Large Craters Research Articles

A neural network topographic correction method for the Lunar Reconnaissance Orbiter Diviner Christiansen feature map

Topographic correction for lunar optical and thermal infrared remote sensing images is a challenging task. Although geometrical, photometrical or albedo-dependent correction methods have been used in an attempt to eliminate topographic effects in the initial lunar reflectance and emissivity images, these methods did not perform well on lunar steep slopes, large crater interiors or walls. In this paper, a novel neural network topographic correction (NNTC) model that was trained based on the relationships between flat (< 0.1° slope angle) and rugged pixels with similar Kaguya FeO abundance and optical maturity parameters (OMATs) (relative ratio < 0.1%) was applied to the Lunar Reconnaissance Orbiter (LRO) Diviner standard Christiansen feature (CF) image. The topographic correction accuracy is 0.03 μm, and no outliers are produced. Visual comparisons with the previous topographic corrected reflectance and emissivity images indicate that the topographic effects on various slope and aspect pixels were effectively corrected. The excavated anorthosite materials in the highland crater (such as the Jackson, Giordano Bruno and Tycho) interiors, surroundings, ejecta, and ray deposits have very similar NNTC CF values. The crater structures in maria or cryptomaria are identified more clearly. In addition, the NNTC method has the potential to be a universal topographic correction method for lunar optical and thermal infrared images, and it provides reliable data sources and a new method for space weathering correction.

How to Develop Ecotourism in Ijen Banyuwangi Crater ?

Tourism is an important part in supporting the development of social, economic, cultural, and even regional political life. Ijen Crater is listed as the largest crater in the world and one of the tourism industries in Banyuwangi City with high tourism potential in the East Java region, Indonesia. The purpose of this study is to find the right formula to develop ijen crater tourism and maintain nature conservation. The research method uses the AHP (Analytic Hierarchy Process) approach. The results of the analysis obtained that cooperation strategies with stakeholders 0.37%, community empowerment strategies 0.315%, regulatory improvement strategies 0.186% and management management strategies 0.129%. Stakeholder cooperation is an important priority because it is useful to be able to create relationships by building good communication in running the wheels of the ecotourism industry. This study can ultimately be useful for mapping strategies in developing ecotourism in Ijen Crater, Tamansari Village, Banyuwangi, Indonesia.

Effect of Varied Cashew Nut Ash Reinforcement in Aluminum Matrix Composite

In the present article, cashew nut biocarbon (CTB), an agricultural waste, is used as reinforcement in Al6061 by the heating process. The primary XRD study on CTB confirms the presence of SiO2, Al2O3, iron-rich ferro-axinite, MgO, and Mn, which improve the material’s properties when used as reinforcement. SiO2 levels increase with annealing time. The extracted CTB is crushed into a ball mill for 24 hours, and the particle size is measured by SEM as 70–90 nm. An experimental study was performed with a variable percent weight of CTB with an increase of 5%–20% for structural stability applications. X-ray analysis tests the composite’s elemental composition and intermetallic elements. It confirms that no such evidence exists. CTB’s density, tensile, flexural, and impact tests measure CTB’s impact. CTB has the lowest density variation and increases tensile and flexion bearing capacity by 30% and 47%, respectively. The lightweight brittle increment is impact-resistant. SEM fracture analysis shows transgranular and intergranular fractures with dimples, large craters, and peak areas.

Improvement of Lunar Surface Dating Accuracy Utilizing Crater Degradation Model: A Case Study of the Chang’e-5 Sampling Area

