Lunar Craters Research Articles

Identification of Lunar Craters in the Chang’e-5 Landing Region Based on Kaguya TC Morning Map

Impact craters are extensively researched geological features that contribute to various aspects of lunar science, such as evaluating the model age, regolith thickness, etc. The method for identifying impact craters has gradually transitioned from manual counting to automated identification. Automatic crater detection based on the digital elevation model (DEM) is commonly used to detect larger craters. However, using only DEM has limitations in discerning smaller craters (diameter < ~1 km). This study utilizes an improved Faster R-CNN algorithm and the Kaguya Terrain Camera (TC) morning map to detect small impact craters in the Chang’e-5 (CE-5) landing site. It uses model fusion to improve the precision of small crater identification. The results show a recall rate of 96.33% and a precision value of 90.19% for craters with diameters exceeding 200 m. The model found a total of 187,101 impact craters in the CE-5 region. The spatial distribution density of impact craters with diameters ranging from 100 m to 200 m is approximately 2.5706/km2. For craters with diameters ranging from 200 m to 1 km, the average spatial distribution density is about 0.9016/km2. By the unbiased impact crater density of chronological analysis, the model age of the Im2 and Em4 geological units in the CE-5 region is 3.78 Ga and 2.07 Ga, respectively.

Lunar polar volatile remobilization in regolith-filled craters

Under lunar polar cold traps, volatile molecules within porous regolith may experience temperature and depth dependent slow mobility. Many degraded lunar craters exhibit thick regolith fill based on models of topographic diffusion and observations of fresh and degraded craters. Regolith has a low thermal conductivity relative to megaregolith and may act as a blanket for internal lunar heat flow, leading to increased temperatures at depth. We develop 2D thermal models of fresh and regolith-filled lunar craters over depths of meters to hundreds of meters below the surface. We find that the base of the stability and slow mobility zones migrate upward with regolith fill, which leads to temperatures that may increase the sublimation rate of volatiles at depth. For a notional cold trap crater 1.6 km in diameter and 3.6 billion years old, topographic diffusion fills it with approximately 90 m of regolith, and the regolith fill's blanketing effect causes the 110 K isotherm to shift about 180 m upward. This places it approximately 25 m below the current cold trap surface and well above the initial crater floor. The slow water ice mobility zone below the 110 K isotherms also shifts upward with regolith fill, potentially increasing volatile concentrations at shallower depths. These secondary volatile concentrations may be targets for sampling and testing hypotheses of volatile system processes. In addition, remobilized volatile concentrations may be a resource for future In-Situ Resource Utilization (ISRU) applications. The thick regolith fill in degraded craters and volatile remobilization potential in lunar subsurface cold traps have implications for future exploration instruments, sampling, and ISRU architectures.

Recalibration of the lunar chronology due to spatial cratering-rate variability

Cratering chronologies are used to derive the history of planetary bodies and assume an isotropic flux of impactors over the entire surface of the Moon. The impactor population is largely dominated by near-Earth-objects (NEOs) since ∼3.5 billion years ago. However, lunar impact probabilities from the currently known NEO population show an excess of impacts close to the poles compared to the equator as well as a latitudinal dependency of the approach angle of impactors. This is accompanied by a variation of the impact flux and speed with the distance from the apex due to the synchronicity of the lunar orbit around the Earth. Here, we compute the spatial dependency of the cratering rate produced by such variabilities and recalibrate the lunar chronology. We show that it allows to reconcile the crater density measured at mid-latitudes around the Chang'e-5 landing site with the age of the samples collected by this mission. Our updated chronology leads to differences in model ages of up to 30% compared to other chronology systems. The modeled cratering rate variability is then compared with the distribution of lunar craters younger than ∼1 Ma, 1 Ga and 4 Ga. The general trend of the cratering distribution is consistent with the one obtained from dynamical models of NEOs, thus potentially reflecting a nonuniform distribution of orbital parameters of ancient impactor populations, beyond 3.5 Ga ago, i.e., planetary leftovers and cometary bodies. If the nonuniformity of the cratering rate could be tested elsewhere in the Solar System, the recalibrated lunar chronology, corrected from spatial variations of the impact flux and approach conditions of impactors, could be extrapolated on other terrestrial bodies such as Mercury and Mars, at least over the last 3.5 billion years. The modeled cratering rate presented here has strong implications for interpreting results of the Artemis program, aiming to explore the South Pole of our satellite, in particular when it will come to link the radiometric age of the samples collected in this region and the crater density of the sampled units.

