Mission Control Center, Houston, Texas
The fourth spacewalk of Endeavours mission to the International Space Station is scheduled to begin at 9:01 a.m. CDT today.
The Endeavour crew, Commander Scott Kelly, Pilot Charles Hobaugh, and Mission Specialists Tracy Caldwell, Rick Mastracchio, Dave Williams, Barbara Morgan and Alvin Drew, and station Commander Fyodor Yurchikhin and Flight Engineers Oleg Kotov and Clay Anderson, were awakened for spacewalk day at 4:03 a.m. CDT by Learn to Fly, performed by the Foo Fighters. It was played for Drew.
Overnight, mission managers decided to shorten the originally planned 6.5-hour spacewalk to 4.5 hours so that the crew can close hatches between the station and shuttle at the end of the day today. That plan preserves the option to have Endeavour undock from the station on Sunday and prepare for a landing on Tuesday. The earlier landing is being considered in the event Hurricane Dean threatens the Houston area. It could allow an opportunity for the shuttle to land before Mission Control, Houston, would be shut down in preparation for a storm.
However, managers will review the forecast for Dean and mission activities this afternoon during their daily meeting and assess whether they will continue to pursue a possible early undocking and landing.
Today's spacewalk will be conducted by Williams of the Canadian Space Agency and Anderson. Caldwell will serve as the intravehicular officer, guiding spacewalkers through their tasks and keeping them on the timeline.
Spacewalk tasks include installing an External Wireless Instrumentation System antenna, part of a system that measures stresses on the structure of the station. Also, Williams and Anderson will install a stand for the shuttles robotic arm extension boom, allowing it to be temporarily stowed on the station next year. They also will retrieve two containers of the Materials ISS Experiment. These are the last of five containers that look at the effects of the space environment on 1,500 samples of various materials. The study provides investigators insight into how those materials may be used on future spacecraft.
To shorten the spacewalk, two tasks will be deferred to a future station spacewalk. Those include cleaning up and securing debris shielding on the Unity node and Destiny lab and a move of a tool box on the station to a more central location.
Transfer operations, the movement of equipment and supplies between Endeavour and the station, are almost complete.
The next status report will be issued Saturday evening or earlier if events warrant.
