The Mortality of Space Explorers

Outer space exploration poses unique risks to human survival. Here, we review the current literature on United States astronauts and Soviet and Russian cosmonauts and provide updated and original research findings. As in previous research, both astronauts and cosmonauts are shown to have reduced risk of death by natural causes, particularly from chronic diseases such as cardiovascular disease and cancer, compared with appropriately matched general populations. Simultaneously, space explorers are at increased risk of death by external forces, particularly accidents such as plane crashes and spacecraft accidents. In total, both astronauts and cosmonauts are at reduced risk of all-cause mortality in comparison to the general populations of the United States and Russia. However, in comparison to astronauts, cosmonauts have been at equal risk of accidental death, but increased risk of death by chronic disease. We conjecture that the lack of risk from chronic disease may be due to the excellent health and medical monitoring of space explorers coupled with the deliberate attempts to limit their radiation exposure levels below those that would be detrimental. The differences in the astronaut and cosmonaut mortality experiences are likely due to lifestyle factors and the background rates of mortality in the two nations.