Taking the Chang’e-5 (CE-5) sampling area as an example, this study carried out an investigation on improving the crater size-frequency distribution (CSFD) dating accuracy of lunar surface geologic units based on the crater degradation model. We constructed a three-parted crater degradation model, which consists of the diffusion equation describing crater degradation and equations describing the original crater profile for small craters (D &lt; 1 km) and larger craters (D ≥ 1 km). A method that can improve the accuracy of CSFD dating was also proposed in this study, which utilizes the newly constructed degradation model to simulate the degradation process of the craters to help determine the crater degradation process and screen out the craters suitable for CSFD analysis. This method shows a good performance in regional dating. The age determined for the CE-5 sampling area is 2.0 ± 0.2 Ga, very close to the 2.03 ± 0.004 Ga of isotopic dating result of the returned sample. We found that the degradation state of the craters simulated by our constructed degradation model is highly consistent with the real existing state of the craters in terms of their topographic, geomorphological, and compositional (e.g., FeO) features. It fully demonstrates that the degradation model proposed in this study is effective and reliable for describing and distinguishing the degradation state of craters over time due to the cumulative effects of small craters. The proposed method can effectively distinguish between diffusively degraded (which conform to the degradation model) and non-diffusively degraded (which do not conform to the degradation model) craters and improve the CSFD accuracy through the selection of the craters. This not only provides an effective solution to the problem of obtaining a more “exact” frequency distribution of craters, which has long plagued the practical application of the CSFD method in dating the lunar surface but also advances our understanding of the evolutionary history of the geologic units of the study area. The results of this work are important for the in-depth study of the formation and evolution of the moon, especially for lunar chronology.

Natural processes leading to large, pre-historic hydrothermal eruptions in geothermal areas: Rotokawa geothermal field, New Zealand

Hydrothermal eruptions are the most violent and hazardous phenomena within geothermal fields. The largest of these may produce kilometer-sized craters and breccia deposits that are tens of meters thick. The geological and hydrothermal priming that leads to these types of eruptions is poorly understood. To understand large hydrothermal eruptions, we investigated a series of prehistoric events at the Rotokawa geothermal field in New Zealand. By revising the stratigraphy and distribution of hydrothermal breccia deposits and correlating these with componentry, crater morphology, and subsurface geological structure, we estimated the frequency, priming processes, triggers, and dynamics of multiple eruptions. Seventeen large hydrothermal eruptions occurred centuries to millennia apart in the period from ca. 22 cal ka B.P. to ca. 3.4 cal ka B.P. Of six hydrothermal eruptions since ca. 7 ka, four produced oval-shaped craters up to 2 km in diameter, creating a broad, shallow depression within the geothermal field. The two youngest eruptions occurred northeast of earlier eruption centers and have narrower and elongated vents. We infer that in the central depression, newly formed craters rimmed by breccia deposits and high-relief country rock hosted temporary lakes tens of meters deep. Crater-lake breakout(s) and/or seismic events caused sudden pressure reduction above the hydrothermal aquifer, triggering hydrothermal eruptions. Northeast of the basin, hydrothermal alteration produced caprocks above intensively fractured areas. In this case, earthquakes are the most likely trigger for cap-rupture and eruption. All eruptions excavated shallow and large craters mostly within partially altered Oruanui Formation and pre-fragmented breccias. The size and localization of the eruptions was likely due to a combination of (1) availability of undisturbed porous ignimbrite hosting large thermal aquifers, (2) efficient crater excavation within or alongside pre-fragmented breccia, and (3) the location of fracture and fault zones that channeled deep fluid upflow, favoring priming processes. This study highlights how an interplay of tectonic, magmatic, and hydrologic processes is responsible for the timing, dynamics, and ultimate size of hydrothermal eruptions in geothermal fields. Some events may be very large and destructive depending on the right priming and geological conditions.

