Axiom Space shuffles space station assembly sequence – to get it standalone sooner

Axiom Space has shuffled the assembly sequence of its space station to remove any dependence it would have on the International Space Station (ISS) by as soon as 2028.

The plan has always been for Axiom to attach its modules to the ISS. The modules would then detach upon the ISS's retirement, creating a free-flying Axiom station.

Upon hearing the news Axiom was revising the assembly sequence, a space agency source mused, "The end of the ISS could be closer than anyone thinks."

SpaceX was this year contracted to have a deorbit module for the ISS ready by 2029, and the current plan calls for the outpost to be sent back to Earth in 2030. Russia, however, has yet to formally commit to keeping the station going past 2028. ESA astronaut Andreas Mogensen told The Register in October 2024, however, that he "wouldn't be surprised if we extended it [the ISS] a few years."

Axiom's timing was tight and has been getting tighter as the years pass. The original sequence was to attach the Habitat 1 (AxH1) module first, before the power and thermal module. The change swaps the first two modules around – the Payload Power Thermal Module (AxPPTM) will go first, followed by AxH1. An airlock, Habitat 2 (AxH2), and the Research and Manufacturing Facility (AxRMF) will follow.

The AxPPTM structure will be built by Thales Alenia Space in Turin, Italy, and sent to Houston no earlier than fall 2025 for internal fit-out by Axiom. Thales plans to use parts from AxH1 and AxH2 to speed construction.

Axiom Space Chief Operating Officer and Axiom Station program manager Mark Greeley said, "We were ready to answer the call when NASA asked us to relook at our space station development plan.

"Our ongoing assessment of the assembly sequence revealed opportunities for flexibility and enhancements. With the International Space Station needing to protect for the ability to accommodate a deorbit vehicle on station, we were able to accelerate this work to support the program's requirements."

Exactly when the ISS will be retired is difficult to determine. There are the official dates mentioned earlier, but the final mission could occur sooner if there are more hardware issues aboard the aging station, or if the political will to keep the lights on wanes.

Some parts of the ISS are showing their age.

• A decade on from maiden flight, NASA's Orion is still waiting for its Moon moment
• SpaceX hits 400 launches of Falcon 9 rocket
• SpaceX Dragon gives ISS a helping hand with altitude
• Japan's space agency to build a digital twin of its ISS module – right before it retires

The US space agency, NASA, and Russia's Roscosmos continue to disagree on the cause and severity of air leaks in the Russian section of the ISS, with NASA's Office of Inspector General describing the cracks and leaks in the Service Module Transfer Tunnel as "a top safety risk."

The leak rate has increased in 2024, although NASA and Roscosmos have not agreed on when the leak rate would become untenable. According to Mogensen, the worst-case scenario would be if part of the ISS had to be sealed off, meaning Roscosmos would have to forgo a docking port.

Axiom's plan to be capable of free flight earlier than planned gives the company some extra breathing space in the event of delays but also means another space station is more likely to be available should the ISS be retired ahead of schedule. ®