Modeling optical roughness and first-order scattering processes from OSIRIS-REx color images of the rough surface of asteroid (101955) Bennu

Hasselmann, P. H.; Fornasier, S.; Praet, A.; Clark, B. E.; Li, Jian‐Yang; Golish, D. R.; DellaGiustina, D. N.; Deshapriya, J. D. P.; Zou, Xian Duan; Daly, M. G.; Barnouin, O. S.; Simon-Miller, A. A.; Лауретта, Д. С.

doi:10.1016/j.icarus.2020.114106

Cited by 10 publications

(8 citation statements)

References 73 publications

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“…This is corroborated by the experiments on roughness of iron meteorites (Libourel et al 2019), and possibly by results presented by Hasselmann et al (2020). These authors showed that the modelization of the bidirectional reflectance distribution of Bennu is improved when the two scattering components are both included in the model (Hasselmann et al 2020). Considering thus that the bluest spectral slopes are those more dominated by Rayleigh scatters on UV-VIS wavelengths, where the observed stronger phase reddening may be attributable to sub-micron roughness, the weak anticorrelation found for craters may indicate that they have a lower roughness size scale, possibly sub-micron sized, than boulders.…”

Section: Spectral Phase Reddening and Phase Function Parameterssupporting

confidence: 73%

“…Therefore, overall, the mechanism is controlled by two scattering components, diffuse and specular. This is corroborated by the experiments on roughness of iron meteorites (Libourel et al 2019), and possibly by results presented by Hasselmann et al (2020). These authors showed that the modelization of the bidirectional reflectance distribution of Bennu is improved when the two scattering components are both included in the model (Hasselmann et al 2020).…”

Section: Spectral Phase Reddening and Phase Function Parameterssupporting

confidence: 55%

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Phase reddening on asteroid Bennu from visible and near-infrared spectroscopy

Fornasier

Hasselmann

Deshapriya

et al. 2020

A&A

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Context. The NASA mission OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer) has been observing near-Earth asteroid (101955) Bennu in close proximity since December 2018. The spacecraft has collected, on October 2020, a sample of surface material from Bennu to return to Earth. Aims. In this work, we investigate spectral phase reddening-that is, the variation of spectral slope with phase angle-on Bennu using spectra acquired by the OSIRIS-REx Visible and InfraRed Spectrometer (OVIRS) covering a phase angle range of 8-130 o. We investigate this process at the global scale and for some localized regions of interest (ROIs), including boulders, craters, and the designated sample collection sites of the OSIRIS-REx mission. Methods. Spectra were wavelength-and flux-calibrated, then corrected for the out-of-band contribution and thermal emission, resampled, and finally converted into radiance factor per standard OVIRS processing. Spectral slopes were computed in multiple wavelength ranges from spectra normalized at 0.55 µm. Results. Bennu has a globally negative spectra slope, which is typical of B-type asteroids. The spectral slope gently increases in a linear way up to a phase angle of 90 • , where it approaches zero. The spectral phase reddening is monotonic and wavelength-dependent with highest values in the visible range. Its coefficient is 0.00044 µm −1 deg −1 in the 0.55-2.5 µm range. For observations of Bennu acquired at high phase angle (130 •), phase reddening increases exponentially, and the spectral slope becomes positive. Similar behavior was reported in the literature for the carbonaceous chondrite Mukundpura in spectra acquired at extreme geometries. Some ROIs, including the sample collection site, Nightingale, have a steeper phase reddening coefficient than the global average, potentially indicating a surface covered by fine material with high micro-roughness. Conclusions. The gentle spectral phase reddening effect on Bennu is similar to that observed in ground-based measurements of other B-type asteroids, but much lower than that observed for other low-albedo bodies such as Ceres or comet 67P/Churyumov-Gerasimenko. Monotonic reddening may be associated with the presence of fine particles at micron scales and/or of particles with fractal structure that introduce micro-and sub-micro roughness across the surface of Bennu.

