Leonard David's INSIDE OUTER SPACE

Showing its age – the International Space Station.
Image credit: NASA

Yes, in space, everyone can hear a hiss.

“A new pressure signature” has been identified in the Russia-supplied Zvezda service module attached to the International Space Station.

That issue, with NASA working with Russia’s Roscosmos, has led to postponing the launch of the private Axiom Mission 4 to the ISS.

The problem cropped up after a recent post-repair effort with the Zvezda module, NASA stated.

Leak rate

“Cosmonauts aboard the space station recently performed inspections of the pressurized module’s interior surfaces, sealed some additional areas of interest, and measured the current leak rate. Following this effort, the segment now is holding pressure,” NASA added in a Thursday communiqué.

The postponement of Axiom Mission 4 give NASA and Roscosmos added time to evaluate the situation and determine whether any additional troubleshooting is necessary.

Crew of Axiom Mission-4 private astronaut mission. From left are, Pilot Shubhanshu Shukla from India, Commander Peggy Whitson from the U.S., and Mission Specialists Sławosz Uzanański-Wiśniewksi from Poland and Tibor Kapu from Hungary.
Image credit: Axiom

Long-time concern

Problems with the Russian-supplied station segment have been a long-time concern.

Back in 2021, onboard cosmonauts were tasked to fix a 2-inch (4.5-centimeter) air leak in the Zvezda intermediate chamber. Patulas, glue-mastic, Hermetall and Anaterm sealants, sandpaper, foam rubber, fluoroplastic films, alcohol wipes, metal pads, and electrical tape were utilized. Also, toss in goggles, respirators, rubber gloves, a drill and a vacuum cleaner.

A new launch date for the fourth private astronaut mission will be provided once available.

“NASA defers to Roscosmos to answer specific questions about the Zvezda module,” NASA stated.

Roscosmos reaction

In a posting on the Telegram channel, Roscosmos notes that the leak in the Russian segment of the ISS has been eliminated. “Roscosmos continues daily monitoring and maintenance of all systems in the Russian segment of the International Space Station.”

Roscosmos explains that the next stage of sealing the transition chamber of the Zvezda service module has been completed. “According to experts from the Mission Control Center, there is no leak in the Russian segment of the ISS.”

Image credit: Roscosmos

The history of air leakage from the intermediate chamber of the Zvezda service module of the ISS, points out Roscosmos has been going on for more than five years. “It was first reported in September 2019. Several attempts have been made to seal the leak in recent years, but all attempts have led to only partial results.”

After sealing in June 2025, concludes Roscosmos, “tests show that the air leak in the transition chamber has stopped completely, for the first time since it was discovered.”

For a current review of the situation, go to this story by Marcia Smith at the SpacePoilicyOnline.com website:

NASA Confirming Success of ISS Leak Repairs Before Finalizing Ax-4 Launch Date