NASA is looking to launch Axiom Space’s fourth private mission to the International Space Station (ISS) this week, after recent attempts to repair air leaks in the Russian module appear to have been successful.

Last week, the space agency abruptly postponed the launch of Axiom Mission 4, which was set to launch on June 11. NASA cited a new pressure signal in a segment of the Zvezda service module that’s been leaking air, very slowly, for nearly six years. In a follow-up statement on Saturday, NASA explained that the pressure signal (a change in airflow or cabin pressure picked up by sensors) may be a sign that the leaks have been sealed. There’s also a chance, however, that air began flowing to a different area in the aft segment of the Russian module, leading to the new pressure signal.

“Following the most-recent repair, pressure in the transfer tunnel has been stable. Previously, pressure in this area would have dropped,” NASA wrote in a statement. “This could indicate the small leaks have been sealed. Teams are also considering the stable pressure could be the result of a small amount of air flowing into the transfer tunnel across the hatch seal from the main part of [the] space station.”

NASA is monitoring the change in pressure over time, and evaluating the condition of the transfer tunnel and the hatch seal between the space station and the back of the Zvezda module. In the meantime, the agency decided to go ahead with the launch of AX-4 no earlier than Thursday, June 19. The mission will be led by spaceflight veteran Peggy Whitson, a former NASA astronaut who holds the national record for the most cumulative days spent in space. She will be joined by pilot Shubhanshu Shukla of India, mission specialist Sławosz Uznański-Wiśniewski of Poland, and mission specialist Tibor Kapu of Hungary.

The decision to postpone the mission was to allow more time for NASA and the Russian space agency, Roscosmos, to evaluate the situation on board the ISS and decide if more troubleshooting is needed before adding more crew members to the space station. In its most recent statement, NASA said that “teams are making progress evaluating the transfer tunnel configuration.”

Roscosmos first reported the leak in August 2020, tracing it to the Zvezda life support module that Russia launched to low Earth orbit in July 2000. Since then, the rate at which air is leaking from the Zvezda service module has doubled from one pound a day to a little over two pounds a day, according to a report released in 2024. That led NASA to elevate the leak to the highest level of risk. At the time, it was reported that NASA and Roscosmos could not agree on the root cause of the leak or a way to fix it.

Although it’s taken years to address, the recent repair efforts show some progress in trying to fix the leaky space station. Whether or not the aging ISS is fit to host more astronauts right now remains to be seen.