Astronauts experienced reverse blood flow and blood clots on the space station, study says

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From CNN:
"(CNN) - A study of 11 healthy astronauts onboard the International Space Station for six-month missions has revealed a new risk of long-term spaceflight.
Six of the astronauts experienced stagnant or reverse blood flow, one had a blood clot and another was found to have a potential partial blood clot.
...
This is the first time researchers have observed these conditions in astronauts and the implications of their discovery could impact future long-term spaceflight, such as a mission to Mars."

https://www.cnn.com/2019/11/15/health/a ... index.html

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[notFritzArgelander]

Agreed. Then there's the radiation hazards too. The rocket science of it is trivial compared to the biology.