TY - JOUR A1 - Markus, Kathrin A1 - Moroz, Lyuba A1 - Arnold, Gabriele A1 - Henckel, Daniela A1 - Hiesinger, Harald A1 - Rohrbach, Arno A1 - Klemme, Stephan T1 - Reflectance spectra of synthetic Fe-free ortho- and clinoenstatites in the UV/VIS/IR and implications for remote sensing detection of Fe-free pyroxenes on planetary surfaces JF - Planetary and space science N2 - Both enstatite spectra are very bright in the VIS and NIR and show almost neutral to slightly bluish spectral slopes with a steep absorption in the UV. Very low iron in the enstatites (below similar to 0.04 wt% FeO) already results in weak albeit noticeable absorptions in the VNIR between 0.4 and 0.9 mu m. Orthoenstatite and clinoenstatite are not distinguishable based only on their spectra in the VIS and NIR. At the Reststrahlen bands in the MIR a systematic difference in the number and exact position of local minima at similar to 10 mu m between clinoenstatite and orthoenstatite is evident. This can be used to discern between the polymorphs in this wavelength range. Additionally, we can distinguish between Fe-free low- and high-Ca pyroxenes in the MIR. KW - Reflectance spectroscopy KW - Remote sensing KW - Enstatite KW - Synthetic pyroxene KW - Analog material Y1 - 2018 U6 - https://doi.org/10.1016/j.pss.2018.04.006 SN - 0032-0633 VL - 159 SP - 43 EP - 55 PB - Elsevier CY - Oxford ER - TY - CHAP A1 - Arnold, Gabriele T1 - Beiträge zur spektralen Fernerkundung fester planetarer Oberflächen N2 - Dr. Gabriele Arnold ist Leiterin des Bereichs Optische Informationssyteme am Institut für Planetenforschung des Deutschen Zentrums für Luft- und Raumfahrt (DLR) in Berlin-Adlershof
Interdisziplinäres Zentrum für Musterdynamik und Angewandte Fernerkundung Workshop vom 9. - 10. Februar 2006 Y1 - 2006 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-7235 N1 - [Poster] ER - TY - THES A1 - Arnold, Gabriele T1 - Spektrale Fernerkundung der terristrischen Planetoberflächen von Merkur, Venus und Mars vom visuellen bis in den infraroten Wellenlängenbereich Y1 - 2013 CY - Potsdam ER - TY - JOUR A1 - Quirico, E. A1 - Moroz, Liubov V. A1 - Schmitt, B. A1 - Arnold, Gabriele A1 - Faure, M. A1 - Beck, P. A1 - Bonal, L. A1 - Ciarniello, M. A1 - Capaccioni, F. A1 - Filacchione, G. A1 - Erard, S. A1 - Leyrat, C. A1 - Bockelee-Morvan, D. A1 - Zinzi, A. A1 - Palomba, E. A1 - Drossart, P. A1 - Tosi, F. A1 - Capria, M. T. A1 - De Sanctis, M. C. A1 - Raponi, A. A1 - Fonti, S. A1 - Mancarella, F. A1 - Orofino, V. A1 - Barucci, A. A1 - Blecka, M. I. A1 - Carlson, R. A1 - Despan, D. A1 - Faure, A. A1 - Fornasier, S. A1 - Gudipati, M. S. A1 - Longobardo, A. A1 - Markus, K. A1 - Mennella, V. A1 - Merlin, F. A1 - Piccioni, G. A1 - Rousseau, B. A1 - Taylor, F. T1 - Refractory and semi-volatile organics at the surface of comet 67P/Churyumov-Gerasimenko: Insights from the VIRTIS/Rosetta imaging spectrometer JF - Icarus : international journal of solar system studies N2 - The VIRTIS (Visible, Infrared and Thermal Imaging Spectrometer) instrument aboard the Rosetta spacecraft has performed extensive spectral mapping of the surface of comet 67P/Churyumov-Gerasimenko in the range 0.3-5 mu m. The reflectance spectra collected across the surface display a low reflectance factor over the whole spectral range, two spectral slopes in the visible and near-infrared ranges and a broad absorption band centered at 3.2 mu m. The first two of these characteristics are typical of dark small bodies of the Solar System and are difficult to interpret in terms of composition. Moreover, solar wind irradiation may modify the structure and composition of surface materials and there is no unequivocal interpretation of these spectra devoid of vibrational bands. To circumvent these problems, we consider the composition of cometary grains analyzed in the laboratory to constrain the nature of the cometary materials and consider results on surface