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Hypervelocity impact (HVI) on carbon fiber reinforced plastics (CFRPs) is associated with extreme impulse response of material as well as complex characteristics of the composites. It is a challenging task to predict the physical process of CFRP-HVI problems accurately. We apply a GPU-accelerated smoothed particle hydrodynamics (SPH) method which incorporates the composite material model and the decoupled finite particle method to simulate the CFRP-HVI processes. The presented SPH model is validated by simulating the processes of aluminum spheres impacting metallic plates. The simulation results agree well with available experimental and numerical results, and the GPU parallelization technique significantly improves the simulation efficiency (350 times faster than an equivalent serial SPH model). With such computational accuracy and efficiency, the model is extended to simulate CFRP laminate impact problems, and a particle convergence analysis is performed. It is shown that the model can obtain convergent results when modeling each CFRP layer with three SPH particles in the thickness direction and correspondingly using about twenty million particles in total. The simulation can be completed within several hours, and the dominant mechanisms of the CFRP-HVI can be captured quantitatively. To further investigate the protective performance of CFRP structures, HVI on a well-known shielding structure Whipple bumper is investigated numerically. The dynamic response of the structure is well reproduced, and the results show that the CFRP pressure wall is more effective than the metallic one. These simulation results demonstrate that the presented SPH model can model the CFRP-HVI problems accurately and efficiently.

U–Pb geochronology of shocked monazite can be used to date hypervelocity impact events. Impact-induced recrystallisation and formation of mechanical twins in monazite have been shown to result in radiogenic Pb loss and thus constrain impact ages. However, little is known about the effect of porosity on the U–Pb system in shocked monazite. Here we investigate monazite in two impact melt rocks from the Hiawatha impact structure, Greenland by means of nano- and micrometre-scale techniques. Microstructural characterisation by scanning electron and transmission electron microscopy imaging and electron backscatter diffraction reveals shock recrystallisation, microtwins and the development of widespread micrometre- to nanometre-scale porosity. For the first time in shocked monazite, nanophases identified as cubic Pb, Pb 3 O 4 , and cerussite (PbCO 3 ) were observed. We also find evidence for interaction with impact melt and fluids, with the formation of micrometre-scale melt-bearing channels, and the precipitation of the Pb-rich nanophases by dissolution–precipitation reactions involving pre-existing Pb-rich high-density clusters. To shed light on the response of monazite to shock metamorphism, high-spatial-resolution U–Pb dating by secondary ion mass spectrometry was completed. Recrystallised grains show the most advanced Pb loss, and together with porous grains yield concordia intercept ages within uncertainty of the previously established zircon U–Pb impact age attributed to the Hiawatha impact structure. Although porous grains alone yielded a less precise age, they are demonstrably useful in constraining impact ages. Observed relatively old apparent ages can be explained by significant retention of radiogenic lead in the form of widespread Pb nanophases. Lastly, we demonstrate that porous monazite is a valuable microtexture to search for when attempting to date poorly constrained impact structures, especially when shocked zircon or recrystallised monazite grains are not present.

Spacecraft operators rely on various environmental models to assess the risk from micrometeoroid and orbital debris (MMOD) to their spacecraft, but many of these models assume a spherical projectile or lack any shape parameter information which can lead to greater uncertainty in assessing the true risk. To address this risk, NASA’s Orbital Debris Program Office (ODPO) and Hypervelocity Impact Technology (HVIT) team have coordinated to better understand the risks to upper stages and spacecraft from non-spherical orbital debris. It is well understood that fragmentation (collision or explosion) events in orbit produce fragments of various materials, sizes, and shapes. To further characterize these parameters, the ODPO is developing the next-generation Orbital Debris Engineering Model (ORDEM) version 4.0 to include orbital debris shape distributions. Ground-based assets, such as radar and optical sensors, can provide size estimates and some insight into material based on radar return or optical filter photometry/spectroscopy, respectively. Characterizing an object’s shape requires more laboratory analyses to infer how shape affects these measurements. More importantly, in addition to size and material/density, the shape of fragments in orbit will alter the ballistic limit equations used in orbital debris risk assessments with NASA’s Bumper Code. The ODPO plans to release ORDEM 4.0 in the coming years. Performing ground-based laboratory impact tests on high-fidelity spacecraft mockups provides the means to directly measure size, mass, material/density, and shape of fragments, all key parameters needed to characterize real-world break up events. The DebriSat test, the results of which are provided, showcases the details of this type of experiment. The goal of this collaborative research between the ODPO and the HVIT team is to include a shape parameter in the environmental and breakup models used to assess risk for various space structures. This paper examines ground-based laboratory impact tests and the associated fragment shape categories as an initial step to characterizing the shape parameter. Highlights of impact tests conducted by the HVIT team using non-spherical projectiles are presented. Additionally, hydrocode simulations have also been performed to expand on the complexity of variations with non-spherical projectiles. Initial results suggest that non-spherical projectiles are more damaging on an equal mass basis than that of comparative spherical projectiles. Lastly, to characterize variations in optical signatures due to shape, ray-tracing simulations of known materials of various shapes are provided to support the ongoing research to support updates to the current optical size estimation model, which also assumes a spherical parameter when calculating size. The status and plan forward are outlined for NASA’s orbital debris shape effect investigation using a multidisciplinary approach by the ODPO and the HVIT team.

