Seismic waves in the asteroid environment

Sánchez, Paul; Scheeres, Daniel J.

doi:10.1051/epjconf/202124913001

Cited by 3 publications

(1 citation statement)

References 15 publications

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“…If this is the case, Didymos's surface and structure should possess proper conditions that can resist disturbance by the falling of DART-driven ejecta to avoid complete collapse. The key issue, however, is that granular behaviors and slow impact processes in microgravity are likely different from those observed on a terrestrial surface (Garcia et al 2015;Murdoch et al 2017;Brisset et al 2019;Sánchez & Scheeres 2021). Therefore, such disturbing processes could act differently on Didymos, which needs further quantitative assessment.…”

Section: Structural Sensitivity and Possible Failure Behaviorsmentioning

confidence: 99%

Predictions for the Dynamical States of the Didymos System before and after the Planned DART Impact

Richardson¹,

Agrusa²,

Barbee³

et al. 2022

Planet. Sci. J.

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NASA’s Double Asteroid Redirection Test (DART) spacecraft is planned to impact the natural satellite of (65803) Didymos, Dimorphos, at around 23:14 UTC on 2022 September 26, causing a reduction in its orbital period that will be measurable with ground-based observations. This test of kinetic impactor technology will provide the first estimate of the momentum transfer enhancement factor β at a realistic scale, wherein the ejecta from the impact provide an additional deflection to the target. Earth-based observations, the LICIACube spacecraft (to be detached from DART prior to impact), and ESA’s follow-up Hera mission, to launch in 2024, will provide additional characterizations of the deflection test. Together, Hera and DART comprise the Asteroid Impact and Deflection Assessment cooperation between NASA and ESA. Here, the predicted dynamical states of the binary system upon arrival and after impact are presented. The assumed dynamically relaxed state of the system will be excited by the impact, leading to an increase in eccentricity and a slight tilt of the orbit, together with enhanced libration of Dimorphos, with the amplitude dependent on the currently poorly known target shape. Free rotation around the moon’s long axis may also be triggered, and the orbital period will experience variations from seconds to minutes over timescales of days to months. Shape change of either body, due to cratering or mass wasting triggered by crater formation and ejecta, may affect β, but can be constrained through additional measurements. Both BYORP and gravity tides may cause measurable orbital changes on the timescale of Hera’s rendezvous.

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Section: Structural Sensitivity and Possible Failure Behaviorsmentioning

confidence: 99%

Predictions for the Dynamical States of the Didymos System before and after the Planned DART Impact

Richardson¹,

Agrusa²,

Barbee³

et al. 2022

Planet. Sci. J.

View full text Add to dashboard Cite

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Propagation and attenuation of pulses driven by low velocity normal impacts in granular media

Quillen

Neiderbach

Suo

et al. 2022

Icarus

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The influence of gravity on granular impacts

Sunday

Zhang

Thuillet

et al. 2021

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Context. Impacts on small-body surfaces can occur naturally during cratering events or even strategically during carefully planned impact experiments, sampling maneuvers, and landing attempts. A proper interpretation of impact dynamics allows for a better understanding of the physical properties and the dynamical process of their regolith-covered surfaces and their general evolution. Aims. This work aims to first validate low-velocity, low-gravity impact simulations against experimental results, and then to discuss the observed collision behaviors in terms of a popular phenomenological collision model and a commonly referenced scaling relationship. Methods. We performed simulations using the soft-sphere discrete element method and two different codes, Chrono and pkdgrav. The simulations consist of a 10-cm-diameter spherical projectile impacting a bed of approximately 1-cm-diameter glass beads at collision velocities up to 1 m s−1. The impact simulations and experiments were conducted under terrestrial and low-gravity conditions, and the experimental results were used to calibrate the simulation parameters. Results. Both Chrono and pkdgrav succeed in replicating the terrestrial gravity impact experiments with high and comparable computational performance, allowing us to simulate impacts in other gravity conditions with confidence. Low-gravity impact simulations with Chrono show that the penetration depth and collision duration both increase when the gravity level decreases. However, the presented collision model and scaling relationship fail to describe the projectile’s behavior over the full range of impact cases. Conclusions. The impact simulations reveal that the penetration depth is a more reliable metric than the peak acceleration for assessing collision behavior in a coarse-grained material. This observation is important to consider when analyzing lander-regolith interactions using the accelerometer data from small-body missions. The objective of future work will be to determine the correct form and applicability of the cited collision models for different impact velocity and gravity regimes.

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Seismic waves in the asteroid environment

Cited by 3 publications

References 15 publications

Predictions for the Dynamical States of the Didymos System before and after the Planned DART Impact

Predictions for the Dynamical States of the Didymos System before and after the Planned DART Impact

Propagation and attenuation of pulses driven by low velocity normal impacts in granular media

The influence of gravity on granular impacts

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