NASA's two stranded astronauts are approaching a year in space, but what could that mean for their bodies?
In June 2024, astronauts Suni Williams and Butch Wilmore were due to stay for one week on the International Space Station (ISS), but technical difficulties have left the duo stuck in space, 9 months later.
On March 4, Williams and Wilmore took part in a press conference ahead of their planned return on a SpaceX Crew Dragon, which will take place sometime after March 12.
During the press conference, Wilmore said that despite the planned week-long trip, they had come prepared to stay for a long time, as "that's what human space flight is all about, planning for unexpected contingencies, and we did that."
The astronauts were asked about the impact on their bodies, and whether space flights get harder with age, but Wilmore said his "joints don't ache because there's no pressure on them."
So, what happens to the body when in space?
The changing gravity in space can affect the body in multiple ways. Transitioning from one gravity to another, such as from earth's gravity to weightlessness, can affect spatial orientation, head-eye and hand-eye coordination, balance and locomotion, and may cause space motion sickness, according to NASA.
Fluids in the body also shift upwards, risking vision problems and an increased risk of kidney stones due to dehydration.
Weightlessness can also cause weight-bearing bones to lose between 1 percent to 1.5 percent of mineral density per month, which may not be fully restored upon return to Earth with rehabilitation. Astronauts also lose muscle mass in microgravity.
There are ways to help combat these effects, from compression cuffs to keep blood in the lower extremities, to certain medicines to reduce the risk of kidney stones.
On Earth, we're exposed to low levels of radiation every day, which can cause an increased risk of cancer and degenerative diseases, but we are shielded by the planet's magnetic field and atmosphere. In space, astronauts are exposed to an increased level of space radiation, giving long-term health risks. Researchers are working to mitigate this impact.
According to the Baylor College of Medicine's Center for Space Medicine, long durations in space can change a person's eyes, including globe flattening, optic disc edema, and vision changes. The Space-Associate Neuro-ocular Syndrome (SANS) is a recognized condition which causes swelling in the back of the eye after a duration in space.
In microgravity, the heart does not need to work as hard to pump blood around the body, and this can lead to deconditioning and even a decrease in size of the heart. This can lead to increased arrhythmias and, on return to Earth, issues with a weaker heart pumping blood around the body at normal gravity.