The teenaged daughter of NASA astronaut Butch Wilmore has spoken out about his health challenges after spending more than nine months in space. 

Daryn Wilmore, 19, said that while her dad has ‘been adjusting to gravity well,’ he has been struggling with his muscles, joints and inner ears.

That was ‘because [he’s] not used to gravity or having to hold up weight,’ she said in response to a comment in a TikTok video.

Wilmore and his crewmate, Sunita Williams, were initially scheduled to spend eight days on the  International Space Station (ISS), but were left for 286 days after the craft that brought them there malfunctioned. 

Research has shown that astronauts who complete long-term mission on the ISS — which usually last six months — experience muscle and bone loss as well as fluid shifts inside the inner ear due to low gravity.

While it typically only takes a few days for the inner ear to readjust to Earth’s gravity, regaining physical strength can take weeks to months. 

Some former astronauts have found that it can take up to 1.5 times the length of their mission to really feel like themselves again. 

On Monday, Wilmore looked healthy during his first public appearance since returning to Earth, but his daughter’s statement suggest he will still face some challenges in the weeks ahead. 

Daryn Wilmore (L), the teenaged daughter of NASA astronaut Butch Wilmore (center) has spoken out about her dad’s health challenges after spending more than nine months in space

Astronauts on the ISS experience inner-ear fluid shifts that can disrupt hearing, balance and lead to motion sickness or dizziness. 

‘Your inner ear kind of shuts off more or less in weightlessness,’ NASA flight surgeon Dr Natacha Chough told NPR. 

‘So when you reintroduce that sense of gravity, it can be a little bit disorienting.’ 

Once astronauts return to Earth, it can take a few days for the inner ear to readjust to normal gravity. But to help this along, they may do special walking exercises.

Retired NASA astronaut Leland Melvin, who completed two ISS missions, told NPR that he had to walk in a straight line and then gradually start turning.

‘You start turning and your vestibular system is all whacked out and you can just fall over,’ he said. ‘So, you walk straight and then you turn. And then you walk straight and then you turn.’

While living on the ISS, astronauts also experience significant muscle and bone loss because their bodies do not have to work as hard in low-gravity.

To reduce these impacts, they exercise for at least two hours per day on the space station. But when they return to Earth, they still need rehabilitation to help them get back to their pre-flight status. 

When Wilmore (pictured) and Williams first returned to Earth, they were immediately helped out of the Dragon capsule and onto stretchers, then wheeled away for health checks

This is all standard procedure for astronauts coming back from long-term ISS missions, but the crushing weight of gravity was evident as the pair struggled to raise their arms

Wilmore and Williams finally returned to Earth on March 18, splashing down off the coast of Florida inside a SpaceX Dragon capsule. 

The pair will likely undergo NASA’s 45-day reconditioning program, which is split into three phases and requires them to exercise for two hours per day, seven days per week.

Phase one focuses on regaining strength, flexibility and the ability to walk. This may include gait training exercises, range of motion exercises and obstacle training.

Once the astronauts have made sufficient progress, they move on to phase two, which adds proprioceptive exercises and cardio reconditioning.

Proprioceptive exercises strengthen the body and improve the mind’s perception of its movement and position. Examples include reverse lunges, banded toe taps and sumo squats with leg raises.

Phase three, the longest phase, focuses on returning the astronaut to their optimal level of physical performance through functional development training. This helps astronauts regain the skills and abilities they need in order to do their jobs and fully participate in their daily lives with ease and efficiency.

When Wilmore and Williams first returned to Earth, they were immediately helped out of the Dragon capsule and onto stretchers, then wheeled away for health checks.

On Monday, Williams and Wilmore made their first public appearances since returning to Earth, participating in a NASA press briefing where they appeared fit and healthy 

The astronauts also participated in a Fox News interview aired Monday

This is all standard procedure for astronauts coming back from long-term ISS missions, but the crushing weight of gravity was evident as the pair struggled to raise their arms. 

NASA shared photos of Williams and Wilmore the day after they splashed down, which showed them up and walking. But Williams looked noticeably frail.

Now that they have been back on Earth for two weeks, they seem to be adjusting quickly.

On Tuesday, the astronauts made their first public appearances since splashdown, participating in a NASA press briefing and a Fox News interview. Both seemed to be fit and healthy. 

Williams, who once sparked health concerns due to photos showing her apparent weight loss while on the ISS, even said she had been able to start running after just two weeks in Earth’s gravity. 

Speaking at the press conference, Williams said: ‘It’s pretty much a miracle to see how your human body can adapt.’