Part of doing an EVA is the necessity to breathe pure oxygen, which denitrogenates our bloodstreams so that we can avoid getting the bends. This is our good friend Nicole Stott going out the airlock on her first EVA. I helped operate the Canadarm2 here, transporting Nicole and the payload from the station over to the cargo bay of the shuttle.
On May 11th, 2010. See this statement in context.