Participants of manned missions to the Moon were at risk for cardiovascular diseases. Heart attacks and other dangerous problems were recorded in them several times more often than in "ordinary" cosmonauts who did not leave Earth's orbit.
And we, who have never flown above the main airlines, and the astronauts working on the ISS, spend our entire lives within the global magnetic field of the Earth. Its influence extends far beyond the atmosphere, deflecting the lion's share of cosmic radiation - high-energy particles arriving at us from outside the solar system, as well as from the most active processes occurring on the sun.
So far, only 24 people have left the boundaries of the magnetosphere in history - participants in the nine lunar Apollo expeditions, which took place in 1968-1972. Of these, eight have now died, but the authors of the article, published in the journal Scientific Reports, analyzed only the first seven deaths: the eighth died later. And 43% of these deaths were associated with cardiovascular disease.
Michael Delp and colleagues at Florida State University and NASA note that this figure is 4-5 times higher than that of astronauts in low-Earth orbit (11%), and almost double the population average of 27 % (US data). For flightless astronauts, it was 9% at all. Scientists have suggested that the reason for this may be particles of cosmic radiation. And to test this, laboratory experiments were carried out.
The mice were kept in the vivarium for six months on a normal and sufficient diet, but under radiation that mimicked the level of cosmic radiation received by astronauts in the Apollo spacecraft. For mice in the other group, weightlessness was simulated using the NASA-approved Morey-Holton method, with rear belt unloading by hanging from the base of the tail. In the third group, both radiation and "weightlessness" were used.
Six months for mice is a quarter of their life, and by the end of this period those of them that were exposed to radiation, indeed, had problems with the cardiovascular system. Scientists have shown that they are associated with damage to signaling pathways and dysregulation of endothelial tone - the cells that line the inner surface of blood vessels and largely ensure their work.