The FASES project for the investigation of emulsion stability in microgravity

The project FASES (Fundamental and Applied Studies in Emulsion Stability), proposed by a network of European Laboratories is supported by the European Space Agency. The main objective of the project is to study the links between the rheological properties of droplet interfaces and films, and the basic mechanisms involved in the destabilisation of emulsified systems: aggregation and coalescence. Experimentation in reduced gravity can be successfully utilised in these studies. From one side, the damping of gravity driven convection provides a purely diffusive environment for the study of the adsorption dynamics and transfer of surface active material. Moreover, the suppression of the droplet creaming/segregation offers an unique possibility to study coalescence and aggregation processes. In the framework of the FASES project key microgravity experiments are planned providing relevant data and/or tests of the developed models. Two facilities are under study for the International Space Station. The FAST (Facility for Adsorption and Surface Tension study) is a Capillary Pressure tensiometer for the study the physical chemistry of the single interfaces and liquid-liquid films. FAST has already been flown in 1998 on the Shuttle mission STS-95 and it has been refurbished for a new campaign on STS-107 in 2002. The emulsion dynamics and the drop-drop interaction will be specifically investigated by two experiments: ITEM for transparent emulsions, based on optical diagnostics, and EMPI for concentrated and opaque emulsions (EMPI), based on the utilisation of differential scanning calorimetry (DSC), exploiting the undercooling properties of microscopic liquid droplets.