Science | March 28, 2023

The ISS Will Fall From the Sky After the End of the Decade. What Will Replace It?

As NASA plans to retire the orbiting laboratory, these four privately owned and operated space stations are under development

Several private companies are designing space stations that may eventually orbit Earth. Axiom Space / Northrop Grumman / Orbital Reef / Voyager Space

Will Sullivan

Daily Correspondent

Right now, the International Space Station is orbiting the Earth every 90 minutes from around 250 miles above the surface on average at a breakneck speed of 17,500 miles per hour. For more than two decades, the station has served as a microgravity research center, which scientists have used to investigate Alzheimer’s disease and cancer, study our planet from a distance, learn more about the effects of long-duration spaceflight on the human body and conduct thousands of other experiments. But the ISS won’t last forever. Stresses on the primary structure have accumulated over time, including the effects of changing temperatures as the station swings in and out of view of the sun. Last year, NASA announced that the station’s operations would end in 2030, after which it will fall into the Pacific Ocean.

Another factor that could limit the lifespan of the ISS is tensions between Russia and the other entities operating the station—which include the United States, Europe, Japan and Canada. Last April, Roscosmos, Russia’s space agency, threatened to stop cooperating with other countries on the ISS in response to Western sanctions against Russia following the country’s invasion of Ukraine. Last summer, the head of Roscosmos said the country would leave the ISS after 2024, though Reuters reported in July that Russia’s departure may come much later. Russia operates 6 of the ISS’s 17 modules, including the space station’s propulsion system. “The Russian module is designed to be an integral part of its guidance and its operations,” says Henry Hertzfeld, an expert in the economic, legal and policy issues of space at George Washington University’s Space Policy Institute. “So if they were to pull out, particularly in the short term without giving enough advance notice, that’s an issue.”

Alice Gorman, a space archaeologist at Flinders University in Australia, thinks the ISS could theoretically last beyond 2030 if it needed to. But NASA plans to start transitioning to commercially owned and operated space stations by the end of the decade. In 2020, the space agency awarded Axiom Space up to $140 million to make at least one module to attach to the ISS, which c ould eventually be part of a new free-flying station. Then, at the end of 2021, NASA gave Blue Origin, Nanoracks and Northrop Grumman $130 million, $160 million and $125.6 million respectively to develop designs for their own stations.

“We wanted to create this environment where industry would be able to own and operate their vehicles, and then NASA procures the services,” says Misty Snopkowski, the program executive for NASA’s commercial low-Earth orbit development program. The space agency has similarly used private companies to transport crew and cargo to the ISS, she adds. One benefit of these types of arrangements is they allow NASA to use some of its funds on other endeavors.

“What we hope and what NASA hopes as well is that by transitioning from the ISS to a commercial station, NASA can continue to do research and technology development, but it frees up a bunch of money to then go on to the moon and Mars,” says Matt Ondler, chief technology officer for Axiom.

But commercial stations wouldn’t just aim to host NASA’s astronauts and research. NASA envisions being “one of many customers,” Snopkowski says. While 15 countries work together to operate the ISS, there are now 77 space agencies around the world, says Erika Wagner, senior director for emerging markets for Blue Origin. “Many of them are interested in flying astronauts for their own national needs,” she says. Other potential uses include space tourism and in-space manufacturing. For example, researchers have conducted experiments on the ISS to see whether they can design better eye implants in the microgravity environment for improving vision in people with retinal degeneration. Such implants designed on Earth are imperfect due to the tug of gravity, Ondler says.

The big questions that remain about the stations are how many will end up in orbit, and whether the market will exist to support them. China’s Tiangong space station is already operational, and India, like Russia, has announced plans for its own station. “I half joke, but it’s really true—building the space station is really pretty easy for us,” says Rick Mastracchio, director of business development for Northrop Grumman. “Building the business around the space station—that’s where the challenge is for all the companies involved in this.”

