Crater Formation Research Articles

Crater Morphometry on Callisto

Impact crater formation is affected by the physical properties of planetary crusts, allowing comparison of crater dimensions to serve as a proxy for comparing the crustal properties of different planetary bodies. New topographic profiles of Callisto craters, derived from Galileo-based digital terrain models, are presented, and the crater dimensions recorded. These data were used to derive crater morphometry scaling trends, which were then compared to the established trends of Ganymede and the Moon. Our comparative study suggests that the upper brittle portion of Callisto’s ice crust allows for the retention of steep-sided and elevated rim scarps, while subsurface warmer ice leads to an enhanced uplift and shallowing of the crater bowl. Crater dimensions are similar between Callisto and Ganymede, suggesting that the bulk properties of their near-surface crusts are comparable. The most notable difference between craters on these two Galilean moons were the smaller central pit diameters on Callisto. This difference can be explained if the pit formation on these bodies is controlled by the presence and movement (drainage and/or volatile loss) of impact melt water: the lower impact velocity and/or lower expected crustal heat flow on Callisto will result in less impact melt generation, and thus smaller central pits.

Ballistic impact response of reinforced concrete panels subjected to diverse multiple projectile impact scenarios: A numerical study

Concrete has wide applications in civil and military infrastructures. Thorough ballistic damage evaluation of these structures is crucial to safeguard these structures against potential threats. Past studies on reinforced concrete (RC) panels primarily focused on single-impact scenarios. However, real-world situations often involve multiple impacts that need to be examined. Hence, this paper critically examines multiple impact scenarios on RC panels to provide a realistic understanding of their ballistic resilience. A three-dimensional finite element model was developed and validated with the experimental data from the literature to simulate the impact of a 2 kg hemispherical-nosed projectile on an RC panel. Extended analyses further investigated the RC panel subjected to multiple impact scenarios. Four distinct scenarios were studied: (1) single impacts at four separate locations, (2) simultaneous impacts at these four locations, (3) sequential impacts of four projectiles, and (4) single projectile impact with energy equivalent to the combined impact of the four projectiles. The study assessed local damage failures, including penetration depth, crater formation, energy absorption, deceleration and reaction forces on projectiles. Results revealed reduced ballistic performance of RC panels under multiple impacts compared to single impacts. Specifically, simultaneous impacts (case 2) and the equivalent single impact (case 4) caused more damage in terms of spalling and scabbing than single impacts (case 1) and sequential impacts (case 3). Additionally, cases 2 and 4 exhibited similar performance in terms of projectile penetration. This study is useful in understanding RC panels’ ballistic performance under multiple impacts.

Exploring wear resistance: Three-body abrasion evaluation of HVOF-sprayed TiC and CoNi coatings on SS316 steel

This study investigated the performance of High-Velocity Oxygen Fuel (HVOF)-sprayed Titanium Carbide (TiC) and TiC + 50C (50%TiC + 50%CoNi) coatings on SS316 steel under three-body abrasion conditions. The microstructural analysis revealed a homogeneous distribution of TiC particles within the TiC coatings, while the TiC + 50C coatings exhibited a more complex microstructure due to the presence of Co-Ni alloy. Mechanical testing demonstrated the superior microhardness of TiC coatings compared to the SS316 substrate, suggesting enhanced wear resistance. Slurry abrasion tests indicated reduced mass loss rates for both TiC and TiC + 50C coatings compared to uncoated SS316 steel, with TiC coatings exhibiting superior resistance to abrasive wear. Post-abrasion examination revealed distinct wear patterns, including abrasive chipping, plowing marks, crater formation, wear traces, and surface ruggedness.