2022 Joint Barringer Medal for Kai Wünnemann and Gareth S. Collins

2022 Joint Barringer Medal for Kai Wünnemann and Gareth S. Collins

Morphological Characterization of Decimeter‐ to Hectometer‐Scale Impact Craters at the Chang’E‐3/4/5 Landing Sites

AbstractThe morphology of impact craters on the Moon is important for understanding impact cratering process and lunar surface properties. Though the morphology of lunar impact craters at hectometer scales and larger is extensively investigated and well understood, the morphology of very small craters is rarely studied due to the lack of high‐resolution data. In this study, we investigated the morphology of 1,513 craters at decimeter to hectometer scales using the 5 mm/pixel–0.5 m/pixel topographic data of the Chang’E‐3/4/5 (CE‐3/4/5) landing regions. Our results show that crater depth, rim height, and inner wall slope increase with the diameter and that the mean values of depth/diameter ratio, rim height/diameter ratio, and inner wall slope are 0.065, 0.017, and 10.5°, respectively. These morphometric parameters are smaller than those of large craters above hectometer scales, which is probably due to low‐strength surficial regolith and rapid topographic degradation. The comparison of the morphometric parameters among the three regions suggests that the CE‐4, CE‐3, and CE‐5 landing regions have the highest, intermediate, and lowest regolith strengths, respectively. In addition, we first observed widespread meter‐scale concentric and flat‐bottomed craters in optical images, which are most probably formed due to strength heterogeneity within the regolith layer. Our results can help to understand near‐surface properties of the regolith layer, lunar surface evolution, and impact cratering process in the strength regime.

Diversity of New Martian Crater Clusters Informs Meteoroid Atmospheric Interactions

AbstractWe investigated 634 crater clusters on Mars detected between 2007 and 2021, which represent more than half of all impacts discovered in this period. Crater clusters form when meteoroids in the 10 kg–10 ton mass range break up in Mars' atmosphere to produce a few to a few hundred fragments that hit the ground. The properties of the clusters can inform our understanding of meteoroid properties and the processes that govern their fragmentation. We mapped individual craters &gt;1 m within each cluster and defined a range of cluster properties based on the spatial and size distributions of the craters. The large data set, with over eight times more cluster observations than previous work, provides a more robust statistical investigation of crater cluster parameters and their correlations. Trends in size, dispersion, and large crater fraction with elevation support weak atmospheric filtering of material. The diversity in the number of individual craters within a cluster, and their size‐frequency distributions, may reflect either a diversity in fragmentation style, fragility, or internal particle sizes.

Impact abrasive wear behaviour of the multiphase microstructure in a medium carbon quenched and partitioned bainitic steel

To enhance the impact abrasive wear resistance of steel for mining and metallurgy industries, a 0.3C steel with a multiphase microstructure of bainitic, martensitic and retained austenite was produced by a Q&P process involving bainitic transformation, and its wear performance under impact abrasive conditions was evaluated in contrast with fully martensitic and fully bainitic steels. The results revealed that the multiphase microstructure demonstrates outstanding combination of strength (1612 MPa), toughness (105 J), hardness (48.7 HRC) and elongation (19.2%), along with superior impact abrasive wear resistance. After 90 min of impact abrasive wear test, the multiphase microstructure shows lower wear loss than that for the fully martensitic and fully bainitic steels, which can be attributed to its high surface microhardness and increased toughness. The formation of nanograins and an increase in dislocation density as well as the retained austenite transformation leads to the higher surface microhardness. In addition, some larger craters can be observed on the wear surface of fully martensitic and fully bainitic steels, and the crack propagation depth is larger under the wear surface. In contrast, the wear surface of the multiphase microstructure presents some delamination damage, and the crack propagation depth is shallow because of the thicker deformed layer and presence of film-like austenite retained in the deformed microstructure. These results suggested that the multiphase microstructure can be used as a potential candidate structure for enhanced resistance to impact abrasive wear.

CAGE15-5 Cruise Report: Marine Geological Cruise to Storfjordrenna, Bjørnøyrenna and Thor Iversenbanken

