Doctor reveals stranded NASA astronauts may face radiation sickness, increased risk of cancer upon return

TALLAHASSEE, FLORIDA: After spending an astonishing 286 days in space, NASA astronauts Sunita Williams and Barry Wilmore have safely returned to Earth on March 18.

Originally scheduled for a brief eight-day mission, their stay aboard the International Space Station (ISS) was extended by nearly nine months due to technical complications, UNILAD reported.

Doctor reveals hidden health risks astronauts face after 9 months in space

While their long-awaited return is a cause for celebration, experts warn that their extended time in microgravity comes with serious health consequences—some of which could take weeks, months, or even years to fully understand.

Medical professionals emphasize that re-adapting to Earth's gravity is no easy feat. 

Pulmonologist and Air Force veteran Dr Vinay Gupta told the Daily Mail that the astronauts will need an intensive six-week rehabilitation program to regain their physical strength. 

In addition to rebuilding their strength, the duo will need to follow a well-structured fitness routine and a balanced diet. Their initial rehabilitation will likely emphasize walking, flexibility, and muscle strengthening. However, Dr Gupta cautioned that their extended time in space brings another significant health concern, an increased risk of cancer.

“If I was their physician, I would think about a more proactive strategy for cancer screening,” Dr Gupta warned, “We want to take a different approach here, given that they had such a unique exposure history.”

According to Baylor College of Medicine, prolonged space radiation can lead to radiation sickness, neurological effects, degenerative diseases, and a significantly increased lifetime cancer risk.

Here are other health issues the astronauts may deal with after a long stay in space:

Height

Former NASA astronaut Peggy Whitson explained to 'Today' previously that astronauts grow in space due to the lack of gravity, which causes the spinal column to expand.

She mentioned that during her turn in space, she grew about an inch, while fellow astronaut Scott Kelly grew by 2 inches. Without the constant downward pull of gravity, the spinal discs stretch, leading to an increase in height.

This increase is, however, temporary. On Earth, the spinal disks compress again so Whitson experienced “dramatic” back pain upon coming back.

Bone and muscle loss

Extended time in space leads to significant bone density loss, especially in weight-bearing areas like the hips and legs.

Without gravity’s usual stress, bones lose minerals, weakening them. NASA has shared astronauts can lose 1% to 1.5% of bone density per month, increasing the risk of fractures, reduced mobility, and chronic pain.

Muscles also atrophy due to less effort in space. To combat this, astronauts must exercise for about two hours daily, including cardio and resistance training, to maintain bone and muscle strength.

However, they still face health challenges when returning to Earth.

Vision issues

Many astronauts experience vision problems after returning to Earth due to Spaceflight-Associated Neuro-ocular Syndrome (SANS).

While the exact cause is still under investigation, one theory suggests that the lack of gravity alters fluid distribution in the body, increasing pressure on the optic nerve and changing eye shape. This can lead to flattened eyeballs, optic nerve swelling, and reduced vision.

NASA reports that over half of astronauts experience some symptoms of SANS, with fluid shifts in the body causing pressure on the eyes. Although some vision issues can persist, no astronaut has reported permanent vision loss after a mission.

Heart

In microgravity, the heart doesn’t need to work as hard to pump blood, which can cause it to become slightly smaller and less efficient.

This can lead to low blood pressure and dizziness when astronauts return to Earth.

However, research shows these effects are temporary, and some studies suggest astronauts typically have better cardiovascular health than the general population.

Sunita Williams and Butch Wilmore carried on stretchers after nine-month space mission

NASA astronauts Sunita Williams and Butch Wilmore have safely returned to Earth after an unexpected nine-month stay aboard the International Space Station (ISS) far longer than their originally scheduled eight-day mission.

After 286 days in space, the astronauts were checked out by doctors soon after splashing down on Earth. They will undergo a thorough medical exam at NASA’s Lyndon B Johnson Space Center in Houston, senior correspondent Tom Costello reported on 'NBC Nightly News'.

The two astronauts were seen being wheeled off the spacecraft on stretchers, a standard NASA protocol for astronauts returning from extended missions in microgravity.

Prolonged exposure to weightlessness leads to muscle weakening, balance issues, and fluid shifts, making it difficult for astronauts to walk immediately after landing, Financial Express reported.

"A lot of them don’t want to be brought out on a stretcher," former NASA senior scientist John DeWitt told Live Science. "But they’re told they have to be.”

Williams and Wilmore originally launched aboard Boeing’s Starliner spacecraft in June 2024, but a series of technical issues forced NASA to delay their return. Instead of bringing Starliner back with the astronauts, NASA opted to return them to Earth aboard SpaceX’s Dragon capsule.

Williams engaged with students at her alma mater, Needham High School in Massachusetts.

“I’ve been up here long enough that I’ve been trying to remember what it’s like to walk,” Williams told students in January, per CBS affiliate WBZ-TV. “I haven’t walked, I haven’t sat down, I haven’t laid down. You don’t have to. You can just close your eyes and float where you are.”

Throughout the mission, Williams also maintained regular contact with her family. "I talk to my mom practically every day," she shared during a NASA Q&A session. "It’s just a little different relationship than we had planned, but we’re managing."

NASA will continue evaluating the technical failures that led to the prolonged mission.