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SpaceX launch of private Ax-4 astronauts postponed indefinitely due to leaky ISS module

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Ax-4's liftoff had already been delayed by a propellant leak in its Falcon 9 rocket.

portrait of four astronauts — three men and one woman — in black and white spacesuits
The crew of Axiom Space's Ax-4 mission to the International Space Station. From left to right: mission specialist Tibor Kapu; pilot Shubhanshu Shukla, commander Peggy Whitson, and mission specialist Sławosz Uznański-Wiśniewski. (Image credit: SpaceX)

The SpaceX launch of four private astronauts has been delayed again.

The Ax-4 mission to the International Space Station (ISS) had been scheduled to launch atop a SpaceX Falcon 9 rocket from Florida's Space Coast on Wednesday morning (June 11), but a propellant leak in the booster nixed that plan.

And now, another leak — this one in Ax-4's destination — has further postponed the liftoff.

an astronaut in a white spacesuit takes a spacewalk outside a space station

Roscosmos cosmonaut Pyotr Dubrov performs a spacewalk in June 2021 at the International Space Station. The Russian Zvezda module appears below him in the picture. To the right is the old Russian Pirs docking port, which was removed to make way for the updated Nauka science and docking module in July 2021. (Image credit: NASA)

Cosmonauts recently detected a "new pressure signature" in the Zvezda service module, part of the Russian segment of the ISS, NASA officials announced in an update today (June 12).

This development isn't exactly a shock; this area first sprang a leak back in 2019, and cosmonauts have been dealing with it ever since, as the recent spot check shows.

The cosmonauts "sealed some additional areas of interest and measured the current leak rate," NASA officials wrote in the update. "Following this effort, the segment now is holding pressure."

“The crew aboard the International Space Station is safely conducting normal operations," NASA spokesperson Cheryl Warner said in an emailed statement. "We’re assessing this latest update and will provide additional information as available.”

Still, the agency and Axiom Space, the Houston company that organized Ax-4, decided that grounding the mission for now is the prudent course of action.

Doing so "provides additional time for NASA and Roscosmos to evaluate the situation and determine whether any additional troubleshooting is necessary," NASA wrote in today's update, referring to Russia's space agency.

No new target launch date has been announced.

Related stories:

 — Axiom Space: Building the off-Earth economy

— International Space Station: Everything you need to know about the orbital laboratory

 — Top 'safety risk' for the ISS is a leak that has been ongoing for 5 years, NASA audit finds

As its name suggests, Ax-4 will be Axiom's fourth crewed mission to (and from) the ISS. The roughly two-week-long flight will be commanded by record-breaking former NASA astronaut Peggy Whitson, who is now Axiom's director of human spaceflight.

The three other crew members are pilot Shubhanshu Shukla of India, Polish mission specialist Sławosz Uznański-Wiśniewski and Hungarian mission specialist Tibor Kapu.

Nobody from India, Poland or Hungary has ever visited the ISS, so this trio will make history when Ax-4 is finally able to get off the pad.

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Mike Wall
Mike Wall
Senior Space Writer

Michael Wall is a Senior Space Writer with Space.com and joined the team in 2010. He primarily covers exoplanets, spaceflight and military space, but has been known to dabble in the space art beat. His book about the search for alien life, "Out There," was published on Nov. 13, 2018. Before becoming a science writer, Michael worked as a herpetologist and wildlife biologist. He has a Ph.D. in evolutionary biology from the University of Sydney, Australia, a bachelor's degree from the University of Arizona, and a graduate certificate in science writing from the University of California, Santa Cruz. To find out what his latest project is, you can follow Michael on Twitter.

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