# Influence of low gravity on the penetration resistance of lunar regolith

## TL;DR

This study examines how low gravity affects the resistance of lunar soil to penetration, revealing that factors like particle density and shape also play a significant role.

## Contribution

The study introduces a new method to assess lunar regolith penetration resistance under varying gravity and identifies non-gravitational factors influencing it.

## Key findings

- Normalized penetration resistance increases as gravity decreases.
- High relative density and irregular particle morphology enhance penetration resistance through interparticle contact and friction.
- Non-gravitational effects partially offset the expected reduction in resistance under lower gravity.

## Abstract

Lunar surface operations conducted by the United States and the Soviet Union confirmed that penetration resistance is a key indicator for evaluating the engineering properties of lunar regolith. To quantitatively assess the influence of reduced gravity on penetration resistance, this study employed a newly developed Geotechnical Magnetic-gravity Modeling Test (GMMT) system to perform cone penetration tests under controlled gravitational acceleration levels of 1/6 g, 1 g, and 2 g. The results indicated that the normalized penetration resistance increased as gravity decreased, and this effect was amplified at higher relative densities. To investigate the underlying mechanisms, discrete element method (DEM) simulations were conducted. The findings revealed that, in addition to gravity, in situ factors such as high relative density and irregular particle morphology also significantly enhanced penetration resistance by strengthening interparticle contact and friction. These non-gravitational effects partially offset the expected reduction in resistance under lower gravity, leading to a smaller-than-anticipated decline. This study provides new insights into the gravity-dependent penetration behavior of lunar regolith.