Did Traveling to the Moon Take a Toll on Astronauts’ Hearts?

Astronaut Buzz Aldrin is pictured during the Apollo 11 extravehicular activity on the moon. (Credit: NASA) Astronauts who explore deep space may be more likely to suffer from cardiovascular disease later in their lives. That’s the implication of a new study, which found that Apollo astronauts, who had flown to the moon in their 30s, were more likely to die of cardiovascular problems in their 50s and 60s than astronauts who flew missions in low Earth orbit. In low Earth orbit—the domain of ISS and the former Space Shuttle flights—Earth’s magnetic field blocks radiation from further out in space, like galactic cosmic rays or charged particles from solar flares. Physicists call this ionizing radiation, because the particles have so much energy that they strip electrons away from atoms as they pass by. That radiation, especially in the form of heavy, high-energy ions like 56-Fe, seems to damage the cells that line the walls of blood vessels, called endothelial cells. “Healthy endothelial cells help prevent atherosclerotic plaque from forming inside the walls of blood vessels; this is commonly referred to as hardening of the arteries,” says Michael Delp of Florida State University, who led the study. Plaque buildup can eventually lead to blood clots, coronary heart disease, heart attacks, or strokes.