How will two astronauts stuck in space pass time (and survive) until 2025?

It’s the plot of plenty of sci-fi films: two astronauts are stranded in space and don’t yet know how they’re getting back.

Sunita “Suni” Williams and Commander Barry “Butch” Wilmore arrived at the International Space Station (ISS) in June as the first crew to test Boeing’s new Starliner, which suffered helium leaks and thruster failures before it docked – raising questions over how safe it is for the return flight.

Boeing has insisted the astronauts are not stuck and said “there’s no increased risk” in bringing them back in the Starliner, but NASA is contemplating getting them back on a SpaceX flight instead.

They should have only been in space for eight days, but they’ve now been there for more than two months and may have to stay until February.

But do they have enough supplies for such a stint, how are they coping mentally and what is day-to-day life like at the ISS?

Size and facilities

The ISS is 356 feet (109 metres) end-to-end, one yard shy of the full length of an American football field including the end zones.

The living and work space, NASA says, is larger than a six-bedroom house, and has six sleeping quarters, two bathrooms, a gym, and a 360-degree view bay window.

As you’ll see later, it’s not quite as luxurious as it sounds.

Ms Williams and Mr Wilmore aren’t alone; they’re sharing the facilities with seven other astronauts from other missions; four of them fellow Americans and three of them Russians.

Is there enough food, water and oxygen?

Yes, there are reserve supplies up there to keep astronauts going for plenty of time.

The space station has its own oxygen-generating systems, and about 50% of oxygen exhaled from carbon dioxide is recovered.

As for water, the station has a urine-into-drinking-water recycling system, and a part of that system also captures moisture released into the cabin air from the crew’s breath and sweat.

Food supplies are a bit fancier. Meals are created at NASA’s Space Food Systems Laboratory in Houston, where chefs focus on making food appetising as well as nutritious.

Much of it is dehydrated, meaning it has to be filled up with water before being consumed, while some is ready-made and just needs to be heated.

There’s meat (barbecued beef brisket is one example of a meal on offer), eggs, vegetables, bread, savoury snacks and sweet treats in the station’s kitchen.

Crew members are also allowed to request some of their own personal favourites from off the shelves.

In a video on NASA’s YouTube channel, Ms Williams revealed her favourite commodity was Nutter Butter spread – and showed off a jar her family had sent up for her.

When were supplies last sent?

The spacecraft regularly receives more supplies from Earth, with the last one arriving on 6 August.

Launched on a rocket from Kazakhstan on 30 May, the supplies included about three tonnes of food, fuel and other supplies for Ms Williams, Mr Wilmore and the seven other crew members on board.

The crew can essentially place their orders for what they want to come on these crafts by speaking to Mission Control ahead of launches.

That was good news for Mr Wilmore and Ms Williams, who were forced to ditch their personal suitcases before taking off in June to make room for extra equipment, meaning they’ve had to wear spare clothes that were already at the ISS upon arrival.

Their own clothes finally arrived with the 6 August supplies, and more supplies are set to be sent up in a few months.

Once supply ships are emptied at the ISS, the crew fill them with their rubbish before sending them back to Earth.

How do you use a toilet without gravity?

There are some things space-based movies just don’t cover – but Ms Williams got into the grittier details of space life on NASA’s YouTube channel.

In the video filmed in 2012, Ms Williams showed off the toilet, which somewhat resembles one you might see on an airplane.

The difference is there are two separate tubes to go in – one for urine and one for poo. The urine one, which is coloured yellow, is attached to the wall and almost looks like a vacuum cleaner – and fittingly it has a suction function to prevent gravity from causing a mess.

The tube for poo looks like more of a typical toilet, with a seat too – though you have to hold on to a handle on the wall next to it to avoid floating away as you go.

On the bright side, there’s about half-a-dozen types of toilet paper stuffed into bags on the toilet walls, including wet wipes and disinfectant wipes in case “things don’t go correctly,” as Ms Williams puts it.

Astronauts are also each given toiletry kits that come with things like a toothbrush and toothpaste (which you have to either swallow or spit into a tissue) and a hairbrush – which Ms Williams says is pointless in space because gravity constantly keeps your hair upright.

What about sleeping arrangements?

Remarkably you can sleep on the floor, on the wall or on the ceiling.

That’s because without gravity, the crew never feel like they are lying down. It makes no difference whether they are on the floor, standing up or upside down – it all feels the same.

So the ISS has sleeping stations about the size of phone booths that the crew get into, which consist of a sleeping bag and a pillow on the floor, wall and ceiling.

Leisure time

When they aren’t running space experiments, the crew can enjoy their view of Earth from the station’s observatory deck, or head to the Advanced Resistive Exercise Device (ARED) in the Tranquillity node – a fancy term for gym equipment.

The ARED offers traditional upper and lower-body exercises, such as squats, dead lift, heel raises, bicep curls and bench press by using vacuum cylinders to replicate weights in gyms.

The crew is encouraged to use it throughout their space stays, as muscle and bone loss is common on long missions.

How are the pair feeling?

They are both retired navy captains and longtime NASA astronauts who already have long space station missions behind them.

Mr Wilmore, 61, and Ms Williams, 58, said going into this test flight that they expected to learn a lot about Starliner and how it operates.

At their only news conference from space in July, they assured reporters they were keeping busy, helping with repairs and research, and expressed confidence in all the Starliner testing going on behind the scenes.

“I have a real good feeling in my heart that the spacecraft will bring us home, no problem,” Ms Williams told reporters.

There are tests going on back on Earth to determine whether the Boeing craft can still be used safely to bring them back.

“That mantra you’ve heard, ‘Failure is not an option,’ that’s why we are staying here now,” Mr Wilmore said last month.

“We trust that the tests that we’re doing are the ones we need to do to get the right answers, to give us the data that we need to come back.”

There’s been no public word from them yet on the prospects of an eight-month stay.

Mr Wilmore’s wife Deanna told AP earlier this week that he is “content” at the space station, “neither worrying nor fretting”.

She said Mr Widmore, who is a longtime elder at a church in Texas, has faith God is in control, and that this gives his family “great peace”.

What’s happening now?

As it stands, all but one of the Starliner’s five failed thrusters have been reactivated in orbit.

Tests are currently being done on Earth to try to remedy the problems seen in space, but engineers aren’t sure exactly what’s causing them and are also trying to plug helium leaks in Starliner’s propulsion system, which is crucial for manoeuvring.

Boeing has reiterated its capsule could still safely bring the astronauts home, but the company will need to modify Starliner’s software in case it has to return without a crew.

Ken Bowersox, NASA’s space operations mission chief, has suggested coming home on the same aircraft is still an option.

Mr Bowersox said during a recent meeting, they “heard from a lot of folks that had concern, and the decision was not clear”.

The SpaceX flight they would get on instead would leave Earth in September, but two astronauts scheduled to be on it would have to stay home to make room for Ms Williams and Mr Wilmore.

A decision is expected in the next week or so.

Would this be the longest anyone has spent in space?

No – Russian Valeri Polyakov set that record in the mid-1990s, spending 437 days off Earth.

And last year NASA astronaut Frank Rubio came back from a 371-day trip alongside Russian astronauts Sergey Prokopyev and Dmitri Petelin, breaking the record for the longest amount of time spent in space by an American.

That trip, much like this one, was prolonged by technical difficulties, and was only meant to take six months.