The NASA astronauts who were supposed to be on an 8-day mission in space.

Astronauts Sunita "Suni" Williams and Barry "Butch" Wilmore are both veteran professionals when it comes to all things space.

As NASA astronauts and former US Navy test pilots, the pair were thrilled when they were selected to go to the International Space Station (ISS). They were told they'd spend eight days at the ISS, before heading back down to Earth.

Those eight days passed... and so did another eight days. And then another.

It's now been almost 70 days since Williams and Wilmore arrived at the ISS. Now they've just been told they might not return to Earth until 2025. 

So... are the astronauts stuck in space?

The short answer is yes, kind of. 

The International Space Station has been orbiting Earth since 1998, and it's a large spacecraft that serves as a base where crews of astronauts and cosmonauts live while studying space (very generally speaking).

Several nations worked together to build and use the space station, primarily Russia and the US. That's where Williams and Wilmore come in.

They were launched aboard the Boeing Starliner spacecraft, which is designed to transport crew to and from the ISS and other low-Earth-orbit destinations, on June 5, 2024.

The next day they arrived safely at the ISS, where they were supposed to work and stay for approximately eight days.

Watch: Jeff Bezos in space. Post continues below.

However, several issues with Starliner have meant the astronauts' mission has been extended indefinitely.

According to a CBS News report, whistleblowers have claimed that NASA and Boeing were aware of liquid helium leaks in the Starliner. Officials allegedly detected the leak, but the report suggests the problem was deemed too minor to delay the mission. There are also reportedly thruster malfunctions.

Williams, 58, and Wilmore, 61, aren't literally stuck in outer space. But they are essentially forced to remain in the ISS until a safe plan is devised for them to return if the Starliner leak issues and thruster malfunctions aren't sorted. 

They now are facing the likely prospect of spending Christmas and New Year in space.

When will the astronauts return to Earth?

The backup plan is as follows — Williams and Wilmore will remain aboard the ISS, and come down on a different spacecraft, which is scheduled to launch and head to the ISS on September 24.

This different spacecraft, SpaceX's Crew Dragon, can carry up to seven passengers to and from Earth orbit, and beyond. 

The September 24th Crew Dragon mission was already scheduled to take place before the Starliner drama began.

The plan was for it to carry four astronauts from Earth to the ISS for an outposting due to last until February 2-25. 

This would mean Williams and Wilmore would have to stay in the ISS with the four additional crew, wait for the outpost to finalise, and then all would return together on the Crew Dragon. The potentially faulty Starliner would then return to Earth without any crew, under computer control, given it might be deemed unsafe for human life to be aboard that spacecraft. 

Sunita "Suni" Williams and Barry "Butch" Wilmore. Image: AAP.

How are Sunita "Suni" Williams and Barry "Butch" Wilmore coping?

NASA has assured everyone that the astronauts are in good spirits. 

"I have a real good feeling in my heart that this spacecraft will bring us home, no problem," Williams said during a news conference.

Wilmore agreed, telling reporters: "We're absolutely confident. That mantra you've heard, failure is not an option."

If the pair stay in the ISS until February 2025, it will mean they will spend around 250 days in space. It's not the longest stint, Russia's Valeri Polyakov having spent 437 days in space aboard the Mir space station in the mid-1990s. 

The impact will be nonetheless significant. 

During their extended stay, Williams and Wilmore could be exposed to radiation levels equivalent to 150 to 6,000 chest X-rays. Such high exposure levels increase their risk of developing cancer, though the risk level isn't extreme.

The effects of zero gravity long-term on the human body are interesting too — potentially leading to a loss in bone density, and muscle atrophy.

Plus, there are the emotional and mental impacts of facing such unique and isolated conditions. But the remarkable thing about astronauts is they're trained to endure conditions like these. 

As for how the pair have been keeping themselves busy, the Wall Street Journal says the astronauts are conducting various research, including microbe studies, as well as staying fit with microgravity jogging. 

Ultimately, a decision is expected to be made next week about when Williams and Wilmore will return to Earth. For now, they'll make the most of what the ISS has to offer. 

Feature Image: X.