Multi-scale Based Approach for Crater Detection on Lunar Surface using Clustering algorithm

This paper introduced automated detection and analysis of lunar craters are crucial for advancing lunar research and facilitating mission planning. This study introduces a comprehensive multi-scale approach for crater detection on the lunar surface using LROC (Lunar Reconnaissance Orbiter Camera) Dataset, enabling the identification of craters across varying scales and enhancing overall detection accuracy and efficiency. The process involves preprocessing lunar imagery to enhance features and delineate potential crater regions, utilizing edge detection algorithms to extract crater boundaries. Clustering techniques are then applied to group similar edge points and isolate potential crater candidates. A thresholding mechanism based on statistical edge intensity analysis refines the detection process. To address multiple detections of the same crater at slightly different diameters, radius criteria are implemented, yielding high diameter accuracy of 84% for mare Imbrium (test site 1) and 80% for mare Nubium (test site 2). Subsequently, a depth-diameter analysis validates crater-like characteristics by combining depth measurements with crater diameter estimation, showcasing the authenticity of potential craters. we compare our diameter and depth with different reference papers and we get high accuracy of R2 =0.99 then other methods. The results highlight the potential of this multi-scale approach for automated lunar crater detection, providing deeper insights into the Moon's surface morphology and history for future lunar exploration missions.

Microwave Thermal Emissions Features of Lunar Floor-Fractured Craters

Microwave Thermal Emissions Features of Lunar Floor-Fractured Craters

An automatic anchor-free convolutional neural network method for recognizing small-scale lunar impact craters

An automatic anchor-free convolutional neural network method for recognizing small-scale lunar impact craters

Depth-to-diameter Ratios of Fresh Craters on the Moon and Implications for Surface Age Estimates

The depth-to-diameter (d/D) ratios of small lunar craters (D < 400 m) can be used to determine important properties of the upper regolith, specifically material strength or thickness. The d/D is also an important component of topographic diffusion models that describe how different erosive processes influence and change the topography of a surface over time, and these models have been applied to estimate surface ages. These models must make assumptions regarding rates of erosion and the initial d/D of a crater. Previous works investigating d/D of small craters, which use various methodologies to calculate depth, typically assume that a fresh appearing crater is a young crater. Work presented here provides d/D measurements of known—rather than assumed—young, meter-scale craters to provide better constraints on small crater depths and to help further our understanding of lunar surface ages and upper regolith properties. Given the interest in impact crater modification at small, human scales on the Moon and the wide range of assumptions built into topographic diffusion models and their predictions, understanding whether the results for initial d/D from past work hold up under different analyses is critical. We observed no distinct trends in d/D for small, young craters and report a wide range of d/D from 0.08 to 0.215, in contrast with past work that derived different averages based on crater size. The variation in d/D may correspond to heterogeneous regolith properties or be a result of a data source artifact.

