The ISS is the best place for an astronaut to get stuck in space

Being stranded in space sounds like the makings of a dramatic science fiction movie, but reality is a bit less flashy. Real-life space travel involves rigorous preparation, massive teams of support staff, and backup plans for almost every imaginable scenario.

This intense planning is exactly why the recent coolant leak on the Russian Soyuz spacecraft isn’t as dire as it originally seemed. 

In December 2022,  a micrometeorite damaged the Soyuz MS-22 spacecraft docked on the ISS, which affected the capsule’s cooling systems that keep astronauts at safe temperatures on their descent back to Earth. Engineers determined that the craft wasn’t fit for return, except in case of an emergency. The crew originally carried up on the Soyuz was stranded. 

But they were stranded aboard the safest place in space: the International Space Station. “We have the ISS as a safe haven,” says former NASA astronaut Mike Massimino, who flew aboard the space shuttle in 2002 and 2009 to service the Hubble Space Telescope. “If you get stuck up there, you just hang out there for a while until someone comes and gets you.”

The ISS is about the size of an American football field, and made up of almost 40 different modules, as diverse as solar panels to docking ports to pressurized, habitable living areas. Construction on this orbital behemoth began in 1998, and it has been occupied by at least one astronaut since the turn of the century.

[Related: ISS astronauts are building objects that couldn’t exist on Earth]

Its modular design is not only a quirk of its assembly, but a conscious design choice. In the event of an emergency—the top three are fire, depressurization, and toxic air—the crew exits the damaged area, sealing off modules as they go to isolate the leak or other issue. Even if something were to happen aboard the ISS while the crew from Soyuz MS-22 were stuck, “the chances are you’re going to be able to isolate [the problem] until you figure out how to get other folks home,” according to Massimino.

The astronauts are also trained for risky situations. They prepare on the ground before their voyages and aboard the space station. Plus, the American astronauts have to be familiar with the Russian tech on board (and vice versa) and even learn to speak Russian so that they are able to effectively work with their international counterparts.

Yet, among the many different emergencies astronauts prepare for, a damaged return capsule doesn’t feature prominently. The mission teams are more focused on ensuring the ISS remains safe and habitable, and aren’t as concerned about the ferries between space and the ground. “The spacecraft on which astronauts and cosmonauts fly to the space station are the intended spacecraft for their return to Earth,” says NASA media representative Joshua Finch.

[Related: The ISS gets an extension to 2030 to wrap up unfinished business]

In the late 1990s to early 2000s, NASA considered a dedicated “lifeboat” for the ISS, known as the X-38. It would have been a glider, similar to the space shuttle, with the sole purpose of returning astronauts to Earth in emergency situations. Although prototypes were successfully tested, the program was canceled in 2002 due to budget constraints. Instead, astronauts learned to rely on the ever-expanding ISS.

“When we had the shuttle flights after the [Space Shuttle Columbia] accident, there was a real possibility that you might not be able to come back because of your return vehicle,” Massimino recalls. “And we weren’t worried about that because if you inspected the vehicle and you couldn’t repair it, you would just stay on the space station.” Given that people have lived aboard the ISS for as much as a year at a time, a brief layover there while waiting for your connecting spaceflight doesn’t seem so bad.

American and Russian mission support teams also immediately began coordinating their next steps after the recent leak, putting their rigorous training into action while astronauts waited onboard. Numerous plans were considered, from fitting more astronauts into the SpaceX capsule also docked on the ISS to sending up new vehicles to bring them home. “Engineers at each space agency work together to provide safe return options in the event of an emergency situation,” Finch explains, “as NASA and Roscosmos have done while creating the Soyuz 68S crew return plan.”

In early January, NASA and Roscosmos decided the best course of action was to move up the date of the next Soyuz launch, sending up an uncrewed capsule to give the astronauts a ride home. The launch will send up the Soyuz MS-23 on February 20—and until then, the astronauts will continue with business as usual and ride out their stay on the ISS, humanity’s only oasis in space beyond our home planet.