Just two years after walking on the moon, James Irwin suffered a heart attack, and NASA doctors had dismissed any notion of a connection with his trip to space, despite him having experienced irregular heart rhythm there.
Irwin died of another heart attack, at the age of 61. In 1990 astronaut Ron Evans died of a heart attack in his sleep at the age of 56, and Neil Armstrong died of cardiovascular complications at 82.
The deaths of Irwin, Evans, and Armstrong stood out to Michael Delp, a cardiovascular physiology expert at Florida State University. This is because these men have at least one thing in common: all three flew to the moon.
It’s hard to tell the statistical significance of the fact, as the sample size is just too small. Only 24 humans have ever left the orbit of the Earth, and at the time of the study, only seven of them had died. Only Irwin, Evans, and Armstrong among them had died from heart disease.
Mark Shelhamer, ex-Human Resource Scientist, NASA said that the numbers are too small. He believes that the conclusions could be more rigid if the numbers were better proportioned.
A lot of the recent research on astronaut health has been focused on how to prevent cancer caused by the high doses of radiation that the astronauts are exposed to and how to cope with the physiological effects of lack of gravity. But when Mr. Delp, a researcher with NASA was asked to take a look at the causes and reasons of the deaths of the astronauts, he found that cardiovascular problems should also be a major concern.
He exposed mice to simulated space conditions. The weightlessness reduces the chances of cancer as a result of radiation. However six months into the experiment, he found that the weightlessness wore off, but the radiation remained.
NASA made a statement claiming that it keeps its astronauts under health supervision throughout their lives, and was still skeptical of the results from Mr. Delp’s study.
Interestingly enough, the death rates from cardiovascular disease in the low-Earth orbit and non-flight groups were around 10 percent. The figures may be small but according to Mr. Delp, it is worth studying further.