[Influence of various physical factors on the developmental capacities of the ovum of Artemia salina]. / Influence de différents facteurs physiques sur les capacités de développement de l'oeuf d'Artemia salina

Artemia salina dry eggs exhibit a great resistance to different physical factors: acceleration and vibration, low temperature, high vacuum and magnetic fields. Vibration test, alone or combined with acceleration test decreases the Artemia salina egg developmental capacity. Nevertheless, the differences are small and much lower than those observed in previous space experiments. The viability of Artemia eggs is not impaired by low temperature, high vacuum exposure and by high magnetic fields (15, 25 and 150 Koersted) or by earth magnetic field shielding.

Experimental methods of correlation between the trajectories of cosmic heavy ions and biological objects: dosimetric results from the Biostack experiment on Apollo 16 and 17.

The biological objects in the Biostack are stacked alternately between physical detectors of HZE particle tracks which include nuclear emulsions. The pattern of the biological objects is transferred to the upper side of the adjacent emulsion by optical illumination. On each sheet of nuclear emulsion a coordinate grid is transferred to the bottom side by optical illumination. The visible track left by the passage of the heavy ion can then be very clearly localized. The charge of the ions is determined by photometric measurements of the tracks. These measurements are calibrated with known tracks of heavy ions accelerated at the Bevatron at Berkeley. The results are given as: flux, number of stars per cm3, charge of the ions, comparison with other detectors (plastics, AgCl crystals, LiF), energy loss, hit region in the biological objects.

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.