Space Shuttle mission managers Tuesday cleared Discovery's wing leading edge heat shield for re-entry as they methodically deal with concerns over the protruding tile gap fillers. The mission management team also discussed a "puffed out" insulating blanket outside the commander's cockpit window and has decided it poses no risk of overheating during entry. Engineers will continue to analyze whether it could pose a debris problem if it came loose during aerodynamic flight.
Discovery's astronauts worked much of today on preparations for Wednesday's gap filler repair spacewalk. Transfer of materials to and from the International Space Station continued with crewmembers of both spacecraft making good progress.
Spacewalkers Soichi Noguchi and Steve Robinson spent an hour this morning beginning about 2:40 a.m. CDT with Mission Specialists Andy Thomas and Wendy Lawrence, and Pilot Jim Kelly on a review of spacewalk procedures. Thomas, as the intravehicular crewmember, will coach and monitor the spacewalkers, while Lawrence and Kelly will operate the Station's Canadarm2.
That robotic arm will carry Robinson to the repair sites on the underside of the forward part of Discovery where he will either gently pull out the protruding gap fillers with his hand or with forceps, or remove the protrusions with a hacksaw.
After the procedure review, Lawrence and Kelly spent the subsequent 45 minutes in computer training for the arm tasks, using the Dynamic Onboard Ubiquitous Graphics program, or DOUG. Meanwhile, the spacewalkers and Thomas worked on assembly of the hacksaw that would be used if other methods do not work.
About 7:40 a.m. Lawrence and Kelly, using Canadarm2, unberthed External Stowage Platform 2 from Discovery's cargo bay. Noguchi and Robinson installed the platform's attachment device on the mission's first spacewalk on Saturday, and the platform itself is to be installed on the attachment device during Wednesday's spacewalk.
After lunch on board, Noguchi, Robinson and Thomas worked on spacewalk tool configuration. Near the end of their work day, all nine crewmembers on board, including Discovery Commander Eileen Collins and Station crewmembers, Commander Sergei Krikalev and NASA Science Officer John Phillips, did a spacewalk review.
The spacewalkers began a prebreathe of pure oxygen about 10:50 a.m., a little more than an hour before hatches linking Discovery and the Station were closed so the Shuttle could be depressurized to 10.2 psi. Both the prebreathe and the depressurization were aimed at reducing the nitrogen content of the spacewalkers' blood to reduce the possibility of nitrogen bubble formation in their bloodstreams during the spacewalk. Wednesday's spacewalk is scheduled to begin at about 3:14 a.m. CDT.
Late in the crew day Tuesday, astronauts received a phone call from President George Bush. The President thanked the crew for taking risks for the sake of exploration and wished them well in the remainder of their mission.
The next STS-114 mission status report will be issued Wednesday morning or earlier if events warrant.
