Coherent Backscattering Verified Numerically for a Finite Volume of Spherical Particles

Muinonen, K.; Mishchenko, Michael I.; Dlugach, Janna M.; Zubko, Evgenij; Penttilä, Antti; Videen, Gorden

doi:10.1088/0004-637x/760/2/118

Cited by 95 publications

(71 citation statements)

References 31 publications

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“…The studies in Muinonen et al (2012) were limited to sparsely-packed arrangements of scatterers (packing factors only as large as 6.25%). To be more directly applicable to regolithcovered bodies, more work will be needed to determine the method's applicability to densely packed arrangements of scatterers.…”

Section: Muinonen Rt-cb Modelmentioning

confidence: 99%

Asteroid Photometry

Li¹,

Helfenstein²,

Buratti³

et al. 2015

Asteroids IV

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Asteroid photometry has three major applications: providing clues about asteroid surface physical properties and compositions, facilitating photometric corrections, and helping design and plan ground-based and spacecraft observations. The most significant advances in asteroid photometry in the past decade were driven by spacecraft observations that collected spatially resolved imaging and spectroscopy data. In the mean time, laboratory measurements and theoretical developments are revealing controversies regarding the physical interpretations of models and model parameter values. We will review the new developments in asteroid photometry that have occurred over the past decade in the three complementary areas of observations, laboratory work, and theory. Finally we will summarize and discuss the implications of recent findings. ! 2!

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Section: Muinonen Rt-cb Modelmentioning

confidence: 99%

Asteroid Photometry

Li¹,

Helfenstein²,

Buratti³

et al. 2015

Asteroids IV

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“…Recently developed theoretical models have gained some success in simulations of light scattering by particulate media (Mishchenko 1992;Muinonen et al 2012;Mackowski & Mishchenko 1996 to fully explain the observed OE. However, to simulate realistic media, these models require enormous computer resources, which are often unavailable to researchers, and deal with a limited range of parameters.…”

Section: Introductionmentioning

confidence: 99%

Opposition effect on comet 67P/Churyumov-Gerasimenko using Rosetta-OSIRIS images

Masoumzadeh

Oklay

Kolokolova

et al. 2017

A&A

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Aims. We aim to explore the behavior of the opposition effect as an important tool in optical remote sensing on the nucleus of comet 67P/ Churyumov-Gerasimenko (67P), using Rosetta-OSIRIS images acquired in different filters during the approach phase, July-August 2014 and the close flyby images on 14 of February 2015, which contain the spacecraft shadow. Methods. We based our investigation on the global and local brightness from the surface of 67P with respect to the phase angle, also known as phase curve. The local phase curve corresponds to a region that is located at the Imhotep-Ash boundary of 67P. Assuming that the region at the Imhotep-Ash boundary and the entire nucleus have similar albedo, we combined the global and local phase curves to study the opposition-surge morphology and constrain the structure and properties of 67P. The model parameters were furthermore compared with other bodies in the solar system and existing laboratory study. Results. We found that the morphological parameters of the opposition surge decrease monotonically with wavelength, whereas in the case of coherent backscattering this behavior should be the reverse. The results from comparative analysis place 67P in the same category as the two Mars satellites, Phobos and Deimos, which are notably different from all airless bodies in the solar system. The similarity between the surface phase function of 67P and a carbon soot sample at extremely small angles is identified, introducing regolith at the boundary of the Imhotep-Ash region of 67P as a very dark and fluffy layer.

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“…The latter happens when the multiple scattered electromagnetic waves constructively interfere at near zero phase angle. Those mechanisms are intrinsically connected to regolith packing, size distribution, particle shape, inclusions and transparency in a complex relation that it is still subject of on-going research (e.g., Muinonen et al, 2012;Déau et al, 2013). Other aspect is the macroscopic shadowing, a mechanism often significant when a surface is observed at phase angle larger than about 30 degrees and when illumination azimuth is higher.…”

Section: Introductionmentioning

confidence: 99%

Asteroid (21) Lutetia: Disk-resolved photometric analysis of Baetica region

Hasselmann

Fornasier

Leyrat

et al. 2016

Icarus

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ABSTRACT. (21) Lutetia has been visited by Rosetta mission on July 2010 and observed with a phase angle ranging from 0.15 to 156.8 degrees. The Baetica region, located at the north pole has been extensively observed by OSIRIS cameras system. Baetica encompass a region called North Pole Crater Cluster (NPCC), shows a cluster of superposed craters which presents signs of variegation at the small phase angle images. For studying the location, we used 187 images distributed throughout 14 filter recorded by the NAC (Narrow Angle Camera) and WAC (Wide Angle Camera) of the OSIRIS system on-board Rosetta taken during the fly-by. Then, we photometrically modeled the region using Minnaert diskfunction and Akimov phase function to obtain a resolved spectral slope map at phase angles of 5 • and 20 • . We observed a dicothomy between Gallicum and Danuvius-Sarnus Labes in the NPCC, but no significant phase reddening (−0.04 ± 0.045% · microns −1 deg −1 ). In the next step, we applied the Hapke (2008Hapke ( ,2012 model for the NAC F82+F22 (649.2 nm), WAC F13 (375 nm) and WAC F17 (631.6 nm) and we obtained normal albedo maps and Hapke parameter maps for NAC F82+F22. On Baetica, at 649.2 nm, the geometric albedo is 0.205 ± 0.005, the average single-scattering albedo is 0.181 ± 0.005, the average asymmetric factor is −0.342 ± 0.003, the average shadow-hiding opposition effect amplitude and width are 0.824 ± 0.002 and 0.040 ± 0.0007, the average roughness slope is 11.45 • ± 3 • and the average porosity is 0.85 ± 0.002. We are unable to confirm the presence of coherent-backscattering mechanism. In the NPCC, the normal albedo variegation among the craters walls reach 8% brighter for Gallicum Labes and 2% fainter for Danuvius Labes. The Hapke parameter maps also show a dicothomy at the opposition effect coefficients, single-scattering albedo and asymmetric factor, that may be attributed to the maturation degree of the regolith or to compositonal variation. In addition, we compared the Hapke (2008Hapke ( , 2012 and Hapke (1993) parameters with laboratory samples and other small-solar system bodies visited by space missions.

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Coherent Backscattering Verified Numerically for a Finite Volume of Spherical Particles

Cited by 95 publications

References 31 publications

Asteroid Photometry

Asteroid Photometry

Opposition effect on comet 67P/Churyumov-Gerasimenko using Rosetta-OSIRIS images

Asteroid (21) Lutetia: Disk-resolved photometric analysis of Baetica region

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