Small lunar crater identification and age estimation in Chang'e-5 landing area based on improved Faster R-CNN

The Chang'e-5 (CE-5) mission marks China's first lunar sample return endeavor, with its landing site (43.06°N, 51.92°W) situated in the Mons Rümker region of the northern Oceanus Procellarum on the Moon. This region hosts some of the youngest mare basalts of the Moon and contains a relatively youthful geologic unit characterized by crater's equilibrium diameters slightly over 100 m. By refining the Faster Region-based Convolutional Neural Network (Faster R-CNN) algorithm and leveraging high-resolution imagery to create training samples, accurate identification of lunar craters can be achieved. In this study, we enhance the algorithm in aspects such as anchor boxes and Region of Interest alignment. Additionally, we have utilized high-resolution images for training, and identify and statistics craters within the CE-5 landing area. Ultimately, our model attains a validation set Recall of 90%, Precision of 69%, and an Average Precision score of 0.83. Notably, in certain scales, such as for the crater larger than 400 m, recognition results reach Precision of 88% and Recall of 89%. The findings of this study are mapped into a crater catalog. Furthermore, we predict crater density and integrate it with geochronological functions to estimate the absolute model age of nine major geologic units within the CE-5 landing area. The results are generally in agreement with those of other studies who have used manual methods for crater counting, and verify the correctness of our automatic crater identification results.

Lunar Impact Craters: New Perspectives From Full‐Polarimetric Analysis of Chandrayaan‐2 Dual‐Frequency SAR Data

AbstractWith the availability of the full‐polarimetry data from Chandrayaan‐2 Dual‐frequency Synthetic Aperture Radar (DFSAR) for the first time, the lunar impact craters are studied for comprehensive characterization, which was earlier limited due to hybrid‐polarimetry based observations. In conjunction with the conventional Circular Polarization Ratio (CPR), we explore the unique full‐polarimetric parameters such as Single‐bounce Eigenvalue Relative Difference and T‐Ratio which are sensitive to surface roughness and dielectric constant, respectively. We studied the polarimetric behavior of a total of 115 nos. of impact craters within a specific size range (∼1–25 km diameter) belonging to different categories viz. fresh, degraded, polar and non‐polar anomalous craters. Our results confirm that both kinds of non‐polar and polar anomalous craters overall hold centimeter‐decimeter scale surface roughness similar to the exterior of the fresh craters, which mainly leads to the anomalous nature of the craters. Our analysis indicates possible control of the crater degradation process on the change in the radar scattering behavior of the studied lunar craters. The crater degradation causes a reduction in the surface roughness and dielectric property (density) of the scatterers present in various craters leading to a change in the radar scattering behavior. Alongside, water ice, if at all present admixed into the regolith in the polar anomalous craters, is not in the form of dominant scatterers that can influence the radar signature. However, the occurrence of relatively higher CPR values in smooth low dielectric crater interiors supports the possibility of the presence of water ice in some of the studied polar anomalous craters belonging to Pre‐Imbrian to Imbrian lunar geological periods.

Imaging Lunar Craters with the Lucy Long Range Reconnaissance Imager (L’LORRI): A Resolution Test for NASA's Lucy Mission

NASA's Lucy mission is designed to better understand the unique population of Trojan asteroids. Trojans were probably captured in Jupiter's L4 and L5 points early in the solar system's evolution and little altered since then. A critical investigation of Lucy is to use its highest-resolution camera, the Lucy Long Range Reconnaissance Imager (L’LORRI), to image Trojans’ surfaces to understand their geology and impact crater populations. Through crater statistics, the population of smaller bodies that produced those impacts, relative age differences across the bodies, and other comparative investigations between bodies can be studied. Mapping the crater population to the minimum diameters needed to achieve Lucy's objectives might require image subsampling and deconvolution (“processing”) to improve the spatial resolution, a process whereby multiple, slightly offset images are merged to create a single, better-sampled image and deconvolved with L’LORRI's point-spread function. Lucy's first Earth Gravity Assist (EGA1) provided an opportunity to test this process's accuracy using L’LORRI images of the Moon, whose crater population is well characterized and therefore provides ground-truth testing. Specifically, the lunar crater imaging by L’LORRI during EGA1 allowed us to compare crater statistics derived from raw and processed L’LORRI images with ground-truth statistics derived from higher-resolution lunar imaging from other missions. The results indicate the processing can improve impact crater statistics such that features can be identified and measured to ≈70% the diameter that they can otherwise be reliably mapped on native L’LORRI images. This test's results will be used in the observation designs for the Lucy flyby targets.

