Out of an abundance of caution, NASA on Friday directed five of the seven crew members aboard the International Space Station to wait inside the docked SpaceX Crew Dragon “Freedom” spacecraft — known as a “safe haven” — while two cosmonauts work to make the latest repair to some cracks in a transfer tunnel in the Russian module.

These cracks have been the source of a small air leak that has persisted on and off for the last six years or so. The leak is considered a top safety risk. There have been several attempts over the years to repair the cracks.

Friday’s repair effort comes after the Russian space agency noticed a slow pressure drop in that transfer tunnel last month following the arrival of a Russian cargo ship.

This is a developing story and will be updated.