Report on the Second Zero Gravity Experiment 'ARC' on Space Shuttle 'Discovery' Sept/Oct 1988

A space-rated automatic Slit-capillary-photo-viscometer was placed on the middeck of the STS 26 to study effect of near-zero gravity on aggregation of the red blood cells obtained from normal donors and from patients with various disorders, such as heart disease, diabetes, etc. This experiment was able to confirm results obtained on the Space Shuttle 'Discovery' STS 51-C that the degree of aggregation of red cells is much less under microgravity than on the ground, and, especially, that this is valid not only for unmodified human blood but also in the presence of high-molecular weight dextran as well as in the presence of IgG immunoglobulin. This supports our earlier hypothesis that microgravity affects cell-cell interaction and thus the microstructure of the cell membrane.