Leak on International Space Station delays SpaceX launch of Axiom-4 astronauts

The crew members of Axiom-4 are stuck in a holding pattern inside their astronaut quarantine, as a leak persists in of of the space station's Russian modules.

Houston-based Axiom Space was set to launch its fourth astronaut mission (Ax-4) with SpaceX last week, but the mission is being postponed again due to an air leak detected in Russia's Zvezda module of the International Space Station (ISS). The mission was originally slated for June 11, and has been pushed down the calendar three times now, due to the issues aboard the ISS.

The leak in Zvezda isn't new, but a recent pressure change within the module is prompting NASA and Axiom to hold off on the Ax-4 launch until they are sure it poses no danger to the incoming crew. "Following the most-recent repair, pressure in the transfer tunnel has been stable. Previously, pressure in this area would have dropped. This could indicate the small leaks have been sealed," NASA wrote in a June 14 update. Now, the Ax-4 mission has been delayed indefinitely, while NASA continues evaluating the situation up in low-Earth orbit.

"Because of the space station's interconnected and interdependent systems, NASA wants to ensure the station is ready for additional crew members, and the agency is taking the time necessary to review data," NASA said in an update yesterday (June 19).

"NASA, Axiom Space, and SpaceX appreciate the historic nature of this mission for the nations of India, Poland, and Hungary, as well as the world," NASA added in the post.

Ax-4 is commanded by Axiom's director of human spaceflight and former NASA astronaut Peggy Whitson. Joining her are Shubhanshu Shukla of India, Sławosz Uznański-Wiśniewski from Poland, and Tibor Kapu, from Hungary. The three will be the first astronauts from each of their nations to launch on a mission to the ISS.

The quartet will launch on a SpaceX Falcon 9 rocket, aboard a brand-new Crew Dragon spacecraft. When the new launch date is announced, the mission will liftoff from Launch Complex-39A, at NASA's Kennedy Space Center, in Florida.

Their mission is scheduled to last about two weeks, during which the Ax-4 crew will carry out more than 60 research experiments and STEM (science, technology, engineering and math) outreach events  — a record number of science for an Axiom mission.

Each of Axiom's crewed missions grow the company's experience in orbit, and their understanding of how best to operate in microgravity. In the future, Axiom plans to launch its own module to the ISS, which will eventually grow in its components and undock from the orbital lab to become its own independent space station.