rejuvenation and solar wind processing provided by the OSIRIS and ROSINA instruments, respectively. Our results lead to five main conclusions: (i) The low albedo of comet 67P/CG is accounted for by a dark refractory polyaromatic carbonaceous component mixed with opaque minerals. VIRTIS data do not provide direct insights into the nature of these opaque minerals. However, according to the composition of cometary grains analyzed in the laboratory, we infer that they consist of Fe-Ni alloys and FeS sulfides. (ii) A semi-volatile component, consisting of a complex mix of low weight molecular species not volatilized at T similar to 220 K, is likely a major carrier of the 3.2 p.m band. Water ice contributes significantly to this feature in the neck region but not in other regions of the comet. COOH in carboxylic acids is the only chemical group that encompasses the broad width of this feature. It appears as a highly plausible candidate along with the NH4+ ion. (iii) Photolytic/thermal residues, produced in the laboratory from interstellar ice analogs, are potentially good spectral analogs. (iv) No hydrated minerals were identified and our data support the lack of genetic links with the CI, CR and CM primitive chondrites. This concerns in particular the Orgueil chondrite, previously suspected to have been of cometary origin. (v) The comparison between fresh and aged terrains revealed no effect of solar wind irradiation on the 3.2 mu m band. This is consistent with the presence of efficient resurfacing processes such as dust transport from the interior to the surface, as revealed by the OSIRIS camera. (C) 2016 Elsevier Inc. All rights reserved. KW - Comets KW - Organic chemistry KW - Infrared observations KW - Meteorites KW - Spectrophotometry Y1 - 2016 U6 - https://doi.org/10.1016/j.icarus.2016.02.028 SN - 0019-1035 SN - 1090-2643 VL - 272 SP - 32 EP - 47 PB - Elsevier CY - San Diego ER - TY - JOUR A1 - Kappel, David A1 - Arnold, Gabriele A1 - Haus, Rainer T1 - Multi-spectrum retrieval of Venus IR surface emissivity maps from VIRTIS/VEX nightside measurements at Themis Regio JF - Icarus : international journal of solar system studies N2 - Renormalized emissivity maps of Themis Regio at the three surface windows are determined from 64 measurement repetitions. Retrieval errors are estimated by a statistical evaluation of maps derived from various disjoint selections of spectra and using different assumptions on the interfering parameters. Double standard deviation errors for the three surface windows amount to 3%, 8%, and 4%, respectively, allowing geologic interpretation. A comparison to results from an earlier error analysis based on synthetic spectra shows that unconsidered time variations of interfering atmospheric parameters are a major error source. Spatial variations of the 1.02 mu m surface emissivity of 20% that correspond to the difference between unweathered granitic and basaltic rocks would be easily detectable, but such variations are ruled out for the studied target area. Emissivity anomalies of up to 8% are detected at both 1.02 and 1.18 mu m. At present sensitivity, no anomalies are identified at 1.10 mu m, but anomalies exceeding the determined error level can be excluded. With single standard deviation significance, all three maps show interesting spatial emissivity variations. (C) 2015 Elsevier Inc. All rights reserved. KW - Venus, surface KW - Infrared observations KW - Radiative transfer Y1 - 2016 U6 - https://doi.org/10.1016/j.icarus.2015.10.014 SN - 0019-1035 SN - 1090-2643 VL - 265 SP - 42 EP - 62 PB - Elsevier CY - San Diego ER - TY - JOUR A1 - Ciarniello, Mauro A1 - Fulle, Marco A1 - Raponi, Andrea A1 - Filacchione, Gianrico A1 - Capaccioni, Fabrizio A1 - Rotundi, Alessandra A1 - Rinaldi, Giovanna A1 - Formisano, Michelangelo A1 - Magni, Gianfranco A1 - Tosi, Federico A1 - De Sanctis, Maria Cristina A1 - Capria, Maria Teresa A1 - Longobardo, Andrea A1 - Beck, Pierre A1 - Fornasier, Sonia A1 - Kappel, David A1 - Mennella, Vito A1 - Mottola, Stefano A1 - Rousseau, Batiste A1 - Arnold, Gabriele T1 - Macro and micro structures of pebble-made cometary nuclei reconciled by seasonal evolution JF - Nature astronomy N2 - Comets evolve due to sublimation of ices embedded inside porous dust, triggering dust emission (that is, erosion) followed by mass loss, mass redistribution and surface modifications. Surface changes were revealed by the Deep Impact and Stardust NExT missions for comet 9P/Tempel 1 (ref.