August 17, 2023
Yokohama National University
Keio University
A research group led by Professor Shingo Ozaki of the Faculty of Engineering at Yokohama National University, Associate Professor Genya Ishigami of the Faculty of Science and Technology at Keio University, and Associate Professor Shinji Otsuki of the JAXA Institute of Space and Astronautical Science has successfully measured the flow properties of various granular materials (sand and regolith simulants) by recreating various low-gravity environments using the cell culture experiment device in the Kibo module of the International Space Station. This is the world's first successful measurement and analysis of the flow behavior of granular materials under a stable, long-term artificial gravity environment (0.063 G to 2.0 G). Based on the experimental results, the team also revealed that the flow properties of some sands quantitatively follow a well-known physical law, being proportional to the square root of the magnitude of gravity (√G) in low gravity. In addition, a regression analysis of the measurement results suggested that the "bulk density" of sand also decreases with gravity. The results obtained can be used for the development of future space probes and the planning of various missions. This research was published in "npj Microgravity," a Nature partner journal also supported by NASA, online on August 8 (UK time).
Highlights of this Research
Conducted flow experiments on eight types of sand under gravity conditions simulating various celestial bodies, using the artificial gravity generator in the Kibo module of the International Space Station.
Achieved the world's first measurement and analysis of the behavior of granular materials under a stable, long-term artificial gravity environment (0.063 G to 2.0 G).
Suggested that the flow rate of sand is proportional to the square root of the magnitude of gravity even in low gravity, and that the "bulk density" of sand decreases as gravity decreases—findings that had not been previously confirmed.
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