Impacts into porous asteroids

Housen, K. R.; Sweet, William J.; Holsapple, K. A.

doi:10.1016/j.icarus.2017.08.019

Cited by 67 publications

(93 citation statements)

References 25 publications

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“…One way to characterise the compaction response is by a "crushing strength" defined as the pressure required to compact the material by one-half towards its solid density (Housen et al, 2018). For an initial porosity of 20% and 35% the crush curves used in this work are broadly consistent with the quasi-static crush curves of lunar microbreccia and lunar regolith (Fig.…”

Section: Homogeneous Porous Half-spacementioning

confidence: 64%

“…Moreover, without crush-curve measurements of a direct sample of asteroid surface material it is difficult to determine the best analog for the compaction behaviour of asteroidal materials. Proposed asteroid regolith analogs, including gypsum (Nakamura et al, 2009), sand (Hagerty et al, 1993;Housen et al, 2018) and lunar regolith (Stephens and Lilley, 1970;Ahrens and Cole, 1974), show a range of compaction behavior.…”

Section: Homogeneous Porous Half-spacementioning

confidence: 99%

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The effects of asteroid layering on ejecta mass-velocity distribution and implications for impact momentum transfer

Raducan

Davison

Collins

2020

Planetary and Space Science

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Most bodies in the Solar System do not have a homogeneous structure. Understanding the outcome of an impact into regolith layers of different properties is especially important for NASA's Double Asteroid Redirection Test (DART) and ESA's Hera missions. Here we used the iSALE shock physics code to simulate the DART impact into three different target scenarios in the strength regime: a homogeneous porous half-space; layered targets with a porous weak layer overlying a stronger bedrock; and targets with exponentially decreasing porosity with depth. For each scenario we determined the sensitivity of crater morphology, ejecta mass-velocity distribution and momentum transferred from the impact for deflection, β −1, to target properties and structure. We found that for the homogeneous porous half-space, cohesion and porosity play a significant role and the DART impact is expected to produce a β − 1 between 1 and 3. In the two-layer target scenario, the

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Section: Homogeneous Porous Half-spacementioning

confidence: 64%

Section: Homogeneous Porous Half-spacementioning

confidence: 99%

The effects of asteroid layering on ejecta mass-velocity distribution and implications for impact momentum transfer

Raducan

Davison

Collins

2020

Planetary and Space Science

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“…Such a case could reflect that the deeper transient crater of Unnamed8 with steeper walls was created by larger amount of compaction relative to other craters such that during cavity collapse, the finely crushed debris along the walls would be driven further into the crater and would collect in localized regions below the bottom of the crater floor. Therefore, less material would cover the crater floor and result in the observed profile (Housen et al, ; Housen & Holsapple, ). The same concept applies to Polybius A.…”

Section: Discussionmentioning

confidence: 99%

Geologic Investigation of Deep Simple Craters in the Lunar Simple‐to‐Complex Transition

2019

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From a group of well‐preserved lunar simple craters in the 15‐ to 20‐km diameter range and with the help of Lunar Orbiter Laser Altimeter topography data, we identified a subset of eight deep craters (depth/diameter ratio > 0.20). These craters are in the regions around the mare‐highlands boundaries, which are characterized as having the highest porosity on the lunar surface. To understand the cratering mechanics behind the formation of these craters, a geologic investigation of the terrains of these craters was performed. We evaluated the depth/diameter ratios of smaller simple craters surrounding several 15‐ to 20‐km diameter craters, analyzed the morphometry of the craters, and visually examined the cavities using multiple data sets. We conclude that deep transient cavities were formed from compaction of porous target material. The result was a deeper than normal simple crater without an identifiable increase in the volume of excavated material, as inferred from the craters' rim heights and shapes. While all of these craters formed in areas of high porosity, not all craters in high‐porosity regions are deep. It may be that some unusual impactor property is also required to produce a deep crater, such as a high velocity impact, a near‐vertical impact, or a dense impactor that yielded a large penetration depth.

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“…as approximated in equation 32 by Richardson et al (2005) (also see their Figure 16 comparing this approximation to the regimes discussed by Holsapple 1993). Housen et al (2018) has carried out experiments of impacts into porous cohesionless materials. An extrapolation of their highest velocity experiments (by two orders of magnitude past the smallest dimensionless π 2 value on their Figure 15) gives a crater diameter approximately consistent with equation 22.…”

Section: Seismic Spectrum Corner Frequencymentioning

confidence: 99%

Impact excitation of a seismic pulse and vibrational normal modes on asteroid Bennu and associated slumping of regolith

Quillen

Zhao

Chen

et al. 2019

Icarus

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the equatorial ridge. We explore simple flow models for the morphology of vibration induced surface slumping. We find that the initial seismic pulse is unlikely to cause large shape changes. Long lasting seismic reverberation on Bennu caused by a near equatorial impact could have raised the height of its equatorial ridge by a few meters and raised two peaks on it, one near impact site and the other near its antipode.

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Impacts into porous asteroids

Cited by 67 publications

References 25 publications

The effects of asteroid layering on ejecta mass-velocity distribution and implications for impact momentum transfer

The effects of asteroid layering on ejecta mass-velocity distribution and implications for impact momentum transfer

Geologic Investigation of Deep Simple Craters in the Lunar Simple‐to‐Complex Transition

Impact excitation of a seismic pulse and vibrational normal modes on asteroid Bennu and associated slumping of regolith

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