Impact craters are important for understanding the evolution of lunar geologic and surface erosion rates,among other functions.However,the morphological characteristics of these micro impact craters are not obvious an...Impact craters are important for understanding the evolution of lunar geologic and surface erosion rates,among other functions.However,the morphological characteristics of these micro impact craters are not obvious and they are numerous,resulting in low detection accuracy by deep learning models.Therefore,we proposed a new multi-scale fusion crater detection algorithm(MSF-CDA)based on the YOLO11 to improve the accuracy of lunar impact crater detection,especially for small craters with a diameter of<1 km.Using the images taken by the LROC(Lunar Reconnaissance Orbiter Camera)at the Chang’e-4(CE-4)landing area,we constructed three separate datasets for craters with diameters of 0-70 m,70-140 m,and>140 m.We then trained three submodels separately with these three datasets.Additionally,we designed a slicing-amplifying-slicing strategy to enhance the ability to extract features from small craters.To handle redundant predictions,we proposed a new Non-Maximum Suppression with Area Filtering method to fuse the results in overlapping targets within the multi-scale submodels.Finally,our new MSF-CDA method achieved high detection performance,with the Precision,Recall,and F1 score having values of 0.991,0.987,and 0.989,respectively,perfectly addressing the problems induced by the lesser features and sample imbalance of small craters.Our MSF-CDA can provide strong data support for more in-depth study of the geological evolution of the lunar surface and finer geological age estimations.This strategy can also be used to detect other small objects with lesser features and sample imbalance problems.We detected approximately 500,000 impact craters in an area of approximately 214 km2 around the CE-4 landing area.By statistically analyzing the new data,we updated the distribution function of the number and diameter of impact craters.Finally,we identified the most suitable lighting conditions for detecting impact crater targets by analyzing the effect of different lighting conditions on the detection accuracy.展开更多
In the present work,a state-based peridynamics with adaptive particle refinement is proposed to simulate water ice crater formation due to impact loads.A modified Drucker-Prager constitutive model was adopted to model...In the present work,a state-based peridynamics with adaptive particle refinement is proposed to simulate water ice crater formation due to impact loads.A modified Drucker-Prager constitutive model was adopted to model ice and was implemented in the state-based peridynamic equations to analyze the elastic-plastic deformation of ice.In simulations,we use the fracture toughness failure criterion in peridynamics to simulate the quasi-brittle failure of ice.An adaptive particle refinement method in peridynamics was proposed to improve computational efficiency.The results obtained using the peridynamic model were compared with the experiments in previous literatures.It was found that the peridynamic simulation results and the experiments matched well except for some minor differences discussed,and the state-based peridynamic model has shown the specific predictive capacity to capture the detailed crater features of the ice.展开更多
On airless bodies such as the Moon and Mercury, secondary craters on the continuous secondaries facies of fresh craters mostly occur in chains and clusters. They have very irregular shapes. Secondaries on the continuo...On airless bodies such as the Moon and Mercury, secondary craters on the continuous secondaries facies of fresh craters mostly occur in chains and clusters. They have very irregular shapes. Secondaries on the continuous secondaries facies of some Martian and Mercurian craters are more isolated from each other in distribution and are more circular in shape, probably due to the effect of target properties on the impact excavation process. This paper studies secondaries on the continuous secondaries facies of all fresh lunar complex craters using recently-obtained high resolution images. After a global search, we find that 3 impact craters and basins on the Moon have circular and isolated secondaries on the continuous secondaries facies similar to those on Mercury： the Orientale basin, the Antoniadi crater, and the Compton crater. The morphological differences between such special secondaries and typical lunar secondaries are quantitatively compared and analyzed. Our preliminary analyses suggest that the special secondaries were probably caused by high temperature gradients within the local targets when these craters and basins formed. The high-temperature of the targets could have affected the impact excavation process by causing higher ejection angles, giving rise to more scattered circular secondaries.展开更多
The six largest known impact craters of the last 250 Myr(≥70 km in diameter),which are capable of causing significant environmental damage,coincide with four times of recognized extinction events at 36(with 2 craters...The six largest known impact craters of the last 250 Myr(≥70 km in diameter),which are capable of causing significant environmental damage,coincide with four times of recognized extinction events at 36(with 2 craters),66,and 145 Myr ago,and possibly with two provisional extinction events at 168 and215 Myr ago.These impact cratering events are accompanied by layers in the geologic record interpreted as impact ejecta.Chance occurrences of impacts and extinctions can be rejected at confidence levels of99.96%(for 4 impact/extinctions)to 99.99%(for 6 impact/extinctions).These results argue that several extinction events over the last 250 Myr may be related to the effects of large-body impacts.展开更多
Recent attention has been put into recurring slope lineae (RSL), after the discovery that water is present in them. It is assumed that RSL are due to flowing water. However, even though that might be the case, the gen...Recent attention has been put into recurring slope lineae (RSL), after the discovery that water is present in them. It is assumed that RSL are due to flowing water. However, even though that might be the case, the general characteristics of RSL as well as their seasonal and spatial distribution in Mars, and their occurrence within craters, suggest that RSL correspond to the weathering of frozen aquifers, which coincides with slope stability processes occurring in impact craters and scree slopes from Earth. In this study, we associated RSL with similar weathering processes occurring on impact craters and hydrogeological processes occurring on Earth (including ice, water, and wind erosion and natural aquifer recharge processes). We were able to create a conceptual model on how RSL develop, why are they found mostly in mid latitudes around craters, why are they present in more frequency in one side of crates in high latitudes, and why are there more RSL in the Martian southern hemisphere. Considering the whole hydrogeological processes occurring in craters that experience RSL, we were able to predict where large quantities of liquid water are most likely to be present in the red planet.展开更多
Chang’E-4(CE-4)successfully landed on the floor of the Von Kármán crater within the South Pole-Aitken basin(SPA).One of its scientific objectives is to determine the subsurface structure and the thickness o...Chang’E-4(CE-4)successfully landed on the floor of the Von Kármán crater within the South Pole-Aitken basin(SPA).One of its scientific objectives is to determine the subsurface structure and the thickness of lunar regolith at the landing site and along the traverse route of the Yutu-2 rover.Using orbital data,we employed small craters(diameters<1 km)on the floor of the Von Kármán crater as probes to investigate the subsurface structure and stratigraphy of the CE-4 landing site.In this study,40 dark-haloed craters that penetrate through the surface Finsen ejecta and excavate underlying mare deposits were identified,and 77 bright ray craters that expose only the underlying fresh materials but do not penetrate through the surface Finsen ejecta were found.The excavation depths of these craters and their distances from the Finsen crater center were calculated,and the thickness distribution of Finsen ejecta on the Von Kármán floor was systematically investigated.The boundary between Finsen ejecta and underlying mare basalt at the CE-4 landing site is constrained to a depth of 18 m.We have proposed the stratigraphy for the CE-4 site and interpreted the origins of different layers and the geological history of the Von Kármán crater.These results provide valuable geological background for interpreting data from the Lunar Penetrating Radar(LPR)and Visible and Near-infrared Imaging Spectrometer(VNIS)on the Yutu-2 rover.The CE-4 landing site could provide a reference point for crater ejecta distribution and mixing with local materials,to test and improve ejecta thickness models according to the in situ measurements of the CE-4 LPR.展开更多
