VIS-IR Spectroscopy of Mixtures of Water Ice, Organic Matter, and Opaque Mineral in Support of Small Body Remote Sensing Observations

Minerals

David Kappel¹  Stefan E. Schröder¹  Lyuba V. Moroz¹  Cedric Pilorget²  Andrea Raponi³  Batiste Rousseau³  Mauro Ciarniello³  Gianrico Filacchione³  Vito Mennella⁴  Antoine Pommerol⁵  Vassilissa Vinogradoff⁶  Olivier Poch⁷  Pierre Beck⁷  Bernard Schmitt⁷  Istiqomah Istiqomah⁷  Robin Sultana⁷  Eric Quirico⁷ 

[1] German Aerospace Center (DLR), 12489 Berlin, Germany;Institut d’Astrophysique Spatiale, Université Paris-Saclay, CNRS, 91405 Orsay, France;Istituto di Astrofisica e Planetologia Spaziali, Istituto Nazionale di Astrofisica, 00133 Rome, Italy;Osservatorio Astronomico di Capodimonte, Istituto Nazionale di Astrofisica, 80131 Naples, Italy;Physikalisches Institut, University of Bern, 3012 Bern, Switzerland;Physique Des Interactions Ioniques et Moléculaires, Aix-Marseille University, UMR CNRS 7345, 13013 Marseille, France;University Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France;

关键词: water ice;    organics;    VIS-IR spectroscopy;    spectral modelling;    small bodies;   

DOI  :  10.3390/min11111222

来源: DOAJ

【 摘 要 】

Visual-to-infrared (VIS-IR) remote sensing observations of different classes of outer solar system objects indicate the presence of water ice and organics. Here, we present laboratory reflectance spectra in the 0.5–4.2 $\mathsf{\mu }$m spectral range of binary particulate mixtures of water ice, organics analogue (kerite), and an opaque iron sulphide phase (pyrrhotite) to investigate the spectral effects of varying mixing ratios, endmember grain size, and mixing modality. The laboratory spectra are also compared to different implementations of the Hapke reflectance model (Hapke, 2012). We find that minor amounts (≲1 wt%) of kerite (investigated grain sizes of 45–63 $\mathsf{\mu }$m and <25 $\mathsf{\mu }$m) can remain undetected when mixed in coarse-grained (67 ± 31 $\mathsf{\mu }$m) water ice, suggesting that organics similar to meteoritic insoluble organic matter (IOM) might be characterized by larger detectability thresholds. Additionally, our measurements indicate that the VIS absolute reflectance of water ice-containing mixtures is not necessarily monotonically linked to water ice abundance. The latter is better constrained by spectral indicators such as the band depths of water ice VIS-IR diagnostic absorptions and spectral slopes. Simulation of laboratory spectra of intimate mixtures with a semi-empirical formulation of the Hapke model suggests that simplistic assumptions on the endmember grain size distribution and shape may lead to estimated mixing ratios considerably offset from the nominal values. Finally, laboratory spectra of water ice grains with fine-grained pyrrhotite inclusions (intraparticle mixture) have been positively compared with a modified version of the Hapke model from Lucey and Riner (2011).

【 授权许可】

Unknown