Properties of rubble-pile asteroid (101955) Bennu from OSIRIS-REx imaging and thermal analysis

@article{DellaGiustina2019PropertiesOR,
  title={Properties of rubble-pile asteroid (101955) Bennu from OSIRIS-REx imaging and thermal analysis},
  author={Daniella N. DellaGiustina and J. P. Emery and Dathon R. Golish and Benjamin Rozitis and Carina A. Bennett and Keara N. Burke and R.‐L. Ballouz and Kris J. Becker and Philip R. Christensen and C. Y. Drouet d’Aubigny and Victoria E. Hamilton and Dennis C. Reuter and Bashar Rizk and Amy A. Simon and Erik Asphaug and Joshua L. Bandfield and Olivier S. Barnouin and Maria Antonietta Barucci and Edward B. Bierhaus and Richard P. Binzel and William F. Bottke and N. E. Bowles and Humberto Campins and Benton C. Clark and Beth Ellen Clark and Harold C. Connolly and Michael G. Daly and Julia de Le{\'o}n and Marco Delbo’ and Jasinghege Don Prasanna Deshapriya and Catherine M. Elder and Sonia Fornasier and Carl W. Hergenrother and Ellen S. Howell and Erica R. Jawin and Hannah H. Kaplan and Theodore Kareta and Lucille Le Corre and J.‐Y. Li and Javier Licandro and Lucy F. Lim and Patrick Michel and Jamie L. Molaro and Michael C. Nolan and Maurizio Pajola and Marcel Popescu and Jolai R. Garcia and Andrew J. Ryan and Stephen R. Schwartz and N. K. Shultz and Matthew A. Siegler and P. H. Smith and Eri Tatsumi and C. A. Thomas and Kevin J. Walsh and Catherine W. V. Wolner and X.-D. Zou and Dante S. Lauretta and the OSIRIS-REx Team},
  journal={Nature Astronomy},
  year={2019},
  volume={3},
  pages={341-351}
}
Establishing the abundance and physical properties of regolith and boulders on asteroids is crucial for understanding the formation and degradation mechanisms at work on their surfaces. Using images and thermal data from NASA’s Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) spacecraft, we show that asteroid (101955) Bennu’s surface is globally rough, dense with boulders, and low in albedo. The number of boulders is surprising given Bennu’s… 

Variations in color and reflectance on the surface of asteroid (101955) Bennu

TLDR
Maps of color and albedo on asteroid Bennu indicate complex evolution of its surface due to space weathering, and constrain Bennu's evolution and provide context for the sample collected in October 2020.

Bright carbonate veins on asteroid (101955) Bennu: Implications for aqueous alteration history

TLDR
Global spectral observations by the OSIRIS-REx spacecraft have shown that carbon-bearing materials, including organics and/or carbonates, are widespread on the surface of near-Earth asteroid (101955) Bennu.

Craters, boulders and regolith of (101955) Bennu indicative of an old and dynamic surface

Small, kilometre-sized near-Earth asteroids are expected to have young and frequently refreshed surfaces for two reasons: collisional disruptions are frequent in the main asteroid belt where they

Evidence for limited compositional and particle size variation on asteroid (101955) Bennu from thermal infrared spectroscopy

Context. Asteroid (101955) Bennu is the target of NASA’s Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer (OSIRIS-REx) mission. The spacecraft’s instruments

The Unexpected Surface of Asteroid (101955) Bennu

TLDR
Early OSIRIS-REx observations of Bennu are considered to understand how the asteroid’s properties compare to pre-encounter expectations and to assess the prospects for sample return.

Low thermal conductivity boulder with high porosity identified on C-type asteroid (162173) Ryugu

C-type asteroids are among the most pristine objects in the Solar System, but little is known about their interior structure and surface properties. Telescopic thermal infrared observations have so

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

TLDR
These findings imply that other C-complex NEAs likely have boulders similar to those on Bennu rather than finer-particulate regoliths, and a tentative correlation between albedo and thermal inertia of C- complex NEAs may be due to relative abundances of boulder types.

Shape of (101955) Bennu indicative of a rubble pile with internal stiffness

TLDR
The shape model indicates that near-Earth asteroid Bennu formed by reaccumulation and underwent past periods of fast spin, which led to its current shape, similar to other top-shaped asteroids.

Widespread carbon-bearing materials on near-Earth asteroid (101955) Bennu

TLDR
The OSIRIS-REx results constrain Bennu's evolution and provide context for the sample collected in October 2020, as well as finding evidence for organic and carbonate materials that are widely distributed across the surface but are most concentrated on individual boulders.

Characterization of Exogenic Boulders on the Near-Earth Asteroid (101955) Bennu from OSIRIS-REx Color Images

A small number of anomalously bright boulders on the near-Earth rubble-pile asteroid (101955) Bennu were recently identified as eucritic material originating from asteroid (4) Vesta. Building on this
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References

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Craters, boulders and regolith of (101955) Bennu indicative of an old and dynamic surface

Small, kilometre-sized near-Earth asteroids are expected to have young and frequently refreshed surfaces for two reasons: collisional disruptions are frequent in the main asteroid belt where they

The Unexpected Surface of Asteroid (101955) Bennu

TLDR
Early OSIRIS-REx observations of Bennu are considered to understand how the asteroid’s properties compare to pre-encounter expectations and to assess the prospects for sample return.

The OSIRIS‐REx target asteroid (101955) Bennu: Constraints on its physical, geological, and dynamical nature from astronomical observations

We review the results of an extensive campaign to determine the physical, geological, and dynamical properties of asteroid (101955) Bennu. This investigation provides information on the orbit, shape,

Shape of (101955) Bennu indicative of a rubble pile with internal stiffness

TLDR
The shape model indicates that near-Earth asteroid Bennu formed by reaccumulation and underwent past periods of fast spin, which led to its current shape, similar to other top-shaped asteroids.

The dynamic geophysical environment of (101955) Bennu based on OSIRIS-REx measurements

TLDR
Combining the measured Bennu mass and shape obtained during the Preliminary Survey phase of the OSIRIS-REx mission, a notable transition is found in Bennu’s surface slopes within its rotational Roche lobe, defined as the region where material is energetically trapped to the surface.

Evidence for widespread hydrated minerals on asteroid (101955) Bennu

TLDR
Evidence for abundant hydrated minerals on the surface of near-Earth asteroid Bennu is revealed in the form of a near-infrared absorption near 2.7 µm and thermal infrared spectral features that are most similar to those of aqueously altered CM-type carbonaceous chondrites.

The operational environment and rotational acceleration of asteroid (101955) Bennu from OSIRIS-REx observations

TLDR
The authors show the operational environment of asteroid Bennu, validate its photometric phase function and demonstrate the accelerating rotational rate due to YORP effect using the data acquired during the approach phase of OSIRIS-REx mission.

Physical characterisation of near-Earth asteroid (1620) Geographos. Reconciling radar and thermal-infrared observations

The Yarkovsky (orbital drift) and YORP (spin state change) effects play important roles in the dynamical and physical evolution of asteroids. Thermophysical modelling of these observed effects, and

Thermal fatigue as the origin of regolith on small asteroids

TLDR
It is reported that thermal fatigue, a mechanism of rock weathering and fragmentation with no subsequent ejection, is the dominant process governing regolith generation on small asteroids and that thermal fragmentation induced by the diurnal temperature variations breaks up rocks larger than a few centimetres more quickly than do micrometeoroid impacts.
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