The ever-increasing recovery rate of natural resources from terrestrial impact craters over the last fewdecades across the globe offers new avenues for further exploration of mineral and hydrocarbon resources in such ...The ever-increasing recovery rate of natural resources from terrestrial impact craters over the last fewdecades across the globe offers new avenues for further exploration of mineral and hydrocarbon resources in such settings.As of today,60 of the 208 terrestrial craters have been identified to host diverseresources such as hydrocarbons,metals and construction materials.The potential of craters as plausibleresource contributors to the energy sector is therefore,worthy of consideration,as 42(70%)of the 60craters host energy resources such as oil,gas,coal,uranium,mercury,critical and major minerals as wellas hydropower resources.Among others,19 craters are of well-developed hydrocarbon reserves.Mineraldeposits associated with craters are also classified similar to other mineral resources such as progenetic,syngenetic and epigenetic sources.Of these,the progenetic and syngenetic mineralization are confinedto the early and late excavation stage of impact crater evolution,respectively,whereas epigenetic deposits are formed during and after the modification stage of crater formation.Thus,progenetic andsyngenetic mineral deposits(like Fe,Ni,Pb,Zn and Cu)associated with craters are formed as a directresult of the impact event,whereas epigenetic deposits(e.g.hydrocarbon)are hosted by the impactstructure and result from post-impact processes.In the progenetic and syngenetic deposits,the shockwave induced fracturing and melting aid the formation of deposits,whereas in the epigenetic deposits,the highly fractured lithostratigraphic units of higher porosity and permeability,like the centralelevated area(CEA)or the rim,act as traps.In this review,we provide a holistic view of the mineral andenergy resources associated with impact craters,and use some of the remote sensing techniques toidentify the mineral deposits as supplemented by a schematic model of the types of deposits formedduring cratering process.展开更多
The newly identified Jinlin crater in southern China lies on a hillside covered by a thick granite weathering crust.It appears as a slightly elliptical bowl-shaped depression with a diameter of 820-900 m.The structure...The newly identified Jinlin crater in southern China lies on a hillside covered by a thick granite weathering crust.It appears as a slightly elliptical bowl-shaped depression with a diameter of 820-900 m.The structure is a tilted impact crater,showing a maximum rim height difference of about 200 m and an apparent depth of 90 m.The crater rim is composed mainly of granite weathered soil and a small amount of granite fragments,while the bottom of the crater is filled with the same mixture of granite weathered soil and granite fragments.Planar deformation features in quartz grains from the rock fragments of the crater provide decisive evidence for its impact origin.The impact event is inferred to have taken place during the Holocene.展开更多
The object-oriented approach is a powerful method in making classification.With the segmentation of images to objects,many features can be calculated based on the objects so that the targets can be distinguished.Howev...The object-oriented approach is a powerful method in making classification.With the segmentation of images to objects,many features can be calculated based on the objects so that the targets can be distinguished.However,this method has not been applied to lunar study.In this paper we attempt to apply this method to detecting lunar craters with promising results.Craters are the most obvious features on the moon and they are important for lunar geologic study.One of the important questions in lunar research is to estimate lunar surface ages by examination of crater density per unit area.Hence,proper detection of lunar craters is necessary.Manual crater identification is inefficient,and a more efficient and effective method is needed.This paper describes an object-oriented method to detect lunar craters using lunar reflectance images.In the method,many objects were first segmented from the image based on size,shape,color,and the weights to every layer.Then the feature of"contrast to neighbor objects"was selected to identify craters from the lunar image.In the next step,by merging the adjacent objects belonging to the same class,almost every crater can be taken as an independent object except several very big craters in the study area.To remove the crater rays diagnosed as craters,the feature of"length/width"was further used with suitable parameters to finish recognizing craters.Finally,the result was exported to ArcGIS for manual modification to those big craters and the number of craters was acquired.展开更多
The distribution characteristics of the impact craters can provide a large amount of information on impact history and the lunar evolution process. In this research, based on the digital elevation model （DEM） data o...The distribution characteristics of the impact craters can provide a large amount of information on impact history and the lunar evolution process. In this research, based on the digital elevation model （DEM） data originating from Change＇E-1 CCD stereo camera, three automatic extraction methods for the impact craters are implemented in two research areas： direct extraction from flooded DEM data （the Flooded method）, object-oriented extraction from DEM data by using ENVI ZOOM function （the Object-Oriented method） and novel object-oriented extraction from flooded DEM data （the Flooded Object-Oriented method）. Accuracy assessment, extracted degree computation, cumulative frequency analysis, shape and age analysis of the extracted craters combined display the following results. （1） The Flooded Object-Oriented method yields better accuracy than the other two methods in the two research areas; the extraction result of the Flooded method offers the similar accuracy to that of the Object-Oriented method. （2） The cumulative frequency curves for the extracted craters and the confirmed craters share a simi- lar change trajectory. （3） The number of the impact craters extracted by the three methods in the Imbrian period is the largest and is of various types; as to their age earlier than lmbrain, it is difficult to extract because they could have been destroyed.展开更多
The spatiotemporal evolution of lunar impact craters is crucial for investigating lunar interior structure,internal and external dynamic processes,and interplanetary impact history.Advances in lunar crater identificat...The spatiotemporal evolution of lunar impact craters is crucial for investigating lunar interior structure,internal and external dynamic processes,and interplanetary impact history.Advances in lunar crater identification are reviewed based on topography and gravity data,and the features and mechanisms of topographic or buried craters are analyzed regarding morphology,gravity anomalies,gravity gradients,and the underlying crust-mantle interface relief.Based on the compiled crater catalog,the early lunar impact flux and thermal evolution are further discussed according to the basin ages and their interior structures.For some ancient impact basins,the crater size-frequency distribution measurements revealed age discrepancies from previous studies,suggesting that the lunar late heavy bombardment event started at~3.95 Ga.The degraded bulge structures of the crust-mantle interface beneath mare basins reveal that these basins formed on the lunar crust surface under high-temperature conditions and underwent prolonged relaxation compared to highland basins.Finally,we reveal that the up-to-date identification of lunar buried craters remains inaccurate and incomplete,preventing us from accurately reconstructing lunar and interplanetary impact histories.Therefore,we propose that a gravity model constructed using localized orthogonal basis functions can be useful for identifying lunar craters.展开更多
