Thank you for visiting nature. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser or turn off compatibility mode in Internet Explorer. In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript. Our experiments aboard the Chinese Space Station reveal a gravity-driven transition in intruder dynamics within vibrated granular media.
While vibrations typically enable an intruder to ascend in a granular bed, low-gravity conditions induce it to descend under similar vibrations. As gravity decreases, we observe a significant reduction in the scaled damping coefficient and hydrostatic pressure coefficient indicating that bed particles disperse more readily upon intruder impact, facilitating deeper penetration. Our findings highlight a critical transition from downward to upward motion of the intruder as vibration acceleration exceeds a threshold, which increases as gravity decreases.
These insights into intruder dynamics in low-gravity environments have significant implications for asteroid exploration and lunar base construction, enhancing our understanding of the Brazil nut effect and the formation of planetesimal.
The surface morphology of celestial bodies is often shaped by impact craters formed by meteorite collisions, such as the impact craters observed on the lunar surface. These impacts can also lead to the rearrangement of surface materials on asteroids, as evidenced by the observed seismic shaking of asteroid surfaces that results in the aggregation of large rocks 1 , 2 , 3. Granular segregation, is found playing a possible role in shaping the surface features of small celestial bodies, such as the formation of craters and the distribution of large boulders on the surface of asteroid.
Reasonable explanations include ballistic sorting 4 and Brazil-nut effect BNE 5 , 6 , 7 , 8 , 9. The low gravity intruder dynamics is crucial in providing insights into the mechanism of BNE on microgravity celestial bodies and the formation and evolution of planetesimals. With the increasing frequency of human deep space exploration activities, the detection of lunar regolith composition by small satellite impacts, and the landing and traversal of rovers, it is essential to further investigate and gain a deeper understanding of the penetration dynamics of intruder particles in low-gravity granular media.
