Apollo Astronauts May Be More Likely to Die from Heart Disease

Thursday, 18 August 2016 - 4:47PM
Space
Thursday, 18 August 2016 - 4:47PM
Apollo Astronauts May Be More Likely to Die from Heart Disease
Traveling to the moon might be even more dangerous than we thought. According to a new NASA-funded study, Apollo lunar astronauts might be more likely to suffer from fatal cardiovascular disease as a result of the deleterious effects of long-term deep space travel.

The health effects of space travel are only beginning to be understood, and even trips to low-Earth orbit have been found to have an impact, such as weakened bones and temporary growth spurts, mostly due to the microgravity. But when it comes to trips to deep space, there may be an even more frightening side effect: an increased risk of death from heart disease.

In their study of astronauts who have traveled to space, the researchers found that Apollo astronauts who had traveled to the moon were significantly more likely to suffer from cardiovascular disease (CVD) than both astronauts who had gone to low-earth orbit (LEO) and astronauts who never went to space. But even stranger, there was no statistically significant difference the LEO astronauts and the Earth-bound astronauts, leading the researchers to believe that it was specifically a factor related to deep space travel.

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"Despite virtually identical estimates for galactic cosmic ray exposure, the mortality rate of LEO astronauts for CVD is significantly lower than in Apollo lunar astronauts," the authors wrote in their paper. "Furthermore, LEO astronauts do not exhibit significant differences in mortality compared to non-flight astronauts."
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Since deep space missions are generally longer than near-Earth missions, the researchers considered whether this was simply another effect of long-term weightlessness, or whether there was a factor specific to the lunar missions that caused the damage to the cardiovascular tissue. In order to determine this experimentally, they simulated weightlessness on one group of mice, and subjected another group of mice to full-body radiation. They found that the mice who had experienced weightlessness were no more likely to have heart damage, while the irradiated mice showed similar effects to the Apollo astronauts.

Although there's a slim chance that the radiation shields weren't working properly on the Apollo missions, the researchers concluded that this is likely an effect of the increased radiation levels in deep space. Although there is also radiation in low-Earth orbit, the Apollo astronauts are the only ones to have traveled outside of Earth's geomagnetic shield, which deflects many of the potentially harmful charged particles from the galactic cosmic rays.

The researchers acknowledge that there are several flaws inherent to their study, mostly as a result of the necessarily small human sample size. But still, studies like these indicate that there is still plenty that we don't know about the health effects of space travel, and scientists need to investigate further in order to protect astronauts on future space missions.

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"As multiple spacefaring nations contemplate extended manned missions to Mars and the Moon, health risks could be elevated as travel goes beyond the Earth's protective magnetosphere into the more intense deep space radiation environment," the authors wrote.
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