There are small pit chains in the floor of lunar Copernican craters. They are usually so small in scale that there are few lunar spacecrafts to detect their detailed morphology. Combining camera data from Lunar Orbite...There are small pit chains in the floor of lunar Copernican craters. They are usually so small in scale that there are few lunar spacecrafts to detect their detailed morphology. Combining camera data from Lunar Orbiter, Lunar Reconnaissance Orbiter (LRO), Kaguya and Chang’e-1 missions, 5 representative large Copernican craters on various terrains of the lunar surface are chosen to study the origin of the pit chains in the crater floor. The morphology and distribution characteristic of the pit chains are referred by the high resolution images in this research. It is suggested that it is the magma activities from the subsurface magma layer combining with the existence of fractures and faults under the crater floor that leaded the formation of the pit chains. The model is further verified and discussed using the regolith thickness data in the crater floor. Our model suggests that the pit chains are still developing in the floor of the Copernican craters and the Moon may not be totally cold. Finally, the model limitation and potential future work are discussed based on available data.展开更多
Craters, one of the most significant features of the lunar surface, have been widely researched because they offer us the relative age of the surface unit as well as crucial geological information. Research on crater ...Craters, one of the most significant features of the lunar surface, have been widely researched because they offer us the relative age of the surface unit as well as crucial geological information. Research on crater detec- tion algorithms （CDAs） of the Moon and other planetary bodies has concentrated on detecting them from imagery data, but the computational cost of detecting large craters using images makes these CDAs impractical. This paper presents a new approach to crater detection that utilizes a digital elevation model instead of images; this enables fully automatic global detection of large craters. Craters were delineated by terrain attributes, and then thresholding maps of terrain attributes were used to transform topographic data into a binary image, finally craters were detected by using the Hough Transform from the binary image. By using the proposed algorithm, we produced a catalog of all craters ≥ 10 km in diameter on the lunar surface and analyzed their distribution and population characteristics.展开更多
Lunar impact crater detection is crucial for lunar surface studies and spacecraft landing missions,yet deep learning still struggles with accurately detecting small craters,especially when relying on incomplete catalo...Lunar impact crater detection is crucial for lunar surface studies and spacecraft landing missions,yet deep learning still struggles with accurately detecting small craters,especially when relying on incomplete catalogs.In this work,we integrate Digital Elevation Model(DEM)data to construct a high-quality dataset enriched with slope information,enabling a detailed analysis of crater features and effectively improving detection performance in complex terrains and low-contrast areas.Based on this foundation,we propose a novel two-stage detection network,MSFNet,which leverages multi-scale adaptive feature fusion and multisize ROI pooling to enhance the recognition of craters across various scales.Experimental results demonstrate that MSFNet achieves an F1 score of 74.8%on Test Region1 and a recall rate of 87%for craters with diameters larger than 2 km.Moreover,it shows exceptional performance in detecting sub-kilometer craters by successfully identifying a large number of high-confidence,previously unlabeled targets with a low false detection rate confirmed through manual review.This approach offers an efficient and reliable deep learning solution for lunar impact crater detection.展开更多
The formation process of blasting craters and blasting fragments is simulated using the continuumdiscontinuum element method(CDEM),providing a reference for blasting engineering design.The calculation model of the bla...The formation process of blasting craters and blasting fragments is simulated using the continuumdiscontinuum element method(CDEM),providing a reference for blasting engineering design.The calculation model of the blasting funnel is established,and the formation and fragmentation effect of the blasting crater under different explosive burial depths and different explosive package masses are numerically simulated.The propagation law of the explosion stress wave and the formation mechanism of the blasting crater are studied,and the relationship between the rock-crushing effect and blasting design parameters is quantitatively evaluated.Comparing the results of numerical simulation with the results of field tests and theoretical calculations indicated that the three are consistent,which proves the accuracy of numerical simulation.The results showed that the area of the blasting crater rises with the increase of explosive package mass and explosive burial depth.Taking the proportion of broken blocks with particle size ranging from 0.01 to 0.1 m as the research object,it can be found that the proportion of broken blocks with an explosive burial depth of 0.62 to 1.12 m is 0.45 to 0.18 times that with an explosive burial depth of 0.5 m.The proportion of broken blocks with an explosive radius of 4 to 12 cm is 1.14 to 3.29 times that with an explosive radius of 2 cm.The quantitative analysis of the blasting effect and blasting design parameters provides guidance for the design of blasting engineering.展开更多
Landing spacecraft experience significant impact forces during landing,resulting in large deformation and failure in the soil surface,which severely affects landing safety and stability.This paper establishes a smooth...Landing spacecraft experience significant impact forces during landing,resulting in large deformation and failure in the soil surface,which severely affects landing safety and stability.This paper establishes a smoothed particle hydrodynamics(SPH)model based on the theory of soil elastoplastic constitutive relations to describe the process of a lander’s footpad impacting lunar regolith vertically.The model can provide engineering indices such as impact load and penetration depth,and illustrate the large deformation and crater characteristics of the regolith.A detailed analysis of the response of the footpad and lunar regolith during landing reveals that the process can be broadly divided into two stages of rapid penetration and oscillatory attenuation.Furthermore,there are significant similarities in the landing process under different landing velocities and footpad masses.The research investigates the large deformation and crater characteristics of the lunar regolith bed.The results demonstrate two failure modes in the regolith.Under the impact of a footpad with a smaller mass,the final failure surface of the regolith exhibits a bowl-shaped profile with a uniformly open mouth.In contrast,under the impact of a footpad with a larger mass,the final failure surface of the regolith presents an urn-shaped profile with a large abdomen and a small opening.However,the impact craters in both scenarios show a bowl-like distribution.In cases of high-velocity impacts,the impact crater exhibits obvious blocky spalling on its sides.The SPH model developed in this study can be applied to predict the large deformation and failure response of lunar soil under the impact of rigid structures as well as the impact load and penetration depth.It effectively predicts the dynamic response of the landing process,which is expected to provide a reference for engineering design.展开更多
