Rheological Lunar Regolith Simulants

TL;DR

This paper develops and validates enhanced lunar regolith simulants that better replicate the mechanical and rheological properties of true Moon soil under lunar gravity conditions, aiding space research.

Contribution

It introduces techniques to modify existing simulants to match lunar regolith properties and validates these against in-situ lunar data.

Findings

Simulants' friction angles are close to lunar regolith.

Cohesion in simulants is higher than on the Moon due to gravity differences.

Proposed cohesion enhancement method improves simulant fidelity.

Abstract

Regolith simulants are essential for space research and technology development. Yet, their physical properties often differ from those of true planetary soil, particularly when compared to regolith properties in-situ, that experience notably reduced gravity. We focus on lunar regolith simulants and explore various techniques to modify existing simulants to replicate the mechanical/rheological behavior of Moon regolith in true lunar conditions. Our results are validated against data from in-situ tests conducted during the Luna and Apollo missions, enabling a direct comparison of physical properties of our enhanced simulants to true Lunar regolith, on the Moon. Analyzed in the Mohr-Coulomb model framework, the friction angle of most simulants is generally close to that of true regolith, but the measured cohesion is often higher on the Moon, notably due to the reduced gravity environment. We propose a method to increase the cohesion of an existing simulant and assess the mechanical behavior of our rheological regolith simulant using a standardized geotechnical, shear test. The experimental results are then directly compared to in-situ data, providing a quantitative basis for evaluating the fidelity of the enhanced simulants.