Axiom Space will create its space station by detaching modules it initially installs on the International Space Station. Credit: Axiom Space

For most of NASA’s history, it dealt with only one space station at a time: the space station. A half-century ago, that space station was Skylab, giving the agency its first experience with long-duration spaceflight. In the 1980s, it became the proposed Space Station Freedom, which evolved in the 1990s into the International Space Station once Russia joined the effort. The ISS, its oldest modules now nearly 25 years old, is slated to operate through the end of the decade.

The agency and the space industry, though, are preparing for a future that may involve multiple space stations operated commercially. NASA is currently supporting four such efforts, while others are making plans for commercial stations of their own. Yet, it’s not clear how many stations can be supported by the demand from NASA and other customers or if that demand will emerge in time, given the limited lifetime of the ISS.

The Vast Space Haven-1 space station is designed to host four-person crews for up to 30 days at a time.

Vast goes fast

The latest entrant in the commercial space station race is a startup called Vast. The company, funded by cryptocurrency billionaire Jed McCaleb, revealed plans in September 2022 to build large space stations that could spin, generating artificial gravity. Vast, though, offered few details about those plans or other company activities other than a February acquisition of Launcher, a small launch vehicle company whose technology Vast planned to use on those future space stations.

In May, Vast announced its first space station. Haven-1 will be a single module that can launch on a Falcon 9. It will support visits by four-person crews on SpaceX Crew Dragon spacecraft, spending up to a month at a time at the station. Vast announced an agreement with SpaceX both for the launch of Haven-1, slated for as soon as August 2025, and a Crew Dragon mission there called Vast-1. The contract includes an option for a second such mission.

Vast still plans large rotating space stations but sees Haven-1 as a way to gain experience and get ahead of competitors. “We believe that it’s more important that we demonstrate that we can have the first but also a full space station system in orbit,” Max Haot, who joined Vast as president when the company acquired Launcher, said in an interview.

Gravitics’ StarMax would offer about 40% of the International Space Station’s pressurized volume with a single module.

Vast’s schedule would put it ahead of Axiom Space, which plans to launch its first commercial module to the ISS in late 2025. Haot acknowledged that his company’s schedule was ambitious but that the simplicity of its approach, including leveraging Crew Dragon systems to support crews when docked to Haven-1, made that schedule feasible. He was also skeptical of Axiom’s schedule, noting the company hasn’t yet announced launch plans for its initial module.

Getting Haven-1 launched early would also, he said, give the company a leg up on the next phase of NASA’s Commercial Low Earth Orbit Destinations, or CLD, program to support development of commercial stations. Vast has not yet started when NASA selected teams led by Blue Origin, Northrop Grumman and Voyager Space in late 2021 for funded Space Act Agreements to assist in the initial design work on their stations. (Axiom has a separate agreement, announced in early 2020, giving it access to a port on the ISS for attaching its commercial modules.)

The next phase of the CLD program, where NASA will fund certification of those stations for use by agency astronauts, will be a full and open competition, not limited to those who won earlier awards.

“We see NASA as our biggest opportunity,” he said, and Vast plans to bid on the next CLD competition, scheduled around the time Haven-1 enters service. “Haven-1 is all about it, to some extent. It’s saying we’re not going to send you renders or prototypes in a warehouse. We have flight hardware.”

Haot said Haven-1 is fully funded but did not disclose how much the Vast expected it to cost. McCaleb, with an estimated net worth of $2.4 billion, has stated he plans to fund at least the initial phases of Vast’s operations on his own. In a May 24 court filing as part of Virgin Orbit’s bankruptcy proceedings — Vast bought Virgin Orbit’s test facility in Mojave, California, for engine development work — McCaleb said he has committed to providing up to $300 million for Vast. “To date, I have solely funded the enterprise and expect to continue to do so for the foreseeable future,” he stated.

An expanding array of companies and technologies

Other companies are planning to get into the space station market. Gravitics, a startup that has, so far, kept a low profile, is working on large space station modules. A design it calls StarMax would offer 400 cubic meters of volume — about 40% of the entire ISS — in a rigid design 7.6 meters in diameter. The company has started testing prototypes of StarMax but has not disclosed long-term development plans or schedules.

Above Space aims to develop large rotating space station but has shown little public progress.

Another startup, Above Space (until recently known as Orbital Assembly), has talked for several years about developing large rotating space stations, but has shown little public progress in either technology or fundraising. The company did secure a $1.7 million U.S. Space Force contract in March to work on technologies for deployable structures.

As in many emerging fields, the companies involved are pursuing a wide range of technical approaches for their stations. Northrop Grumman, for example, plans to develop space station modules that leverage its experience with the Cygnus cargo spacecraft and HALO module for the lunar Gateway. Axiom Space plans to convert a shuttle-era multipurpose logistics module (MPLM) used to carry cargo to the station into a research and lab module.

Sierra Space, which is working with Blue Origin on the Orbital Reef space station, is developing inflatable modules, a technology pioneered by now-defunct Bigelow Aerospace and demonstrated on the ISS. Sierra Space is testing versions of its Large Inflatable Flexible Environment (LIFE) modules that initially will each have about one-third the pressurized volume of the ISS.

“We looked at how we can accelerate the affordability of space,” said Tom Vice, chief executive of Sierra Space, of the company’s focus on inflatable modules. He said that technology is far more scalable that traditional approaches to meet the needs of future customers, like companies planning to do research or manufacturing in orbit.