Planetary surfaces,shaped by billions of years of geologic evolution,display numerous impact craters whose distribution of size,density,and spatial arrangement reveals the celestial body's history.Identifying thes...Planetary surfaces,shaped by billions of years of geologic evolution,display numerous impact craters whose distribution of size,density,and spatial arrangement reveals the celestial body's history.Identifying these craters is essential for planetary science and is currently mainly achieved with deep learning-driven detection algorithms.However,because impact crater characteristics are substantially affected by the geologic environment,surface materials,and atmospheric conditions,the performance of deep learning models can be inconsistent between celestial bodies.In this paper,we first examine how the surface characteristics of the Moon,Mars,and Earth,along with the differences in their impact crater features,affect model performance.Then,we compare crater detection across celestial bodies by analyzing enhanced convolutional neural networks and U-shaped Convolutional Neural Network-based models to highlight how geology,data,and model design affect accuracy and generalization.Finally,we address current deep learning challenges,suggest directions for model improvement,such as multimodal data fusion and cross-planet learning and list available impact crater databases.This review can provide necessary technical support for deep space exploration and planetary science,as well as new ideas and directions for future research on automatic detection of impact craters on celestial body surfaces and on planetary geology.展开更多
The sediments of crater lakes are one of the ideal archives for high-resolution paleoenvironmental reconstruction.This paper presents sedimentary records of 21 crater lakes in monsoonal China and systematically discus...The sediments of crater lakes are one of the ideal archives for high-resolution paleoenvironmental reconstruction.This paper presents sedimentary records of 21 crater lakes in monsoonal China and systematically discusses the geographical distribution and formation ages of these crater lakes.Sediment provenance of the crater lakes and its influencing factors were analyzed,and paleoenvironmental sequences and human activities records on different timescales reconstructed by crater lake sediments in monsoonal China were reviewed.The following points are highlighted:(1)Crater lakes in monsoonal China have been shown to preserve continuous long-time sediments that can exceed even 400 ka,although the chronology of some sediments in the southern part is debated and there were currently fewer long time records from the northern part;(2)the sediment provenance of crater lakes in northern China(e.g.,aeolian inputs)was different from that in the south(e.g.,the volcanic-lake rim),due to the different location and deposition conditions of crater lakes;(3)crater lake sediments have been used to reconstruct the history of climate changes on different timescales,but reconstruction studies of glacial-interglacial and decadal-annual scale records and studies of spatial comparisons of records on different timescales still need to be strengthened;(4)the anthropogenic signals,which include cultivation,logging,and industrial activity,are well documented in crater lake sediments from different areas and can therefore provide key evidence for the study of the Anthropocene.展开更多
The development of guidance technology has made it possible for the earth penetration weapons(EPWs)to impact the target repeatedly at a close range. To investigative the damage of single and sequential strike induced ...The development of guidance technology has made it possible for the earth penetration weapons(EPWs)to impact the target repeatedly at a close range. To investigative the damage of single and sequential strike induced by the EPWs, experimental and numerical investigations are carried out in this paper.Firstly, a series of sequential explosion tests are conducted to provide the basic data of the crater size.Then, a numerical model is established to simulate the damage effects of sequential explosions using the meshfree method of Smoothed particle Galerkin. The effectiveness of numerical model is verified by comparison with the experimental results. Finally, based on dimensional analysis, several empirical formulas for describing the crater size are presented, including the conical crater diameter and the conical crater depth of the single explosion, the conical crater area and the joint depth of the secondary explosion. The formula for the single explosion expresses the relationship between the aspect ratio of the charge ranging from 3 to 7, the dimensionless buried depth ranging from 2 to 14 and the crater size. The formula for the secondary explosion expresses the relationship between the relative position of the two explosions and the crater size. All of data can provide reference for the design of protective structures.展开更多
Double-wall effusion cooling coupled with thermal barrier coating(TBC)is an important way of thermal protection for gas turbine vanes and blades of next-generation aero-engine,and formation of discrete crater holes by...Double-wall effusion cooling coupled with thermal barrier coating(TBC)is an important way of thermal protection for gas turbine vanes and blades of next-generation aero-engine,and formation of discrete crater holes by TBC spraying is an approved design.To protect both metal and TBC synchronously,a recommended geometry of crater is obtained through a fully automatic multi-objective optimization combined with conjugate heat transfer simulation in this work.The length and width of crater(i.e.,L/D and W/D)were applied as design variables,and the area-averaged overall effectiveness of the metal and TBC surfaces(i.e.,Φ_(av) and τ_(av))were selected as objective functions.The optimization procedure consists of automated geometry and mesh generation,conjugate heat transfer simulation validated by experimental data and Kriging surrogated model.The results showed that the Φ_(av) and τ_(av) are successfully increased respectively by 9.1%and 6.0%through optimization.Appropriate enlargement of the width and length of the crater can significantly improve the film coverage effect,since that the beneficial anti-CRVP is enhanced and the harmful CRVP is weakened.展开更多
基金the National Key Research and Development Program of China (Grant No.2022YFF0711400)the National Space Science Data Center Youth Open Project (Grant No. NSSDC2302001)
文摘Impact craters are important for understanding the evolution of lunar geologic and surface erosion rates,among other functions.However,the morphological characteristics of these micro impact craters are not obvious and they are numerous,resulting in low detection accuracy by deep learning models.Therefore,we proposed a new multi-scale fusion crater detection algorithm(MSF-CDA)based on the YOLO11 to improve the accuracy of lunar impact crater detection,especially for small craters with a diameter of<1 km.Using the images taken by the LROC(Lunar Reconnaissance Orbiter Camera)at the Chang’e-4(CE-4)landing area,we constructed three separate datasets for craters with diameters of 0-70 m,70-140 m,and>140 m.We then trained three submodels separately with these three datasets.Additionally,we designed a slicing-amplifying-slicing strategy to enhance the ability to extract features from small craters.To handle redundant predictions,we proposed a new Non-Maximum Suppression with Area Filtering method to fuse the results in overlapping targets within the multi-scale submodels.Finally,our new MSF-CDA method achieved high detection performance,with the Precision,Recall,and F1 score having values of 0.991,0.987,and 0.989,respectively,perfectly addressing the problems induced by the lesser features and sample imbalance of small craters.Our MSF-CDA can provide strong data support for more in-depth study of the geological evolution of the lunar surface and finer geological age estimations.This strategy can also be used to detect other small objects with lesser features and sample imbalance problems.We detected approximately 500,000 impact craters in an area of approximately 214 km2 around the CE-4 landing area.By statistically analyzing the new data,we updated the distribution function of the number and diameter of impact craters.Finally,we identified the most suitable lighting conditions for detecting impact crater targets by analyzing the effect of different lighting conditions on the detection accuracy.
