Microscopic ejecta measurements from hypervelocity impacts on aluminum and powdered regolith targets

Shohet, Gil; Estacio, Benjamin; Matthews, I.; Young, Sean I.; Lee, Nicolas; Close, Sigrid

doi:10.1016/j.ijimpeng.2021.103840

Cited by 10 publications

(3 citation statements)

References 42 publications

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“…As many of these small craters are likely to be in advanced stages of degradation and therefore shallower than their initial morphology, our minimum d/D of 0.1 for fresh craters appears to be a reasonable cutoff. Laboratory-based experiments have long demonstrated that impacts into weakly cohesive target materials produce ejecta cones and bowlshaped craters at centimeter scales (Gault 1970;Shohet et al 2021). Although the applicability of these low-velocity impacts to planetary surfaces is limited, they support the assumption that small craters forming in lunar regolith are capable of initiating downslope ejecta transport.…”

Section: Scale Dependence Of Impact Erosionmentioning

confidence: 96%

“…The SFD with that slope passes through the observed crater density N(>10 m) with coefficient A p0 = 2.10 × 10 −7 and intersects the NPF at a diameter of D break = 11.81 m. As seen in Figure 7, the D min required to produce the observed maria diffusivity under this cratering rate is ∼50 μm. Impact experiments do not exist at such small scales, but the most relevant experiments support a D min of this approximate scale, with craters at millimeter to centimeter scales producing ejecta cones and bowl-shaped final profiles (Gault et al 1972;Shohet et al 2021). The 95% confidence interval of LRO slopes (4.15-5.14) corresponds to a required D min ranging from effectively zero to a few millimeters.…”

Section: Tuning the Model To Lro Observationsmentioning

confidence: 99%

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Degradation of the Lunar Surface by Small Impacts

O'Brien¹,

Byrne²

2022

Planet. Sci. J.

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The surfaces of airless bodies like the Moon are bombarded by a steady stream of small impactors that lead to erosion of the topography over time. However, the rate of degradation from small impacts, a key parameter in interpreting the ages of present-day lunar surface features, is not well constrained. Here we demonstrate, using a numerical mass transport model, that impact erosion is a nonlinear diffusion process, in contrast to past studies of crater degradation that have assumed that the downslope mass flux of ejecta is linearly proportional to hillslope gradient. Nonlinearity is a consequence of the asymmetric shape of ejecta blankets on sloped surfaces, and as a result, the degradation rate on steep slopes is over 40% greater than on nearly flat surfaces. Using measurements of the morphology and formation rate of small primary and secondary craters, the kilometer-scale lunar landscape diffusivity is computed and compared to the value inferred from topographic profiles of degraded craters. We show that the abundance of decameter-scale craters forming on the Moon over the past decade is consistent with small impacts dominating the erosion of the lunar landscape, but only if the primary size−frequency distribution remains steep down to the submillimeter scale.

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Section: Scale Dependence Of Impact Erosionmentioning

confidence: 96%

Section: Tuning the Model To Lro Observationsmentioning

confidence: 99%

Degradation of the Lunar Surface by Small Impacts

O'Brien¹,

Byrne²

2022

Planet. Sci. J.

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“…Under certain conditions, this plasma can trigger electromagnetic pulses (EMPs) that may disable or destroy spacecraft electronics and, in the worst case scenario, result in complete loss of mission [5,7,[15][16][17]. Previous reports show that spacecraft usually experience electrical anomalies correlated with meteoroid showers [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32], while few works have reported on the damage to satellite electronics through these processes. We will focus on the electrical effect associated with a meteoroid impact in the present work, especially the EMP, excited by the collision between a hypervelocity meteoroid and a spacecraft.…”

Section: Introductionmentioning

confidence: 99%

Detecting the meteoroid by measuring the electromagnetic waves excited by the collision between the hypervelocity meteoroid and spacecraft

Liu

Zhang²,

Xu³

et al. 2022

Plasma Sci. Technol.

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The electromagnetic pulse excited by the collision between the hypervelocity meteoroid and the spacecraft is studied both numerically and theoretically. It is found that there are two kinds of electromagnetic pulse. The high-frequency electromagnetic pulse may be excited by the sum of all the electric dipoles. Each electron can be considered as an electric dipole. The low-frequency electromagnetic pulse is produced by the Langmuir oscillation of electrons. The energy flux density and the duration time of the excited low-frequency electromagnetic pulse by the meteoroid are also studied in the present paper. It is shown that the energy flux density increases as either the impact speed or the mass of the meteoroid increases. It is also shown that the duration time decreases as both the impact speed and the mass of the meteoroid increase. By measuring the strength and the duration time of the electromagnetic pulse excited by the collision between the hypervelocity meteoroid and spacecraft, we can estimate the speed and the mass of the hypervelocity meteoroid, which will be helpful in the space flight and space exploration.

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