Evaluation of Slurry-Eroded Rubber Surface Using Gloss Measurement

Slurry erosion testing is essential for evaluating the durability of materials under erosive conditions. This study examines the slurry erosion behaviours of chloroprene rubber (CR) under varying impact conditions to assess its durability. Traditional mass loss methods and qualitative techniques, including microscopy, SEM, and AFM, were employed to analyse eroded CR samples. Results indicate that cumulative material loss in CR increases linearly with sand impingement after approximately 60 kg of sand and correlates with an impact energy of about 30 kJ. The highest erosion rate was found at an impact angle of 15°. Erosion mechanisms vary with impact angle, affecting surface topography from cutting and ploughing at lower angles to deformation and crater formation at higher angles. Despite their efficacy, these methods are time-intensive and costly. This paper presents a novel approach utilising gloss measurement for continuous, non-destructive monitoring of eroded rubber surfaces. Gloss measurements are 24 times faster than traditional mass loss methods. Correlating gloss values with cumulative material loss, steady-state erosion, and impact energy offers significant time savings and an enhanced understanding of the erosion process. Experimental results demonstrate the effectiveness of gloss measurement as a reliable tool in slurry erosion testing of rubbers. The quantitative output from gloss measurements could support proactive maintenance strategies to extend service life and optimise operational efficiency in industrial applications, particularly in the mining industry.

The “suevite” conundrum, Part 2: Re‐examining the type locality at the Ries impact structure, Germany

AbstractOne of the most common types of allochthonous impactite produced in hypervelocity impact events is impact breccia that contains melt particles. In numerous terrestrial hypervelocity impact structures such melt‐bearing breccias have been termed “suevite,” after the type locality at the Ries impact structure, Germany. Despite its widespread occurrence, the origin, emplacement, and classification of suevite remains debated. In this contribution, we re‐examine the nature and origin of suevite at the Ries impact structure. The results of new field and laboratory investigations, when combined and synthesized with results from previous studies, lead to a multi‐stage model for the origin and emplacement of allochthonous impactites during the Ries impact event. Following the creation of a transient cavity the so‐called Bunte Breccia and “megablocks” were emplaced via ballistic sedimentation and subsequent radial flow during the excavation stage to form a continuous ejecta blanket. At the end of the excavation stage, a mixture of melt and lithic fragments formed a lining to the transient cavity and it is this material that later became the crater, dike, and outer suevite (OS) units. The crater suevite represents the material from the displaced zone of the transient cavity that was transported and mixed but never left the cavity. The emplacement of dike suevite occurred during the modification stage as the crater suevite was intruded into fractures in the underlying crater floor. The OS and rare impact melt rocks overlying the ballistic (Bunte Breccia) ejecta deposits were emplaced as outwards‐directed ground‐hugging flows largely during the modification stage of crater formation. The OS flows varied both spatially and temporally in terms of the flow characteristics, from being dominated by solid particles and gas (cf. pyroclastic density currents) to a mixture of solid particles, liquid (impact melt), and minor gases (i.e., particulate impact melt‐rich flows). These particulate impact melt‐rich flows dominated by far. Minor “fallback” of material from an ejecta plume is evidenced by accretionary lapilli in the Nördlingen 1973 core. In summary, allochthonous impactites at the Ries impact structure are not unusual but are consistent with observations from other terrestrial and planetary craters, where melt‐rich impactites overly ballistic ejecta deposits both outside and inside crater rims and where melt‐rich impactites occur in crater interiors.

The Effect of Antecedent Topography on Complex Crater Formation

AbstractImpact craters that form on every planetary body provide a record of planetary surface evolution. On heavily cratered surfaces, new craters that form often overlap antecedent craters, but it is unknown how the presence of antecedent craters alters impact crater formation. We use overlapping complex crater pairs on the lunar surface to constrain this process and find that crater rims are systematically lower where they intersect antecedent crater basins. The rim morphology of the new crater depends on the depth of the antecedent crater and the degree of overlap between the craters. Our observations suggest that new craters do not always obliterate underlying topography and that transient rim collapse is altered by antecedent topography. This study represents the first formalization of the influence of antecedent topography on rim morphology and provides process insight into a common impact scenario relevant to the geology of potential Artemis landing sites.

