Credit: NASA / Wikimedia Commons
July 9, 2026 — The dream of sending humans to Mars has never felt closer, but a sobering new study from the University of Central Florida suggests the journey itself may come with a biological price tag that reads like an accelerated clock.
Researchers at UCF’s College of Medicine have found that the brutal one-two punch of weightlessness and space radiation triggers changes in the liver that are nearly indistinguishable from the molecular hallmarks of aging, and the damage begins within a single day.
The study, led by Professor Michal Masternak and published in the journal GeroScience, exposed animal models to a simulated deep-space environment that replicates what astronauts would endure on a round trip to Mars: 14 days of microgravity combined with galactic cosmic radiation and solar particle events. The results were stark.
“Just 24 hours after radiation exposure, there are many genetic changes in the liver that are remarkably similar to what happens during aging,” Masternak said.
The liver showed a trifecta of aging-like effects: increased cellular senescence, where cells lose their ability to function normally; rising inflammation; and the early development of fibrosis, or tissue scarring. These are conditions that, left unchecked, can lead to declining organ function over time.
Crucially, the team did not stop at the lab bench. They compared their findings against real human blood samples from NASA’s landmark Twins Study, which tracked astronaut Scott Kelly during his year in orbit alongside his Earth-bound twin Mark, and from SpaceX’s Inspiration4 civilian mission. The genetic signatures matched, confirming that the lab model accurately reflects what happens inside the human body during actual spaceflight.
“If we see some acceleration of aging in space, then we can observe processes happening much faster, understand them better and eventually use that knowledge to improve health for people here on Earth,” Masternak said.
The implications are double-edged. For space agencies eyeing missions to Mars, a journey that would expose crews to deep-space radiation and microgravity for months at a time, the findings underscore the urgent need for biomedical countermeasures. The UCF team identified one promising avenue: molecules called antagomirs, which can interact with microRNA to influence aging and inflammation pathways. While still in early stages, the approach points toward targeted therapies that could protect astronauts on long-duration missions.
But the study’s reach extends far beyond orbit. Aging researchers see space as a kind of time machine, a compressed environment where biological processes that normally play out over decades can be observed in weeks. Understanding the early molecular triggers of aging in the liver could help scientists develop therapies for age-related diseases that affect millions on Earth, from fatty liver disease to cirrhosis.
“Age is the gradual and cascading failure of multiple organs and systems happening together,” Masternak noted. Space, it seems, offers a front-row seat to that cascade.
The study was funded by the National Science Foundation, the Florida Department of Health, and the National Science Centre Poland, with contributions from researchers at Rensselaer Polytechnic Institute, Weill Cornell Medicine, the University of Pittsburgh, and UNC Chapel Hill.
As NASA and its international partners push deeper into the solar system, the message from UCF is clear: the path to Mars runs through the liver, and the clock starts ticking the moment you leave Earth.