文摘In the present work,a state-based peridynamics with adaptive particle refinement is proposed to simulate water ice crater formation due to impact loads.A modified Drucker-Prager constitutive model was adopted to model ice and was implemented in the state-based peridynamic equations to analyze the elastic-plastic deformation of ice.In simulations,we use the fracture toughness failure criterion in peridynamics to simulate the quasi-brittle failure of ice.An adaptive particle refinement method in peridynamics was proposed to improve computational efficiency.The results obtained using the peridynamic model were compared with the experiments in previous literatures.It was found that the peridynamic simulation results and the experiments matched well except for some minor differences discussed,and the state-based peridynamic model has shown the specific predictive capacity to capture the detailed crater features of the ice.
基金supported by National Natural Science Foundation of China (Nos. 41403053, J1210043)fund CUG130106 of China University of Geosciences (Wuhan)
文摘On airless bodies such as the Moon and Mercury, secondary craters on the continuous secondaries facies of fresh craters mostly occur in chains and clusters. They have very irregular shapes. Secondaries on the continuous secondaries facies of some Martian and Mercurian craters are more isolated from each other in distribution and are more circular in shape, probably due to the effect of target properties on the impact excavation process. This paper studies secondaries on the continuous secondaries facies of all fresh lunar complex craters using recently-obtained high resolution images. After a global search, we find that 3 impact craters and basins on the Moon have circular and isolated secondaries on the continuous secondaries facies similar to those on Mercury： the Orientale basin, the Antoniadi crater, and the Compton crater. The morphological differences between such special secondaries and typical lunar secondaries are quantitatively compared and analyzed. Our preliminary analyses suggest that the special secondaries were probably caused by high temperature gradients within the local targets when these craters and basins formed. The high-temperature of the targets could have affected the impact excavation process by causing higher ejection angles, giving rise to more scattered circular secondaries.
基金Support for Rampino came from an NYU Research Challenge grant
文摘The six largest known impact craters of the last 250 Myr(≥70 km in diameter),which are capable of causing significant environmental damage,coincide with four times of recognized extinction events at 36(with 2 craters),66,and 145 Myr ago,and possibly with two provisional extinction events at 168 and215 Myr ago.These impact cratering events are accompanied by layers in the geologic record interpreted as impact ejecta.Chance occurrences of impacts and extinctions can be rejected at confidence levels of99.96%(for 4 impact/extinctions)to 99.99%(for 6 impact/extinctions).These results argue that several extinction events over the last 250 Myr may be related to the effects of large-body impacts.
文摘Recent attention has been put into recurring slope lineae (RSL), after the discovery that water is present in them. It is assumed that RSL are due to flowing water. However, even though that might be the case, the general characteristics of RSL as well as their seasonal and spatial distribution in Mars, and their occurrence within craters, suggest that RSL correspond to the weathering of frozen aquifers, which coincides with slope stability processes occurring in impact craters and scree slopes from Earth. In this study, we associated RSL with similar weathering processes occurring on impact craters and hydrogeological processes occurring on Earth (including ice, water, and wind erosion and natural aquifer recharge processes). We were able to create a conceptual model on how RSL develop, why are they found mostly in mid latitudes around craters, why are they present in more frequency in one side of crates in high latitudes, and why are there more RSL in the Martian southern hemisphere. Considering the whole hydrogeological processes occurring in craters that experience RSL, we were able to predict where large quantities of liquid water are most likely to be present in the red planet.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41490633 and 41590851)the open fund of the State Key Laboratory of Lunar and Planetary Sciences (Macao University of Science and Technology) (Macao FDCT Grant No. 119/2017/A3)+6 种基金the open fund of the Key Laboratory of Lunar and Deep Space Exploration, Chinese Academy of Sciencessupported by the National Natural Science Foundation of China (U1931211, 41972322 and 11941001)the Natural Science Foundation of Shandong Province (ZR2019MD008)Qilu (Tang) Young Scholars Program of Shandong University, Weihai (2015WHWLJH14)supported by the Program for JLU Science and Technology Innovative Research Team (JLUSTIRT, 2017TD-26)the Focus on Research and Development Plan in Shandong Province (2018GGX101028)the Shandong Provincial Natural Science Foundation (ZR2019MD015)
文摘Chang’E-4(CE-4)successfully landed on the floor of the Von Kármán crater within the South Pole-Aitken basin(SPA).One of its scientific objectives is to determine the subsurface structure and the thickness of lunar regolith at the landing site and along the traverse route of the Yutu-2 rover.Using orbital data,we employed small craters(diameters<1 km)on the floor of the Von Kármán crater as probes to investigate the subsurface structure and stratigraphy of the CE-4 landing site.In this study,40 dark-haloed craters that penetrate through the surface Finsen ejecta and excavate underlying mare deposits were identified,and 77 bright ray craters that expose only the underlying fresh materials but do not penetrate through the surface Finsen ejecta were found.The excavation depths of these craters and their distances from the Finsen crater center were calculated,and the thickness distribution of Finsen ejecta on the Von Kármán floor was systematically investigated.The boundary between Finsen ejecta and underlying mare basalt at the CE-4 landing site is constrained to a depth of 18 m.We have proposed the stratigraphy for the CE-4 site and interpreted the origins of different layers and the geological history of the Von Kármán crater.These results provide valuable geological background for interpreting data from the Lunar Penetrating Radar(LPR)and Visible and Near-infrared Imaging Spectrometer(VNIS)on the Yutu-2 rover.The CE-4 landing site could provide a reference point for crater ejecta distribution and mixing with local materials,to test and improve ejecta thickness models according to the in situ measurements of the CE-4 LPR.
