Two astronauts on the International Space Station are preparing for a possible impromptu spacewalk to work on a leaking coolant line.
NASA spokesman Rob Navias (NA'-vee-us) says the line will run out of ammonia coolant late Friday morning. The line chills power systems but power was rerouted and is operating normally. The six-member crew is not in danger.
NASA will decide Friday evening if the spacewalk is needed on Saturday.
NASA suspects the leak might be on the far left truss of the station, but doesn't know for sure.
If needed, U.S. astronauts Chris Cassidy and Tom Marshburn would make about a six-hour spacewalk. They have trained for this type of repair.