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.