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.”