Determining mechanical parameters of asteroid rocks using NWA13618 meteorites and microscopic rock mechanics experiment

In the future, the extraterrestrial human activities, such as resources exploitation and base construction beyond earth need the aid of geotechnical engineering technology. Currently, there are only two approaches for humans to obtain the rock samples beyond earth: sample-return activities by spacecraft and meteorite survey. Meteorites are rare, expensive, small in size and arbitrary in shape, so it is difficult to process them into standard rock samples required by mechanical testing & simulation (MTS) and other traditional macroscopic rock mechanical tests. In this paper, a novel technique for measuring mechanical property of small-size meteorites is developed based on microscopic rock mechanics experiments (micro-RME) and statistical probability models. Firstly, the composition, content and distribution of NWA13618 meteorite rock-forming minerals were obtained by TESCAN integrated mineral analyzer(TIMA). Then, the nanoindentation technology was used to carry out a large number of indentation tests to obtain the multi-point elastic modulus. After that, the mechanical parameters of four main minerals in meteorite NWA13618 were derived by using Gaussian mixture model, and the elastic moduli of olivine, pyroxene, Fe-Ni and feldspar were 116.73, 101.77, 87.24 GPa and 70.74 GPa, respectively. Finally, the macroscopic cm-scale elastic modulus of NWA13618 meteorite determined by the homogenization method Mori-Tanaka model was 90.48 GPa according to the mineral content and mechanical properties. The novel micro-rock mechanical experiment technique and scale upgrading method proposed in this paper provide theoretical basis and technical means for predicting the mechanical properties of L4 parent asteroid.