Space debris impacts on whipped shields are dominantly non-vertical. During the initial impact stage of a projectile on a target, wave propagation and evolution occur in their interior with co-dominant material fragmentation. In this study, the effects of the impact conditions (impact velocity and attack angle) on the critical conditions for jet generation were examined based on the asymmetric jetting theory. In the geometric propagation model (GPM), the effect of the attack angle was considered, and a wave front deflection angle parameter was introduced. The modified GPM could describe the geometric features and position of a wave front during an oblique impact. Combined with smoothed particle hydrodynamics numerical simulations, the interior of projectiles, fragmentation features and pressure attenuation were studied. It was found that in large attack angle cases, the projectile material is more likely to reach the critical conditions for jet generation. The modified GPM is an oblique elliptic equation that is a function of the equivalent speed, impact velocity, attack angle, time and deflection angle. It may be applicable to hypervelocity events involving any monolithic material as long as the equivalent speed and deflection angle can be provided from numerical simulations. The impact conditions exhibit a quantitative relationship with the pressure attenuation in a projectile, among which the impact velocity has a more significant effect. This study established a quantitative analysis method for the initial impact stage of the oblique hypervelocity impact of a spherical projectile on a flat plate.

Raman spectroscopy is a non-destructive analytical technique for characterizing organic and inorganic materials with spatial resolution in the micrometer range. This makes it a method of choice for space-mission sample characterization, whether on return or in situ. To enhance its sensitivity, we use signal amplification via interaction with plasmonic silver-based colloids, which corresponds to surface-enhanced Raman scattering (SERS). In this study, we focus on the analysis of biomolecules of prebiotic interest on extraterrestrial dust trapped in silica aerogel, jointly with the Japanese Tanpopo mission. The aim is twofold: to prepare samples as close as possible to the real ones, and to optimize analysis by SERS for this specific context. Serpentinite was chosen as the inorganic matrix and adenine as the target biomolecule. The dust was projected at high velocity into the trapping aerogel and then mechanically extracted. A quantitative study shows effective detection even for adenine doping from a 5·10−9mol/L solution. After the dust has been expelled from the aerogel using a solvent, SERS mapping enables unambiguous adenine detection over the entire dust surface. This study shows the potential of SERS as a key technique not only for return samples, but also for upcoming new explorations.

Electromagnetic tethers of hundreds or thousands of meters have been proposed for maneuvring spacecraft in Low Earth Orbit, and in particular, for post-mission disposals. The debate on tether survivability to debris impact is still influencing further advances in the implementation of such technology because of the large area they expose to the debris environment; thin tape geometries have been proposed instead of round ones to increase the survivability to hypervelocity impacts. In this context, this paper introduces a new Ballistic Limit Equation (BLE) for thin tape tethers, derived from experimental results, numerical simulations, and literature data. The resulting equation is non-monotonic with respect to impact angle, presenting a minimum depending on the debris velocity and size; for high obliquities, the debris fragmentation triggered by shock waves propagating into the material reduces the damage. This feature allows to set a minimum particle diameter for risk assessment, excluding a significant part of the debris flux. The proposed BLE confirms the performance of thin tape tethers, with respect to round wires, due to their better ballistic response as well as their reduced cross-section at high-obliquity impacts.