文摘The ever-increasing recovery rate of natural resources from terrestrial impact craters over the last fewdecades across the globe offers new avenues for further exploration of mineral and hydrocarbon resources in such settings.As of today,60 of the 208 terrestrial craters have been identified to host diverseresources such as hydrocarbons,metals and construction materials.The potential of craters as plausibleresource contributors to the energy sector is therefore,worthy of consideration,as 42(70%)of the 60craters host energy resources such as oil,gas,coal,uranium,mercury,critical and major minerals as wellas hydropower resources.Among others,19 craters are of well-developed hydrocarbon reserves.Mineraldeposits associated with craters are also classified similar to other mineral resources such as progenetic,syngenetic and epigenetic sources.Of these,the progenetic and syngenetic mineralization are confinedto the early and late excavation stage of impact crater evolution,respectively,whereas epigenetic deposits are formed during and after the modification stage of crater formation.Thus,progenetic andsyngenetic mineral deposits(like Fe,Ni,Pb,Zn and Cu)associated with craters are formed as a directresult of the impact event,whereas epigenetic deposits(e.g.hydrocarbon)are hosted by the impactstructure and result from post-impact processes.In the progenetic and syngenetic deposits,the shockwave induced fracturing and melting aid the formation of deposits,whereas in the epigenetic deposits,the highly fractured lithostratigraphic units of higher porosity and permeability,like the centralelevated area(CEA)or the rim,act as traps.In this review,we provide a holistic view of the mineral andenergy resources associated with impact craters,and use some of the remote sensing techniques toidentify the mineral deposits as supplemented by a schematic model of the types of deposits formedduring cratering process.
基金financial support from Shanghai Key Laboratory Novel Extreme Condition Materials,China(Grant No.22dz2260800)the Shanghai Science and Technology Committee,China(Grant No.22JC1410300).
文摘The newly identified Jinlin crater in southern China lies on a hillside covered by a thick granite weathering crust.It appears as a slightly elliptical bowl-shaped depression with a diameter of 820-900 m.The structure is a tilted impact crater,showing a maximum rim height difference of about 200 m and an apparent depth of 90 m.The crater rim is composed mainly of granite weathered soil and a small amount of granite fragments,while the bottom of the crater is filled with the same mixture of granite weathered soil and granite fragments.Planar deformation features in quartz grains from the rock fragments of the crater provide decisive evidence for its impact origin.The impact event is inferred to have taken place during the Holocene.
基金National Natural Science Foundation of China(Grant No.40573047)National High-Tech Research&Development Program of China(Grant No.2008AA12A212)
文摘The object-oriented approach is a powerful method in making classification.With the segmentation of images to objects,many features can be calculated based on the objects so that the targets can be distinguished.However,this method has not been applied to lunar study.In this paper we attempt to apply this method to detecting lunar craters with promising results.Craters are the most obvious features on the moon and they are important for lunar geologic study.One of the important questions in lunar research is to estimate lunar surface ages by examination of crater density per unit area.Hence,proper detection of lunar craters is necessary.Manual crater identification is inefficient,and a more efficient and effective method is needed.This paper describes an object-oriented method to detect lunar craters using lunar reflectance images.In the method,many objects were first segmented from the image based on size,shape,color,and the weights to every layer.Then the feature of"contrast to neighbor objects"was selected to identify craters from the lunar image.In the next step,by merging the adjacent objects belonging to the same class,almost every crater can be taken as an independent object except several very big craters in the study area.To remove the crater rays diagnosed as craters,the feature of"length/width"was further used with suitable parameters to finish recognizing craters.Finally,the result was exported to ArcGIS for manual modification to those big craters and the number of craters was acquired.
基金supported by the National Natural Science Foundation of China (Grant Nos. 40871177 and 41171332)the Knowledge Innovation Project of the Institute of Geographic and Natural Resources Research, the Chinese Academy of Sci-ences (Grant No. 201001005)
文摘The distribution characteristics of the impact craters can provide a large amount of information on impact history and the lunar evolution process. In this research, based on the digital elevation model （DEM） data originating from Change＇E-1 CCD stereo camera, three automatic extraction methods for the impact craters are implemented in two research areas： direct extraction from flooded DEM data （the Flooded method）, object-oriented extraction from DEM data by using ENVI ZOOM function （the Object-Oriented method） and novel object-oriented extraction from flooded DEM data （the Flooded Object-Oriented method）. Accuracy assessment, extracted degree computation, cumulative frequency analysis, shape and age analysis of the extracted craters combined display the following results. （1） The Flooded Object-Oriented method yields better accuracy than the other two methods in the two research areas; the extraction result of the Flooded method offers the similar accuracy to that of the Object-Oriented method. （2） The cumulative frequency curves for the extracted craters and the confirmed craters share a simi- lar change trajectory. （3） The number of the impact craters extracted by the three methods in the Imbrian period is the largest and is of various types; as to their age earlier than lmbrain, it is difficult to extract because they could have been destroyed.
