Disk-Integrated Photometry of 433 Eros

Domingue, D. L.; Robinson, M. S.; Carcich, B.; Joseph, J.; Thomas, P. C.; Clark, B. E.

doi:10.1006/icar.2001.6764

Cited by 47 publications

(44 citation statements)

References 33 publications

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“…The observed solar phase curves for each filter were modeled using a least squares grid search over the Hapke parameter space using the same algorithm from Domingue et al (2002) and Lederer et al (2005). The least squares grid search routine searches over the Hapke parameters w, B o , h, b, c, and θ , described above.…”

Section: Modeling Methodsmentioning

confidence: 99%

“…This is done to decouple the different parameter effects for the same region of the solar phase curve. For example, the U, J, H, K filter data do not have coverage in the opposition region, thus solutions were found based on different assumptions for the opposition effect parameters (ranging from null values to those values obtained by Domingue et al (2002) for Eros). Ranges for the other parameter values were found that resulted in models within the error bars of the measurements, and thus provided the error estimates for these parameters.…”

Section: Modeling Methodsmentioning

confidence: 99%

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The 2004 Las Campanas/Lowell Observatory campaign II. Surface properties of Hayabusa target Asteroid 25143 Itokawa inferred from Hapke modeling

et al. 2008

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We present an analysis of Hapke photometric modeling applied to uniform ground-based UBVRIJHK broadband data of asteroid 25143 Itokawa collected over a wide range of solar phase angles (4• -130• ) during the 2004 apparition (Thomas-Osip et al., this issue, hereafter Paper I). Our photometric analyses indicate that Itokawa has a blocky surface with properties different from other, albeit larger, S-class asteroids studied using similar Hapke modeling analyses. Images from the Hayabusa spacecraft affirm the Hapke modeling results, demonstrating the ability of Hapke photometric modeling to predict a rocky asteroid surface correctly; this is the first time that a predicted rocky surface has been observed by a spacecraft. The single particle scattering functions are dominantly forward scattering, suggesting the surface material is composed primarily of clear particles whose scattering is dictated by the particle's surface as opposed to internal scatterers (more typical of S-class asteroids), while the opposition parameters indicate that the regolith may be more compact than most of the limited number of asteroids visited by spacecraft to date. The roughness properties, single particle scattering properties, and opposition surge characteristics are all indicative of a surface where multiple scattering does not play a major role in defining the photometric properties of the regolith.

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Section: Modeling Methodsmentioning

confidence: 99%

Section: Modeling Methodsmentioning

confidence: 99%

The 2004 Las Campanas/Lowell Observatory campaign II. Surface properties of Hayabusa target Asteroid 25143 Itokawa inferred from Hapke modeling

et al. 2008

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“…The ponds also exhibit a somewhat elevated reflectance at 750 nm relative to their surroundings «5%). To date all analysis of NEAR Shoemaker remote sensing measurements (gamma-ray spectroscopy (GRS), magnetometer (MAG), MSI, near-infrared spectroscopy (NIS), x-ray spectroscopy (XRS)) ofthe asteroid imply a compositionally homogeneous body (Acuna et al, 2002;Bell et al, 2002;Murchie et al, 2002b;Evans et al, 2001;McCoy et al, 2001McCoy et al, , 2002Nittler et al, 2001;Trombka et al, 2001;Domingue et al, 2002;Lucey et al, 2002) discounting the possibility that the pond color properties indicate exposures of a different rock type. Alternative explanations for these color differences include secondary alteration (space weathering), mineral sorting, or differences in grain size (see discussion below).…”

