Expedition 35 Flight Engineers Chris Cassidy (pictured) and Tom Marshburn (out of frame) completed a spacewalk on 11 May 2013 to inspect and replace a pump controller box on the International Space Station’s far port truss (P6), which was leaking ammonia coolant. The spacewalk took five hours and 30 minutes.
A leak of ammonia coolant from the area near or at the location of a Pump and Flow Control Subassembly was detected on Thursday, 9 May, prompting engineers and flight controllers to begin plans to support the spacewalk. The device contains the mechanical systems that drive the cooling functions for the port truss.
Image credit: Nasa