基金supported by the Institute of Geology and Geophysics,Chinese Academy of Sciences(Grant Nos.IGGCAS202102,IGGCAS-201904)the National Natural Science Foundation of China(Grant Nos.42288201,41704080,42274114)the National Key Research and Development Program of China(Grant No.2022YFF0503200)。
文摘The spatiotemporal evolution of lunar impact craters is crucial for investigating lunar interior structure,internal and external dynamic processes,and interplanetary impact history.Advances in lunar crater identification are reviewed based on topography and gravity data,and the features and mechanisms of topographic or buried craters are analyzed regarding morphology,gravity anomalies,gravity gradients,and the underlying crust-mantle interface relief.Based on the compiled crater catalog,the early lunar impact flux and thermal evolution are further discussed according to the basin ages and their interior structures.For some ancient impact basins,the crater size-frequency distribution measurements revealed age discrepancies from previous studies,suggesting that the lunar late heavy bombardment event started at~3.95 Ga.The degraded bulge structures of the crust-mantle interface beneath mare basins reveal that these basins formed on the lunar crust surface under high-temperature conditions and underwent prolonged relaxation compared to highland basins.Finally,we reveal that the up-to-date identification of lunar buried craters remains inaccurate and incomplete,preventing us from accurately reconstructing lunar and interplanetary impact histories.Therefore,we propose that a gravity model constructed using localized orthogonal basis functions can be useful for identifying lunar craters.
文摘There are small pit chains in the floor of lunar Copernican craters. They are usually so small in scale that there are few lunar spacecrafts to detect their detailed morphology. Combining camera data from Lunar Orbiter, Lunar Reconnaissance Orbiter (LRO), Kaguya and Chang’e-1 missions, 5 representative large Copernican craters on various terrains of the lunar surface are chosen to study the origin of the pit chains in the crater floor. The morphology and distribution characteristic of the pit chains are referred by the high resolution images in this research. It is suggested that it is the magma activities from the subsurface magma layer combining with the existence of fractures and faults under the crater floor that leaded the formation of the pit chains. The model is further verified and discussed using the regolith thickness data in the crater floor. Our model suggests that the pit chains are still developing in the floor of the Copernican craters and the Moon may not be totally cold. Finally, the model limitation and potential future work are discussed based on available data.
文摘Craters, one of the most significant features of the lunar surface, have been widely researched because they offer us the relative age of the surface unit as well as crucial geological information. Research on crater detec- tion algorithms （CDAs） of the Moon and other planetary bodies has concentrated on detecting them from imagery data, but the computational cost of detecting large craters using images makes these CDAs impractical. This paper presents a new approach to crater detection that utilizes a digital elevation model instead of images; this enables fully automatic global detection of large craters. Craters were delineated by terrain attributes, and then thresholding maps of terrain attributes were used to transform topographic data into a binary image, finally craters were detected by using the Hough Transform from the binary image. By using the proposed algorithm, we produced a catalog of all craters ≥ 10 km in diameter on the lunar surface and analyzed their distribution and population characteristics.
基金National Natural Science Foundation of China(12103020,12363009)Natural Science Foundation of Jiangxi Province(20224BAB211011)+1 种基金Open Project Program of State Key Laboratory of Lunar and Planetary Sciences(Macao University of Science and Technology)(Macao FDCT grant No.002/2024/SKL)Youth Talent Project of Science and Technology Plan of Ganzhou(2022CXRC9191,2023CYZ26970)。
文摘Lunar impact crater detection is crucial for lunar surface studies and spacecraft landing missions,yet deep learning still struggles with accurately detecting small craters,especially when relying on incomplete catalogs.In this work,we integrate Digital Elevation Model(DEM)data to construct a high-quality dataset enriched with slope information,enabling a detailed analysis of crater features and effectively improving detection performance in complex terrains and low-contrast areas.Based on this foundation,we propose a novel two-stage detection network,MSFNet,which leverages multi-scale adaptive feature fusion and multisize ROI pooling to enhance the recognition of craters across various scales.Experimental results demonstrate that MSFNet achieves an F1 score of 74.8%on Test Region1 and a recall rate of 87%for craters with diameters larger than 2 km.Moreover,it shows exceptional performance in detecting sub-kilometer craters by successfully identifying a large number of high-confidence,previously unlabeled targets with a low false detection rate confirmed through manual review.This approach offers an efficient and reliable deep learning solution for lunar impact crater detection.
基金funded by the National Natural Science Foundation of China(Program Nos.52379128,52209162)Natural Science Foundation of Hubei Province of China(Program Nos.2023AFA048,2023AFB657)+3 种基金Hubei Provincial Key Laboratory of Construction and Management in Hydropower Engineering(Program Nos.2023KSD03,2023KSD04)Natural Science Research of Jiangsu Higher Education Institutions of China(Program No.21KJB580001)Educational Commission of Hubei Province of China(Program No.T2020005)the Young Top-Notch Talent Cultivation Program of Hubei Province.
文摘The formation process of blasting craters and blasting fragments is simulated using the continuumdiscontinuum element method(CDEM),providing a reference for blasting engineering design.The calculation model of the blasting funnel is established,and the formation and fragmentation effect of the blasting crater under different explosive burial depths and different explosive package masses are numerically simulated.The propagation law of the explosion stress wave and the formation mechanism of the blasting crater are studied,and the relationship between the rock-crushing effect and blasting design parameters is quantitatively evaluated.Comparing the results of numerical simulation with the results of field tests and theoretical calculations indicated that the three are consistent,which proves the accuracy of numerical simulation.The results showed that the area of the blasting crater rises with the increase of explosive package mass and explosive burial depth.Taking the proportion of broken blocks with particle size ranging from 0.01 to 0.1 m as the research object,it can be found that the proportion of broken blocks with an explosive burial depth of 0.62 to 1.12 m is 0.45 to 0.18 times that with an explosive burial depth of 0.5 m.The proportion of broken blocks with an explosive radius of 4 to 12 cm is 1.14 to 3.29 times that with an explosive radius of 2 cm.The quantitative analysis of the blasting effect and blasting design parameters provides guidance for the design of blasting engineering.
基金funded by the National Natural Science Foundation of China(Nos.12172057 and 12032005).
