, Bryan Stiles, B. J. Buratti, Kevin H. Baines, Catherine D. Neish, Christophe Sotin, Roger N. Clark, Shannon MacKenzie, A. Le Gall, Department of Physics and Space Sciences [FIT], Florida Institute of Technology [Melbourne], Department of Physics [Moscow,USA], University of Idaho [Moscow, USA], Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Massachusetts Institute of Technology (MIT), Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Astrogeology Science Center [Flagstaff], United States Geological Survey [Reston] (USGS), ESTER - 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), PLANETO - LATMOS, Lunar and Planetary Laboratory [Tucson] (LPL), University of Arizona, US Geological Survey [Denver], Department of Astronomy [Ithaca], and Cornell University [New York]

Subjects
[SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Planets, Fluvial, Weathering, Erosion and weathering, Methane, Astrobiology, symbols.namesake, chemistry.chemical_compound, Planetary Sciences: Solar System Objects, Impact crater, Impact Phenomena, Cratering, Research Letter, Ejecta, Planetary Sciences: Solid Surface Planets, Spectral properties, Impact Phenomena, Research Letters, Tectonophysics, Geophysics, chemistry, 13. Climate action, symbols, General Earth and Planetary Sciences, Impact cratering, Planetary Sciences: Comets and Small Bodies, Water ice, Titan (rocket family), Titan, Geology
Abstract

We examined the spectral properties of a selection of Titan's impact craters that represent a range of degradation states. The most degraded craters have rims and ejecta blankets with spectral characteristics that suggest that they are more enriched in water ice than the rims and ejecta blankets of the freshest craters on Titan. The progression is consistent with the chemical weathering of Titan's surface. We propose an evolutionary sequence such that Titan's craters expose an intimate mixture of water ice and organic materials, and chemical weathering by methane rainfall removes the soluble organic materials, leaving the insoluble organics and water ice behind. These observations support the idea that fluvial processes are active in Titan's equatorial regions., Key Points We examine the spectral properties of Titan's impact cratersDegraded crater rims are more enriched in water ice than fresh crater rimsObservations suggest chemical weathering of organics in water ice matrix

Published
2015

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