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 -