During the spacewalk, Tani (EV1) & Whitson (EV2), supported by FE-1 Yuri Malenchenko as intravehicular (IV) crewmember, inspected the Stbd (right-side) 1A BGA (Beta Gimbal Assembly) and BMRMM (Bearing Motor Roll Ring Module), followed by a detailed investigation and photo documentation of the Stbd SARJ (Solar Alpha Rotary Joint).
Specifically, the spacewalkers -
Found no obvious signs of external damage on cables or hardware of the BGA & BMRMM that might have caused the repeated tripping of circuit breakers (RPCs/Remote Power Controllers), making it more likely that the issue is internal to the hardware or its electrical system;
Entered into the S5 truss to disconnect some wiring to allow the ground to perform diagnostic continuity tests, and later reconnected the cables;
Temporarily removed 22 protective MLI (Multi-Layer Insulation) covers to inspect the SARJ, its two DLAs (Drive Lock Assemblies), and its 12 TBAs (Trundle Bearing Assemblies), reattaching the covers afterwards,
Found most metal shavings around TBA-4 and TBA-5, i.e., metallic, magnetic contamination on the main gear bearing's outboard angled race ring as well as pitting and abrasions on the ring but no obvious damage on the inboard race ring or on the gear teeth themselves. DLA (Drive Lock Assembly) #2 appeared especially 'ugly', i.e., filled with contamination, and, according to the spacewalkers, the further away from the DLA, the less contamination was observed;
Took photographs, measured the depth of surface pits with a special probe and collected debris samples; and
Deinstalled and removed TBA-5 from its housing under cover #20, using a PGT (Pistol Grip Tool), then brought it inside in a bag for eventual return to Earth aboard STS-122/Atlantis (SARJ can function OK on only 11 TBAs).
(Official start time of the spacewalk was 4:50am EST, 70 minutes ahead of the timeline, ending at 11:46am. Total EVA duration (PET = Phase Elapsed Time) was 6h 56min. It was the 100th spacewalk for ISS assembly & maintenance and the 72nd from the station (28 from Shuttle, 50 from Quest, 22 from Pirs) totaling 436h 3m, and the 4th for Expedition 16 (totaling 28h 11m. During the spacewalk, her fifth, Peggy Whitson set a new record of aggregated EVA time by a woman (of 32h 36m) when she exceeded the 29h 18m held by Sunita Williams. After today's EVA, a total of 121 spacewalkers (90 NASA astronauts, 21 Russians, and ten astronauts representing Japan-1, Canada-4, France-1, Germany-1 and Sweden-3) have logged a total of 624h 25m outside the station on building, outfitting and servicing. It was also the 122nd spacewalk by U.S. astronauts. The 100th EVA dedicated to ISS assembly & maintenance originally was to have been conducted by Rex Walheim & Hans Schlegel of the delayed STS-122/1E mission.)
Prior to the spacewalk, FE-1 Malenchenko verified closure of the protective Lab window shutter.
Malenchenko also completed the pre-egress reconfiguration of the Russian STTS (onboard telephone/telegraph subsystem) to its EVA settings. After the crew's return, Yuri reconfigured the STTS for nominal ops. (The "Voskhod-M" STTS enables telephone communications between the SM (Service Module), FGB, DC1 Docking Compartment and U.S. segment (USOS), and also with users on the ground over VHF channels selected by an operator at an SM comm panel, via STTS antennas on the SM's outside. There are six comm panels in the SM with pushbuttons for accessing any of three audio channels, plus an intercom channel. Other modes of the STTS include telegraphy (teletype), EVA voice, emergency alarms, Packet/Email, and TORU docking support.)
During the spacewalk, Yuri provided IV support, prepared the DCS 760 camera setup for post-ingress photographing of the EVA gloves and subsequently assisted the spacewalkers in ingressing, CL (Crew Lock) repressurization and post-EVA activities.
The FE-1 also performed the routine servicing of the SOZh system (Environment Control & Life Support System, ECLSS) in the SM (Service Module). (Regular daily SOZh maintenance consists among else of replacement of the KTO & KBO solid waste containers and replacement of EDV-SV waste water and EDV-U urine containers.)
During Campout, after wakeup and before breakfast, FE-2 Dan Tani again accessed the SLEEP experiment (Sleep-Wake Actigraphy & Light Exposure during Spaceflight) software for data logging and completing questionnaire entries in the experiment's laptop session file on the HRF-1 laptop for later downlink. (To monitor the crewmember's sleep/wake patterns and light exposure, Dan wears a special Actiwatch device which measures the light levels encountered by him as well as his patterns of sleep and activity throughout the Expedition. The log entries are done within 15 minutes of final awakening for seven consecutive days, as part of the crew's discretionary 'job jar' task list.)
After returning on board from outside, Whitson and Tani doffed the EMUs, after taking photographs of the gloves and overgloves while still pressurized. As part of post-EVA tasks, the spacewalkers also reported on size fit of their EMUs and components.
Later today, CDR Whitson will downlink the EVA imagery to the ground and reconfigure the DCS 760 for regular use (e.g., removing its thermal blanket).
Afterwards, Peggy and Dan are also scheduled for their regular post-EVA PMCs (Private Medical Conferences) with the ground.
CEO photo target uplinked for today was Khartoum, Sudan (Greater Khartoum (population 8.3 million, 2007 est.) includes Khartoum (2.2 million) in the acute angle between the Blue and White Niles, and Omdurman (3+ million) on the west side of the White Nile. Omdurman is the largest city in the Sudan and the fastest growing, partly because of refugees fleeing western Sudan. The growth of cities, especially in the Third Word, is best documented by remote means from the air or space. Looking a touch right for Khartoum and at nadir for Omdurman, shooting city margins).