Astronauts aboard the International Space Station detected an ammonia leak coming from the station's cooling system Thursday, NASA says.
Although the leak is apparently worsening, the agency says that the station "continues to operate normally otherwise and the crew is in no danger."
Ammonia is used to cool the station's power systems.
In an audio file posted on the agency's website, Commander Chris Hadfield, an astronaut on the station, reported a "very steady stream of [ammonia] flakes." Crews on the ground said astronauts are "working feverishly" to repair the leak.
There was a similar ammonia leak on the station in November 2012; NASA is unsure whether the two are related.
If the leak isn't plugged within 48 hours, it could result in the shutdown of one of the station's cooling loops.
A request for more information from NASA by U.S. News was not immediately answered.
The International Space Station was launched in 1998 as a partnership between the United States, Russia, Canada, Japan and the countries participating in the European Space Agency. To date, astronauts from 14 countries have visited the station. Currently, there are six astronauts, including two Americans, onboard.