WASHINGTON — Commercial space station developer Vast Space has signed a deal with SpaceX for two private astronaut missions to the International Space Station, pending NASA approval.

Vast announced Dec. 19 that it completed an agreement with SpaceX to fly two Crew Dragon spacecraft to the ISS on what NASA calls private astronaut missions, or PAMs. These are short-duration missions to the station and serve as a stepping-stone to future commercial space stations.

“Enabling payload and crewed missions to the ISS is a key part of Vast’s strategy, allowing us to further our collaboration with NASA and global space agencies,” Max Haot, chief executive of Vast, said in a statement. “These missions not only strengthen our expertise in human spaceflight operations and collaboration with NASA but also position Vast as a leading contender to deliver the next-generation successor to the ISS.”

“I am excited to work with Vast as they build more opportunities and destinations for more people to travel amongst the stars,” Gwynne Shotwell, president and chief operating officer of SpaceX, said in the same statement.

Those missions are contingent on winning NASA approval. The agency has to date awarded four PAM opportunities, all to Axiom Space and with little or no competition from other providers. Axiom has flown three of those missions and is preparing for the fourth, Ax-4, scheduled for launch in the spring of 2025. All of those missions have used Crew Dragon spacecraft.

Haot announced in February Vast’s intent to bid for future PAM opportunities. NASA has yet to issue a solicitation for any future missions, although the agency has previously said it would support up to two PAMs a year. In practice, the agency has allowed one mission a year so far.

Vast will face competition from Axiom for PAM opportunities. That company announced Dec. 18 revised plans to assemble its own commercial space station, which previously involved docking a series of habitat and research modules to the ISS that would form the core of a later standalone station. Axiom now plans to install a power and payload module to the ISS that will not have crew accommodations, later removing it to dock with a habitat module to form a free-flying station.

Axiom executives said in an interview about the plans that they would continue to rely on PAM opportunities to visit the ISS. “Our plan is to continue to compete for PAM missions as long as they make them available,” said Mark Greeley, chief operating officer of Axiom Space and program manager for Axiom Station.

Vast said its agreement with SpaceX for Crew Dragon missions to the ISS is in addition to an earlier contract with the company for the launch of its Haven-1 module and at least one Crew Dragon mission to it. Haven-1, scheduled for launch as soon as late 2025, will be able to support up to four short-duration visits, helping Vast test technologies and gain experience for its larger Haven-2 space station it is proposing to NASA’s Commercial Low Earth Orbit Destinations program.

Vast said it is in “active discussions” with government space agencies about participating on any private astronaut missions it flies to the ISS. It cited as one example the Czech Republic, which signed an agreement with Vast in November to examine potential flight opportunities for Czech astronauts on Vast missions.

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...