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Effects of viewing geometry, aggregation state, and particle size on reflectance spectra of the Murchison CM2 chondrite deconvolved to Dawn FC band passes

Izawa, Matthew R. M. and Schäfer, Tanja and Pietrasz, Valerie B. and Cloutis, Edward A. and Mann, Paul and Nathues, Andreas and Mengel, Kurt and Schäfer, Michael and Thangjam, Guneshwar and Hoffmann, Martin and Tait, Kimberly T. and Applin, Daniel M. (2016) Effects of viewing geometry, aggregation state, and particle size on reflectance spectra of the Murchison CM2 chondrite deconvolved to Dawn FC band passes. Icarus, 266 . pp. 235-248. ISSN 0019-1035. https://resolver.caltech.edu/CaltechAUTHORS:20160204-104057949

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Abstract

Several current and soon-to-launch missions will investigate ‘dark’ asteroids, whose spectra have few weak or no distinct spectral features. Some carbonaceous chondrites, particularly the CI and CM groups, are reasonable material analogues for many dark asteroid surfaces. In addition to compositional variations, many non-compositional effects, including viewing geometry, surface particle size and particle sorting, can influence reflectance spectra, potentially complicating mineralogical interpretation of such data from remote surfaces. We have carried out an investigation of the effects of phase angle, particle size, aggregation state, and intra-sample heterogeneity on the reflectance spectra (0.4–1.0 μm) of the Murchison CM2 carbonaceous chondrite, deconvolved to Dawn Framing Camera (FC) band passes. This study was motivated by the desire to derive information about the surface of Ceres from Dawn FC data. Key spectral parameters derived from the FC multispectral data include various two-band reflectance ratios as well as three-band ratios that have been derived for mineralogical analysis. Phase angle effects include increased visible slope with increasing phase angle, a trend that may reverse at very high phase angles. Fine-grained particles exert a strong influence on spectral properties relative to their volumetric proportion. Grain size variation effects include a decrease in spectral contrast and increased visible spectral slope with decreasing grain size. Intra-sample heterogeneity, while spectrally detectable, is of relatively limited magnitude.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1016/j.icarus.2015.10.029DOIArticle
http://www.sciencedirect.com/science/article/pii/S0019103515005072PublisherArticle
Additional Information:© 2015 Elsevier Inc. Received 10 June 2015; Revised 16 October 2015; Accepted 31 October 2015; Available online 7 November 2015. The University of Winnipeg’s HOSERLab was established with funding from the Canada Foundation for Innovation, the Manitoba Research Innovations Fund and the Canadian Space Agency, whose support is gratefully acknowledged. Thanks to Julia de Leon and an anonymous reviewer for constructive criticisms that led to substantial improvements to this manuscript. This study was supported by research grants from NSERC, the Canadian Space Agency, the Hatch foundation, and the University of Winnipeg. This work benefited from discussions with Ian Nicklin, and Brendt Hyde at the Royal Ontario Museum. Thanks also to Jim Bell at Arizona State University for providing additional Murchison samples.
Funders:
Funding AgencyGrant Number
Canada Foundation for InnovationUNSPECIFIED
Manitoba Research Innovations FundUNSPECIFIED
Canadian Space Agency (CSA)UNSPECIFIED
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Hatch FoundationUNSPECIFIED
University of WinnipegUNSPECIFIED
Subject Keywords:Asteroid Ceres; Spectroscopy; Meteorites
Record Number:CaltechAUTHORS:20160204-104057949
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20160204-104057949
Official Citation:Matthew R.M. Izawa, Tanja Schäfer, Valerie B. Pietrasz, Edward A. Cloutis, Paul Mann, Andreas Nathues, Kurt Mengel, Michael Schäfer, Guneshwar Thangjam, Martin Hoffmann, Kimberly T. Tait, Daniel M. Applin, Effects of viewing geometry, aggregation state, and particle size on reflectance spectra of the Murchison CM2 chondrite deconvolved to Dawn FC band passes, Icarus, Volume 266, 1 March 2016, Pages 235-248, ISSN 0019-1035, http://dx.doi.org/10.1016/j.icarus.2015.10.029. (http://www.sciencedirect.com/science/article/pii/S0019103515005072)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:64222
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:04 Feb 2016 19:48
Last Modified:03 Oct 2019 09:35

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