Does astronauts’ blood flow backwards in space?
The US space agency NASA has observed a bizarre effect of human space flight: Blood going backwards in astronauts’ veins and clotting.
An astronaut on the International Space Station (ISS) was carrying out an ultrasound on their body – guided by experts on the ground. An ultrasound is a scan to study inside the body.
Similar tests before the astronaut went to space came back normal.
But the scan taken in space revealed a clot of blood. The astronaut didn’t have any clot-related symptoms, but was given blood-thinning medication for the rest of their time in orbit to prevent more clots.
This clotting and reverse flow was declared a new risk for humans in spaceflight, which will have to be better understood and planned for before astronauts can spend months or years in space, or before regular people can go to space for holidays or to live and spend extended periods in reduced gravity.