According to a report today at Ars Technica, the Zvezda module on ISS is once again leaking station air, despite recent repairs to the stress fractures in its hull that had appeared in recent months to halt the air loss.

After a couple of sources reported this to Ars, NASA confirmed the issue on Thursday. On May 1, after Russian cosmonauts unloaded cargo from the Progress 95 cargo spacecraft, Roscosmos noted a “slow pressure drop” in the PrK module.

“Teams performed data analysis, which indicated a loss of about one pound per day,” NASA spokesperson Josh Finch told Ars. “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.”

A loss of one pound of air per day is comparable to the leak rate back in 2019, as shown in the lower right corner of the graphic below. It is also one third the loss rate seen for much of the following five years, which is I suppose good news.

Figure 3 from September 2024 Inspector General report, showing Zvezda’s location on ISS, as well as the station’s leak rate at that time.

At the same time, it suggests once again that every docking to Zvezda puts stress on its hull, and apparently causes either new cracks or the reopening of old ones. In such a situation, a catastrophic failure of the module remains a possibility that cannot be dismissed. NASA closes the hatch between the Russian and American halves of the station whenever there is a docking, but that is only band-aid covering a much more serious problem.

Without question ISS’s life span is impacted by this issue. The sooner the U.S. can replace it with at least one or two of the private commercial stations under development, the better.