Ondler thinks NASA’s work alone could probably only support one station. Jeffrey Manber, president of international and space stations for Voyager Space and the co-founder and chairman of the board of Nanoracks, envisions two or three commercial stations joining three to four national stations in orbit. In the middle of the decade, NASA will select “at least one, maybe two” stations that it would certify for its astronauts to use and for the agency to conduct research on, says Snopkowski. Here are some of the stations that could begin orbiting Earth in the next decade.

Axiom Space Station

At least part of Axiom’s station may make it to space first. Ondler says the organization is planning to launch a module that would attach directly to the ISS in 2025. Three additional modules would follow. Each module is itself a spacecraft. So after a rocket carried each craft to orbit, it would rendezvous with the aging space station. The early modules would get power and some thermal control from the ISS, Ondler says.

The first two units would be very similar and would have the life support necessary to accommodate four crew members each. The second module would have a communications system. The third would be a research and manufacturing facility—Ondler says, for example, alloys used in high-stress parts of high-performing engines could be as much as two times stronger if manufactured in space; the crystalline structures of some alloys align perfectly when they cool in microgravity, but align imperfectly on Earth. The fourth module would have power and thermal capabilities. Its solar arrays would absorb energy for electricity, and the module would also release excess heat and contain the station’s airlock, which astronauts could use to exit and return to the station for space walks.

“Once we get that fourth module, then we have the full capability to be independent of the ISS,” Ondler says. Axiom’s station could then detach from the ISS and orbit Earth on its own. The station would combine the carbon dioxide crew members exhale with hydrogen from water to create the methane that can fuel orbit raises, debris-avoidance maneuvers and more

Crew Quarters on Axiom Space Station — An artist’s rendering of the crew quarters on Axiom’s station Axiom Space

Axiom also wants to make living on the station a pleasant experience—at least on the spectrum of space station life. “If you look at the inside of the ISS, it generally looks like a crazy person’s garage,” Ondler says. “There’s just stuff everywhere, there’s wires everywhere.” An artist’s renderings of the crew quarters inside Axiom’s station feature eggnog-colored walls and small, bright but warm lights. The crew quarters would have large, Earth-facing windows, and the station would also have an Earth observatory that would fly to the station with the third module and attach to the bottom of the station. The observatory’s eight roughly six-by-three-foot windows, arranged in an octagon, would be the largest space windows ever by far, Ondler says. The observatory would be able to hold the entire crew, and they could, for example, all share a meal in it, Ondler says.

Northrop Grumman Space Station

Instead of starting its space station from scratch, Northrop Grumman is basing its design on things it’s already building. “We want to deliver a very low-risk technical solution, something that can be put into orbit fairly quickly if the market is out there,” Mastracchio says. The company is already designing a Habitation and Logistics Outpost (HALO) module for Gateway, NASA’s planned space station orbiting the moon. The first module of its Earth-orbiting station would be a stretched-out version of that habitat. While astronauts would only visit the Gateway for several weeks to, at most, a couple months at a time, the Earth-orbiting station would be crewed year-round, so the astronauts there would need more space, Mastracchio explains.

As early as 2028 or 2029, the HALO-like module would launch to orbit first. It would have a service component that would keep the station in orbit and avoid things in its path. Shortly after, as many as two stretched versions of the Cygnus spacecraft the company already uses to fly cargo to the ISS could temporarily dock to the station. These spacecraft would provide additional space for storage, crew habitation and science, Mastracchio says.

The initial module is meant to provide similar services to the customers using the ISS, but at the same time, Northrop Grumman is looking for new potential users, such as countries that want to get involved in space but aren’t involved with the ISS, Mastracchio says. The company’s station would have the capability to add additional larger modules also based on HALO’s design if the demand arose, whether that’s for tourism, manufacturing or science. While NASA has made a lot of scientific progress on the ISS, there are some topics it will need to continue to study, such as the effects of microgravity on the human body over long periods of time, Mastracchio says.

