Summary
Two veteran Russian cosmonauts floated outside the International Space Station Wednesday to replace experimental equipment that is testing how materials and biological samples fare in the harsh environment of space.
Station flight engineers Yuri Malenchenko and Sergey Volkov left the station's airlock at 7:55 a.m. EST (12:55 GMT) for what was expected to be a five-and-a-half-hour spacewalk, a live broadcast on NASA Television showed.
The station is a $100 billion research complex owned and operated by 15 nations.
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