“The only way you ever get the economics to work is with large inflatables,” he argued, enabling space stations to be operational after just a few launches. With traditional structures, he said, “you’re back to building space stations the way the ISS was.”

During the 38th Space Symposium in Colorado Springs, Sierra Space used part of its large exhibit to show off LIFE, including plans for larger versions. A third generation of LIFE could have more volume than the entire ISS once inflated, yet still fit within the payload fairing of a vehicle like New Glenn or Starship. “It’s the same basic technology,” Vice said.

Uncertain markets

NASA sees the emergence of more companies pursuing space stations as a validation of its strategy to transition from the ISS to commercial stations.

“To see other companies now entering the fray, using their own funding and aren’t necessarily looking for NASA financial assistance at this point, is a very positive development,” said Phil McAlister, director of the commercial space division in NASA’s Space Operations Mission Directorate, during a meeting of a NASA Advisory Council (NAC) meeting a few days after Vast’s announcement of Haven-1.

Sierra Space used part of its large exhibit at the 38th Space Symposium in April to show off its Large Inflatable Flexible Environment (LIFE) modules.

The companies that have won CLD awards are making good progress on their designs, he said. There have been some issues, such as when Voyager Space switched from its original partner, Lockheed Martin, to Airbus, but he noted that the company has been doing well since that change. “I’m very pleased with the performance of the providers.”

The biggest challenge for those companies is likely not going to be technical, but instead economic. Both NASA and the companies involved acknowledge it’s unclear how big of a market there is beyond NASA for commercial stations from other governments, companies or space tourists, creating uncertainty about how many companies can close their business cases.

“There’s no one business case” for commercial stations in general, McAlister said. The different companies working with NASA on the CLD program are taking different approaches, he explained, with Northrop emphasizing government astronauts, Voyager Space focusing on research, while Blue Origin and Sierra Space paying more attention than the others on tourism. Axiom, meanwhile, was devoting similar attention to all three markets.

One thing is clear, he added. “They are all going to need non-NASA business to close their business cases.”

Companies acknowledge uncertainty about the sources of demand for commercial space stations and their size. “I don’t fundamentally believe there is a market yet,” said Tejpaul Bhatia, chief revenue officer of Axiom Space, during a Space Symposium panel in April. His company is, for now, going after “low-hanging fruit” from individual countries and companies that have expressed interest.

“Is there a market? I think that is what we are all racing to figure out,” he said. “It’s not racing to see who develops the first commercial space station. The question is, is it sustainable from a business standpoint?”

Sierra Space and Blue Origin are developing the Orbital Reef concept as a “mixed-use business park.”

“Nobody really knows how fast this market is going to grow,” said another panelist, Brent Sherwood, senior vice president for advanced programs development at Blue Origin. He argued that the company was covering its bases with a “mixed-use business park” approach to Orbital Reef that can accommodate a variety of potential customers.

Other companies are making more focused bets on where that market will be. “Our goal is not to be everything for everyone,” said Marshall Smith, vice president of exploration at Voyager Space, during the panel. The focus of his company’s Starlab is, for now, on research, citing the demand from NASA and other prospective customers. It will have the same space for payloads as the ISS in just 40% of the volume.

“Let’s see how the market develops,” he said. “As we move forward and markets develop, the next one may be more focused on tourism or manufacturing.”

But neither the companies developing stations nor NASA have the luxury of patience to see how those markets develop. NASA wants at least one commercial station in service by 2028 to enable a gradual transition from the ISS, set to be retired in 2030.

“That’s an aggressive schedule,” Sherwood acknowledged, but one that was necessary. “The number one objective is the avoidance of a gap.”

Axiom Space has flown two crewed missions to the ISS aboard SpaceX Dragon capsules but is skeptical about the viability of commercial space stations, including its own. “I don’t fundamentally believe there is a market yet,” an Axiom exec said in April.

A post-ISS gap would be more significant than the post-shuttle one, he argued, when NASA could still get its astronauts to the ISS by paying the Russians. “If we have a gap this time, there is no partner,” he said. “From a geopolitical perspective, it is fundamental to Western society and the promulgation of democracy and capitalistic principles that we do not abandon LEO for human spaceflight.”

That might mean more NASA funding to support space station development. Smith noted that the CLD program started before broader economic changes, like rising interest rates, that made it more difficult for companies to raise funding. “That may mean there needs to be more public engagement to keep this on track.”

NASA has, so far, not signaled any plans to increase spending on CLD beyond its current budget projections. McAlister told the NAC committee that NASA was focused on securing the proposed sharp increase in funding from $224 million in 2023 to more than $400 million by 2027.

He admitted that having at least one commercial station operating by the end of 2028 to enable that two-year handover from the ISS is a “very aggressive” goal. He said NASA did have some flexibility in that it didn’t necessarily need two years to transition from the ISS, and having multiple companies working on stations offered some redundancy.

“We’re going to have to monitor the health of the ISS and the speed at which the commercial destinations become reality,” he said. “We don’t have everything figured out on commercial LEO.”

Vast’s Haot said that while his company is committed to developing Haven-1, its future plans — the company released a roadmap showing plans for building larger modules designed for SpaceX’s Starship that could form spinning stations — will depend on what happens with the next NASA CLD competition.

“It all depends on the state of the low Earth orbit economy,” he said, including the emergence of commercial applications that can close the business case for a large space station without help from NASA. “It’s hard to tell at this point.”

This article originally appeared in the June 2023 issue of SpaceNews magazine.

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...