Blue Origin’s Orbital Reef

Orbital Reef Space Station — A rendering of Blue Origin’s Orbital Reef Orbital Reef

Blue Origin envisions its Orbital Reef station as a business park in space. It would have a core module that functioned like a lobby, to which modules for habitation and research would attach. The core would also join to a mast with solar panels for capturing energy and a large fin-like radiator for releasing excess heat from the station. The core and mast would also take care of the station’s environmental control systems and communications, as well as guidance, navigation and control, Wagner says.

Astronauts on Blue Origin would not have to work where they rest. “We have zoned the space station so that you are not sleeping in the laboratory and you are not working in your bedroom,” Wagner says. A lab module would attach to one side of the core, and an inflatable “life habitat” and a node module would attach to the other. The lab would have facilities for research in fields such as life sciences and material sciences on the inside, and experiments would also be able to attach to the outside of the module. The “life habitat” would contain sleeping quarters, the kitchen and exercise facilities. The node would be attached to that section and would allow additional visiting vehicles to dock to the station—and have an air lock that the astronauts would use to enter and exit for work outside the station.

Blue Origin plans for Orbital Reef to host more than just science experiments and manufacturing. Wagner says people in the entertainment industry could theoretically use the station for anything from a movie studio to a sports facility. She imagines the station could also someday add facilities specialized for consumers, such as a luxury hotel. Despite having significantly fewer modules than the ISS, Orbital Reef’s internal volume would still be 90 percent that of the ISS, and up to ten astronauts could live on the station once the life habitat and node joined. At any one time, these astronauts could be a mix of Orbital Reef crew, NASA crew, space tourists, private researchers or entertainers. While the ISS is packed, with bags strapped to the walls, wires snaking around and narrow working corridors, she adds, Blue Origin envisions its station being less cluttered. “If you’re going to go on a vacation to space, you don’t want to feel like you’re living in cramped quarters on a submarine,” Wagner says.

Starlab from Voyager Space and Nanoracks

Starlab Space Station — A rendering of the Starlab station orbiting Earth Voyager Space

While the other stations would be made up of different modules launched separately, Voyager Space and Nanoracks’ station, Starlab, would launch all at once. The station would include a habitat, docking node, propulsion system, robotic arm and solar panels, which would unfurl once the station got to space. “We’ll be fully operational after that one launch,” says Manber. “We believe that this will be the largest mass ever launched.”

The cylindrical habitat would likely be separated into three different floors for the crew quarters, research and manufacturing, and it would be able to support four astronauts. While the ISS has a lot of room, it’s crowded. “You’ve got sleeping bags velcroed to the wall, and there’s very little privacy, and you’ve got researchers right near where you sleep,” Manber says of the ISS. “We’re hoping to separate that all out.” The team has brought in the hotel chain Hilton to design the habitation space, and the sleeping area would be more spacious than on the ISS.

Not only would Starlab have a science laboratory in space, but Nanoracks would also operate a replica of the laboratory hosted on Earth by the Ohio State University. Before carrying out research in orbit, visitors would be able to work with hardware and familiarize themselves with the lab on the ground in Ohio.

The station could take on an additional module, but Manber says a partner or customer would have to want to attach something to the station for that to happen. An organization like the European Space Agency, for example, might want to attach a module for research or tourism to the station. But what Manber sees as the more likely scenario is that the companies eventually build a second Starlab. They’re already thinking through what an additional space station could look like and what additional markets it could serve. Right now, all stations are exploring a wide range of possible uses, including hosting space agencies’ astronauts, manufacturers and tourists. Similarly, Manber likens the ISS to the first store on the frontier in the American West: the general store. But over time, Manber thinks stations will specialize. “You’re going to see platforms emerge where one may be devoted to manufacturing, one may be [for] tourism, one may be a habitat for professional astronauts,” he says. “As I look out over the next ten years, it starts to get exciting.”