The FAST project: Surface tension and adsorption studies in microgravity pre-evaluation of STS-95 flight results

The Facility for Adsorption and Surface Tension studies (FAST) has recently flown (october 1998) onboard the Shuttle Discovery, in the SPACEHAB module, during the STS-95 mission. In this paper the basic working principle of the Capillary Pressure Tensiometer, which is the core of the facility, and the main lines of the three selected experiments for this first flight are given together with a first evaluation of the experimental results obtained. All these experiments deal with the adsorption dynamics of soluble surfactants for which diffusion plays a fundamental role. Due to the large attenuation of convective fluxes, microgravity provides an ideal environment where studying adsorption processes in purely diffusive conditions.