Astronauts David Wolf and Thomas Marshburn are preparing for a planned six-and-a-half-hour spacewalk today to move critical spare parts to the International Space Station as a hedge against failures after the shuttle is retired. Crewmates inside, meanwhile, will continue work to repair the toilet in the U.S. lab module after a malfunction Sunday.

Credit: NASA

"On EVA 2 we will be moving three boxes, space-to-ground antenna, a pump module and a linear drive unit (for the station's robot arm transporter)," Wolf said in a NASA interview. "These are critical spares to survival of the space station in the years past shuttle retirement.

"In the case of the space-to-ground antenna, it has a very delicate, large antenna. I'll be holding this box through a very large maneuver (on the end of the station's robot arm) as we bring it in to the stowage platform. Part of the structure of the stowage platform will actually come within an inch or so of this delicate antenna, so Tom and I will be manipulating this box slowly down, kind of holding our breath. And I can tell you after we get that locked into place and didn't damage that antenna, I'm going to be breathing a lot easier."

Today's spacewalk, scheduled to begin around 11:28 a.m., is the 127th EVA devoted to station assembly and maintenance since construction began in 1998, the eighth so far this year and the second of five planned for Endeavour's crew. It will be Wolf's sixth spacewalk and Marshburn's first.

For identification, Wolf, call sign EV-1, will be wearing a spacesuit with solid red stripes around the legs. Marshburn, EV-2, will be wearing a suit with broken stripes.

After the antenna, the 1,300-pound pump module and the drive unit are transferred to external storage platform No. 3, Wolf and Marshburn will move up to the newly installed Japanese Exposed Facility experiment platform on the outboard end of the Kibo lab module and attach the first of two television cameras. The cameras are needed for normal operations and for the September approach of a new Japanese cargo ship. A second camera will be installed later in the mission.

The official crew patch for Endeavour's flight to finish building Japan's section of the space station is available in the Spaceflight Now Store.
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Space station commander Gennady Padalka and Frank De Winne, meanwhile, will work in the Destiny laboratory module to replace components in the waste and hygiene compartment, or WHC, a NASA-supplied, Russian-inspired toilet that's tied into the U.S. segment's water and urine recycling system.

The high-tech toilet malfunctioned Sunday when chemically treated water "flooded" a pump module and contaminate several other components.

Space station Flight Director Derek Hassman said early Monday that engineers are hopeful the toilet can be repaired and returned to service in short order.

"It's actually going very well," he said. "When we first started seeing the issues early in the crew day yesterday, there was a lot of concern it may take multiple days, if not close to a week, to recover the toilet functionality, which is obviously a big deal with this many people on board."

The shuttle-space station complex currently is hosting a record combined crew of 13 astronauts and cosmonauts. The station is equipped with two toilets for its six-person crew, the one that malfunctioned and one in the Russian Zvezda command module. The space shuttle Endeavour also is equipped with a toilet. After the malfunction Sunday, the station crew was told to use the Russian potty and Endeavour's seven-member crew was told to use the shuttle's.

"As it turns out, on the second half of the crew day we were able to remove a number of the components in the toilet system that were affected by the failure we saw," Hassmann said. "(Today) there are two more components in the system that we're going to replace. There are between six and seven individual components that by the middle of the crew day we expect to have been removed and replaced. These are all spares that are designed to be changed out.

"So we made a lot of progress much quicker than we expected initially based on the initial signatures we saw," he said. "I have some hope that by the end of the crew day we may have recovered the functionality."

Today is the 40th anniversary of the Apollo 11 moon landing on July 20, 1969. NASA plans to hold an Apollo news conference at 9:30 a.m. that will be carried on NASA television. At 8 p.m. this evening, NASA TV's public channel will carry coverage of an Apollo celebration at the Smithsonian's Air & Space Museum. As a result, today's mission status briefing, scheduled for 8:30 p.m., will be carried on NASA's media channel.

