Developing a Lightweight Martian Soil Simulant for a High-Sinkage Mobility Test

The geotechnical properties of Martian soils are critical parameters in predicting and simulating soil behavior with regard to vehicle performance on Mars. In preparation for manned or robotic missions to Mars, surface vehicles must be tested on terrains that represent the mechanical characteristics of the Martian ground. This paper presents the development of a lightweight simulant and its preparation method to emulate the mechanical properties of Martian soil for high sinkage mobility tests. A geotechnical testing program was developed to measure specific gravity, particle size distribution, bulk density, compression indices and shear strength. The simulant can achieve the typical Martian regolith density range, which is approximately 38% of that on earth. This is of particular importance because strength parameters of granular materials, which characterize the plastic behavior of soil samples in sinkage tests, are controlled by the effective confining pressure, which itself is induced by gravity. (C) 2014 American Society of Civil Engineers.