The cruise was a part of the Centre of Excellence for Gas Hydrate, Environment and Climate (CAGE) at UiT – The Arctic University of Norway. The cruise aimed at investigating areas with gas venting from the seabed in central Bjørnøyrenna and outer Storfjordrenna, as well as subglacial meltwater systems in Thor Iversenbanken, central Barents Sea. More specific objectives included: Acquisiton of a P-cable 3D seismic survey over part of a large crater and pingo field in central BjørnøyrennaSampling gas in water, sediments and air in areas of gas venting within the crater and pingo fieldAcquisiton of gravity cores for identification of palaeo-subglacial lakes in Thor IversenbankenAcquisiton of 2D seismic across subglacial meltwater systems in Thor IversenbankenAcqusition of 2D seismic across pingos identified in StorfjordrennaSampling of gas in air in the area where pingos have been identified in Storfjordrenna The cruise may be known as: CAGE15_5

A Large New Crater Exposes the Limits of Water Ice on Mars

AbstractWater ice in the Martian mid‐latitudes has advanced and retreated in response to variations in the planet's orbit, obliquity, and climate. A 150 m‐diameter new impact crater near 35°N provides the lowest‐latitude impact exposure of subsurface ice on Mars. This is the largest known ice‐exposing crater and provides key constraints on Martian climate history. This crater indicates a regional, relatively pure ice deposit that is unstable and has nearly vanished. In the past, this deposit may have been tens of meters thick and extended equatorward of 35°N. We infer that it is overlain by pore ice emplaced during temporary stable intervals, due to recent climate variability. The marginal survival of ice here suggests that it is near the edge of shallow ice that regularly exchanges with the atmosphere.

Constraining surface properties of asteroid (162173) Ryugu from numerical simulations of Hayabusa2 mission impact experiment

The Hayabusa2 mission impact experiment on asteroid Ryugu created an unexpectedly large crater. The associated regime of low-gravity, low-strength cratering remained largely unexplored so far, because these impact conditions cannot be re-created in laboratory experiments on Earth. Here we show that the target cohesion may be very low and the impact probably occurred in the transitional cratering regime, between strength and gravity. For such conditions, our numerical simulations are able to reproduce the outcome of the impact on Ryugu, including the effects of boulders originally located near the impact point. Consistent with most recent analysis of Ryugu and Bennu, cratering scaling-laws derived from our results suggest that surfaces of small asteroids must be very young. However, our results also show that the cratering efficiency can be strongly affected by the presence of a very small amount of cohesion. Consequently, the varying ages of different geological surface units on Ryugu may be due to the influence of cohesion.

Sample studies and SELENE (Kaguya) observations of purest anorthosite (PAN) in the primordial lunar crust for future sample return mission

Purest anorthosite (PAN), which consists mostly of plagioclase (≥98%), provides key information for understanding the deep crust of the Moon, because PAN observed at central peaks of large impact craters was uplifted from a deep-seated layer. For future sample return of PAN, we examined the visible and near-infrared spectra of lunar meteorites and the mineralogical and petrological studies for Apollo FAN 60015. Sample analyses for lunar meteorites and Apollo FAN 60015 showed the existence of PAN in lunar samples. However, PAN clasts in lunar meteorites were so small that not enough sampled material could be secured for multiple analyses, such as determining their crystallization ages. The lunar meteorites were also heavily brecciated by multiple impacts on the surface. The brecciation and recrystallization on the surface may have disturbed the original information (i.e., age, texture, etc). Therefore, sample return of PAN rocks that have recently fallen from the central peaks of the large craters is required for analysis to determine the parent magma composition and timing of PAN formation. We investigated the PAN distributions in Jackson crater on the lunar farside and found that PAN rocks are widely distributed over the central peak and parts of the crater wall, using SELENE (Kaguya) observational data to locate where PAN would best be collected from the lunar surface. Based on the slope that a rover can manage, we recommend two areas appropriate for collecting samples of PAN rocks that have separated from the central peak.

Advective nature of ring crater structures on the Moon and Earth, &#x0D; problems of their astrobleme interpretation

In this paper, we compare different-scale ring crater structures on the surface of the Moon and the Earth. Here we show the regular zonal change of craters of different sizes around the largest crater on the Moon and the periodicity of the distribution of craters along the lines according to the wave principle. On Earth, we consider the position of the famous Arizona crater, the relationship with the external environment and structural features that cast doubt on its astrobleme nature. Arguments are given about the possible terrestrial origin of the specific largest iron meteorites found without craters, and the ambiguous diagnosis of explosion products attributed to those associated with meteorite impacts.

