I am currently following the live broadcast of today's SpaceX launch. For a few hours already, astronauts are sitting inside the vessel, barely able to move. I wonder what precautions are taken to minimize the risk of a thrombosis. Of course health status of astronauts is closely monitored before and throughout a mission. But even a healthy individual does have a risk for thrombosis when sitting still for a longer duration. Do astronauts take blood thinners or take any other precautions?