Note: Planetary gravities made simple: Sample test of a Mars rover wheel

Abstract

We introduce an instrument for a wide spectrum of experiments on gravities other than our planet's. It is based on a large Atwood machine where one of the loads is a bucket equipped with a single board computer and different sensors. The computer is able to detect the falling (or rising) and then the stabilization of the effective gravity and to trigger actuators depending on the experiment. Gravities within the range 0.4 g-1.2 g are easily achieved with acceleration noise of the order of 0.01 g. Under Martian gravity, we are able to perform experiments of approximately 1.5 s duration. The system includes features such as WiFi and a web interface with tools for the setup, monitoring, and data analysis of the experiment. We briefly show a case study in testing the performance of a model Mars rover wheel in low gravities.

Intruders cooperatively interact with a wall into granular matter

“…In particular, the penetration of solid intruders into granular materials is a complex process where our intuition based on the observation of fluids and solids separately is of little help. A large body of work dealing with the penetration of low-velocity projectiles into granular beds has developed over the last two decades or so [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. Most of those studies have focused on the penetration far from the limits of the granular container: intruderwall interactions have rarely been studied.…”

Experiments in the penetration of cuboid intruders near walls into granular matter

“…For instance, the penetration of a solid intruder into a granular bed shows a non-trivial combination of solid-like and fluid-like behaviors. Over the last years, the study of low-velocity penetration of solid objects into granular matter has gained substantial momentum, especially within the Physics community [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. However, the vast majority of such research focuses on the penetration away from the boundaries of the granular container: intruderwall interactions are an almost virgin research topic, with very few reports before 2020 [12,25].…”