Radiobiological results of the Biostack experiment on board Apollo 16 and 17.

After penetrating the Biostack capsule, some of the HZE particles hit the biological objects carried: bacterial spores (Bacillus subtilis), seeds (Arabidopsis thaliana and Vicia faba), and shrimp eggs (Artemia salina). The different biological objects were affected by heavy ions in widely varying ways. A broad range of radiobiological investigations has been carried out in regard to the objects' response to HZE particles. The most sensitive biological objects in the Biostack experiments proved to be the shrimp eggs. The development of 500 eggs hit by heavy cosmic ions was investigated. This differed significantly from the flight controls (eggs flown in the Biostack but not hit by heavy ions) and from the ground controls. From this it has been concluded that penetration on the part of a single heavy ion may injure the encysted blastula. This damage was found to influence gastrula formation and even the hatching process of the nauplius. Abnormalities (increased by a factor of 10) in the orthonauplius were observed during the development of the hit eggs; they consisted, for example, of shortened extremities or an abnormal thorax or abdomen. In addition, eggs of Tribolium confusum and Carausius morosus, which were included in Biostack 2 (Apollo 17), have been investigated, and the influence of single heavy ions on the development process of these highly organized insects has been studied.

Preliminary results on the action of cosmic heavy ions on the development of eggs of Artemia salina.

The Biostack experiment (Principal Investigators: H. Bucker) aboard Apollo 16 contained one unit with eggs of the brine shrimp Artemia salina. The eggs were fixed in polyvinyl alcohol foils. Nuclear emulsions and plastics were used as track detectors. The development of 260 eggs hit by cosmic heavy ions was investigated. It differed significantly from the development of the flight controls--eggs flown in the Biostack but not hit by heavy ions--and of the ground controls. From these results it was concluded that a hit of a single heavy ion may injure the encysted blastula. This damage was found to influence the gastrula formation and even the hatching process of the nauplius. Abnormalities of the orthonauplius were observed during the development of the hit eggs. These are shortened extremities, or abnormal thorax or abdomen. In addition, in the Biostack II aboard Apollo 17 eggs of Tribolium confusum and Carausius morosus were included. The influence of single heavy ions on the development process of these highly organized insects was investigated.

The Biostack experiment on Apollo 16.

The object of the Biostack experiment is to study the biological effects of high ZE particles of cosmic radiation in order to obtain information on the mechanism of these particles in biological matter. For this purpose individual local evaluation methods have been developed which allow one to identify each biologically effective particle and to correlate the individual hitting particle with the biological effect produced. The Biostack experimental package contains a series of monolayers of selected biological objects (Bacillus subtilis spores, Arabidopsis thaliana seeds, Vicia faba radiculae, Artemia salina eggs) with each layer sandwiched between several different cosmic ion track detectors (nuclear emulsions, cellulose nitrate, polycarbonate). By this arrangement a variety of biological effects due to a single penetrating particle can be analysed. Influence on cellular and tissue development, nuclear damages, and mutation induction are the main investigated effects. These space flight findings will be completed by results of balloon flight and accelerator experiments.