The debris cloud generated by the hypervelocity impact (HVI) of orbiting space debris directly threatens the spacecraft. A full understanding of the damage mechanism of rear plate is useful for the optimal design of protective structures. In this study, the hypervelocity yaw impact of a cylindrical aluminum projectile on a double-layer aluminum plate is simulated by the FE-SPH adaptive method, and the damage process of the rear plate under the impact of the debris cloud is analyzed based on the debris cloud structure. The damage process can be divided into the main impact stage of the debris cloud and the structural response of the rear plate. The main impact stage lasts a short time and is the basis of the rear plate damage. In the stage of structure response, the continuous deformation and inertial motion of the rear plate dominate the perforation of the rear plate. We further analyze the damage mechanism and damage distribution characteristics of the rear plate in detail. Moreover, the connection between velocity space and position space of the debris cloud is established, which promotes the general analysis of the damage law of debris cloud. Based on the relationship, the features of typical damage areas are identified by the localized fine analysis. Both the cumulative effect and structural response cause the perforation of rear plate; in the non-perforated area, cratering by the impact of hazardous fragments is the main damage mode of the rear plate.

An improved shielding structure of a bumper that constructed from Ti/Al/Mg density-graded materials was presented. Two types of Ti/Al/Mg density-graded materials with the same areal density were prepared by diffusion bonding and powder metallurgy, respectively. The characteristics of hypervelocity impact including penetration holes in the bumper, damage patterns on the rear wall and micrographs of the crater were investigated. The results show that damage mechanism of Ti/Al/Mg density-graded materials is closely related to the interface bonding strength and matrix strength. The penetration holes of Ti/Al/Mg density-graded material obtained by diffusion bonding exhibit typical ductile characteristics. The Ti/Al/Mg density-graded material prepared by powder metallurgy shows significant mechanical synergistic response under high strain compression and appears fragile characteristic. The shielding performance of Ti/Al/Mg bumper is increased by 20.4% compared with aluminum bumper. A theoretical analysis suggests that a Ti-Al-Mg bumper can fully break the projectile and greatly increase the entropy during the impact process. Larger projectile kinetic energy is converted into the internal energy during the impact process, thereby causing an obvious increase in shielding performance.

The NASA Double Asteroid Redirection Test (DART) mission performed a kinetic impact on asteroid Dimorphos, the satellite of the binary asteroid (65803) Didymos, at 23:14 UTC on 26 September 2022 as a planetary defence test 1 . DART was the first hypervelocity impact experiment on an asteroid at size and velocity scales relevant to planetary defence, intended to validate kinetic impact as a means of asteroid deflection. Here we report a determination of the momentum transferred to an asteroid by kinetic impact. On the basis of the change in the binary orbit period 2 , we find an instantaneous reduction in Dimorphos’s along-track orbital velocity component of 2.70 ± 0.10 mm s −1 , indicating enhanced momentum transfer due to recoil from ejecta streams produced by the impact 3 , 4 . For a Dimorphos bulk density range of 1,500 to 3,300 kg m −3 , we find that the expected value of the momentum enhancement factor, β , ranges between 2.2 and 4.9, depending on the mass of Dimorphos. If Dimorphos and Didymos are assumed to have equal densities of 2,400 kg m −3 , β = 3.61 − 0.25 + 0.19 ( 1 σ ) . These β values indicate that substantially more momentum was transferred to Dimorphos from the escaping impact ejecta than was incident with DART. Therefore, the DART kinetic impact was highly effective in deflecting the asteroid Dimorphos. The authors report on a determination of the momentum transferred to an asteroid by kinetic impact, showing that the DART kinetic impact was highly effective in deflecting the asteroid Dimorphos.

Material phase-transition represents a significant phenomenon and mechanism in the context of hypervelocity protection. This study presents a thorough analysis of the phase-transition phenomena induced by shock pressure as the shock wave propagates initially to the rear of the projectile. The shock wave that induces a phase-transition is commonly referred to as a macroscopic phase-transition wave, whereas the interface that separates the distinct phases is referred to as macroscopic phase-boundary. The contact interface between the spherical projectile and the thin plate, characterized by its curved surface, plays a significant role in the nonlinear propagation and evolution of wave systems. The pressure distribution along the central axis of a spherical projectile is derived in accordance with the linear decay law observed for axial pressure. On this basis, a quadratic function is employed to characterize the trend of changes in wave front pressure, thereby facilitating the establishment of a model for wave front pressure distribution. Using the phase-transition pressure criterion for materials, the wave front phase evolution process is derived, and the macroscopic phase-boundary is determined. Based on the geometric propagation model (GPM) and the pressure distribution of the wave front, a phase geometric propagation model (PGPM) is proposed. The phase distribution of a spherical projectile impacting a thin plate is obtained by theoretical methods. The accuracy of the PGPM is subsequently validated through a comparison of its results with those obtained from numerical simulations.