An arc-shaped front nose for the mole in space exploration

The mole is an axially symmetric intrusion device, which can be treated as a carrier of different sensors that investigate the subsurface environment and properties of the material component. To some extent, the maximum penetration depth of a single stroke for hammer-driven mole is not only limited by the stroke energy but also the influence of the soil resistance which links to the shape of the front nose. In this paper, a circular arc shape is proposed and the mechanical model is established between the soil and the mole with an arc-shaped nose. The approximate axial resistance equations of the mole derived from soil mechanics theory are analysed with the geometric parameters caliber-radius-head. Also, the relationship between the resistance force and the geometric parameters are verified by the EDEM simulations. Moreover, experiments are performed to observe the penetration phenomena of the mole with an arc-shaped nose in the dry sand.