Here is an updated timeline of today's activity (in EDT and mission elapsed time; includes revision I of the NASA television schedule):

EDT........DD...HH...MM...EVENT

07:13 AM...04...13...10...EVA-2: 14.7 psi repress/hygiene break
07:30 AM...04...13...27...Video file
07:58 AM...04...13...55...EVA-2: Airlock depress to 10.2 psi
08:18 AM...04...14...15...ISS daily planning conference
08:23 AM...04...14...20...EVA-2: Campout EVA preps
08:48 AM...04...14...45...ISS: Toilet repair work
09:30 AM...04...15...27...Apollo 11 news conference
09:53 AM...04...15...50...EVA-2: Spacesuit purge
10:08 AM...04...16...05...EVA-2: Spacesuit prebreathe
10:58 AM...04...16...55...EVA-2: Crew lock depressurization
11:28 AM...04...17...25...EVA-2: Spacesuits to battery power
11:33 AM...04...17...30...EVA-2: Airlock egress
11:43 AM...04...17...40...EVA-2: Setup
11:58 AM...04...17...55...EVA-2: ICC ORU transfers
04:13 PM...04...22...10...EVA-2: JEF forward camera installation
05:13 PM...04...23...10...EVA-2: Cleanup and airlock ingress
05:58 PM...04...23...55...EVA-2: Airlock repressurization
06:08 PM...05...00...05...Spacesuit servicing
06:48 PM...05...00...45...Evening planning conference
08:00 PM...05...01...57...Apollo 11 event (public channel)
08:30 PM...05...02...27...Mission status briefing (media channel)
09:33 PM...05...03...30...ISS crew sleep begins
10:03 PM...05...04...00...STS crew sleep begins
11:00 PM...05...04...57...Daily highlights reel

Additional coverage for subscribers:
VIDEO: OVERVIEW OF FLIGHT DAY 6 ACTIVITIES PLAY
VIDEO: STEP-BY-STEP SUMMARY OF SPACEWALK NO. 2 PLAY

VIDEO: CANADIANS IN SPACE PLAY
VIDEO: SUNDAY'S MISSION STATUS BRIEFING PLAY
VIDEO: PALLET HANDED OFF TO SPACE STATION PLAY
VIDEO: CARGO CARRIER UNBERTHED FROM SHUTTLE BAY PLAY
VIDEO: SUNDAY MORNING FLIGHT DIRECTOR INTERVIEW PLAY
VIDEO: OVERVIEW OF FLIGHT DAY 5 ACTIVITIES PLAY

VIDEO: FLIGHT DAY 4 HIGHLIGHTS MOVIE PLAY
VIDEO: SATURDAY'S MISSION STATUS BRIEFING PLAY
VIDEO: UPDATE ON ENDEAVOUR'S HEAT SHIELD CHECKS PLAY
VIDEO: JAPANESE OUTDOOR SCIENCE PLATFORM ATTACHED PLAY
VIDEO: SHUTTLE AND STATION ARMS HANDOFF SCIENCE DECK PLAY
VIDEO: JAPAN'S EXPOSED FACILITY UNBERTHED FROM SHUTTLE PLAY
VIDEO: THERMAL COVER JETTISONED FROM THE KIBO MODULE PLAY
VIDEO: HELMET-CAMERA VIEWS AS KOPRA CLIMBS TO SHUTTLE PLAY
VIDEO: TIM KOPRA EMERGES FROM AIRLOCK FOR EVA NO. 1 PLAY
VIDEO: SATURDAY MORNING FLIGHT DIRECTOR INTERVIEW PLAY
VIDEO: OVERVIEW OF FLIGHT DAY 4 ACTIVITIES PLAY
VIDEO: STEP-BY-STEP SUMMARY OF SPACEWALK NO. 1 PLAY
VIDEO: NARRATED TOUR OF ENDEAVOUR'S PAYLOAD BAY PLAY

VIDEO: FLIGHT DAY 3 HIGHLIGHTS MOVIE PLAY
VIDEO: FRIDAY'S MISSION STATUS BRIEFING PLAY
VIDEO: SHUTTLE CREW WELCOMED ABOARD STATION PLAY
VIDEO: ENDEAVOUR DOCKS TO THE SPACE STATION PLAY
VIDEO: ASTRONAUTS' ONBOARD CAMCORDER FOOTAGE PLAY
VIDEO: SHUTTLE FLIES OUT IN FRONT OF STATION PLAY
VIDEO: ENDEAVOUR PERFORMS 360-DEGREE BACKFLIP PLAY
VIDEO: BEAUTIFUL VIEWS OF ENDEAVOUR APPROACHING PLAY
VIDEO: STATION CAMERA CATCHES ENDEAVOUR'S "TI BURN" PLAY
VIDEO: NARRATED PREVIEW OF RENDEZVOUS AND DOCKING PLAY

