The subsurface structure and stratigraphy of the Chang’E-4 landing site:orbital evidence from small craters on the Von Kármán crater floor  

作　　者：Xiao-Hui Fu Le Qiao Jiang Zhang Zong-Cheng Ling Bo Li 付晓辉;乔乐;张江;凌宗成;李勃(Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment,Institute of Space Sciences,Shandong University,Weihai 264209,China;State Key Laboratory of Lunar and Planetary Sciences,Macao University of Science and Technology,Taipa,Macao,China;CAS Center for Excellence in Comparative Planetology,Hefei 230026,China;State Key Laboratory of Remote Sensing Science,Institute of Remote Sensing and Digital Earth,Chinese Academy of Sciences,Beijing 100101,China)

机构地区：[1]Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment,Institute of Space Sciences,Shandong University,Weihai 264209,China [2]State Key Laboratory of Lunar and Planetary Sciences,Macao University of Science and Technology,Taipa,Macao,China [3]CAS Center for Excellence in Comparative Planetology,Hefei 230026,China [4]State Key Laboratory of Remote Sensing Science,Institute of Remote Sensing and Digital Earth,Chinese Academy of Sciences,Beijing 100101,China

出　　处：《Research in Astronomy and Astrophysics》2020年第1期57-68,共12页天文和天体物理学研究（英文版）

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);the open fund of the Key Laboratory of Lunar and Deep Space Exploration, Chinese Academy of Sciences;supported 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)

摘　　要：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.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.

关 键 词：Chang’E-4 dark-haloed crater ejecta thickness MOON 

分 类 号：P184[天文地球—天文学]