Masatsugu Otsuki

The updated Table 1 with a comment indicating that micrographs #05 and #08 at the bottom of the images should be replaced. However, in the response to author query 4, Micrographs #4 and #8 were changed in Table 1. While processing the suggested changes based on the eProofing comments, the correction team updated the existing table figures and replaced image #05 with the micrograph of image #08 and image #08 with the micrograph of image #04 in the revised table. As a result, the changes got reverted and images were incorrect and duplicated.

Studying the gravity-dependent characteristics of regolith, fine-grained granular media covering extra-terrestrial bodies is essential for the reliable design and analysis of landers and rovers for space exploration. In this study, we propose an experimental approach to examine a granular flow under stable artificial gravity conditions for a long duration generated by a centrifuge at the International Space Station. We also perform a discrete element simulation of the granular flow in both artificial and natural gravity environments. The simulation results verify that the granular flows in artificial and natural gravity are consistent. Further, regression analysis of the experimental results reveals that the mass flow rate of granular flow quantitatively follows a well-known physics-based law with some deviations under low-gravity conditions, implying that the bulk density of the granular media decreases with gravity. This insight also indicates that the bulk density considered in simulation studies of space probes under low-gravity conditions needs to be tuned for their reliable design and analysis.