Florida State University Professor Michael Delp has identified a link between deep space radiation exposure, and a high rate of mortality due to cardiovascular problems in astronauts who flew beyond low-Earth orbit (LEO) during the Apollo program. Research based on the discovery could be used to safeguard future astronauts undertaking the next phase of manned space exploration.

Numerous studies have been carried out aimed at understanding and mitigating the health risks to astronauts operating in low-Earth orbit (LEO). Research in the area has led to the development of equipment and exercise regimes designed to maintain the health of astronauts operating in microgravity environments such as that prevailing aboard the International Space Station (ISS).

However, as nations across the globe, including the United States, China, and even commercial entities such as SpaceX turn their gaze back towards the sphere of manned deep space exploration, a different form of danger must be considered — the threat posed by cosmic radiation.

LEO astronauts, such as those that make up the crew of the ISS are largely protected from deep space radiation thanks to the protective influence of Earth's magnetosphere, which works to deflect the dangerous particles emanating from our Sun.

Processed Hasselblad footage of the Earth hanging over the lunar surface as captured during the historic Apollo 11 mission(Credit: NASA)

Members of the Apollo program that flew beyond LEO had no such protection, and were fully exposed to the deep space radiation. Space exploration by its very nature requires pioneers to step into the unknown, and cope with environments that our species has not evolved to survive. The best that we can do to prepare for future missions is to learn from the experiences of those brave souls who have ventured beyond the microgravity environment.

Delp's study went one step further by observing the cause of death for Apollo astronauts in order to determine the risk to future human explorers. Between 1968 and 1972 nine manned Apollo missions flew beyond LEO into deep space. Of the 24 astronauts that crewed the spacecraft, 8 have passed away.

Upon reviewing their causes of death, the professor noted that 43 percent of the Apollo astronauts had fallen victim to cardiovascular issues, a rate five times higher than ground crew and astronauts who never passed beyond Earth's protective magnetosphere. According to Delp, it is possible that the cardiovascular defects result from an exposure to cosmic radiation.

Image of the lunar surface captured during the historic Apollo 11 mission(Credit: NASA)

To explore his theory further, Delp subjected laboratory mice to radiation doses similar to those which would be absorbed by astronauts operating in deep space. It was discovered that six months after exposure, which would be the equivalent of 20 human years for the mice, the subjects began to exhibit signs of artery impairment. Such degradation in a human patient could in time lead to the onset of atherosclerotic vascular disease.

Having provided evidence for a link between exposure to cosmic radiation and deterioration to vascular health, Delp is now working with NASA to develop methods by which we may be able to counteract the effect of deep space radiation. Antioxidants are being examined as one line of potential treatment, the administering of which could theoretically protect a space explorer's blood vessels from damage due to oxidant stress.

The capacity to mitigate the dangers to future astronauts posed by cosmic radiation will be of vital importance if NASA is to progress with its mission to Mars, the next step of which involves the development of long term habitats orbiting in cislunar space.

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