The large crater on the small Asteroid (2867) Steins

Burchell, M. J.; Leliwa-Kopystyński, J.

doi:10.1016/j.icarus.2010.07.026

Cited by 18 publications

(9 citation statements)

References 29 publications

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“…The subscript c denotes critical, and the impact leading to the formation of a crater with a diameter larger than D c leads to a breakup of the target. We believe that the data collected in Table 1 are all the available data concerning observed large craters on small bodies in the solar system, with the exception of the large crater on asteroid Stein recently observed by the Rosetta spacecraft (which, however, is in agreement with the limit in Equation 3; see Burchell and Leliwa-KopystyÒski 2009). Fig.…”

Section: Observational Foundationssupporting

confidence: 72%

The impact origin of Eunomia and Themis families

Leliwa-Kopystyński

Burcheli

Włdarczyk³

2009

Meteorit & Planetary Scien

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-KopystyÒski et al. 2008). We find that the Eunomia parent body itself was not catastrophically disrupted in the family-generating impact event; after impact, the current body contains as much as 70% of its primordial mass. However, by contrast with Eunomia, the present mass of 24 Themis is only about 21% of that of its primordial body. Limits are placed on the sizes of the impactors in both examples, and for the case of Eunomia, the radius of the just sub-critical crater (which may be present on 15 Eunomia) is predicted as <58 km.

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Section: Observational Foundationssupporting

confidence: 72%

The impact origin of Eunomia and Themis families

Leliwa-Kopystyński

Burcheli

Włdarczyk³

2009

Meteorit & Planetary Scien

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“…For example, Stickney crater is ~1/3 the diameter of Phobos, which has an average porosity of ~30% (Andert et al 2010). A similar relative crater diameter and porosity are inferred for 2867 Steins (Burchell & Leliwa-Kopystynski 2010). Without additional composition information, we cannot estimate EV5's porosity, but an unusually high porosity is not required to explain the concavity, although it is one possible cause of efficient dissipation.…”

Section: The Concavitymentioning

confidence: 76%

“…It is roughly 30 m deep and its delay-Doppler structure is suggestive of an impact crater. Concavities of similar size relative to the object have also been seen in radar images and shape models of asteroids 1998 ML14 (Ostro et al 2001) and 1998WT24 (Busch et al 2008 and in spacecraft images of 2867 Steins (Burchell & Leliwa-Kopystynski 2010), although not on 25143 Itokawa (Fujiwara et al 2006, Saito et al 2006.…”

Section: Delay-doppler Imagesmentioning

confidence: 85%

Radar observations and the shape of near-Earth asteroid 2008 EV5

Busch

Ostro

Benner

et al. 2011

Icarus

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We observed the near-Earth asteroid 2008 EV5 with the Arecibo and Goldstone planetary radars and the Very Long Baseline Array during December 2008. EV5 rotates retrograde and its overall shape is a 400 ± 50 m oblate spheroid. The most prominent surface feature is a ridge parallel to the asteroid's equator that is broken by a concavity 150 m in diameter. Otherwise the asteroid's surface is notably smooth on decameter scales. EV5's radar and optical albedos are consistent with either rocky or stony-iron composition. The equatorial ridge is similar to structure seen on the rubble-pile near-Earth asteroid (66391) 1999 KW4 and is consistent with YORP spin-up reconfiguring the asteroid in the past. We interpret the concavity as an impact crater. Shaking during the impact and later regolith redistribution may have erased smaller features, explaining the general lack of decameter-scale surface structure.

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“…As there is no accurate measurement of mass and therefore the bulk density, the only criteria to derive a macroporosity is the ratio of the largest crater diameter to the size of the asteroid (Burchell and Leliwa-Kopystynski 2010). (Burchell and Leliwa-Kopystynski 2010), significantly larger than crater Diamond. Therefore, crater Diamond is not necessarily at the critical limit, as an asteroid of the size of Šteins could even accommodate a larger crater.…”

Section: šTeins' Constituent Fragment Size Distributionmentioning

confidence: 99%

Hyper-Velocity Impacts on Rubble Pile Asteroids

Deller¹

2017

Springer Theses

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SummaryMost asteroids in the size range of approximately 100 m to 100 km are rubble piles, aggregates of rocky material held together mainly by gravitational forces, and only weak cohesion. They contain high macroporosities, indicating a large amount of void space in their interiors. How these voids are distributed is not yet known, as in-situ measurements are still outstanding.In this work, a model to create rubble pile asteroid simulants for use in SPH impact simulations is presented. Rubble pile asteroids are modelled as gravitational re-aggregating remnant fragments of a catastrophically disrupted parent body, which are represented by spherical pebbles. It is shown that this approach allows to explicitly follow the internal restructuring of rubble pile asteroids during impact events, while preserving the expected properties of the bulk asteroid as known from observations and experiments. The bulk behaviour of asteroid simulants, as characterized by the stability against disruption and fragment size distribution, follows the expected behaviour and is not sensitive to the exact distribution of voids in the interior structure, but rather to the void fraction as the amount of consolidated void space in between the constituent fragment pebbles. No exact a priory knowledge of the fragment size distribution inside the body is therefore needed to use this model in impact simulations.Modelling the behaviour of the large-scale rubble pile constituents during impact events is used as a tool to infer the internal structure of asteroids by linking surface features like hills or pits to the creation of sub-catastrophic craters.In this work, the small rubble pile asteroid (2867) Šteins is analysed. The flyby of the Rosetta spacecraft at Šteins has revealed several interesting features: the large crater Diamond close to the southern pole, a hill like feature almost opposite to the crater, and a catena of crater pits extending radially from the rim of the crater.A possible link between these two structures and the cratering event is investigated in a series of impact simulations varying the interior of a plausible shape of Šteins prior to the event that formed crater Diamond. A connection between the cratering event and the hill is shown to be highly unlikely. Therefore, the hill is most likely a remnant of the formation of Šteins. Its size therefore helps to infer the initial size distribution of fragments forming the asteroid.The formation of a fracture radially from the crater can be observed for rubble pile simulants with highly collimated voids. This fracture could plausibly form the catena of pits observed on Šteins. This can therefore serve as a link between observable surface features and Šteins internal structure. The interior of Šteins is most likely an aggregate of fragments that themselves are only lightly fractured, and large void spaces might be found inside the asteroid. As Šteins seems to be a good example of a YORPoid, an asteroid that has been evolved to a top-like shape by radiative forces due to the YORP ...

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The large crater on the small Asteroid (2867) Steins

Cited by 18 publications

References 29 publications

The impact origin of Eunomia and Themis families

The impact origin of Eunomia and Themis families

Radar observations and the shape of near-Earth asteroid 2008 EV5

Hyper-Velocity Impacts on Rubble Pile Asteroids

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