What happened to Sunita Williams’s hair? NASA explains

U.S. astronauts Barry "Butch" Wilmore and Sunita Williams returned to Earth early Sunday morning after a nine-month space mission, with noticeable changes in their appearances. Williams, in particular, drew attention for her newly greyed hair, a striking transformation from her previous look.

NASA later addressed this, explaining that extended time in space can lead to significant physiological changes. In an online post, the agency stated: "Imagine if all of your physiological changes were hyper-accelerated so that you passed through life cycles in weeks instead of decades. You’d be able to grow a beard overnight, your hair might start greying in days, or menopause could arrive by next weekend."

NASA further elaborated: "This may seem far-fetched, but spaceflight induces major physiological changes, including accelerated muscle and bone density loss and immune system dysfunction—effects that parallel natural aging on Earth."

The Impact of Space Travel on Hair and Aging

Research suggests that space travel can significantly affect human hair. A 2016 National Institutes of Health (NIH) study found that spaceflight alters hair follicle gene expression. Additionally, a 2015 study involving mice on the International Space Station (ISS) observed changes in skin thickness and hair follicle cycles after three months in orbit.

Radiation Risks and Long-Term Effects

A previous report suggested that astronauts face a higher risk of cancer due to prolonged radiation exposure in space. Scientists continue to study the long-term health impacts of extended space missions, with Williams’s transformation reigniting discussions on how space travel accelerates aging and affects the human body.

Williams, 59, and Wilmore, 62, arrived at the ISS in June via Boeing Starliner. Technical issues delayed their scheduled return, extending their stay until SpaceX's Crew-9 mission in March. During their time 240 miles above Earth, they experienced various physical adaptations to the space environment. Williams, one of NASA’s most experienced spacewalkers, has logged 62 hours and 6 minutes across nine spacewalks—the second-highest for any female astronaut.