Astronaut who spent over a year in space had major changes to his body as two remain stuck up there now

NASA astronauts Butch Wilmore and Suni Williams may have been stranded in space for nine months, but they are nowhere near the US record.

Technical issues on their Boeing Starliner spacecraft prevented them from returning after stepping aboard the International Space Station (ISS) in June 2024.

Ever since, a return date for their return has been up in the air, and delayed numerous times.

There was hope this week, as a potential launch date was set for 12 March by NASA and SpaceX, who have been working on the Crew-10 mission, though this has been delayed due to a hydraulic fault.

It could still launch this evening (14 March) with four astronauts on board, with a potential return for Wilmore and Williams on Monday (17 March).

President Donald Trump and Elon Musk have been working to get the pair back down to Earth, but even their extended stay in space doesn't come close to what NASA astronaut Frank Rubio experienced in 2023, after spending 371 days in space, setting an American record.

After more than a year in space, he set foot on Earth on 27 September, 2023, and went through several bodily changes as he readjusted to life with climate and gravity.

Rubio's mission was intended to be six months long, but as his time was more than doubled, we got to find out the effects of living gravity-free for an extended period of time.

While the vast majority of humans will never get the opportunity to visit space, this might be the closest we can get.

So, what are these effects, and how many of these might apply to Wilmore and Williams?

The pair will have to undergo a number of medical tests (MIGUEL J. RODRIGUEZ CARRILLO/AFP via Getty Images)

The lack of gravity causes a decrease in muscle mass and even bone loss within just the first couple months of a mission – let alone the year Rubio spent up there.

At the time of the NASA astronaut's landing, Dr Jennifer Fogarty, chief scientific officer at Baylor College of Medicine's Translational Research Institute for Space Health, told ABC News: "How do you coordinate movement like walking, which you haven't done for a long period of time, and then the idea of balance?

"When you put those two together, it can kind of create a little bit of a precarious situation and something that's very well-monitored with the crew members when they land on Earth."

The expert also added that the longer the time in space goes on for, the longer the time it takes for the astronaut to reacclimatise when they get back.

So while Wilmore and Williams may take some time to get back to normal, it will be nowhere as extreme as Rubio's experience.

Nine months is bad, but more than a year in space is brutal (Paolo Nespoli - ESA/NASA via Getty Images)

Also, when living in space, an astronaut’s blood flow can be heavily affected.

This can cause symptoms including blurred vision or eye swelling due to something known as Spaceflight Associated Neuro-Ocular Syndrome.

According to the co-director of the Center for Aerospace Physiology at Case Western Reserve University School of Medicine, Dr Michael Decker, our veins have handy-dandy valves in them to make sure ‘blood doesn’t flow backwards when we stand up’.

And being enclosed in a weightless room for a long period of time will certainly impact the body's blood flow.

He added: "Some of this increased intracranial pressure can actually impact the eye and lead to visual impairment.

"Sometimes when astronauts land, that visual impairment does not necessarily resolve."