FEM-DEM coupled modeling of cone penetration tests in lunar soil

Cone penetration test(CPT)is an appropriate technique for quickly determining the geotechnical properties of lunar soil,which is valuable for in situ lunar exploration.Utilizing a typical coupling method recently developed by the authors,a finite element method(FEM)-discrete element method(DEM)coupled model of CPTs is obtained.A series of CPTs in lunar soil are simulated to qualitatively reveal the flow of particles and the development of resistance throughout the penetration process.In addition,the effects of major factors,such as penetration velocity,penetration depth,cone tip angle,and the low gravity on the Moon surface are investigated.

Introduction to the TT&C Scheme for Chang’e⁃5 Mission

Chang’e-5 mission is China’s first lunar sample return mission.It contains several new flight phases compared with the previous lunar missions,such as the lunar take-off and orbit insertion phase,the rendezvous and docking phase,etc.Chang’e-5 mission is extremely complicated and full of new challenges.This paper sorts out the characteristics and the difficulties in telemetry,tracking,and command(TT&C)of Chang’e-5 mission.The main technical contribution is a reliable general design of the TT&C system,including the application of X-band TT&C in launch and early orbit phase(LEOP),multiple targets simultaneous TT&C in X-band,lunar surface benchmark calibration,high-precision and rapid orbit trajectory determination for the lunar surface take-off,remote guidance rendezvous and docking,the determination of the initial navigational value for the separation point of the Chang’e-5 orbiter and returner,and the design of the reentry measurement chain.Based on this scheme,a global deep space TT&C network and interplanetary reentry measurement chain have been established for China,and near-continuous TT&C support for China’s first extraterrestrial object sampling and return mission has been realized,ensuring reliable tracking,accurate measurement and accurate control.The global deep space network can provide TT&C support comparable to that of National Aeronautics and Space Administration(NASA)and European Space Agency(ESA)for subsequent lunar and deep space exploration missions.The techniques of rapid trajectory determination of lunar take-off and orbit entry,as well as high precision and remote guidance of lunar orbit rendezvous and docking can lay a technological foundation for the future manned lunar exploration missions and planetary sampling and return missions.