Saturday Morning Spacewalk: The fourth (and now final) EVA of the STS-120 mission is on tap for today. NASA reports:
Crews to Perform Fourth Spacewalk
The STS-120 and Expedition 16 crews are preparing for today’s spacewalk to repair a torn solar array. It will be the fourth spacewalk of the mission. Mission Specialists Scott Parazynski and Doug Wheelock are scheduled to leave the station about 6:30 a.m. EDT.
The 6.5-hour spacewalk begins with Parazynski riding the station’s robotic arm up to the damaged area of the array. He will be secured in a foot restraint on the end of the Orbiter Boom Sensor System, or OBSS - the extension to the shuttle robot arm used for inspection of the orbiter’s thermal protection system.
Though this will be the first operational use of the OBSS to reach a worksite, the task was demonstrated during a spacewalk on the STS-121 mission in July 2006 to prove the boom could provide a stable environment for this type of work.
As Parazynski installs homemade stabilizers and releases the snag suspected of causing the tear in the array panel, Wheelock will assist from the base of the solar array. The distance from the station’s center is about 165 feet out on the truss and approximately 90 feet up to the damaged site.
If all goes as planned, the crew inside will then deploy the array half a bay at a time while Parazynski watches for any new complications. The spacewalk is scheduled to wrap up about 1:00 p.m.
Flight Day 11 pics and video are up at the JSC Gallery. Discussion here. Status Report #23 here. Check the links at right for play-by-play and NASA TV.