NASA says Russian International Space Station module leaks about one pound daily

NASA said Thursday that the Russian segment of the international space station has begun leaking atmosphere into space again. The renewed leak comes from the PrK transfer tunnel attached to the Zvezda Service Module, where teams have been watching pressure changes for months.

Josh Finch, a NASA spokesperson, said data analysis showed a loss of about one pound per day. NASA said there are no impacts to station operations, even as Roscosmos keeps the tunnel at a lower pressure with small repressurizations as needed.

PrK transfer tunnel

In January, NASA said the PrK module had reached a stable configuration after multiple inspections and sealant applications. That assessment changed after Roscosmos noted a slow pressure drop in the module on May 1, when Russian cosmonauts unloaded cargo from the Progress 95 cargo spacecraft.

Finch said, "Teams performed data analysis, which indicated a loss of about one pound per day." He also said, "Roscosmos allowed the pressure in the transfer tunnel to gradually decrease while monitoring the rate. The area now is being maintained at a lower pressure, with small repressurizations as needed. There are no impacts to station operations, and NASA and Roscosmos are coordinating on next steps."

NASA risk matrix

NASA has tracked the leak rate from the small Russian module for more than half a decade, and it classifies the Russian leaks as a 5 on both high likelihood and high consequence in its 5×5 risk matrix. Roscosmos has largely managed the problem by keeping the hatch to the PrK module closed to the rest of the station.

The renewed leak lands while NASA and the US Congress consider extending the station’s lifespan to at least 2032, after the International Space Station was due to be retired in 2030. The question now is whether a module that has already required repeated sealant work can stay inside a station architecture that may be asked to run beyond its original endpoint.