In 2031, the International Space Station (ISS) will be deorbited in a fiery inferno, crashing back through Earth's atmosphere to its final resting place at the bottom of the Pacific Ocean. It will be the end of a decades-long international partnership that has seen the US, Russia, Europe, Japan, and other nations work peacefully together.

NASA hopes one or more commercial space stations will replace the ISS, run not by governments but, for the first time, by private companies. The goal is to “continue to do research for the benefit of humanity and maintain a sustained presence of humans in space,” says Camille Alleyne, deputy manager for NASA’s commercial space station program at the Johnson Space Center in Texas.

In December 2021, NASA funded three US companies a total of $415 million to look into developing space stations — Blue Origin, Nanoracks, and Northrop Grumman – alongside an existing partnership with the US firm Axiom Space. Similar to NASA’s Commercial Crew program in the 2010s that fostered the arrival of SpaceX’s Crew Dragon capsule and Boeing’s delayed Starliner vehicle, the plan is for multiple commercial space stations to arise from these partnerships. “We like competition,” says Alleyne.

But this dream has faltered somewhat in recently, with several companies wavering. Earlier this month, Northrop Grumman announced it would end its solo bid for a commercial space station and join a competing effort. In September, Blue Origin’s proposal for a space station was said to be in limbo as other programs, such as Blue Origin’s lunar lander for NASA’s Artemis program, took precedence.

Artemis is NASA’s plan to return humans to the Moon, which will start with four astronauts flying around the Moon in an Orion capsule in 2024. Later this decade astronauts will touch down on the lunar surface, initially in a SpaceX Starship with Blue Origin’s lander in development for future missions. NASA also plans to begin construction of a new space station near the Moon, the Lunar Gateway, as soon as next year.

All of this is interspersed with the planned retirement of the ISS. Its aging hardware means that NASA and the other ISS partners have decided, at the moment, to end the project in 2031. Commercial space stations in low Earth orbit, it’s hoped, will replace much of the current work done by the ISS. “We do a lot of science in microgravity that you cannot do here on Earth,” says Frank de Winne, head of ESA's European Astronaut Centre in Germany.

Any of these stations would not be as big as the ISS, likely comprising a few habitable modules at most. That will be enough for prolonged stays in space, or to conduct research in Earth orbit. Exactly what sort of research that might be conducted is still being ironed out. “We are in discussion with NASA and with the other ISS partners about how we’ll conduct science on commercial space stations,” says de Winne.

Axiom has already started flying private astronauts to space on SpaceX’s Crew Dragon capsule, at suggested ticket prices of some $55 million per seat — out of reach to most of us but attractive to the super-rich. Commercial space stations, if they come to fruition, could feasibly play host to lots of willing paying customers who would stay on board, like a space hotel, for days or weeks at a time.

However, the exact market case for companies to make money from operating commercial space stations remains murky, says Caleb Williams, vice president at space analyst firm Quilty Space. “The amount of development funding NASA has given out has not been huge,” he says. “We haven’t seen a lot of killer applications or high revenue-generating activities,” noting that some companies are “getting cold feet.”

Laura Forczyk, the founder of US space consulting firm Astralytical, agrees that the market potential is a little unclear. “I don’t believe anybody expected all four of the commercial space station awardees to have operational space stations because of the business case,” she says. “It’s a risky business, and we know from the International Space Station that it is very expensive to run a human-rated platform in space. It’s extremely challenging to make a space station that is profitable.”

With seven years of the ISS still left to run, the need to rush into commercial space stations for NASA or other governments may not seem immediately apparent. However, after the ISS retires, the sole space station orbiting Earth will be China’s Tiangong outpost.

That means if NASA is serious about keeping its own humans in Earth orbit it will need to put its weight behind commercial space stations. Having no space station in low Earth orbit would give China important prestige over the US, and given the rhetoric from NASA Administrator Bill Nelson on how the US is in a “space race” with China, that would be unlikely to go down well in Congress.

In 2026, NASA will announce further funding for commercial space stations in Phase 2 of its program. That could include funding not just for the aforementioned four companies, but any of a number of new players that have emerged more recently, such as the US company Vast Space. “There could be new entrants that show up that we don’t even know exist today,” says Alleyne.

The potential benefits, says Alleyne, are large. “The market is showing to be quite vibrant in the future,” she says. “Hundreds of billions of dollars [from] private astronauts, in-space manufacturing, and marketing and advertisement.”

ESA has also thrown its weight behind commercial space stations, signing a Memorandum of Understanding with Axiom in October to “explore collaborative opportunities in human spaceflight, science, technology, and commercialization” and including access to Axiom’s planned space station.

NASA’s goal is for commercial space stations to overlap with the end of the ISS, with first launches to begin “around 2029,” says Alleyne. The aim now is to make sure that one or more of the projects is viable, and can take up the mantle of the ISS when it heads towards retirement.

“We need to still be in low Earth orbit,” says Alleyne. Missions to the Moon, and perhaps one day Mars, could be separated by years, but having a space station gives a “continuous presence” in space, she says. “That’s really important.”

Can we make them work financially? All bets are off.