A growing leak on the International Space Station has sparked fears that astronauts on board may need to evacuate, including the two stranded by Boeing's Starliner. 

All seven astronauts have been forced into the US side of the orbiting laboratory due to 50 'areas of concern' and four cracks in a Russian-made module.

If the leaks become severe, the space station could rapidly lose oxygen and pressure. 

The moment Houston sounds the alarm of a threat, astronauts would have to race to shut the hatch of the leaking section and head to 'lifeboats' docked on the ship. 

A spaceflight expert told DailyMail.com that if evacuation became necessary, each crew would escape in their assigned NASA spacecraft, including the SpaceX Dragon capsule and the Russian Soyuz.

NASA's Commercial Crew Program Manager Steve Stich said that in the event of an emergency, SpaceX's Dragon could be powered up within minutes. 

The capsules have been stocked with emergency suits, allowing the crew to quickly put on the proper gear as they flee the orbiting laboratory, saving more valuable time. 

However, the US space agency has admitted that it is not prepared for capsule failures due to the lack of ready-to-launch vehicles, which could leave the crew stranded without a way home.

NASA has committed to fully use and safely operate the space station through 2030, with plans to retire the ISS sometime after.

Independent spaceflight safety expert Laura Forczyk told DailyMail.com: 'If the leaks on the ISS worsen significantly to the point where NASA and Russia conclude the situation is unsafe, it may mean decommissioning the ISS sooner than expected.'

The main leak was identified in a service module transfer tunnel in Russia's Zvezda module that provides station living quarters, life support systems, electrical power distribution and data processing, flight control and propulsion systems.

American astronauts who came to the ISS on SpaceX's capsule are prepared to escape on their spacecraft if necessary.

But the evacuation plan for Don Pettit, a NASA astronaut who flew to the ISS aboard the Roscosmos Soyuz MS-26 spacecraft with two Russian astronauts in September, is a bit more complicated.

In the event of an emergency, he would not return to Earth on Soyuz. Instead, he would have to cram inside the SpaceX capsule, which was recently equipped with an extra seat just in case Pettit needs it, NASA spokesperson Jimi Russell told DailyMail.com.

It is unclear why Pettit would not return in the Russian craft, but some have suggested the swap would be due to the growing tensions between Russia and the US. 

NASA does not currently have an official evacuation plan for American astronauts assigned to Russian spacecraft. But the agency has awarded a $266,000 contract order for SpaceX to build one out. 

In the event that the leaks, cracks and other issues render the entire ISS uninhabitable, the astronaut crews would follow protocol to shelter in their respective spacecraft.  

Each crew's capsule has an assigned shelter-in-vehicle plan that will protect astronauts from threats aboard the ISS, and allow them to flee the space station if necessary, according to a September report from NASA's Office of the Inspector General (OIG). 

'It was designed with these kinds of contingencies in mind,' Stich said previously. 

They also contain astronaut suits so that crews can quickly and conveniently suit-up in an emergency situation.

It can take up to 30 minutes to get inside a spacesuit, according to NASA.

Streamlining this process as much as possible would be critical in an emergency situation. 

These vehicles would be the astronauts' only hope of escape. If something happened to them, it would be a different story.

'Due to the high costs and a limited budget, the lack of ready-to-launch vehicles prevent the Agency from having an immediate response capability if crew vehicles encounter significant damage and are no longer safe for crew evacuation,' the report states. 

Russia's Zvezda module launched in 2000 and 'served as the early cornerstone for the first human habitation of the station,' NASA has said. But like the rest of the ISS, this module is aging and requires maintenance to keep working. 

The leak has been ongoing since 2019 when air began escaping from the module's transfer tunnel, a vestibule that separates the Russian docking port from the rest of the rest of the module.

There was no immediate danger, but it was eventually located and has been patched multiple times over the last five years. 

A new leak was identified in 2021, also in the Russian Zvezda module, which was deemed a 'fairly serious issue.' 

If the leak grew severe, NASA and Roscosmos may be forced to permanently close the hatch to the affected tunnel.

And if the leaks worsened to a point where the habitability of the entire space station was affected, astronauts would be forced to sequester inside their spacecraft and potentially return to Earth. 

Former NASA astronaut Bill Shepherd, who served as the first commander on the ISS from October 2000 to March 2001, told a House of Representatives committee at the time that NASA and Russian engineers 'don't exactly understand why the cracks are appearing now.' 

Shepherd reiterated claims by Roscosmos, the Russian space agency, that it was 'becoming a serious issue.'

Despite the fact that NASA has patched the main leak repeatedly, the amount of air escaping the station has only increased over the last five years.

It was the focus of the September report from the OIG, which found that the leak then hit record rates in April - losing 3.7 pounds of air every day.

The OIG has escalated the threat rating to five out of five in NASA's internal risk assessments. 

But this leak is just the tip of the iceberg. NASA officials told the Washington Post they are tracking four other cracks and 50 'areas of concern' on the ISS.

Speaking to the Washington Post, NASA associate administrator Jim Free said: 'We have conveyed the seriousness of the leaks multiple times, including when I was in Russia earlier this year.'

The cracks have 'all been covered with a combination of sealant and patches,' by Roscosmos, and further repairs are ongoing. 

But they remain a concern, especially because the leaks are located near a hatch. NASA and Roscosmos to only open the hatch when absolutely necessary and to keep it sealed in the evenings. 

The aging ISS has remained in orbit for 10 years longer than NASA originally planned. 

The OIG identified 588 replacement parts that were operating beyond their operational lifetimes, according to the September report. 

To make matters worse, OIG is monitoring several other risks that could imperil the ISS, including potential collisions with micro-meteors and space debris. 

NASA currently plans to decommission the ISS by 2031, and has tasked SpaceX with building a Dragon-type spacecraft that could remove the station from orbit.

But there's a chance that this recent scourge of technical issues could shorten that timeline, according to spaceflight safety expert Laura Forczyk.

Though she said that worsening geopolitical relations between the US and Russia are the higher risk factor to the ISS decommissioning timeline.