International Space Station Expedition 35 Flight Engineers Chris Cassidy and Tom Marshburn of NASA switched their spacesuits to battery power at 8:44 a.m. EDT, signifying the start of today's planned six hour, 30 minute excursion.
Cassidy will be performing his fourth spacewalk. He has spent a total of 18 hours, 5 minutes outside during three spacewalks in support of the International Space Station. Cassidy will don a spacesuit with red stripes. His helmet camera displays the number 20.
Marshburn also will be conducting his fourth spacewalk. He has spent a total of 18 hours, 59 minutes outside during three spacewalks in support of the International Space Station. Marshburn will wear a spacesuit with no stripes. His helmet camera displays the number 18.
This is the 168th spacewalk in support of space station assembly and maintenance and is designated U.S. Spacewalk #21.
The spacewalkers will inspect and possibly replace a pump controller box on the station's far port-side truss, designated P6, suspected of leaking ammonia coolant.
For more information the International Space Station, visit: http://www.nasa.gov/station