Cracking of submerged beds

We investigate the phenomena of crater formation and gas release caused by projectile impact on underwater beds, which occurs in many natural, geophysical and industrial applications. The bed in our experiment is constructed of hydrophobic particles, which trap a substantial amount of air in the pores of the bed. In contrast to dry beds, the air–water interface in a submerged bed generates a granular skin that provides rigidity to the medium by producing skin over the bulk. The projectile's energy is used to reorganize the grains, which causes the skin to crack, allowing the trapped air to escape. The morphology of the craters as a function of impact energy in submerged beds exhibits different scaling laws than what is known for dry beds. This phenomenon is attributed to the contact line motion on the hydrophobic fractal-like surface of submerged grains. The volume of the gas released is a function of multiple factors, chiefly the velocity of the projectile, depth of the bed and depth of the water column.

Investigating crater formation in nanosecond laser ablation of aluminum foils

A nanosecond Nd:YAG laser was used to study the laser ablation of aluminum foil in the phase explosion regime at a laser intensity range of 0.63–3.61 ×1012W/cm2. Laser ablation and plasma characteristics were studied using microscopic ablation crater images, plasma emission spectra, and plasma plume images. Measured plasma density using a Stark width of Al I (396.2 nm) showed a strong linear correlation with crater size, with a Pearson correlation coefficient (r) of 0.97. To understand the origin of this linear correlation, plasma temperature was estimated using Bremsstrahlung emission from 512 to 700 nm. The estimated plasma temperature and aspect ratio of the plasma plume were negatively correlated, having r=−0.76. This negative correlation resulted from a laser-plasma interaction, which heated the plasma and increased its hydrodynamic length. The percentages of laser energy used for plasma heating (Ep/EL) and Al foil ablation (EAl/EL) were estimated from plasma temperature. Increased EAl/EL, such as crater size, with increasing laser intensity, confirms that greater mass ablation is the fundamental reason for the strong linear correlation between crater size and plasma density.

In-situ mapping of monocrystalline regions on Mars

Elemental quantification instruments for planetary missions provide a capability for in-situ identification of mineral phases via stoichiometry, an essential step in petrological investigations. X-ray fluorescence (XRF) has been employed for this purpose by multiple generations of Mars rovers (i.e., Pathfinder, Spirit and Opportunity, Curiosity and Perseverance). The Planetary Instrument for X-ray Lithochemistry (PIXL) aboard Perseverance rasters a micro-focused X-ray beam to generate micron-mm-sized maps illustrating variations in elemental composition and allowing mission scientists to identify rock components (i.e., sedimentary grains, veins and igneous crystals). Energy-dispersive X-ray diffraction can also be detected with PIXL and can be used as an additional constraint on component boundaries, providing PIXL with the capability to map monocrystalline regions in-situ. Here we introduce and apply a new method where each diffraction peak is partitioned independently according to its energy, using the instrument geometry to inform consistent partitioning. Applying this method to datasets acquired from the Dourbes abrasion patch in the Séítah formation of Jezero crater, Mars, reveals monocrystalline regions that were hidden using previous methods. This application of the technique allows faster and more accurate visualization of petrographic textures in future PIXL datasets, in particular those with rock components that are not easily separable using stoichiometry alone.

Ejecta splashing and scaling of projectile oblique impact on granular media

Ejecta splashing is accompanied by the formation of impact craters in oblique impact of a sphere onto a granular target. We investigated the morphology and scaling of the ejection, together with the evolution and final size of crater by performing a series of experiments, varying the impact angle θ and impact speed V0. The experiment categorized the crater shapes in the space parameters Fr and θ and revealed that the maximum ejecta height exhibits two regimes related to Froude number, while the crater length, width, and depth are all collapsed to a master line. Then, the evolution characteristics of the corolla dimensions (top diameter, neck size, bottom diameter, and height) are determined. Moreover, a simple ballistic model taking into account the air drag force acting on the ejecta has been proposed to predict the dynamic processes of the corolla in oblique impacts. Furthermore, the opening of the crater formation deduced by the dynamics of the corolla formed and the collapsing process (i.e., the splashed sand avalanching down along the wall of the crater) have been investigated in detail using a simplified Bouchaud–Cates–Ravi–Edwards model. Our theoretical model demonstrated high accuracy in reproducing the evolution of a crater during impacting and in predicting the final crater scaling after avalanching.

