scholarly journals Rigorous light-scattering simulations of nanophase iron space-weathering effects on reflectance spectra of olivine grains

Icarus ◽  
2020 ◽  
Vol 345 ◽  
pp. 113727 ◽  
Author(s):  
Antti Penttilä ◽  
Timo Väisänen ◽  
Johannes Markkanen ◽  
Julia Martikainen ◽  
Tomáš Kohout ◽  
...  
Keyword(s):  
Light Scattering ◽  
Reflectance Spectra ◽  
Space Weathering ◽  
Weathering Effects ◽  
Nanophase Iron

Rigorous light-scattering simulations of space-weathering effects on reflectance spectra

2021 ◽  
Author(s):  
Antti Penttilä ◽  
Timo Väisänen ◽  
Johannes Markkanen ◽  
Julia Martikainen ◽  
Tomas Kohout ◽  
...  
Keyword(s):  
Light Scattering ◽  
Reflectance Spectra ◽  
Space Weathering ◽  
Spectral Slope ◽  
Simulation Tools ◽  
Multi Scale ◽  
Spectral Bands ◽  
Size Scales ◽  
Weathering Effects

<p>We present a multi-scale light-scattering model that is capable of simulating the reflectance spectra of a regolith layer. In particular, the model can be applied to a case where the regolith grains have varying amounts of nanophase inclusions due to space weathering of the material. As different simulation tools are employed for different size scales of the target geometry (roughly, nano-, micro-, and millimeter scales), the particle size effects, the surface reflections, and the volume scattering can all be properly accounted for. Our results with olivine grains and nanophase iron inclusions verify the role of the nanoinclusions in the reflectance spectra of space-weathered materials. Together with the simulation results, we give simplified explanations for the space-weathering effects based on light scattering, namely the decrease of albedo, the general increase of the red spectral slope, and the dampening of the spectral bands. We also consider the so-called ultraviolet bluing effect and show how the change in the spectral slope over the ultraviolet-visual wavelengths is due to the decrease of reflectance in the visual wavelengths rather than the increase of reflectance in the ultraviolet part.</p>

scholarly journals Space Weathering of S-Complex Asteroids Manifested in the UV/Blue: Recent Insights and Future Directions

2015 ◽  
Vol 10 (S318) ◽  
pp. 201-205
Author(s):  
Faith Vilas ◽  
Amanda R. Hendrix
Keyword(s):  
Spectral Reflectance ◽  
Near Infrared ◽  
Uv Absorption ◽  
Reflectance Spectra ◽  
Absorption Feature ◽  
Space Weathering ◽  
The Moon ◽  
Future Directions ◽  
Absorption Features ◽  
Weathering Effects

AbstractSpace weathering affects reflectance spectra of the Moon and S-complex asteroids by spectral bluing (increasing reflectance with decreasing wavelength) of their surface materials at UV/blue (less than 400 nm) wavelengths. This spectral bluing is attributed to a degradation of the UV absorption feature seen in spectral reflectance of olivine as a result of the creation of nanophase (npFe0) iron. We have modeled the effect of the addition of small amounts of npFe0 intimately mixed with particles from a hypothetical material and a terrestrial basalt. The addition of 0.0001% npFe0 affects the reflectance at these UV/blue wavelengths, while the addition of 0.01% is required to see the visible/near infrared reddening and diminution of VNIR absorption features. Thus, the UV/blue spectral reflectance characteristics allow earlier detection of the onset of space weathering effects.

scholarly journals Distinguishing between Shock-darkening and Space-weathering Trends in Ordinary Chondrite Reflectance Spectra

2020 ◽  
Vol 1 (2) ◽  
pp. 37
Author(s):  
Tomas Kohout ◽  
Antti Penttilä ◽  
Paul Mann ◽  
Ed Cloutis ◽  
Jan Čuda ◽  
...  
Keyword(s):  
Ordinary Chondrite ◽  
Reflectance Spectra ◽  
Space Weathering

scholarly journals Spectral variability on primitive asteroids of the Themis and Beagle families: Space weathering effects or parent body heterogeneity?

Icarus ◽  
2016 ◽  
Vol 269 ◽  
pp. 1-14 ◽  
Author(s):  
S. Fornasier ◽  
C. Lantz ◽  
D. Perna ◽  
H. Campins ◽  
M.A. Barucci ◽  
...  
Keyword(s):  
Parent Body ◽  
Space Weathering ◽  
Spectral Variability ◽  
Weathering Effects

Combining Experiments and Modelling to Understand the Role of Potential Sputtering by Solar Wind Ions

