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Thermal infrared emissivity of felsic-rich to mafic-rich analogues of hot planetary regoliths

Ferrari, Sabrina and Maturilli, Alessandro and Carli, C. and D'Amore, M and Helbert, Jörn and Nestola, Fabrizio and Hiesinger, H. (2020) Thermal infrared emissivity of felsic-rich to mafic-rich analogues of hot planetary regoliths. Earth and Planetary Science Letters, 534, p. 116089. Elsevier. doi: 10.1016/j.epsl.2020.116089. ISSN 0012-821X.

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Official URL: https://www.sciencedirect.com/science/article/abs/pii/S0012821X20300327

Abstract

Inner Solar System bodies with absent or extremely tenuous atmospheres such as Mercury and several high-eccentricity Near Earth Objects (NEOs) are subject to a wide range of surface temperatures. Here we show how the thermal expansion induced by strong diurnal insolation variations affects the thermal infrared spectra of felsic-rich to mafic-rich regoliths. 1400-700 cm−1 spectra of granular plagioclase-pyroxene mixtures were measured in the laboratory at four temperatures between 425 K and 725 K, simulating different daily surface temperatures within the Solar System. At the same time, we describe for the first time how two minerals with different thermal expansion coefficients combined in the same granular sample appear in a non-ambient (i.e., non-298 K) thermal infrared spectrum. The spectra of plagioclase-rich analogues appear to be dominated by felsic features regardless of the daily surface temperature, and do not exhibit any of the short-wavelength absorptions of pyroxenes. When detectable, on the other hand, the 870-cm−1 pyroxene absorption, which is not affected by thermal variations, functions instead as a proxy for the solid-solution composition (i.e., the Mg-Fe relative contents). In contrast, indications of the plagioclase solid solution occurring at ambient temperatures (i.e., Ca-Na relative contents) disappear at temperatures over 525 K. Christiansen feature position and spectral contrast, which show a clear dependency on composition even at high temperatures, require an accurate reproduction of the shallow thermal gradient in order to be used as indices. In general, in order to decipher planetary hyperspectral data, surface temperature acquisition seems to be a prerequisite, as well as a comparison with analogue spectra obtained under realistic environmental conditions.

Item URL in elib:https://elib.dlr.de/138419/
Document Type:Article
Title:Thermal infrared emissivity of felsic-rich to mafic-rich analogues of hot planetary regoliths
Authors:
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Ferrari, Sabrinasabrina.ferrari (at) dlr.deUNSPECIFIED
Maturilli, AlessandroAlessandro.Maturilli (at) dlr.dehttps://orcid.org/0000-0003-4613-9799
Carli, C.INAF-IAPS, Via del Fosso del Cavaliere 100, I-00133 Rome, ItalyUNSPECIFIED
D'Amore, MMario.Damore (at) dlr.deUNSPECIFIED
Helbert, JörnJoern.Helbert (at) dlr.dehttps://orcid.org/0000-0001-5346-9505
Nestola, Fabriziodipartimento di geoscienze, università degli studi di padova, italyUNSPECIFIED
Hiesinger, H.Institut für Planetologie, Westfälische Wilhelms-Universität, GermanyUNSPECIFIED
Date:March 2020
Journal or Publication Title:Earth and Planetary Science Letters
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:534
DOI :10.1016/j.epsl.2020.116089
Page Range:p. 116089
Publisher:Elsevier
ISSN:0012-821X
Status:Published
Keywords:planetary, silicate, plagioclase, pyroxene, emissivity, temperature
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Exploration
DLR - Research area:Raumfahrt
DLR - Program:R EW - Space Exploration
DLR - Research theme (Project):R - Project BepiColombo - MERTIS and BELA
Location: Berlin-Adlershof
Institutes and Institutions:Institute of Planetary Research > Planetary Laboratories
Deposited By: Maturilli, Dr. Alessandro
Deposited On:03 Dec 2020 14:07
Last Modified:08 Dec 2020 13:44

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