Stability of granular media impacts morphological characteristics under different impact conditions

Abstract In planetary surfaces, oblique impact events are commonplace, and their study holds significant importance for understanding planetary impact processes and aiding in the design of landers and impactors. Current research predominantly focuses on simplified models to study the force and motion under vertical impact craters in terms of scale and impact loading. For oblique impacts, investigations have primarily concentrated on the final crater shape. However, the specific influence of impact load motion on particle bed movement and the precise impact angle’s effect on the ultimate crater shape during the impact process remain unclear. In this study, we used a custom-built oblique impact experimental setup to analyze changes in the velocity field of the particle bed and the horizontal movement of the impact load. Using quasi-static region to assess ellipticity, we aimed to reveal the state of particle movement during oblique impacts and explore the impact of impact angles and energies on crater formation. The results indicate that under large impact angles, the obliquely acquired kinetic energy is minimal, leading to a predominant static point source movement of the particle bed. At higher energy levels, the impact load primarily excavates downward, resulting in the formation of circular impact craters. These findings underscore the sensitivity of particle bed motion to impact angles, making it a crucial metric for assessing the impact of oblique angles on final crater morphology.

Experimental Investigation on Wire Electric Erosion Behaviour of Silicon Dioxide Particulate Reinforced Composite

The intend of current study was focused on the prediction of material removal rate (MRR) and surface roughness (SR) for the AA7050-SiO2 composite during wire electric erosion or discharge machining (WEDM) process using a brass (Br) wire electrode. Here, stir casting process was employed to develop the AA7050 matrix composite with inclusion of 10wt.% SiO2 particle reinforcement. The multi-objective optimization method of Technique for order preference by similarity to ideal solution (TOPSIS) approach has been applied to find out the optimal setting of input machining parameters such as peak current (Ip), pulse-on time (Ton) and pulse-off time (Toff). Furthermore, the significant effects of parameters were identified by analysis of variance (ANOVA). Taguchi L9 (33) orthogonal design has been formulated to perform the experimental work. TOP SIS results stated that the optimal setting of Ip at 30 amps, Ton of 130 μs and Toff of 55 μs provide the better MRR with lesser SR. The ANOVA results noticed that Ip has the prime noteworthy parameter over the adopted responses having a contribution of 45.67%, followed by Ton (32.34%) and Toff (12.26%), respectively. The confirmation test was carried out by the optimal parameters setting to verify the predicted results. Finally, the scanning electron microscopy (SEM) test was carried out for the machined surface of the composite specimen and it was reveals that the formation of craters and recast layer thickness in the machined surfaces.

Взрывная дегазация Земли на полуострове Ямал и прилегающей акватории Карского моря

Remote sensing data from space and using UAVs make it possible to solve a wide range of tasks related to the study of Earth degassing processes in the Arctic. For the first time, via comprehensive aerospace research on the Yamal Peninsula, we have discovered 4992 zones of gas blowouts (explosions) in the form of craters (pockmarks) at the bottom of 3551 thermokarst lakes and 16 rivers. In addition, we have identified another 669 zones of explosive degassing in the coastal zones of the Kara Sea, mainly in gulfs, estuaries and bays. Taking into account the Yugorsky Peninsula and Bely Island, we have detected 6022 explosive degassing zones in the studying region, including 905 ones offshore. We have proved previously made conclusions that the Neytinsko-Seyakhinsky and Sabetta districts are the most gas-explosive. It is substantiated that possible intense natural degassing of the Earth, especially occurring in the process of degradation of subaquatic permafrost and dissociation of gas hydrates, can radically change the elastic-strength properties of bottom soil, while its saturation with gas can disrupt conditions for the construction of various objects, including underwater gas pipelines. Widespread gas blowouts in the north of Western Siberia with the formation of craters on land and offshore can lead to emergencies and even disasters at oil and gas industrial facilities and to fires in the tundra.

