Repairs in Space

ROUGH CUT (NO REPORTER NARRATION)

STORY: Two astronauts aboard the International Space Station (ISS) try to fix an ammonia leak in a cooling system on one of the station's solar arrays that provide electricity to the orbital outpost.

The crew spotted a steady stream of small, white frozen ammonia flakes floating away from a coolant line outside the station on Thursday (May 9), according to NASA.

Mission managers reviewed images and data before deciding to send American astronauts Chris Cassidy and Tom Marshburn out on Saturday morning to try to stop the leak by replacing a pump on the cooling system.

Ammonia is used to cool the power systems that operate each of the station's eight solar arrays. The leak is on the far left side of the station's truss structure, in an ammonia loop that astronauts previously tried to troubleshoot during a spacewalk in November 2012.

While Cassidy and Marshburn are working outside the space station, crew commander Chris Hadfi