Advective structures of the bottom of lake Natron and its surroundings (Tanzania)

In this study we consider the features of the development of weakly lithified bottom sediments and the general structure of lake Natron against the background of its seasonal drying and watering. This study takes into account the laws of advection and the periodic placement of cellular zonal advective structures in space. The consedimentary structures in the lake sediments demonstrate the conditions for the formation of sodic ores and their positions. Provided space and aerial photographs depict unique genetic information about the evolution of geochemistry and the development of bottom morphology during sedimentation. This includes the presence of two sources that feed the lake - river and mud eruptions of the adjacent Oldoinyo-Lengai volcano, supposedly the only one on Earth that erupts carbonatite lavas. The combination of two sources and two processes leads to the development of an epimagmatic phreatic-hydrothermal recycling system. In it, the masses of the lake penetrate through fissure structures into the suprafocal space of the volcano, providing mud volcanism with solutions of soda masses containing organic matter of sediments. Volcanic soda eruptions are not carbonatite lavas. The morphological similarities and differences of structures are shown - small craters on the bottom of the lake, associated with the advection of thin layers of sedimentary material; large craters located nearby among volcanic strata along the shores of the lake; and both subsidence calderas and explosion calderas associated with magmatic and mud types of volcanism in the setting of strike-slip transtension.

Ejecta Pattern of Oblique Impacts on the Moon From Numerical Simulations

AbstractThe commonly adopted ejecta deposit models always assume vertical impacts for simplification. However, most impacts on planetary surfaces are oblique, which produce significantly different ejecta patterns from vertical impacts. Although the asymmetric ejecta patterns from oblique impacts have been studied in laboratory experiments, they cannot be directly applied to large craters on the planetary scale. Here, we use the three‐dimensional shock physics code iSALE‐3D to systematically simulate impact excavation processes under Moon's gravity with varied impact angles (10°–90° with respect to the horizontal), impactor diameters (1–120 km), and impact velocities (10–20 km/s), which produce craters or basins ranging from ∼5 to ∼1,000 km. For each model, we record ejecta launch velocities and angles and calculate their integrated patterns after ballistic sedimentation. Our model results show that as the impact angle departs from the vertical, launch velocities of the uprange ejecta decrease, forming a V‐shaped zone devoid of ejecta. For even lower impact angles, the downrange ejecta thickness significantly decreases due to reduced launch angles and smaller deposit distances, forming a butterfly pattern with most ejecta concentrating in crossrange. In addition, our model results indicate that large impactors tend to produce more asymmetric ejecta patterns and the ejecta patterns are insensitive to typical impact velocities on the Moon. Our modeling results provide a semi‐quantitative relation between the ejecta pattern and impact parameters for oblique impacts on the Moon, which can be used to constrain the possible impact parameters for lunar crater or basins according to the observed ejecta pattern.

Complex Crater Formation by Oblique Impacts on the Earth and Moon

AbstractAlmost all meteorite impacts occur at oblique incidence angles, but the effect of impact angle on crater size is not well understood, especially for large craters. To improve oblique impact crater scaling, we present a suite of simulations of complex crater formation on Earth and the Moon over a range of impact angles, velocities and impactor sizes. We show that crater diameter is larger than predicted by existing scaling relationships for oblique impacts; there is little dependence on obliquity for impacts steeper than 45° from the horizontal. Crater depth, volume and diameter depend on impact angle in different ways—relatively shallower craters are formed by more oblique impacts. Our simulation results have implications for how crater populations are determined from impactor populations and vice‐versa. They suggest that existing approaches to account for impact obliquity may underestimate the number of complex craters larger than a given size by as much as one‐third.

