SURFACE-CONTROLLED DROP OSCILLATIONS IN SPACE

Large liquid drops were deformed by an acoustic standing wave in a res onant air chamber called the Drop Physics Module, which was carried on Space Shuttle Columbia as part of the second United States Microgravi ty Laboratory mission. When this deforming force was suddenly reduced, the drops executed free oscillations about a perfect spherical equili brium. The complex frequency of these oscillations was measured. The f irst results from a series of experiments are presented here. Results for purl water compare favorably with fundamental theoretical predicti ons. Drops containing aqueous solutions of soluble surfactants exhibit ed remarkable differences in both frequency and damping, and these are explained phenomenologically by a discussion of the multiple time sca les introduced by the addition of surfactants. (C) 1997 Acoustical Soc iety of America. [S0001-4966(97)06611-3].