The developer of a commercial space station on Wednesday plans to launch its fourth private astronaut mission to the orbital laboratory it aims to replace.
Axiom Space—which expects to launch the first module for its Axiom Station in 2027—is leading the approximately two-week International Space Station (ISS) mission, scheduled for liftoff Wednesday at 2:31 a.m. EDT from Kennedy Space Center in Florida. The SpaceX Dragon capsule carrying Axiom Mission 4’s (Ax-4) four international crewmembers is expected to dock with the ISS in the early morning Thursday. The rendezvous will be streamed live by Axiom, SpaceX, and NASA. SpaceX’s workhorse Falcon 9 rocket will launch the crew to orbit.
NASA has contracted Axiom for five ISS missions. So far, all have featured entirely private crews, with the most recent, Ax-3, splashing down in February 2024 after 18 days aboard the ISS.
Ax-4 commander Peggy Whitson, the company’s director of human spaceflight, is a former NASA astronaut who commanded Ax-2 the year prior. Whitson has spent more time in space than any American—675 days and counting. Joining her are India’s Shubhanshu Shukla, Hungary’s Tibor Kapu, and Poland’s Sławosz Uznański-Wiśniewski, making each nation’s first ISS visit and second human spaceflight.
Each Axiom mission includes science objectives designed to take advantage of the microgravity environment on orbit. The research will set the stage for Axiom Station—one of several commercial ISS alternatives that could come online after the ISS is destroyed at the end of the decade. Axiom is also working with Prada to develop spacesuits that NASA astronauts will wear to explore the lunar surface in mid-2027.
Ax-4 will continue to push the envelope, with about 60 planned activities marking the most on an Axiom mission to date. NASA—which Axiom will reimburse for crew training and access to facilities—will conduct a few of them. But the mission is billed as a highly collaborative effort involving 31 nations. The European Space Agency (ESA), Indian Space Research Organization (ISRO), and Hungarian to Orbit (HUNOR) program all contributed experiments.
Crewmembers will research human health not just in space but on Earth. Experiments will cover a range of topics, from cancer treatments to on-orbit farming to the effects of microgravity on the brain, heart, and muscles.
In addition to the science, each mission gives Axiom valuable experience working in space—and managing that work from mission control in Houston. By the time the first Axiom Station module launches in 2027, the company expects to have five or more ISS trips under its belt.
“We’ve got to get the [new] station up and running before the ISS is decommissioned,” Whitson told Time magazine. “That push for…expansion in space is important from a technology perspective [and] from a space power perspective.”
Station assembly will take place entirely on orbit. Four or more subsequent modules will link to the initial power, payload, and thermal module, which will detach from the ISS shortly after arriving and fly freely.
Axiom Station is one of several ISS replacements being developed under NASA-backed efforts. Other contractors include SpaceX, Blue Origin, Northrop Grumman, and Vast Space. The space agency envisions a transition to these private destinations to open opportunities for more commercial activity. Before then, though, it hopes to launch at least two more private astronaut missions to the aging laboratory.
Ax-4 has been delayed several times this month in order for NASA to examine a “new pressure signature” on the station’s Zvezda service module. Managed by Russia’s Roscosmos, the segment recently underwent repairs to seal small leaks that have plagued it for years. NASA postponed the launch to ensure the ISS—currently occupied by the seven crewmembers of its six-month Expedition 73—is ready to welcome new personnel.
The mission has also been delayed due to weather conditions and a liquid oxygen leak on SpaceX’s Falcon 9, which has since been repaired, per NASA.
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