A new UC San Diego-led study has found that space travel accelerates cellular aging, weakening astronauts’ immune systems and heightening disease risks.
A new study has found that space travel may accelerate the aging process at the cellular level, raising concerns for astronaut health on long missions.
The research, published in Cell Stem Cell and led by UC San Diego biochemist Jessica Pham, examined human hematopoietic stem and progenitor cells (HSPCs) sent aboard SpaceX missions and kept on the International Space Station for up to 45 days.
These cells, which produce and maintain blood, showed signs of decades-worth of aging under the combined stress of microgravity and cosmic radiation.
The study revealed that space exposure increased inflammatory proteins, reduced healthy cell regeneration, and accelerated cellular burnout. The most alarming marker was the shortening of telomeres—the protective tips of chromosomes that shrink with age—leading to higher risks of disease and immune dysfunction. Some cells also failed to suppress the “dark genome,” normally dormant DNA segments that can destabilize the immune system when activated.
Dr. Catriona Jamieson, a co-author, described space as “the ultimate stress test for the human body.” While some cellular damage may be reversible once astronauts return to Earth, scientists say the findings will be vital for protecting crews on long-duration missions and could even provide insights into slowing aging on Earth.