Pearl Lin
Pronouns: she/her
Research Mentor(s): Cheng Li
Research Mentor School/College/Department: Climate and Space Sciences and Engineering / Engineering
Program:
Authors: Pearl Lin, Yun Zhang, Cheng Li
Session: Session 4: 1:40 pm – 2:30 pm
Poster: 102
Abstract
On small celestial bodies such as asteroids, comets, and small moons, reduced gravity conditions pose significant challenges for robotic in-situ exploration technology. Despite this, scientists continue to have great interest in them due to their potential in helping us understand the Solar System’s formation and evolution. Knowledge of how landers and rovers interact with small-body surfaces is crucial to expeditions like JAXA’s upcoming Martian Moons eXploration (MMX) mission, which plans to land an exploratory space probe on Phobos in 2027. This study focuses on lander sinkage, specifically examining the effects of gravity, friction, grain shape, and cohesion on the pressure-sinkage relationship generated by compressing a bed of particles. Granular beds are generated with 3 material cases: (1) low friction with no cohesion, (2) high friction with no cohesion, and (3) high friction with cohesion, with both sphere and multisphere-type particles. They are then settled on Earth and Phobos gravity using a discrete element simulation software and penetrated with a cylindrical intruder at constant velocity. Current results indicate that the pressure-sinkage relationship for all tests consistently exhibits 2 primary regimes: a brief initial phase where the pressure-sinkage relationship is fast-rising and nonlinear, followed by an extended phase where it is linear. The depth at which it transitions from nonlinear to linear appears to be positively related to the effective size of the particles. On all tests, it was consistently observed that, for the same sinkage depth, granular beds with high friction and cohesion exert a greater pressure on the intruder, followed by those with high friction and no cohesion, and those with low friction and no cohesion. Between the same material cases, the pressure-sinkage relationship scales by gravity. These findings suggest that a lander on Phobos would experience less sinkage with increasing friction, cohesion, and effective size of the surface regolith, but more analysis is required to determine if sinkage is the same on Earth and Phobos for identical materials.