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Section: Spectral Phase Reddening and Phase Function Parameterssupporting

confidence: 73%

Section: Spectral Phase Reddening and Phase Function Parameterssupporting

confidence: 55%

Phase reddening on asteroid Bennu from visible and near-infrared spectroscopy

Fornasier

Hasselmann

Deshapriya

et al. 2020

A&A

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“…Results for 𝐶 = 1 were almost identical to the ones for 𝐶 = 0, so were not included in this plot. Hasselmann et al 2021). Because of this, a lower 𝛽 value for the coma agglomerates is consistent with the smaller size of the dust agglomerates in the coma compared to that of the nucleus.…”

Section: Phase Functionmentioning

confidence: 99%

Distribution and dynamics of decimeter-sized dust agglomerates in the coma of 67P/Churyumov-Gerasimenko

Lemos¹,

Agarwal²,

Schröter³

2023

Preprint

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We present a method to analyze images of the coma of 67P/Churyumov-Gerasimenko obtained using OSIRIS, the main imaging system onboard Rosetta, where dust aggregates can be seen as bright tracks because of their relative velocity with respect to the spacecraft. We applied this method to 105 images taken in 2015 July, 2015 December and 2016 January, identifying more than 20000 individual objects. We performed a photometric analysis of them, finding their phase function. This phase function follows the same trend as the one found for the nucleus, consistent with the detected particles having a size larger than ∼ 1 mm. Additionally, the phase function becomes shallower for increasing heliocentric distances, indicating a decrease in the mean agglomerate size. In order to characterize the agglomerates observed in the image, we developed a simplified model for their ejection and dynamics in the coma, and generated synthetic images based on it. We solved the inverse problem by finding the simulation parameters that give the best fit between synthetic and real images. In doing so, we were able to obtain a mean agglomerate size ∼ dm and initial speed 1 m s -1 . Both show a decrease with increasing heliocentric distance, sign of the reduction in activity. Also, the sizes obtained by the comparison are not compatible with ejection caused by water activity, so other sources have to be invoked, mainly CO 2 .

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“…The photometric phase curve will reveal some scattering properties of the granular surface medium. With the bidirectional reflectance distribution function (BRDF) reconstructed from these data in combination with ancillary images from SPICE kernel image simulations (Hasselmann et al 2021;Zinzi et al 2022), we will be able to undertake disk-resolved photometric modeling (Hapke 2012;Hasselmann et al 2017Hasselmann et al , 2021 and apply photometric-topographic corrections (Shkuratov et al 2011;Li et al 2015). Within this phase angle coverage, the surface texture, particle irregularities, multiple scattering, and multiscale roughness are the dominant properties (Muinonen et al 2011;Labarre et al 2017).…”

Section: Photometric Phase Curve Analysismentioning

confidence: 99%

Expected Investigation of the (65803) Didymos–Dimorphos System Using the RGB Spectrophotometry Data Set from the LICIACube Unit Key Explorer (LUKE) Wide-angle Camera

Poggiali¹,

Brucato²,

Hasselmann³

et al. 2022

Planet. Sci. J.

Self Cite

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The Light Italian Cubesat for Imaging of Asteroids (LICIACube) is part of the NASA Double Asteroid Redirection Test (DART), the first mission aiming to demonstrate the applicability of the kinetic impactor method for planetary defense. The mission was launched on 2021 November 24 to perform the impact experiment on Dimorphos, the small secondary of the binary asteroid (65803) Didymos. The 6U LICIACube, stored as a piggyback of the DART spacecraft, is the first Italian mission operating in deep space managed by the Italian Space Agency that will witness the effects of the DART impact on Dimorphos. On board LICIACube, there is a suite of cameras that will perform imaging of Didymos and Dimorphos to investigate the DART impact effects and study the binary system. Among them, the LICIACube Unit Key Explorer (LUKE), a wide-angle camera coupled to an RGB Bayer pattern filter, will be pivotal to constrain the surface composition and heterogeneity of the binary system due to differences in surface properties linked with possible space weathering effects and/or the presence of exogenous material. Multiband photometric analysis of LUKE data and laboratory experiments in support of data interpretation will provide new insights on the binary asteroid nature and evolution. Moreover, photometric phase curve analysis will reveal the scattering properties of the granular surface medium providing important constraints for the microphysical properties of the Didymos–Dimorphos system. In this work, we will present the state of the art of the LUKE scientific activities with an overview of the instrument setup, science operations, and expected results.

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Modeling optical roughness and first-order scattering processes from OSIRIS-REx color images of the rough surface of asteroid (101955) Bennu

Cited by 10 publications

References 73 publications

Phase reddening on asteroid Bennu from visible and near-infrared spectroscopy

Phase reddening on asteroid Bennu from visible and near-infrared spectroscopy

Distribution and dynamics of decimeter-sized dust agglomerates in the coma of 67P/Churyumov-Gerasimenko

Expected Investigation of the (65803) Didymos–Dimorphos System Using the RGB Spectrophotometry Data Set from the LICIACube Unit Key Explorer (LUKE) Wide-angle Camera

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