Following previous studies on blood cell dynamics in microgravity and on the ground [1-3] and interest in improving the understanding of fundamental mechanisms of red blood cell aggregation [4], the KRABS project was selected by ESA for sounding rocket experiments (planned for MASER 17) and a parabolic flight setup was developed and has been flowing in several CNES and ESA parabolic flight campaigns since 2023. The objective of the experiment is to carry out the first quantitative study of the kinetics of aggregation and variations in associated blood viscosity during slow and unsteady flow sequences. These situations have been studied very little until now despite their relevance to pathological situations and space flight. This experiment is carried out in channels representative of the flow conditions in the veins, by characterizing the aggregation using optical techniques (microscopy, light scattering) and by simultaneously measuring the instantaneous viscosity. So far, these experiments have been successful. They have allowed to refine techniques and protocols for future experiments and provided accurate evaluations of aggregation timescales and related rheological changes.

These studies provide crucial information for the understanding and modeling of blood rheology, blood circulation disorders associated to space flight as well as aggregation related pathologies.