Highs and lows of 30 years research of fluid physics in microgravity, a personal memory

On October 4th 1957 the western world was shocked from the news that a Russian satellite, called Sputnik, had been launched and revolves the earth within 90 minutes periodically. This was the starting signal for the race to monde and stars; the "Star War" began. Just at that time I started with the investigation of the static and dynamic behavior of fluids at and near their critical point [1]. With an optical method I measured density stratifications caused by the diverging compressibility of critical fluids in the earth gravity field. There, the real critical state is compressed by its own weight to a layer of the order of the correlation length. I was myself aware that in a satellite a weightlessness environment exists. Thus a dream waked up within me; if it would be possible to perform critical point experiments in such a satellite our knowledge and understanding of its physics must be much improved, and questions violently discussed at that moment should find an answer. But I would never had thoughts that such a dream could be realized within my lifetime. However, in 1975 the German ministry for development and research instructed the DLR to inquiry scientists if weightlessness can support their research. Based on my experience I proposed two research programs: Study of critical phenomenon, and Study of boiling heat transfer. Two years later both proposals have been accepted and scheduled for the D-1 mission. The dream became true. Due to the limited space only a very short summary of the results of these research projects with highs and less of the lows will be presented in the following.[PUBLICATION ABSTRACT]