How will Sunita Williams’ body have changed when she returns from space in February 2025?

Indian origin astronaut Sunita Williams has found herself in a predicament that only a handful of humans have experienced: she’s “stuck” in space. No, she’s not literally stuck — her return is finally scheduled for February of next year. But in the nine months that Williams will spend in space, her body will have undergone a series of changes that are both fascinating and concerning.

Muscle and bone loss

In space, everything changes — especially when it comes to the human body. The lack of gravity aboard the International Space Station (ISS) means that Sunita’s muscles and bones haven’t been working as hard as they would on Earth. Without the constant pull of gravity, astronauts experience muscle atrophy and significant bone density loss — sometimes losing as much as 1% of bone mass per month. Upon her return, Sunita will likely undergo a rigorous rehabilitation program to help her regain strength and bone density.

The eyes have it

One of the lesser-known but more intriguing effects of long-term space travel is its impact on vision. Astronauts often suffer from what’s known as Spaceflight-Associated Neuro-ocular Syndrome (SANS), a condition where fluid shifts in the body cause pressure on the optic nerve, leading to changes in eyesight. Sunita’s vision might be temporarily impaired, requiring monitoring and possibly corrective measures when she’s back on Earth.

Fluid shift and swollen head

In the microgravity of space, fluids in the body redistribute, leading to what’s often described as the “puffy face and chicken legs” — a phenomenon where fluids like blood shift towards the upper body in the absence of hydrostatic pressure. This fluid shift also causes increased pressure on the brain, which can affect cognitive function and lead to headaches. Sunita will need time to readjust to Earth’s gravity as these fluids return to their normal distribution. Fortunately, these fluid levels return to normal within three days of returning to Earth.

Radiation and the DNA dilemma

Space is a hostile environment in more ways than one. The ISS offers some protection from cosmic radiation, but Sunita has still been exposed to levels much higher than on Earth. This radiation can damage DNA, increasing the risk of cancer and other health issues down the line. Her cells might show signs of molecular changes, and she will likely be under medical surveillance for years to monitor any long-term effects.

Mental and emotional strain

Spending extended periods in space is also mentally taxing. Isolation, confinement, and distance from Earth can take a toll on an astronaut’s psychological well-being. In fact, astronauts receive significant mental training to steel themselves for time in space. Many astronauts also indulge in regular social activities such as movie and game nights to ease their stress during this time.

What caused her delayed return?

Sunita Williams' return from the International Space Station (ISS) has been delayed due to issues with the Boeing Starliner spacecraft, which was initially planned to bring her back to Earth. Technical challenges with the Starliner’s thrusters and other systems have caused NASA and Boeing to conduct additional reviews and tests to ensure the spacecraft's safety before it is cleared for the return journey.
After many delays and considerations, NASA has confirmed that they plan to bring Williams back on the SpaceX Crew-9 mission, which is scheduled for February 2025. This would involve some adjustments, including launching Crew-9 with only two members instead of the usual four, to accommodate Williams and her fellow astronaut Butch Wilmore.

The delay has left Williams and Wilmore aboard the ISS longer than initially planned. Despite this, NASA has assured that they are well-prepared for an extended stay, with sufficient supplies of food, clothing, and oxygen. Additionally, the ISS regularly receives resupply missions to ensure all astronauts have what they need.