Predicted LET-spectra of HZE-particles for the Free Flyer Biostack Experiment on the long duration exposure facility...

The LDEF (long duration exposure facility) mission, scheduled for a launch on the Space Shuttle in 1981, will fly for about 9 months in a near-earth orbit with an inclination angle of 28 degrees. In this flight the Free Flyer Biostack Experiment has the objective of measuring the biological effects of individual heavy ions from cosmic radiation (HZE particles). This paper presents results of a calculation of LET-spectra in free space and within the absorber of the experiment. The calculation considers the geomagnetic shielding of the space craft against charged particles with low energies and the disintegration of the heavy ions within the absorbing material by fragmentation. For this mission the LET spectra turn out to differ from those of previous experiments. The steepness of the spectra changes significantly with LET and also with depth of absorber.