2020 ◽  
Author(s):  
Paul Stefan Szabo ◽  
Herbert Biber ◽  
Noah Jäggi ◽  
Matthias Brenner ◽  
David Weichselbaum ◽  
...  
Keyword(s):  
Solar Wind ◽  
Solar System ◽  
Surface Composition ◽  
Space Weathering ◽  
Mineral Surfaces ◽  
Multiply Charged ◽  
History Of ◽  
System 2 ◽  
Sputtering Yields ◽  
Weathering Effects

<p>In the absence of a protecting atmosphere, the surfaces of rocky bodies in the solar system are affected by significant space weathering due to the exposure to the solar wind [1]. Fundamental knowledge of space weathering effects, such as optical changes of surfaces as well as the formation of an exosphere is essential for gaining insights into the history of planetary bodies in the solar system [2]. Primarily the exospheres of Mercury and Moon are presently of great interest and the interpretation of their formation processes relies on the understanding of all space weathering effects on mineral surfaces.</p><p>Sputtering of refractory elements by solar wind ions is one of the most important release processes. We investigate solar wind sputtering by measuring and modelling the sputtering of pyroxene samples as analogues for the surfaces of Mercury and Moon [3, 4]. These measurements with thin film samples on Quartz Crystal Microbalance (QCM) substrates allow recording of sputtering yields in-situ and in real time [5]. For the simulation of kinetic sputtering from the ion-induced collision cascade we use the software SDTrimSP with adapted input parameters that consistently reproduce measured kinetic sputtering yields [4, 6].</p><p>This study focuses on investigating the potential sputtering of insulating samples by multiply charged ions [7]. Changes of these sputtering yields with fluence are compared to calculations with a model based on inputs from SDTrimSP simulations. This leads to a very good agreement with steady-state sputtering yields under the assumption that only O atoms are sputtered by the potential energy of the ions. The observed decreasing sputtering yields can be explained by a partial O depletion on the surface [4]. Based on these findings expected surface composition changes and sputtering yields under realistic solar wind conditions can be calculated. Our results are in line with previous investigations (see e.g. [8, 9]), creating a consistent view on solar wind sputtering effects from experiments to established modelling efforts.</p><p> </p><p><strong>References:</strong></p><p>[1]          B. Hapke, J. Geophys. Res.: Planets, <strong>106</strong>, 10039 (2001).</p><p>[2]          P. Wurz, et al., Icarus, <strong>191</strong>, 486 (2007).</p><p>[3]          P.S. Szabo, et al., Icarus, <strong>314</strong>, 98 (2018).</p><p>[4]          P.S. Szabo, et al., submitted to Astrophys. J. (2020).</p><p>[5]          G. Hayderer, et al., Rev. Sci. Instrum., <strong>70</strong>, 3696 (1999).</p><p>[6]          A. Mutzke, et al., “SDTrimSP Version 6.00“, IPP Report, (2019).</p><p>[7]          F. Aumayr, H. Winter, Philos. Trans. R. Soc. A, <strong>362</strong>, 77 (2004).</p><p>[8]          H. Hijazi, et al., J. Geophys. Res.: Planets, <strong>122</strong>, 1597 (2017).</p><p>[9]          S.T. Alnussirat, et al., Nucl. Instrum. Methods Phys. Res. B, <strong>420</strong>, 33 (2018).</p>

Simulation of nanophase iron production in lunar space weathering

2012 ◽  
Vol 60 (1) ◽  
pp. 322-327 ◽  
Author(s):  
Hong Tang ◽  
Shijie Wang ◽  
Xiongyao Li
Keyword(s):  
Iron Production ◽  
Space Weathering ◽  
Nanophase Iron

Diffuse Reflectance Studies of Edible Fats

2002 ◽  
Vol 56 (8) ◽  
pp. 1094-1097 ◽  
Author(s):  
N. Ghosh ◽  
A. Datta ◽  
P. K. Gupta
Keyword(s):  
Light Scattering ◽  
Absorption Coefficient ◽  
Diffuse Reflectance ◽  
Reflectance Spectra ◽  
Integrating Sphere ◽  
Diffuse Reflectance Spectra ◽  
Edible Fats ◽  
Partially Hydrogenated Vegetable Oil ◽  
Hydrogenated Vegetable Oil ◽  
Absorption Characteristics

Light scattering properties of ghee (a form of clarified butter) and vanaspati (partially hydrogenated vegetable oil) have been investigated in order to explore the use of optical techniques for detection of adulteration of vanaspati in ghee. Significant differences in the diffuse reflectance spectra of ghee and vanaspati were observed. The estimates for the reduced scattering coefficient (μs′) and the absorption coefficient (μa) for ghee and vanaspati were also obtained from integrating sphere measurements. These suggest that the differences in the diffuse reflectance spectra of ghee and vanaspati are primarily due to the differences in their absorption characteristics in the spectral range of 400 to 550 nm. Further, the results obtained show that the ratio of diffuse reflectance at 460 nm to that at 410 nm could be used to detect adulteration of vanaspati in ghee.

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