NASA ISS Emergency EVA: Expedition 35 Flight Engineer Chris Cassidy

Expedition 35 Flight Engineers Chris Cassidy (pictured) and Tom Marshburn (out of frame) completed a spacewalk at 2:14 p.m. EDT May 11, 2013. 

The emergency EVA was needed to inspect and replace a pump controller box on the International Space Station’s far port truss (P6) leaking ammonia coolant. 

The two NASA astronauts began the 5-hour, 30-minute spacewalk at 8:44 a.m.

A leak of ammonia coolant from the area near or at the location of a Pump and Flow Control Subassembly was detected on Thursday, May 9, 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

NASA ISS Expedition 34: Flight Engineer Tom Marshburn Dress Rehearsal

At the Baikonur Cosmodrome in Kazakhstan, Expedition 34 Flight Engineer Tom Marshburn of NASA conducts a "fit check" dress rehearsal inside the Soyuz TMA-07M spacecraft on Dec. 7, 2012.

Along with Soyuz Commander Roman Romanenko and Flight Engineer Chris Hadfield of the Canadian Space Agency, who are not pictured, Marshburn is preparing for launch scheduled for Dec. 19 for a five-month mission on the International Space Station. 

Image Credit: NASA/Victor Zelentsov