CAPE CANAVERAL, Florida (AP) - Nasa says an impromptu spacewalk seems to have fixed a big ammonia leak at the International Space Station.

The "gusher" erupted last Thursday. Two days later, spacewalking astronauts replaced a suspect ammonia pump. Nasa is now calling the old, removed pump Mr. Leaky.

On Thursday, a Mission Control official said the spacewalking repairs definitely took care of the big leak. Engineers don't know whether the pump replacement also took care of a smaller leak that has plagued the system for years. It will take at least a couple months of monitoring to know the full status.

Ammonia is used as a coolant in the space station's radiator system.

The leak forced one of the station's seven power channels to go offline. Nasa hopes to resume normal operations early next week.