Abstract
Recent theory and experiments have shown that heat conduction in simple fluids and mass diffusion in binary mixtures are inevitably accompanied by the presence of large amplitude fluctuations in temperature or concentration, respectively. These fluctuations occur at all length scales, and their mean squared amplitude diverges as the fourth power of their size. However, on Earth, the divergence of large size fluctuations is prevented due to gravitational stabilization. The aim of the GRADFLEX experiment is to investigate the non-equilibrium fluctuations in microgravity, and to measure the divergence of large size fluctuations. GRADFLEX was flown on the FOTON M3 mission September 14-26, 2007. Some images of the fluctuations were downlinked to Earth during the mission by means of the Telesupport Unit. In this paper we present preliminary quantitative results based on the images downloaded during the mission. We show that under microgravity the amplitude of fluctuations diverges as anticipated by theory.
