Astronaut life expectancy and the limits of general population comparisons.

Abstract

NASA's rigorous medical selection has successfully limited in-flight medical emergencies throughout six decades of human spaceflight, but its effectiveness in identifying individuals with exceptional long-term survival remains unquantified. We estimated age-specific mortality rates based on 299 male US astronauts selected 1959-2021, using mortality data through 2022 (9602 person-years, 69 deaths). We restricted analyses to male astronauts due to insufficient follow-up time and observed mortality among female astronauts, who were first selected in 1978 and remain relatively young. We estimated astronaut hazards across the lifespan by combining rates from a Poisson regression model (for natural-cause mortality) with calculated empirical rates for external causes. These mortality rates were used to construct life tables, from which we derived life expectancy estimates and compared them to 2022 US general population values. Astronauts demonstrated substantial survival advantages at all ages, with life expectancy exceeding the general population by approximately 5 to 7 years between ages 30-70. At age 50, astronauts had a life expectancy of 36.7 years versus 29.1 years for the general population (a difference of 7.6 years). These findings quantify selection effectiveness as a countermeasure while highlighting fundamental epistemological limitations in using general population comparisons to assess spaceflight health risks.