The Zvezda service module’s transfer tunnel, known as the PrK, on the International Space Station has experienced cracks since 2019 that have resulted in small atmosphere leaks and prompted ongoing monitoring and repair efforts by Roscosmos. NASA and Roscosmos have worked together to identify the root cause while Roscosmos has been applying leak mitigation measures, including temporary and permanent sealants.
The week of June 1, during Progress 95 spacecraft cargo operations, Roscosmos noted an increase of the previous leak rate to two pounds per day and identified new suspected leak areas in the PrK. Following this observation, Roscosmos made the decision to begin work toward a more extensive inspection and structural repair effort Friday morning. This revised approach involved cutting a bracket to better access an area identified as a possible leak source for further inspection, using a method that could have resulted in elevated risk to the structure in the area. In response, NASA directed the four SpaceX Crew-12 members and NASA astronaut Chris Williams, who flew to station aboard the Soyuz MS-28 spacecraft, to take a heightened safety posture, known as a safe haven, inside the SpaceX Dragon spacecraft during the procedure.
Later Friday morning, Roscosmos paused and did not perform the structural repair work in favor of conducting additional measurements and data assessments, which included inspection of suspected areas of interest and review of areas where sealant was previously applied. NASA strongly supported that decision, and as a result, following that decision, Crew-12 and Williams ended their safe haven activities and returned to normal operations aboard the orbiting laboratory.
NASA will continue to work with our Russian counterparts, along with the rest of the international partners that support the space station, to assess and ensure a resolution to this matter.
Learn more about station activities by following the space station blog, @space_stationon X, as well as the ISS Facebook and ISS Instagram accounts.
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