(1)), and a full inventory of the processes modifying cometary nuclei was provided by Rosetta while it escorted comet 67P/Churyumov-Gerasimenko for approximately two years(2-4). Such observations also showed puzzling water-ice-rich spots that stood out as patches optically brighter and spectrally bluer than the average cometary surfaces(5-9). These are up to tens of metres large and indicate macroscopic compositional dishomogeneities apparently in contrast with the structural homogeneity above centimetre scales of pebble-made nuclei(10). Here we show that the occurrence of blue patches determines the seasonal variability of the nucleus colour(4,11,12) and gives insight into the internal structure of comets. We define a new model that links the centimetre-sized pebbles composing the nucleus(10) and driving cometary activity(13,14) to metre-sized water-ice-enriched blocks embedded in a drier matrix. The emergence of blue patches is due to the matrix erosion driven by CO2-ice sublimation that exposes the water-ice-enriched blocks, which in turn are eroded by water-ice sublimation when exposed to sunlight. Our model explains the observed seasonal evolution of the nucleus and reconciles the available data at micro (sub-centimetre) and macro (metre) scales. KW - Asteroids, comets and Kuiper belt KW - Planetary science Y1 - 2022 U6 - https://doi.org/10.1038/s41550-022-01625-y SN - 2397-3366 VL - 6 IS - 5 SP - 546 EP - 553 PB - Nature Research CY - Berlin ER - TY - JOUR A1 - Alemanno, Giulia A1 - D'Amore, Maddalena A1 - Maturilli, Alessandro A1 - Helbert, Joern A1 - Arnold, Gabriele A1 - Korablev, Oleg A1 - Ignatiev, Nikolay A1 - Grigoriev, Alexei A1 - Shakun, Alexey A1 - Trokhimovskiy, Alexander T1 - Martian atmospheric spectral end-members retrieval from ExoMars Thermal Infrared (TIRVIM) data JF - JGR / Planets N2 - Key knowledge about planetary composition can be recovered from the study of thermal infrared spectral range datasets. This range has a huge diagnostic potential because it contains diagnostic absorptions from a planetary surface and atmosphere. The main goal of this study is to process and interpret the dataset from the Thermal Infrared channel (TIRVIM) which is part of the Atmospheric Chemistry Suite of the ExoMars2016 Trace Gas Orbiter mission to find and characterize dust and water ice clouds in the atmosphere. The method employed here is based on the application of principal component analysis and target transformation techniques to extract the independent variable components present in the analyzed dataset. Spectral shapes of both atmospheric dust and water ice aerosols have been recovered from the analysis of TIRVIM data. The comparison between our results with those previously obtained on Thermal Emission Spectrometer (TES) data and with previous analysis on TIRVIM data, validates the methodology here applied, showing that it allows to correctly recover the atmospheric spectral endmembers present in the TIRVIM data. Moreover, comparison with atmospheric retrievals on PFS, TES and IRIS data, allowed us to assess the temporal stability and homogeneity of dust and water ice components in the Martian atmosphere over a time period of almost 50 years. Y1 - 2022 U6 - https://doi.org/10.1029/2022JE007429 SN - 2169-9097 SN - 2169-9100 VL - 127 IS - 9 PB - Wiley CY - Hoboken, NJ ER -