Space is not for the faint of heart. Astronauts will eventually suffer cardiovascular damage if they stay in the void long enough unless we get better at mitigating the effects of radiation.
That's according to a paper published in the journal Frontiers of Cardiovascular Medicine. It describes how heart muscle is replaced by tough, stringy fibers, a process known as myocardial remodeling after long space flights.
And, yes, we all know that radiation has unpleasant effects on people, though the solution can't be to add more and more shielding to a spacecraft, for various practical purposes. As the study points out, there are radioprotective compounds astronauts could take to avoid heart complications, yet none are approved for use – and they really may well be needed in future.
If we want to see human long distance space travel, we need to understand the impact of space-induced disease and how to protect our bodies from it
Charged particles from solar flares and cosmic rays react readily with molecules in our bodies, forming free radicals and kickstarting abnormal chemical reactions. This damages the structure of our cells, which can lead to malfunctioning DNA, causing it to mutate, which leads to bodily tissues breaking down and organs failing.
For instance, the overall size and shape of the heart can be altered, impairing its normal functions, and this can lead to heart failure. Radiation can also cause inflammation, and plaque to build up in blood vessels, clogging the heart’s arteries. Oxygen supply to the brain is choked off, increasing the risk of strokes.
“If we want to see human long distance space travel, we need to understand the impact of space-induced disease and how to protect our bodies from it,” said Jesper Hjortnaes, a researcher at the University Medical Center Utrecht. Although there is some research into new medicines that might protect future astronauts from the effects of radiation, none have been approved.
“If you do not protect this way, and the radiation is now able to come into your body,” Sean Wu, co-author of the paper and an associate professor of medicine at Stanford University, told The Register, "it becomes very hard to have anything else to protect you since once the radiation hits your cells, the damage is immediate and you then are really now dealing with the treatment of injury from radiation which is much harder rather than protection against radiation."
You always wanted to be an astronaut, right? Careful: Space is getting more and more deadlyREAD MORE
It’s tricky to work out how best to protect against space-induced cardiovascular damage because it has yet to be observed. Past crew members of the International Space Station experienced symptoms including blurred vision and muscle loss, though their hearts have not started to fail, presumably because they did not venture too far into the Solar System nor for too long.
To see the effects in a practical sense, the team believes future research should simulate the impact of radiation on “heart-on-chips,” devices that contain pressure sensors to mimic heart function. “Having a heart-on-chip, like other tissue- and organ-on-chip, is to have a way to mimic important physical forces experienced by heart cells, and then be able to irradiate them and study how the cells respond, and to test new ideas for treatment,” Jane Grande-Allen, a professor of bioengineering at Rice University, told us.
“All of this could be done in a lab, in an incubator, and it could be faster than working with people or animals. One aspect of irradiation that could be studied is the effect on inflammation and fibrosis of the heart tissue.”
In the meantime, before there is a magic cocktail of drugs that can be guzzled to protect future space travelers from the effects of radiation, the researchers recommend consuming an antioxidant-rich diet. Foods like spinach, tomatoes, and milk contain compounds to counteract free radicals produced from exposure to radiation. ®