Laboratory simulations of planetary surfaces: Understanding regolith physical properties from remote photopolarimetric observations

Nelson, Robert M.; Boryta, M. D.; Hapke, Bruce; Manatt, K.; Shkuratov, Yuriy; Psarev, V. A.; Vandervoort, K. G.; Kroner, Desire; Nebedum, Adaze; Vides, C.; Quiñones, John

doi:10.1016/j.icarus.2017.11.021

Cited by 23 publications

(6 citation statements)

References 59 publications

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“…All these observations indicate that P min seems correlated to the average size of pure particles of ice. This is in agreement with previous works by Geake and Geake () and Nelson et al () with aluminum oxide particles, who described a continuous change of the shape and deepening of the NPB with decreasing particle size to wavelength ratio (d/λ).…”

Section: Discussionsupporting

confidence: 93%

“…Ground-based polarimetric observations of Solar System bodies collected over many years (Kolokolova et al, 2015), constitute a precious data set having the potential to reveal the micro-texture of these distant planetary surfaces. A large number of measurements of analogues of planetary regolith were compiled by (Geake & Dollfus, 1986;Nelson et al, 2018;Ovcharenko et al, 2006;Shkuratov, 2002;Shkuratov et al, 2006) among others, and compared with observations. Polarimetry is also used in Earth remote sensing to characterize mainly the atmospheric aerosols or the surfaces.…”

Section: Introductionmentioning

confidence: 99%

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Polarimetry of Water Ice Particles Providing Insights on Grain Size and Degree of Sintering on Icy Planetary Surfaces

et al. 2018

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The polarimetry of the light scattered by planetary surfaces is a powerful tool to provide constraints on their microstructure. To improve the interpretation of polarimetric data from icy surfaces, we have developed the POLarimeter for ICE Samples complementing the measurement facilities of the Ice Laboratory at the University of Bern. The new setup uses a high precision Stokes polarimeter to measure the degree of polarization in the visible light scattered by surfaces at moderate phase angles (from 1.5° to 30°). We present the photometric and polarimetric phase curves measured on various surfaces made of pure water ice particles having well‐controlled size and shape (spherical, crushed, and frost). The results show how the amplitude and the shape of the negative polarization branch change with the particles sizes and the degree of metamorphism of the ice. We found that fresh frost formed by water condensation on cold surfaces has a phase curve characterized by resonances (Mie oscillations) indicating that frost embryos are transparent micrometer‐sized particles with a narrow size distribution and spherical shape. Comparisons of these measurements with polarimetric observations of the icy satellites of the Solar System suggest that Europa is possibly covered by relatively coarser (~40–400 μm) and more sintered grains than Enceladus and Rhea, more likely covered by frost‐like particles of few micrometers in average. The great sensitivity of polarization to grain size and degree of sintering makes it an ideal tool to detect hints of ongoing processes on icy planetary surfaces, such as cryovolcanism.

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Section: Discussionsupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Polarimetry of Water Ice Particles Providing Insights on Grain Size and Degree of Sintering on Icy Planetary Surfaces

et al. 2018

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“…Within the error limits, the parameters P , min min a , and α inv of the NPB are independent of the wavelength in the visible domain. The morphological profiles are qualitatively consistent with theoretical studies of the angular profile of the polarization opposition effect (Mishchenko 1993;Mishchenko et al 2000Mishchenko et al , 2006Mishchenko et al , 2009Muinonen & Videen 2012) and laboratory measurements of the polarization of different high-albedo samples, e.g., MgO, Al 2 O 3 , or water ice (Lyot 1929;Geake & Geake 1990;Shkuratov et al 2002;Nelson et al 2018;Poch et al 2018). 2.…”

Section: Discussionsupporting

confidence: 81%

New Polarimetric Data for the Galilean Satellites: Europa Observations and Modeling

et al. 2022

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This paper is dedicated to a long-standing problem of the shape of the negative branch of polarization (NBP) for Jupiter's moon Europa, determination of which is crucial for the characterization of the icy regolith on this satellite and similar objects, as well as for further progress in understanding light scattering by particulate surfaces. To establish the shape of Europa's NBP, in 2018–2021 we accomplished high-precision disk-integrated polarimetry of Europa in the UBVR I bands using the identical two-channel photoelectric polarimeters mounted on the 2.6 m Shajn reflector of the Crimean Astrophysical Observatory and the 2 m telescope of the Peak Terskol Observatory. We found that the polarization dependence on the phase angle in each filter is an asymmetric curve with a sharp polarization minimum P min ≈ − 0.3 % at phase angle α min ≤ 0 .° 4 , after which the polarization degree gradually increases to positive values, passing the inversion angle at α inv ≈ 6° − 7°. Within the error limits, the parameters P min, α min , and α inv of the NPB are independent of the wavelength in the visible spectrum. The polarization curve clearly demonstrates the so-called polarization opposition effect (POE). Our analysis of the previous and new polarimetric observations of Europa allows us to conclude that the POE is caused by coherent backscattering of sunlight on microscopic icy grains covering Europa’s surface. Computer modeling with the numerical radiative transfer coherent backscattering method demonstrates that the best fit to the polarimetric observations and geometric albedo of Europa is provided by a regolith layer of elementary single-scattering albedo ∼0.985 and extinction mean free path length 2π l/λ eff ≈ 150, λ eff representing the effective wavelength in the UBVR I spectral bands.

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“…In addition, the upper most layer of the surface is likely formed of <1.5 mm particles with void spaces of up to 95% or more. 13,15 RADAR measurements 16 show that both Europa and Enceladus are bright to backscatter at a wide range of wavelengths implying likelihood of a very well-graded regolith that may be many meters deep.…”

Section: Cryogenic Ice Regolithmentioning

confidence: 99%

Design optimization of a lightweight rocker–bogie rover for ocean worlds applications

Nayar

Kim

Chamberlain-Simon

et al. 2019

International Journal of Advanced Robotic Systems

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Relatively recent discoveries have shown that large quantities of water can be found on moons of some of the planets among the gas giants in our solar system. Robotic mobility systems can study the varied geology and origins of these bodies if they are able to navigate the complex terrains of ocean worlds. The topographical features of ocean worlds present a unique combination of challenges for mobility. These include cryogenic ice, penitentes, salt evaporites, chaotic regions, and regolith with uncertain shear and sinkage properties. Uncertainty in both terrain properties and geometry motivates design of a platform that is mobile within a large range of obstacle geometries and terrain properties. This article reports on a research effort to study the requirements and numerically optimize the kinematic parameters of the rover to satisfy these goals. The platforms selected in the process were further verified via simulation. A simulation and analysis of grousers generated suitable designs for interaction with similar ledges and rough terrain. From this analysis, a prototype was developed and tested to meet the wide range of topography and terramechanics conditions expected on these bodies.

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Laboratory simulations of planetary surfaces: Understanding regolith physical properties from remote photopolarimetric observations

Cited by 23 publications

References 59 publications

Polarimetry of Water Ice Particles Providing Insights on Grain Size and Degree of Sintering on Icy Planetary Surfaces

Polarimetry of Water Ice Particles Providing Insights on Grain Size and Degree of Sintering on Icy Planetary Surfaces

New Polarimetric Data for the Galilean Satellites: Europa Observations and Modeling

Design optimization of a lightweight rocker–bogie rover for ocean worlds applications

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