Geologic History of the Amundsen Crater Region Near the Lunar South Pole: Basis for Future Exploration

We provide the first detailed 1:100,000 scale geomorphologic map of the ∼100 km Amundsen crater region, which is of high scientific relevance for future exploration, e.g., NASA’s VIPER mission, the Artemis program, and the Chinese International Lunar Research Station. We investigated the complex geological history of the region before and after the formation of Amundsen crater on the rims of the South Pole–Aitken (SPA) and Amundsen–Ganswindt basins. We present a new Amundsen crater formation age of ∼4.04 Ga, which, in contrast to previously derived ages, is based on non-light-plains terrain. The estimated maximum excavation depth for Amundsen crater is ∼8 km, and elevated concentrations of FeO near the crater suggest that Amundsen may have redistributed SPA-derived materials. Plains materials of various kinds were observed both inside and outside Amundsen crater and are estimated to be up to 350 m thick and ∼3.8 Ga old. A less cratered, tens of meters thick mantling unit indicates a resurfacing event ∼3.7 Ga ago. We highlight five potential exploration sites that satisfy technical constraints (such as shallow slopes, solar illumination, and Earth visibility), provide materials that can be sampled, and are capable of addressing multiple science objectives. Due to its accessibility and traversability, combined with its geologic diversity, proximity of permanently shadowed regions for studying volatile processes, and ability to address multiple science objectives, we confirm and reinforce the Amundsen crater region as a high-priority landing and exploration site.

Crater depth prediction in granular collisions: A uniaxial compression model.

Impact crater experiments in granular media traditionally involve loosely packed sand targets. However, this study investigates granular impact craters on both loosely and more tightly packed sand targets. We report experiments that consistently adhere to power-law scaling laws for diameter as a function of impacting energy, similar to those reported by other groups for their experiments utilizing both solid and granular projectiles. In contrast, we observe significant deviations in the depth versus energy power law predicted by previous models. To address this discrepancy, we introduce a physical model of uniaxial compression that explains how depth saturates in granular collisions. Furthermore, we present an energy balance alongside this model that describes the energy transfer mechanisms acting during crater formation. We found a better way to transfer vertical momentum to horizontal degrees of freedom as the impact surface compacts, resulting in shallow craters on compacted sandbox targets. Our results reveal depth-to-diameter aspect ratios from approximately 0.051 to 0.094, allowing us to interpret the shallowness of planetary craters at the light of the uniaxial compression mechanism proposed in this work.

Experimental Study on Electro-Discharge Drilling of NiTiCu10 Shape Memory Alloy

Shape memory alloys (SMAs) are potential materials in various areas such as engineering and medicine, and their applications are being studied for practical use. SMAs show competence in their main material properties in response to their working environment or external stimuli. Machining of NiTiCu10 SMAs is difficult using traditional machining because of their wide-ranging mechanical properties like high toughness, strength, and sensitivity to phase transformation temperature. Nonconventional machining methods such as electro-discharge machining (EDM) are suitable for effective machining SMAs. The work material NiTiCu10 SMA has been used in this study, and processed using the vacuum induction melting (VIM) technique. The addition of copper leads to increase in the martensitic transformation temperatures. This paper focuses on the electro-discharge drilling (EDD) of NiTiCu10 SMA using copper tool electrode. Experimental analysis of performance criteria has been evaluated by conducting experiments following one factor at a time (OFAT) approach. Machining features such as material removal rate (MRR), tool electrode wear rate (TEWR), and surface roughness (SR) have been studied by considering pulse current ([Formula: see text]), gap voltage ([Formula: see text]), pulse on time ([Formula: see text]), pulse off time ([Formula: see text]), and rotational speed of tool electrode (N). Experimental results have shown that machining at the highest [Formula: see text] of 12[Formula: see text]A yields the highest MRR with the value of 4.077[Formula: see text]mm3/min, whereas mcahining at [Formula: see text] of 15[Formula: see text][Formula: see text]s yields the lowest TEWR with the value of 0.031[Formula: see text]mm3/min. The lowest SR is 2.8[Formula: see text][Formula: see text]m achieved at the lowest [Formula: see text] of 15[Formula: see text][Formula: see text]s. Surface morphology is significant in quality evaluation in the manufacturing, and building industries because it directly determines the mechanical performance of parts, and the service life of products. Morphological investigation via scanning electron microscope (SEM) has confirmed the formation of craters, debris, microcracks, and resolidified layers. The benefit of this study has been that we have been able to select the range of significant control factors, and predict their levels, for decisive experimentation.