Artificial intelligence in remote sensing geomorphology—a critical study

Planetary geomorphological maps over a wide range of spatial and temporal scales provide important information on landforms and their evolution. The process of producing a geomorphological map is extremely time-consuming and maps are often difficult to reproduce. The success of deep learning and machine learning promises to drastically reduce the cost of producing these maps and also to increase their reproducibility. However, deep learning methods strongly rely on having sufficient ground truth data to recognize the wanted surface features. In this study, we investigate the results from an artificial intelligence (AI)–based workflow to recognize lunar boulders on images taken from a lunar orbiter to produce a global lunar map showing all boulders that have left a track in the lunar regolith. We compare the findings from the AI study with the results found by a human analyst (HA) who was handed an identical database of images to identify boulders with tracks on the images. The comparison involved 181 lunar craters from all over the lunar surface. Our results show that the AI workflow used grossly underestimates the number of identified boulders on the images that were used. The AI approach found less than one fifth of all boulders identified by the HA. The purpose of this work is not to quantify the absolute sensitivities of the two approaches but to identify the cause and origin for the differences that the two approaches deliver and make recommendations as to how the machine learning approach under the given constraints can be improved. Our research makes the case that despite the increasing ease with which deep learning methods can be applied to existing data sets, a more thorough and critical assessment of the AI results is required to ensure that future network architectures can produce the reliable geomorphological maps that these methods are capable of delivering.

YOLO-Crater Model for Small Crater Detection

Craters are the most prominent geomorphological features on the surface of celestial bodies, which plays a crucial role in studying the formation and evolution of celestial bodies as well as in landing and planning for surface exploration. Currently, the main automatic crater detection models and datasets focus on the detection of large and medium craters. In this paper, we created 23 small lunar crater datasets for model training based on the Chang’E-2 (CE-2) DOM, DEM, Slope, and integrated data with 7 kinds of visualization stretching methods. Then, we proposed the YOLO-Crater model for Lunar and Martian small crater detection by replacing EioU and VariFocal loss to solve the crater sample imbalance problem and introducing a CBAM attention mechanism to mitigate interference from the complex extraterrestrial environment. The results show that the accuracy (P = 87.86%, R = 66.04%, and F1 = 75.41%) of the Lunar YOLO-Crater model based on the DOM-MMS (Maximum-Minimum Stretching) dataset is the highest and better than that of the YOLOX model. The Martian YOLO-Crater, trained by the Martian dataset from the 2022 GeoAI Martian Challenge, achieves good performance with P = 88.37%, R = 69.25%, and F1 = 77.65%. It indicates that the YOLO-Crater model has strong transferability and generalization capability, which can be applied to detect small craters on the Moon and other celestial bodies.

Slopes of Lunar Crater Size‐Frequency Distributions at Copernican‐Aged Craters

AbstractCraters on the lunar surface can provide valuable information about the timing and sequence of surface‐forming processes on the Moon. A commonly used method for age determination is the analysis of the crater size‐frequency distribution (CSFD) to which a production function (PF) is fitted that represents the size‐frequency distribution of the impactors. However, the commonly used PF of Neukum (1983) is valid for crater diameters between 10 m and 300 km. Neukum et al. (2001, https://doi.org/10.1007/978-94-017-1035-0_3) revised the PF for crater diameters of 100 m–200 km. However, it is suggested to also be valid for the diameter range of 10 m–300 km as well. To assess whether we can extend a PF to craters ≤10 m in diameter, we investigated the slopes of the CSFDs of small craters formed on ejecta of young Copernican‐aged craters Giordano Bruno, Moore F, North Ray, and South Ray. A PF for smaller diameters would allow dating of young geological units, which are typically small, and would reduce the statistical error in age determinations, since smaller craters are more abundant. However, small craters are strongly influenced by geological factors, such as target properties, crater degradation, and secondary craters. For craters between 10 and 20 m we obtain a steeper CSFD slope than Neukum's proposed −3 slope (cumulative), whereas for craters ≤10 m the slope is about −3. We conclude that the PF of Neukum (1983) provides a reasonable CSFD slope for smaller craters, although it was not developed for this crater diameter range.

