The aim of the Biostack, namely, to contribute to a dosimetry of the HZE-particles as the highly structured component of the cosmic radiation, leads to a variety of physical and biological requirements in order to achieve that goal. The temporal, spatial and atomic characteristics of that radiation field rendered visual track detectors with the capability of individually recording and correlating single hit events as the most suitable physical detectors. One of the objects selected had been the spores ofBacillus sub tills, which were flown in the missions of Apollo 16, 17 and the Apollo-Soyuz Test Project (ASTP). A substantial biological improvement was the development of routine methods which allowed the investigation of various biological endpoints of one individual spore together with a more precise determination of its impact parameter with respect to the path of the heavy ion. Preliminary results of the ASTP experiment are presented which strongly support the findings of the previous Biostack experiments