Section: Introductionmentioning

confidence: 99%

The geology of 433 Eros

Robinson

Thomas

Veverka

et al. 2002

Meteorit & Planetary Scien

156

140

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Abstract-The global high-resolution imaging of asteroid 433 Eros by the Near-Earth Asteroid Rendezvous (NEAR) Shoemaker spacecraft has made it possible to develop the first comprehensive picture of the geology of a small S-type asteroid. Eros displays a variety of surface features, and evidence of a substantial regolith. Large scale facets, grooves, and ridges indicate the presence of at least one global planar structure. Directional and superposition relations of smaller structural features suggest that fracturing has occurred throughout the object. As with other small objects, impact craters dominate the overall shape as well as the small-scale topography of Eros. Depth/diameter ratios of craters on Eros average -0.13, but the freshest craters approach lunar values of -0.2. Ejecta block production from craters is highly variable; the majority oflarge blocks appear to have originated from one 7.6 km crater (Shoemaker). The interior morphology of craters does not reveal the influence of discrete mechanical boundaries at depth in the manner of craters formed on lunar mare regolith and on some parts of Phobos. This lack of mechanical boundaries, and the abundant evidence of regolith in nearly every high-resolution image, suggests a gradation in the porosity and fracturing with depth. The density of small craters is deficient at sizes below -200 m relative to predicted slopes of empirical saturation. This characteristic, which is also found on parts ofPhobos and lunar highland areas, probably results from the efficient obliteration of small craters on a body with significant topographic slopes and a thick regolith. Eros displays a variety ofregolith features, such as debris aprons, fine-grained "ponded" deposits, talus cones, and bright and dark streamers on steep slopes indicative ofefficient downslope movement ofregolith. These processes serve to mix materials in the upper loose fragmental portion ofthe asteroid (regolith). In the instance of "ponded" materials and crater wall deposits, there is evidence of processes that segregate finer materials into discrete deposits. The NEAR observations have shown us that surface processes on small asteroids can be very complex and result in a wide variety of morphologic features and landforms that today seem exotic. Future missions to comets and asteroids will surely reveal still as yet unseen processes as well as give context to those discovered by the NEAR Shoemaker spacecraft.

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“…Such work will be useful in analyzing the reflectance condition of the regolith on small bodies in terms of the bidirectional reflectance determined using optical instruments onboard asteroid missions, in the same manner as Domingue et al (2002) investigated the porosity of the regolith surface of 433 Eros. This work is one of the first steps in the experimental verification of such studies.…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, asteroid surfaces with escape velocities beyond tens of cm/s can have a regolith layer made from such fallen ejecta. Moreover, data from spacecraft observations interpreted using Hapke's (1993) model indicate that the surface of asteroid 433 Eros has a porosity exceeding 70% (Domingue et al, 2002). Therefore, the surface is probably rougher and more porous than laboratory surfaces smoothed using a spatula.…”

Section: Introductionmentioning

confidence: 99%

Quantification of porosity and surface roughness in laboratory measurements of the bidirectional reflectance of asteroid surface analogues

Sakai

Nakamura

2005

Earth Planet Sp

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We studied the effects of the surface roughness and porosity of a sample layer on its light-scattering properties in laboratory experiments using fly ash, iron, graphite, and olivine powders. Three types of surface structure were prepared: compacted, knocked, and fluffy surfaces. The surface roughness is represented by the mean slope angle of small facets on the surface. We found a positive correlation between the surface roughness and the porosity of the layer. The bidirectional reflectance of the surface at the wavelength of a He-Ne laser (633 nm) was measured to illustrate the influence of surface structure on scattering properties, with the incidence angle fixed at 0• , while varying the phase angle from 2 to 80• . The reflectance of a relatively rough surface was lower than that of a relatively smooth one for all of the materials measured. The reflectance measured at 30• in phase angle decreased by between ∼25 and ∼60%. This effect may explain the discrepancy between the absolute reflectance in previous laboratory results and the observed results for C class asteroids Nakamura et al., 2002).

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Disk-Integrated Photometry of 433 Eros

Cited by 47 publications

References 33 publications

The 2004 Las Campanas/Lowell Observatory campaign II. Surface properties of Hayabusa target Asteroid 25143 Itokawa inferred from Hapke modeling

The 2004 Las Campanas/Lowell Observatory campaign II. Surface properties of Hayabusa target Asteroid 25143 Itokawa inferred from Hapke modeling

The geology of 433 Eros

Quantification of porosity and surface roughness in laboratory measurements of the bidirectional reflectance of asteroid surface analogues

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