Automated precision counting of small lunar craters - A broader view

An automated system for counting small craters at lunar landing sites has been expanded to include selected locations on the Moon's far side and high latitudes. Highland areas were generally excluded from this new survey, because sloping terrain can have a significant effect on crater lifetimes. But some locations on highland light plains units were analysed, as were some young Copernican age crater ejecta blankets and impact melts.This study focuses on craters having diameters between 2.5 m and 50 m, for which counts are so high that they are best plotted as Crater Size Frequency Histograms (CSFHs), rather than the conventional cumulative plots (CSFDs). This histogram representation enables the finest details of the plots to be compared across sites. Using multiple precisely aligned images of each site enables false negatives to be included and false positives rejected, ensuring that no visually recognisable craters are missed, a capability that is not possible when analysing single images.There are some very distinct differences between the curves at different sites. Based on the known ages of boulder tracks and counts of craters formed over the last 50 years, the largest craters within the size range up to 50 m are thought to be no more that a few hundred million years old. A model for the evolution of small crater populations on an absolute time scale is presented and the absolute ages of young features are estimated.There is no evidence in the data for secondary cratering, nor is there any clear variation of counts and slopes with longitude or latitude, so other possible explanations for the variabilities between sites must be found.The results obtained by this project should prove useful for modelling crater formation and destruction and also as training data for machine learning systems.

Émile Belot’s Models, or an Engineer’s Quest for Scientific Legitimacy

Abstract Between 1905 and 1937, Émile Belot, an engineer and then director of a public tobacco factory, threw himself into scientific research seeking to reconstruct the history of the formation of the solar system. This article goes over and analyses the experimental practices Belot drew on in support of his theory, looking at the equipment he manufactured and operated in his “experimental cosmogony laboratory.” Together with a few other French engineers, Belot persistently sought to prove his legitimacy to address astronomical and geological issues. His machines reproducing the formation of spiral nebulae, volcanoes, or lunar craters acted both as material resources for deciding between rival scientific hypotheses, and as tools which, by analogy, materialised the mechanical nature of the cosmos Belot hoped to study without being confined to the scientific margins.

Three-Dimensional Reconstruction and Geometric Morphology Analysis of Lunar Small Craters within the Patrol Range of the Yutu-2 Rover

Craters on the lunar surface are the most direct method for the study of geological processes and are of great significance to the study of lunar evolution. In order to fill the research gap on small craters (diameter less than 3 m), we focus on the small craters around the moving path of the Yutu-2 lunar rover and carry out a 3D reconstruction and geometrical morphology analysis on them. First, a self-calibration model with multiple feature constraints is used to calibrate the navigation camera and obtain the internal and external parameters. Then, the sequence images with overlapping regions from neighboring stations are used to obtain the precise position of the rover through the bundle adjustment (BA) method. After that, a cross-scale cost aggregation for a stereo matching network is proposed to obtain a parallax map, which can further obtain 3D point clouds of the lunar surface. Finally, the indexes of the craters are extracted (diameter D, depth d, and depth–diameter ratio dr), and the different indicators are fitted and analyzed. The results suggest that CscaNet has an anomaly percentage value of 1.73% in the KITTI2015 dataset, and an EPE of 0.74 px in the SceneFlow dataset, both of which are superior to GC-Net, DispNet, and PSMnet, and have higher reconstruction accuracy. The correlation between D and d is high and exhibits a positive correlation, while the correlation between D and dr is low. The geometric morphology expressions of small craters fitted by using D and d are significantly different from the expressions proposed by other scholars for large craters. This study provides a priori knowledge for the subsequent Von Karmen crater survey mission in the SPA Basin.

