Bennu’s near-Earth lifetime of 1.75 million years inferred from craters on its boulders

  title={Bennu’s near-Earth lifetime of 1.75 million years inferred from craters on its boulders},
  author={R.‐L. Ballouz and Kevin J. Walsh and O. S. Barnouin and Daniella N. DellaGiustina and Manar Al Asad and Erica R. Jawin and Michael G. Daly and William F. Bottke and Patrick Michel and Chrysa Avdellidou and Marco Delbo’ and R. T. Daly and Erik Asphaug and Carina A. Bennett and Edward B. Bierhaus and Harold C. Connolly and Dathon R. Golish and Jamie L. Molaro and Michael C. Nolan and Maurizio Pajola and Bashar Rizk and Stephen R. Schwartz and David Trang and Catherine W. V. Wolner and Dante S. Lauretta},
An asteroid’s history is determined in large part by its strength against collisions with other objects 1 , 2 (impact strength). Laboratory experiments on centimetre-scale meteorites 3 have been extrapolated and buttressed with numerical simulations to derive the impact strength at the asteroid scale 4 , 5 . In situ evidence of impacts on boulders on airless planetary bodies has come from Apollo lunar samples 6 and images of the asteroid (25143) Itokawa 7 . It has not yet been possible, however… 
Low surface strength of the asteroid Bennu inferred from impact ejecta deposit
The surface strength of small rubble-pile asteroids, which are aggregates of unconsolidated material under microgravity, is poorly constrained but critical to understanding surface evolution and
Crater population on asteroid (101955) Bennu indicates impact armouring and a young surface
The impactor-to-crater size scaling relationships that enable estimates of planetary surface ages rely on an accurate formulation of impactor–target physics. An armouring regime, specific to
Alignment of fractures on Bennu’s boulders indicative of rapid asteroid surface evolution
On asteroids, fractures develop due to stresses driven by diurnal temperature variations at spatial scales ranging from sub-millimetres to metres. However, the timescales of such rock fracturing by
The Brittle Boulders of Dwarf Planet Ceres
We mapped all boulders larger than 105 m on the surface of dwarf planet Ceres using images of the Dawn framing camera acquired in the Low Altitude Mapping Orbit. We find that boulders on Ceres are
Global-scale Reshaping and Resurfacing of Asteroids by Small-scale Impacts, with Applications to the DART and Hera Missions
We use a novel approach to model the entire cratering process resulting from impacts on small, weak asteroids that uses shock physics code calculations directly. We found that small-scale impacts
Geologic Context of the OSIRIS-REx Sample Site from High-resolution Topography and Imaging
The OSIRIS-REx spacecraft collected a surface sample from Hokioi crater (55.8° N, 42.3° E; diameter ∼20 m) on the asteroid Bennu in 2020 October. We explore the geology of the sample collection site,
The Morphometry of Impact Craters on Bennu
Bennu is an ~500‐m‐diameter rubble‐pile asteroid that is the target of detailed study by the Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer (OSIRIS‐REx)


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 Geologically Recent Giant Impact Basins at Vesta’s South Pole
Dawn’s global mapping of Vesta reveals that its observed south polar depression is composed of two overlapping giant impact features, which provide exceptional windows into impact processes at planetary scales, and spacecraft data provide a detailed characterization of the second most massive asteroid in the solar system.
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
Thermal fatigue as the origin of regolith on small asteroids
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.
Impact process of boulders on the surface of asteroid 25143 Itokawa—fragments from collisional disruption
The subkilometer-size asteroid 25143 Itokawa is considered to have a gravitationally bounded rubble-pile structure. Boulders appearing in high-resolution images retrieved by the Hayabusa mission
Rubble Pile Asteroids
  • K. Walsh
  • Geology, Physics
    Annual Review of Astronomy and Astrophysics
  • 2018
The moniker rubble pile is typically applied to all Solar System bodies >200 m and <∼10 km in diameter; in this size range, there is an abundance of evidence that nearly every object is bound
The flux of small near-Earth objects colliding with the Earth
Satellite records of bolide detonations in the atmosphere over the past 8.5 years are reported and it is found that the flux of objects in the 1–10-m size range has the same power-law distribution as bodies with diameters >50 m.