This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Astronauts who undergo long-duration spaceflight aboard the International Space Station often return with health problems that resemble some age-related conditions in people on Earth. Remarkably, some of these declines reverse within months of their return, but others persist.
This raises an intriguing question: What can be learned from these rapid changes, and could they help prevent or reverse aspects of age-related decline on Earth? That question has turned space into a laboratory for aging research. Spaceflight reproduces many features of aging.
Astronauts also experience unusual conditions, including very low gravity, increased radiation and disrupted sleep. Even so, changes that usually develop over decades on Earth can appear within weeks or months in space, giving scientists an opportunity to observe some aging-related processes in fast-forward. A 2026 study, which tracked four astronauts during the nine-day Axiom-2 mission, examined chemical markers attached to DNA that can be used to estimate biological age.
This is an estimate of how old the body appears to be based on molecular changes, rather than the number of years a person has lived. The astronauts' estimated biological age increased during the mission and began to fall after they returned to Earth. This does not mean that they physically aged by years in a matter of days.
With only four participants, the study cannot provide firm conclusions, but it shows how rapidly the body can respond to the conditions of spaceflight. Why would leaving gravity behind affect the body in ways that resemble aging? On Earth, muscles, bones, the cardiovascular system and other organs are adapted to function under the constant pull of gravity.
That continual mechanical load helps keep these systems healthy, although their function often declines later in life. In space, many of those demands disappear. Skeletal muscle provides one of the clearest examples.
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