Lunar crater names. The invisible face of epistemic violence shining upon us every night

&#x0D; &#x0D; &#x0D; &#x0D; Lunar craters are the only and most significant surface features of a planetary body in Outer Space that are visible to the naked eye. While we can only look at the surface of other planets and their moons through probes, robots and telescopes, the moon requires no instruments or technological tools to be seen. Despite this significant difference – that the Moon’s surface features are visible to any human on a clear night, the history and current process of naming Lunar craters does not recognize that dif- ference. Rather, Lunar craters are subject to the same type of seemingly scientific naming process as that ascribed to the remaining 40 planetary bodies in our Solar System that currently have a naming protocol for surface features. In this paper, I argue that both this lack of distinction and the resistance (under the umbrella of both historical precedent and scientific selenographic naming conventions) to name changes of prominent Lunar craters has resulted in a unique form of post-terrestrial epistemic violence – a violence evident in global social pedagogies of outer space that remain silent on this most important issue of who has the right to name the heavens.&#x0D; &#x0D; &#x0D; &#x0D;

Analysis of the permanently shadowed region of Cabeus crater in lunar south pole using orbiter high resolution camera imagery

The Orbiter High Resolution Camera (OHRC) on-board India's Chandrayaan-2 orbiter mission had acquired two images of the Permanently Shadowed Region (PSR) and adjacent area of Cabeus crater at an unprecedented resolution (<0.3 m/pixel). Numerous small features, such as meter scale boulders, craters, and slope-normal lobes were identified in these images. Boulders and craters as small as 1.5 m and 1.8 m, respectively, were identified in PSR making this size limit two times better than the currently reported values (>3 m for boulders and > 4 m for craters). The crater size distributions in PSR and Non-PSR regions were found to be alike in the size range of 3–20 m. We identified over 20% more smaller craters (<3 m) in the Non-PSR areas as compared to the PSR because of the higher illumination in the Non-PSR. Slope-normal lobes (potentially related to the presence of ice) were present in PSR as well as in Non-PSR areas. The impact generated debris (potentially) of Lunar Crater Observation and Sensing Satellite (LCROSS) impactors were also identified inside the Cabeus crater. Finally, it is concluded that OHRC is one of the most suitable camera, presently available on any orbiter around the Moon, for the imaging of PSRs to facilitate the study of small surface features that might be related to surface/subsurface ice, and equally important for the trafficability inside the PSRs.

Study on the volume of landslides in lunar impact craters

The lunar exploration project is of great significance, among which the statistics and measurement of lunar landslide are an important part of lunar exploration. With the help of Google Earth software, lunar image data were obtained, and the volume calculation and analysis of landslides in 14 meteorite impact craters on the Moon were performed using the Alfred S. McEwen formula. It is found by calculation and observation that the diameter of the crater is proportional to the volume of the landslide in most of the meteorite impact craters on the moon.

Comparative Analysis of Diurnal Thermal Radiation Variation among Lunar Craters of Different Ages Using CE-2 MRM Data

Microwave radiometer (MRM) is one of the important payloads on the Chang’e-2 (CE-2) Lunar satellite. In the Chang’e satellite’s observation of the microwave radiation brightness temperature (TB) on the lunar surface, there are some “cold spots” of microwave thermal radiation at night containing the Jackson crater. In order to compare the diurnal radiation TB differences of “cold spots” on the lunar surface, two typical craters at similar latitudes on the northern hemisphere on the lunar farside were selected: Jackson, which represents the new craters with a large number of discrete rocks on their surfaces; and Morse, which no longer has a large number of rocks after long-term meteorite impact and lunar evolution. In this paper, the diurnal variation of CE-2 MRM data in the two craters is presented, and a comparative analysis is made with the (FeO + TiO2) abundance (FTA) obtained by Clementine UV-VIS data and the rock abundance (RA) data of LRO Diviner. We find that the variation of the "cold spots" of lunar surface thermal radiation is closely related to the RA distribution in the newly formed craters on the lunar surface, and also has a certain correlation with the FTA.