Journal Article Effect of 1/6 Gravity Environment on Atmospheric Suspension of Simulated Lunar Regolith

Maki, Syou  ,  Honma, Yoshiyuki  ,  Tsuchiya, Hidetoshi  ,  Tanaka, Kazunari  ,  Aoki, Shigeru  ,  Takeoka, Hajime  ,  Miki, Takeo  ,  Ohshima, Hiroshi  ,  Yamamoto, Masafumi  ,  Morimoto, Yasuo  ,  Ogawa, Yasutaka  ,  Mukai, Chiaki

20 ( 1 )  , pp.7 - 19 , 2015-07 , Biomedical Fuzzy Systems Association , バイオメディカル・ファジィ・システム学会
In order to investigate the behavior of suspended particle matter (SPM) in a 1/6 gravity(1/6 G) environment, simulated lunar regolith was diffused in a chamber, realizing a quasi 1/6gravity environment by parabolic flight. The effect of the 1/6 G environment on the atmosphericsuspension was evaluated by means of the cutoff value of an elutriator; the cutoff value in the 1/6 Gshould be 6 times larger than at the earth’s surface. The results of our experiment confirmed thatthe falling velocity of SPM in a 1/6G approximates Stokes’ law, and the falling time is inverselyproportional to the force of gravity. Numerical computation suggested that residual SPM in aconvection-free room becomes high in a low-gravity environment or in a high-ceilinged room. Theseresults suggest that once lunar dust intruded into a lunar base, it would take a considerably longtime to clean up. Since the suspension time of SPM is different according to the particle size, theexposure risk of SPM will also vary according to the particle size. Considering that the risk dependsonly on the drifting time, the actual influence of low gravity on fine particles (Dp 1.0 mm indiameter) and on large particles (Dp > 10 mm) in a 1/6G would be negligible. In contrast, formedium sized particles (2.5 < Dp 10 mm) the difference in the drifting time between that on theearth and on the lunar surface is much larger than can be confirmed with the senses. Safetyprecautions used for this size of particle on the earth should be altered on the lunar surface.
Accepted: 2015-03-09

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