文摘Landing spacecraft experience significant impact forces during landing,resulting in large deformation and failure in the soil surface,which severely affects landing safety and stability.This paper establishes a smoothed particle hydrodynamics(SPH)model based on the theory of soil elastoplastic constitutive relations to describe the process of a lander’s footpad impacting lunar regolith vertically.The model can provide engineering indices such as impact load and penetration depth,and illustrate the large deformation and crater characteristics of the regolith.A detailed analysis of the response of the footpad and lunar regolith during landing reveals that the process can be broadly divided into two stages of rapid penetration and oscillatory attenuation.Furthermore,there are significant similarities in the landing process under different landing velocities and footpad masses.The research investigates the large deformation and crater characteristics of the lunar regolith bed.The results demonstrate two failure modes in the regolith.Under the impact of a footpad with a smaller mass,the final failure surface of the regolith exhibits a bowl-shaped profile with a uniformly open mouth.In contrast,under the impact of a footpad with a larger mass,the final failure surface of the regolith presents an urn-shaped profile with a large abdomen and a small opening.However,the impact craters in both scenarios show a bowl-like distribution.In cases of high-velocity impacts,the impact crater exhibits obvious blocky spalling on its sides.The SPH model developed in this study can be applied to predict the large deformation and failure response of lunar soil under the impact of rigid structures as well as the impact load and penetration depth.It effectively predicts the dynamic response of the landing process,which is expected to provide a reference for engineering design.
基金funded by the National Natural Science Foundation of China(12363009 and 12103020)Natural Science Foundation of Jiangxi Province(20224BAB211011)+1 种基金Youth Talent Project of Science and Technology Plan of Ganzhou(2022CXRC9191 and 2023CYZ26970)Jiangxi Province Graduate Innovation Special Funds Project(YC2024-S529 and YC2023-S672).
文摘Planetary surfaces,shaped by billions of years of geologic evolution,display numerous impact craters whose distribution of size,density,and spatial arrangement reveals the celestial body's history.Identifying these craters is essential for planetary science and is currently mainly achieved with deep learning-driven detection algorithms.However,because impact crater characteristics are substantially affected by the geologic environment,surface materials,and atmospheric conditions,the performance of deep learning models can be inconsistent between celestial bodies.In this paper,we first examine how the surface characteristics of the Moon,Mars,and Earth,along with the differences in their impact crater features,affect model performance.Then,we compare crater detection across celestial bodies by analyzing enhanced convolutional neural networks and U-shaped Convolutional Neural Network-based models to highlight how geology,data,and model design affect accuracy and generalization.Finally,we address current deep learning challenges,suggest directions for model improvement,such as multimodal data fusion and cross-planet learning and list available impact crater databases.This review can provide necessary technical support for deep space exploration and planetary science,as well as new ideas and directions for future research on automatic detection of impact craters on celestial body surfaces and on planetary geology.
基金supported by the National Natural Science Foundation of China(Nos.41888101,41721002)the National Key Research and Development Program of China(No.2022YFF0801101)+2 种基金the Fundamental Research Funds for the Central Universities,the China Postdoctoral Science Foundation(No.2022M713024)the CAS Youth Interdisciplinary Team(No.JCTD-2021-05)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.2018498).
文摘The sediments of crater lakes are one of the ideal archives for high-resolution paleoenvironmental reconstruction.This paper presents sedimentary records of 21 crater lakes in monsoonal China and systematically discusses the geographical distribution and formation ages of these crater lakes.Sediment provenance of the crater lakes and its influencing factors were analyzed,and paleoenvironmental sequences and human activities records on different timescales reconstructed by crater lake sediments in monsoonal China were reviewed.The following points are highlighted:(1)Crater lakes in monsoonal China have been shown to preserve continuous long-time sediments that can exceed even 400 ka,although the chronology of some sediments in the southern part is debated and there were currently fewer long time records from the northern part;(2)the sediment provenance of crater lakes in northern China(e.g.,aeolian inputs)was different from that in the south(e.g.,the volcanic-lake rim),due to the different location and deposition conditions of crater lakes;(3)crater lake sediments have been used to reconstruct the history of climate changes on different timescales,but reconstruction studies of glacial-interglacial and decadal-annual scale records and studies of spatial comparisons of records on different timescales still need to be strengthened;(4)the anthropogenic signals,which include cultivation,logging,and industrial activity,are well documented in crater lake sediments from different areas and can therefore provide key evidence for the study of the Anthropocene.
文摘The development of guidance technology has made it possible for the earth penetration weapons(EPWs)to impact the target repeatedly at a close range. To investigative the damage of single and sequential strike induced by the EPWs, experimental and numerical investigations are carried out in this paper.Firstly, a series of sequential explosion tests are conducted to provide the basic data of the crater size.Then, a numerical model is established to simulate the damage effects of sequential explosions using the meshfree method of Smoothed particle Galerkin. The effectiveness of numerical model is verified by comparison with the experimental results. Finally, based on dimensional analysis, several empirical formulas for describing the crater size are presented, including the conical crater diameter and the conical crater depth of the single explosion, the conical crater area and the joint depth of the secondary explosion. The formula for the single explosion expresses the relationship between the aspect ratio of the charge ranging from 3 to 7, the dimensionless buried depth ranging from 2 to 14 and the crater size. The formula for the secondary explosion expresses the relationship between the relative position of the two explosions and the crater size. All of data can provide reference for the design of protective structures.
基金Anhui Provincial Natural Science Foundation of China(2108085ME176)the Natural Science Foundation of China(52276043)。
文摘Double-wall effusion cooling coupled with thermal barrier coating(TBC)is an important way of thermal protection for gas turbine vanes and blades of next-generation aero-engine,and formation of discrete crater holes by TBC spraying is an approved design.To protect both metal and TBC synchronously,a recommended geometry of crater is obtained through a fully automatic multi-objective optimization combined with conjugate heat transfer simulation in this work.The length and width of crater(i.e.,L/D and W/D)were applied as design variables,and the area-averaged overall effectiveness of the metal and TBC surfaces(i.e.,Φ_(av) and τ_(av))were selected as objective functions.The optimization procedure consists of automated geometry and mesh generation,conjugate heat transfer simulation validated by experimental data and Kriging surrogated model.The results showed that the Φ_(av) and τ_(av) are successfully increased respectively by 9.1%and 6.0%through optimization.Appropriate enlargement of the width and length of the crater can significantly improve the film coverage effect,since that the beneficial anti-CRVP is enhanced and the harmful CRVP is weakened.
