Assessment of dynamic properties of a new lunar highland soil simulant (LSS-ISAC-1) developed for Chandrayaan missions

Abstract

The distinct difference between the lunar surface (Moon) and the Earth forced space research organizations (SRO) and researchers to study the geotechnical properties of the lunar soils for the successful execution of lunar missions. The planned Chandrayaan Missions of the Indian Space Research Organization include constructing lunar structures on the lunar surface for the future Moon colonization. The stability of such lunar structures is completely dependent upon the foundation systems adopted. The foundation systems of these lunar structures are expected to encounter various types of vibrations due to moonquakes on the lunar surface. The analysis and design of a foundation system with respect to ground motion and vibration rely on the dynamic properties of the lunar soil. Also, the characterization of dynamic soil properties like shear modulus, damping ratio, and Poisson's ratio is essential for the safe design of foundation systems. Therefore, it is imperative to evaluate the dynamic properties of the lunar soil against moonquake-induced vibrations. Past research has utilized lunar soil simulants were used to assess the lunar soil's geotechnical properties. In that order, this study explains the dynamic properties of the new lunar highland simulant LSS-ISAC-1 under simulated moonquake conditions using cyclic triaxial tests. The shear modulus and damping ratio were determined from the cyclic triaxial tests for the different relative densities (30%, 63%, and 80%), confining pressures (5 kPa–75 kPa), and frequencies to represent the loose, medium, and dense states of the lunar surface. The bender element test is also done to find the shear wave velocity and maximum shear modulus. The results were compared with the lunar soil simulant CAS-1 and lunar soils to show the reliability of the obtained test results of LSS-ISAC-1. • A new lunar highland soil simulant (LSS-ISAC-1) was developed by ISRO using terrestrial anorthosite rocks to mimic the geotechnical properties of the highland soils of the lunar surface. • Dynamic properties of the LSS-ISAC-1 were determined using the cyclic triaxial test. • The measured dynamic properties would be considered for proposing a suitable foundation system for lunar structures considering the Moonquake effects. • Test results were compared with the actual lunar soil and lunar soil simulant CAS-1 to show the reliability of the obtained test results of LSS-ISAC-1.