T141 From Stardust to Planets: A Geological Tour of the Career of Harry Y. McSween Jr.

Monday, 26 September 2016
1:30 PM - 5:30 PM
Room 201

RADIATIVE TRANSFER MODELING OF NEAR-INFRARED REFLECTANCE DATA OF MERCURY

Paper number: T141-10
Program: Technical Sessions
Time: 3:45 PM – 4:00 PM

Authors

Abstract

In this study we applied the radiative transfer model of Hapke [1-3] to predict the bidirectional reflectance spectra in a forward modeling approach [4,5] to produce spectral matches to MESSENGER data. To accurately interpret reflectance spectra for airless bodies, the effects of opaque phases (e.g., Fe, Ni, sulfides) must be considered properly. Opaque metals are present as native igneous minerals in meteorites and on planetary surfaces in the form of grains significantly larger than the wavelength of the incident light. However, submicroscopic metal grains are also a key by-product of space weathering [3,7-9] and introduce confounding effects on ultraviolet (UV), visible (VIS), and near-infrared (NIR) spectra as seen in laboratory and spacecraft data for airless bodies. Specifically, nanophase metal particles (<50 nm) decreases the overall reflectance and introduce a strong positive spectral slope across the visible to near-infrared (i.e., spectral “reddening”) [8, 9], whereas microphase metal "Britt-Pieters" particles (50-3000 nm) produce an overall decrease in reflectance only [9, 14, 15].

To address this issue, our model also includes optical constants for opaque metal and mineral phases. The model used for this study was adapted from the work of [17], which uses optical constants for metals (Fe, Ni) to introduce the darkening and/or reddening effects macroscopic and submicroscopic metal on reflectance spectra. We have two main goals of the current study. First, we seek to extend the opaque phases available for spectral mixing and space weathering, which were previously centered on the Fe-rich nature of the Moon (e.g., metallic Fe), including sufides (FeS, MgS, CaS) and graphite (C). Second, we aim to dissociate the microphase and the nanophase metal phases within the model. Results of these models for planetary spectra will be presented.

References: [1] Hapke, B. (1981). [2] Hapke, B. (1993). [3] Hapke, B. (2001. [4] Lucey (1998). [5] Wilcox et al. (2006). [7] Keller and McKay (1997). [8] Pieters et al. (2000). [9] Noble, et al. (2007). [10] Britt and Pieters (1994). [11] Pieters et al. (2000). [12] Noble and Pieters (2003). [13] Nobel et al. (2006). [14] Lucey and Noble (2008). [15] Lucey and Riner (2011). [16] Lawrence and Lucey (2007). [17] Cahill et al. (2015).

Geological Society of America Abstracts with Programs. Vol. 48, No. 7

doi: 10.1130/abs/2016AM-284299

© Copyright 2016 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.