Observations on Macroscopic Surface Modification and Oxidation of Tungsten and Tungsten Carbide in Laser Focus in Air

Tungsten and tungsten carbide were damaged in ambient air with varying incident angles (0, 30, 45, and 60 deg) for approximately 5000 shots. The goal of these experiments was to observe the macroscopic surface modification in tungsten and tungsten carbide surfaces in harsh environments. At low pulse numbers (one to eight laser pulses on the same spot), tungsten aerial surface damage was less than tungsten carbide damage; however, at very high pulse numbers (5000), the opposite was true. Surface damage was mostly in the form of craters that were near circular at low impact angles and became more elongated at higher laser pulse impact angles. On the tungsten surface, a cluster of tungsten oxide debris formed. During laser exposure, laser-induced periodic surface structures and grooves were formed, and their geometries varied with laser intensity and laser impact angle. The period of laser-induced surface changes increased as the incident angle increased for both tungsten and tungsten carbide surfaces. More mass was lost in tungsten than tungsten carbide, which agrees with the morphological responses.

Effect of heat treatment on microstructure and mechanical characteristics of laser powder bed fusion (LPBF) produced CuCrZr alloy

In this work, the CuCrZr alloy was fabricated by employing the laser powder bed fusion (LPBF) process. For elevating the mechanical characteristics offered by the LPBF parts, heat treatment was performed and three cooling pathways such as water quenching, air cooling and furnace cooling were adapted. The obtained results showed that the water quenching leads to the formation of more craters in its microstructure compared to the air cooled and furnace cooled samples. The nanoindentation analysis revealed that the furnace cooled sample had higher hardness (1.56 GPa) which is attributed to the precipitation of Cu-Zr intermetallic precipitates. Moreover, this sample tends to have a low wear rate and higher tensile characteristics due to the formation of intermetallic precipitates.

Influence of boundary conditions on initiation of gas blowout in permeable rock

Free gas in permafrost may originate from dissociating methane hydrates that are widespread in the Arctic region. Methane can migrate through sand–clay permafrost and accumulate there, particularly in sand beds. Gas migration is often accompanied by the formation of pressurised zones. As the pressure reaches some critical value, the overburden breaks down, and methane is released explosively with formation of craters on the seabed. In this paper, gas migration is simulated in two dimensions, with implications for the conditions under which an increased gas flow rate can lead to failure of granular rocks, as well as for the place of blowout initiation depending on boundary conditions. The paper shows that the location of sediment blowouts in the presence of an impermeable lid or obstacle differs from the location of blowouts without them. The paper also shows that the type of pressure source (homogeneous or heterogeneous) also affects the location of the blowout initiation. The numerical results are in good agreement with laboratory experiments carried out in a sandy medium at a Hele-Shaw cell and with field data. The presented results should be taken into account when estimating the after-effects of methane hydrate dissociation due to global warming or due to surface condition changes.

Impacts of WWII bomb explosions on weathering damage of architectural heritage: Bath, England

The effects of bomb impacts, including the explosive force and combustion associated with these impacts, are preserved in only a few cities across the UK. In particular, World War Two (WWII) has left scars across a wide range of structures as a result of air raids. On immovable heritage, such as architectural structures, these impacts commonly take the form of craters, fractures and fire damage to stonework. This instantaneous damage is subsequently exposed to environmental stresses, such as moisture cycling, thermal stress and the movement of soluble elements and can thus lead to further deterioration of the stone. In this study, Rock Surface Hardness (RSH) measurements, permeametry measurements and microscopic observations were selected to capture stone deterioration data from 80-year-old bomb impacts on two walls of the Labour Exchange in Bath (UK) for spatial distribution analysis (Kriging) in Geographic Information Systems (GIS). The results show that the weathering forms that were found on the two walls can be attributed to nine different types. They can provide quantitative assessment of damage caused by bomb explosions and combustion in the war. The increase in permeability of walls and craters is shown to be primarily caused by the bomb explosion and combustion, whereas the decrease of hardness is associated with subsequent stone deterioration processes. This indicates that the interplay of initial damage likely accelerates subsequent response to environmental stress, extending the initial damage patterns from the impact crater to larger areas of stonework.