After spending an exhausting nine months in space, it’s no surprise that the NASA astronauts who were ‘stuck’ in orbit have undergone some noticeable changes.

On Tuesday (March 18), astronauts Barry ‘Butch’ Wilmore and Sunita ‘Suni’ Williams finally returned to Earth aboard the SpaceX Dragon spacecraft after being ‘stranded’ on the International Space Station (ISS) since June of last year.

Spending such a long time away from Earth inevitably takes a toll on the body, something NASA is well aware of. This was evident when the crew was immediately placed on stretchers upon landing in the Gulf Coast near Tallahassee, Florida—before they even had a chance to stand on solid ground.

Aside from finally breathing fresh air again, Wilmore and Williams are also experiencing the pull of gravity on their bodies for the first time in nine months—something that brings its own set of health concerns.

According to the Daily Mail, potential issues range from weakened muscles and sensitive feet to a heightened risk of cancer, meaning the astronauts aren’t entirely in the clear just yet.

As they undergo a series of medical tests at NASA’s Johnson Space Center in Houston, some experts have already pointed out early signs of possible health deterioration.

Observers have noted that before-and-after photos of Wilmore and Williams suggest they may have lost weight in space, with both appearing noticeably thinner.

Beneath the surface, experts suggest that fluid buildup in the head—caused by pressure on the eyes and optic nerves—could be altering their appearance.

This condition is known as Spaceflight Associated Neuro-Ocular Syndrome (SANS), which can lead to optic nerve swelling and cause blurry or distorted vision.

Although most astronauts’ eyesight returns to normal after they return to Earth, NASA warns that some effects could be permanent, depending on the duration of their mission—raising concerns for this particular crew given their extended time in space.

When it comes to cognitive function, shifts in brain pressure, combined with stress and sleep deprivation, could contribute to mental decline, as has been observed in other astronauts.

Microgravity poses the biggest challenge for the pair, as the absence of Earth’s gravitational pull leads to muscle weakening over time, making it harder to maintain a healthy weight.

This is also why they struggled to walk upon returning to Earth.

Even with a strict workout routine and a high-calorie diet on the ISS, astronauts can still experience muscle atrophy, which may explain their frail appearance.

Another factor is Spaceflight Venous Thrombosis (SVT), which causes fluids to shift upward, often giving astronauts a “puffy” look as if they were hanging upside down.

Fortunately, NASA reports that most astronauts regain their pre-mission fitness levels within 45 days, though in severe cases, recovery can take months or even years.

Retired British astronaut Tim Peake shared on RadioX: “For me, going into space was no problem at all, but for the first two days on Earth, I felt pretty rough. I think Butch and Suni will be feeling a bit rough right now. You know, the whole body is just getting used to gravity. The vestibular system’s a bit messed up. You feel dizzy, a bit nauseous. So, it’ll take them a couple of days to get over that.”