The influence of different preparation methods on the erosion behavior of NiP-ZrO2 nanocomposite coating

Three different deposition techniques were utilized to synthesize NiP-ZrO2 nanocomposite coatings. The structural and mechanical merits for the as-prepared coatings were compared through XRD, XRF, SEM, AFM, microhardness, and nanoindentation analysis. The pulse-electrodeposition was the most suitable technique with a hardness value of 653HV25. The erosion behavior for the different NiP-ZrO2 coatings was investigated based on erosion duration, particles velocity, and impact angle. The results shows that the erosion rate decreases linearly with increasing angle of incidence and increases with increasing particle velocity. The erosion mechanism is mainly fracturing of splats and ploughing action at low particle velocity due to the ductility merits of the different coatings. In contrast, larger craters, radial cracks, and micro cuttings were observed at higher speeds.

Understanding the mineralogy of a compositional anomaly north of the Korolev basin using Moon mineralogy mapper

The work attempts to understand the mineralogy of the reported geochemical anomaly located in the north – northeast region of the Korolev basin using Moon Mineralogy Mapper (M3) onboard Chandrayaan −1 and other lunar datasets. To understand the mineralogy, colour composite images using integrated band depth parameters and mineral indices were prepared, and the M3 spectral signatures corresponding to the unique colours of these colours composites were investigated. Further, Modified Gaussian Model (MGM) deconvolution was applied to these spectra. The results of spectra studies reveal that the area is made up of heterogeneous lithologies, predominantly composed of anorthosite along with minor occurrences of pyroxene-bearing (both low-calcium and high-calcium variety) and spinel-bearing lithologies. Correlation of spectral studies with the morphology revealed that pyroxene was typically associated with fresh craters and their ejecta. Spinel was found to be ubiquitous and is well-dispersed, possibly distributed along with the ejecta blanket of large impact craters. This association hints that the pyroxene-hosted layer most likely occurs beneath the spinel-bearing layer. Such observed assemblages may have resulted from physical mixing during the impact cratering events. This mixed lithology could arise due to the mafic mineral-bearing ejecta of the South-Pole Aitken (SPA) basin and spinel-bearing Orientale ejecta. Korolev most likely impacted on a thick layer of SPA ejecta, and impact basins such as Hertzsprung and Orientale have occurred post-Korolev formation. Orientale being the youngest of the large impact basins, its ejecta carrying the light plain material would have overprinted the older SPA ejecta. Smaller impact craters would have churned the ejecta so that presently we observe a composite lithology with a variable abundance of pyroxene and spinel.

Investigation into microstructure and mechanical properties effects on sliding wear and cavitation erosion of Al2O3–TiO2 coatings sprayed by APS, SPS and S-HVOF

In this work, different Al2O3–TiO2 coatings, i.e., Al2O3, Al2O3-13 wt% TiO2 and Al2O3-40 wt% TiO2, produced by various thermal spray processes, namely: (i) atmospheric plasma spraying (APS), (ii) suspension plasma spraying (SPS), and (iii) suspension high-velocity oxy fuel spraying (S-HVOF), were investigated. For spray purposes, micrometer-sized powders and water-based suspensions of fine submicrometer-sized powders were used. The study aimed to investigate the influence of spray technology and spray feedstock characteristics, mainly chemical composition, i.e., TiO2 content, on the properties of the resulting coating.The sprayed coatings were characterised in terms of selected mechanical and wear properties, including fracture toughness, Vickers and instrumental hardness, Young's modulus, sliding wear resistance, and cavitation erosion resistance.The study showed that the sliding wear rate decreased with the increasing hardness, Young's modulus, and the content of the α-Al2O3 phase in the coating. The dominant wear mechanism was fatigue-induced brittle delamination, followed by the adhesive smearing of the wear debris. The dense microstructures characterised by a high hardness and an increased content of α-Al2O3 favored the resistance of coatings to cavitation erosion. Cavitation erosion was initiated at the microstructural discontinuities like pores or microcracks, resulting in damage by brittle failure with cracking and spallation, which ended up forming large cavitation craters.