Exposure to cosmic radiation during space missions is associated with the reduction in gravitational force. Whereas the genotoxic effects of ionising radiation have been intensely studied on human cells,the consequence of the reduced gravity is still unclear. More recent studies on survival and DNA break joining of unicellular organisms and human cells indicated that the repair capacity of radiation-induced DNA damage shows certain decrease in microgravity Whereas the genotoxic effects of ionizing radiation have been intensely studied on human cells, the consequence of the reduced gravity is still unclear. More recent studies on survival and DNA break joining of unicellular organisms and human cells indicated that the repair capacity of radiation-induced DNA damage shows certain decrease in microgravity