This strongly suggests that volatiles at their surfaces are sublimating, driving off the dust. This refrigeration method cools a contained area by melting ice, or by sublimating dry ice. This band is regularly replenished by sodium sublimating from incoming meteors. Scallops are caused by ice sublimating from frozen soil. Sublimating this platinum at high temperatures leaves behind thin filaments of super-pure graphite. The sublimating capability of camphor gives it several uses. I think I'm sublimating that into the music. Best known is mercury(II) chloride, an easily sublimating white solid. At launch, the balloon weighed , including of sublimating powders of two types.