Spacewalkers Mike Foreman and Randy Bresnik exercised 10 minutes on the Destiny laboratory’s cycle ergometer, wearing masks and breathing pure oxygen to help purge their bodies of nitrogen. They will spend a total of two hours and 20 minutes breathing oxygen before the spacewalk. This procedure was used for years by spacewalkers prior to the arrival of the space station’s Quest Airlock and will help prevent them from experiencing decompression sickness, or the bends, when they enter the vacuum of space.
Foreman and Bresnik’s pre-breathe “campout” protocol in Quest was interrupted by false alarms aboard the station Thursday night. The alarms caused the crew sleep period to be extended by 30 minutes, reduced the spacewalk by 30 minutes to six hours, and shifted the start time for the excursion to 9:38 a.m. EST. The shortened spacewalk will not prevent Foreman and Bresnik from accomplishing all the major tasks that are planned. Thirty minutes had been set aside for “get ahead” tasks, which instead will be rescheduled for a later spacewalk.