The Spatial Pattern of Lunar Craters on a Global Scale

Impact craters over the lunar surface are often arranged in alignments and clusters, which are related to the results of mass wasting, mantling, and structural modifications effected by micrometerorite and meteorite bombardment, volcanic processes and crustal vibrations. High-resolution optical images and DEM returned from Chang'E mission provide a new chance for estimation of spatial variation in the crater density. We used Kernel density and L(d) function coming from Ripley's K to explore the spatial pattern of lunar craters in the mare, highland, latitudinal zones from 28°N to 42°N and longitudinal zones from 40°W to 60°W on the Moon, which included 106 016 impact craters with diameters bigger than 500 m. Spatial distribution pattern analysis suggests a clustered distribution of craters on the Moon, and GIS-based spatial Kernel density identified three main clusters of craters within highlands (the biggest one located in the northeastern high latitude). The observed ratio of the crater density in highland to that in mare region is about 5 within the diameter ranged from 1km to 500 km. It also showed that the average density of craters on the eastern hemisphere was substantially higher than that on the western hemisphere, which was consistent with the proposal that western mare units are generally younger than eastern mare units. L(d) function value of the craters, which provided information on the degree of clustering, suggested the craters generally gathered together first then separated with the distance increasing. An amount of 31 study areas brought out the symmetric variations existed in latitudinal and longitudinal study areas on the local scale, which pointed to the craters density are in fluctuated decline from the equator to two poles and so are they from longitude of central meridian to eastern or western side of the Moon with the distance rising.