A recent study led by Michael Delp, a researcher from the Florida State University, shows a possible link between deep space radiation and cardiovascular diseases in astronauts.

The study started because of the growing interest in deep space travel from both the United States and China and private companies like SpaceX in recent years. For the unaware, deep space travel means going beyond Earth’s orbit, into the unexplored reaches of the Solar System and even further. The NASA has proposed orbital missions around the moon from 2020 to 2030 and SpaceX proposes landing humans on Mars by 2026.

This study gives hints that radiation might also negatively impact astronauts’ hearts. Image Credit: NASA

While it’s been long speculated about the impact of deep space travel and the resultant exposure to cosmic radiation, since there is no radiation-protecting magnetosphere beyond Earth’s orbit, scientists have been more concerned with the risks of developing cancer from this exposure.

The study subjects

Only 24 humans have gone into deep space, beyond the magnetosphere, and those are the astronauts from the Apollo program, which ran from 1961 to 1972.

Eight astronauts from the program have already died; and seven were taken into account for the study.

Of these seven, James Irwin, Ron Evans, and Neil Armstrong died from cardiovascular complications. The first two died from heart attacks and the latter from complications arising from a heart surgery.

Delp and his team compared the seven Apollo astronauts with thirty-five astronauts that have never been to space and thirty-five astronauts that have only been in low Earth orbit, such as those at the International Space Station.

The results show that while the rates of death by cardiovascular disease don’t differ much between those who didn’t travel to space and those who only stayed in low Earth orbit, the Apollo astronauts had rates 4 to 5 times higher.

The research experiments

The hypothesis was tested using mice, which were exposed to a simulation of space (namely weightlessness and radiation exposure).

Some mice were only exposed to radiation, some only to weightlessness and some to both situations simultaneously. After six months, the results showed that the mice who were exposed to radiation were the ones with lasting damage to their blood vessels; the ones that suffered effects of anti-gravity healed, for the most part.

Of course, further studies are necessary; the sample used is very small, and could be affected by factors such as whenever or not the astronauts had a prior family history of cardiovascular disease, high cholesterol, were smokers or had undiagnosed health problems.

The study is, however, a small step forward towards understanding the effects of space travel on human health; Delp mentions that most scientists feel like many years of exposure are needed before the harmful effects occur, but his research shows that as little as two weeks of exposure might be enough to cause damage.

It’s necessary to find the minimum radiation for damage to occur, study the mechanisms behind radiation, and explore countermeasures to better protect astronauts.

Sources: Scientific Reports