Three crew members on board the International Space Station will spend the weekend in the vessel’s Russian segment while they search for the source of a cabin air leak, NASA and Russian space agency Roscosmos said on Thursday.

“In September 2019, NASA and its international partners first saw indications of a slight increase above the standard cabin air leak rate,” NASA said in a statement.

It said the crew, composed of NASA’s Chris Cassidy and Russia’s Ivan Vagner and Anatoly Ivanishin, would close the station’s hatches this weekend to monitor air pressure and find the source of the leak.

NASA and Roscosmos said the situation represented no immediate danger to the crew or to the space station.