Animation of a segment of the NASA video showing the ammonia leak on the space station. Credit: NASA

On Thursday, space station astronauts reported seeing flakes of ammonia drifting from the orbiting outpost’s P6 truss. The source of the leak is the chilled ammonia supply that is used to cool the station’s huge solar arrays.

The six astronauts and cosmonauts are in no danger and measures are being taken to mitigate any power shortages. An emergency spacewalk is being planned to fix the leak, but NASA astronauts Chris Cassidy and Tom Marshburn’s EVA approval probably won’t be made by space station managers until late Friday night.

In a NASA video from the space station, small white specks — the flakes of ammonia — can be seen drifting from the P6 truss. “Houston, let us know if we’re telling you stuff you already know, but all of us agree that (the ammonia flakes) were coming up (inaudible) and repeatedly enough that it looked like it was a point source that they were coming from,” said Space Station Commander and Canadian Space Agency astronaut Chris Hadfield in the video.

The fact that the ammonia flakes appear to originate from a point source suggests it is a single break or hole in the ammonia coolant supply system.

NASA is expected to host a news conference discussing the ammonia leak at 4 p.m. ET on NASA TV.

More on the ISS ammonia leak:

  • Space Station Crew Prepare for Emergency Spacewalk

  • Space Station Suffers Troubling Coolant Leak

Image: Animation of a segment of the NASA video of the ammonia leak on the space station. Credit: NASA