Digital terrain mapping by the OSIRIS-REx mission

Barnouin, Olivier S.; Daly, M. G.; Palmer, E. E.; Johnson, C. L.; Gaskell, R. W.; Asad, M. Al; Bierhaus, E. B.; Craft, Kathleen L.; Ernst, C. M.; Espiritu, R. C.; Nair, Hari; Neumann, Gregory A.; Nguyen, L.; Nolan, M. C.; Mazarico, E.; Perry, Mark; Philpott, L.; Roberts, J. H.; Steele, R.; Seabrook, J. A.; Susorney, H. C. M.; Weirich, J. R.; Лауретта, Д. С.

doi:10.1016/j.pss.2019.104764

Cited by 91 publications

(111 citation statements)

References 39 publications

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“…This study made use of the v42 shape model developed using stereophotoclinometry (SPC) ( 57 ) and slightly higher fidelity than the model presented in ( 54 ) and used in ( 35 ). Detailed assessment of this model using image-derived limb information and range measurements collected in spring of 2019 by the OSIRIS-REx Laser Altimeter ( 58 ) indicate that it has an RMS uncertainty that ranges from 0.5 to 0.7 m. This RMS error folds in an overall scale error and small-scale surface variations.…”

Section: Methodsmentioning

confidence: 99%

“…Optical navigation measurements ( 63 ) are derived from a landmark-tracking process using SPC ( 64 ). Spacecraft imagery from all cameras was used to construct a global shape model of the asteroid, consisting of overlapping networks of landmarks at variety of scales that increased with improving picture resolution ( 57 ). Optical observations for orbit determination consist of the camera-frame coordinates of the center of all of the landmarks that are visible in a given image.…”

Section: Methodsmentioning

confidence: 99%

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Heterogeneous mass distribution of the rubble-pile asteroid (101955) Bennu

et al. 2020

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The gravity field of a small body provides insight into its internal mass distribution. We used two approaches to measure the gravity field of the rubble-pile asteroid (101955) Bennu: (i) tracking and modeling the spacecraft in orbit about the asteroid and (ii) tracking and modeling pebble-sized particles naturally ejected from Bennu’s surface into sustained orbits. These approaches yield statistically consistent results up to degree and order 3, with the particle-based field being statistically significant up to degree and order 9. Comparisons with a constant-density shape model show that Bennu has a heterogeneous mass distribution. These deviations can be modeled with lower densities at Bennu’s equatorial bulge and center. The lower-density equator is consistent with recent migration and redistribution of material. The lower-density center is consistent with a past period of rapid rotation, either from a previous Yarkovsky-O’Keefe-Radzievskii-Paddack cycle or arising during Bennu’s accretion following the disruption of its parent body.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Heterogeneous mass distribution of the rubble-pile asteroid (101955) Bennu

et al. 2020

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“…To determine the smallest spatial scale of roughness to which the infrared data are sensitive, we compared our surface roughness maps with the global 20-cm-facet shape model of Bennu derived from data acquired by the OSIRIS-REx Laser Altimeter (OLA) (39)(40)(41). For a direct comparison, we first calculated the RMS slopes of the global 20-cm shape model with respect to the equivalent 6-m shape model.…”

Section: Spatial Variations In Surface Roughnessmentioning

confidence: 99%

Asteroid (101955) Bennu’s weak boulders and thermally anomalous equator

et al. 2020

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Thermal inertia and surface roughness are proxies for the physical characteristics of planetary surfaces. Global maps of these two properties distinguish the boulder population on near-Earth asteroid (NEA) (101955) Bennu into two types that differ in strength, and both have lower thermal inertia than expected for boulders and meteorites. Neither has strongly temperature-dependent thermal properties. The weaker boulder type probably would not survive atmospheric entry and thus may not be represented in the meteorite collection. The maps also show a high–thermal inertia band at Bennu’s equator, which might be explained by processes such as compaction or strength sorting during mass movement, but these explanations are not wholly consistent with other data. Our findings imply that other C-complex NEAs likely have boulders similar to those on Bennu rather than finer-particulate regoliths. A tentative correlation between albedo and thermal inertia of C-complex NEAs may be due to relative abundances of boulder types.

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“…The scans were corrected for spacecraft position, spacecraft pointing, and Bennu's rotation using the SPICE framework (36,37). They were then assembled into a self-consistent global point cloud by iteratively minimizing the differences between matched features in overlapping scans as described in (13,14) until the scan mismatches were balanced over all the scans. The method depends on each scan being well constructed to minimize long-wavelength shape errors.…”

Section: Global Dtmmentioning

confidence: 99%

Hemispherical differences in the shape and topography of asteroid (101955) Bennu

et al. 2020

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We investigate the shape of near-Earth asteroid (101955) Bennu by constructing a high-resolution (20 cm) global digital terrain model from laser altimeter data. By modeling the northern and southern hemispheres separately, we find that longitudinal ridges previously identified in the north extend into the south but are obscured there by surface material. In the south, more numerous large boulders effectively retain surface materials and imply a higher average strength at depth to support them. The north has fewer large boulders and more evidence of boulder dynamics (toppling and downslope movement) and surface flow. These factors result in Bennu’s southern hemisphere being rounder and smoother, whereas its northern hemisphere has higher slopes and a less regular shape. We infer an originally asymmetric distribution of large boulders followed by a partial disruption, leading to wedge formation in Bennu’s history.

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Digital terrain mapping by the OSIRIS-REx mission

Cited by 91 publications

References 39 publications

Heterogeneous mass distribution of the rubble-pile asteroid (101955) Bennu

Heterogeneous mass distribution of the rubble-pile asteroid (101955) Bennu

Asteroid (101955) Bennu’s weak boulders and thermally anomalous equator

Hemispherical differences in the shape and topography of asteroid (101955) Bennu

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