VIDEO: FLIGHT DAY 2 HIGHLIGHTS MOVIE PLAY
VIDEO: TUESDAY'S MISSION STATUS BRIEFING PLAY
VIDEO: PREVIEW ANIMATION OF HEAT SHIELD INSPECTIONS PLAY

VIDEO: FLIGHT DAY 1 HIGHLIGHTS MOVIE PLAY
VIDEO: THE FULL STS-127 LAUNCH EXPERIENCE PLAY
VIDEO: INSIDE MISSION CONTROL DURING LAUNCH PLAY
VIDEO: LAUNCH REPLAY: VAB ROOF PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: PRESS SITE PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: PAD PERIMETER PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: BEACH TRACKER PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: UCS-23 TRACKER PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: PLAYALINDA BEACH PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: PATRICK AIR FORCE BASE PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: BANANA CREEK VIP SITE PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: PAD FRONT CAMERA PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: WEST TOWER PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: CAMERA 070 PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: CAMERA 071 PLAY | HI-DEF
VIDEO: LAUNCH REPLAY: CAMERA CS-1 PLAY
VIDEO: LAUNCH REPLAY: CAMERA CS-2 PLAY
VIDEO: LAUNCH REPLAY: CAMERA CS-6 PLAY

VIDEO: SHUTTLE ENDEAVOUR BLASTS OFF! PLAY | HI-DEF
VIDEO: STS-127 POST-LAUNCH NEWS CONFERENCE PLAY
VIDEO: FOOTAGE OF FUEL TANK AFTER JETTISON PLAY
VIDEO: ASTRONAUTS REACH PAD 39A PLAY | HI-DEF
VIDEO: CREW DEPARTS QUARTERS FOR LAUNCH PAD PLAY | HI-DEF
VIDEO: ASTRONAUTS DON SPACESUITS FOR LAUNCH PLAY | HI-DEF

VIDEO: WEATHER SCRUBS LAUNCH AGAIN PLAY | HI-DEF
VIDEO: CREW ARRIVES AT PAD 39A ON MONDAY PLAY | HI-DEF
VIDEO: CREW DEPARTS QUARTERS ON MONDAY PLAY | HI-DEF
VIDEO: ASTRONAUTS SUIT UP ON MONDAY PLAY | HI-DEF

VIDEO: THUNDERSTORMS SCRUB SUNDAY'S ATTEMPT PLAY | HI-DEF
VIDEO: CREW DEPARTS QUARTERS ON SUNDAY PLAY | HI-DEF
VIDEO: ASTRONAUTS SUIT UP ON SUNDAY PLAY | HI-DEF
VIDEO: NARRATED SUMMARY SHUTTLE'S PREPARATIONS PLAY | HI-DEF
VIDEO: NARRATED SUMMARY PAYLOADS' PREPARATIONS PLAY | HI-DEF

VIDEO: LIGHTNING STRIKES POSTPONE ENDEAVOUR LAUNCH PLAY
VIDEO: FRIDAY'S PRE-LAUNCH NEWS CONFERENCE PLAY
VIDEO: THURSDAY'S STATUS REPORT ON THE COUNTDOWN PLAY
VIDEO: COUNTDOWN PREVIEW AND WEATHER BRIEFING PLAY
VIDEO: ASTRONAUTS RETURN TO CAPE FOR LAUNCH PLAY | HI-DEF

VIDEO: NO LEAKS FOUND DURING SPECIAL TEST PLAY
VIDEO: EXPLANATION OF THE HYDROGEN LEAK AND THE REPAIR PLAY

VIDEO: POST-SCRUB NEWS BRIEFING PLAY
VIDEO: FIRING ROOM UPDATE WITH LAUNCH DIRECTOR PLAY
VIDEO: SCRUB NO. 2 DECLARED DUE TO HYDROGEN LEAK PLAY

VIDEO: SUNDAY'S UPDATE FROM MISSION MANAGEMENT TEAM PLAY
VIDEO: LEAK POSTPONES SHUTTLE ENDEAVOUR LAUNCH PLAY

VIDEO: TIME-LAPSE OF SUN SETTING OVER PAD 39A PLAY
VIDEO: ANOTHER TIME-LAPSE OF GANTRY RETRACTION PLAY
VIDEO: TIME-LAPSE OF LAUNCH PAD TOWER ROLLBACK PLAY

VIDEO: PRE-LAUNCH INTERVIEW WITH MARK POLANSKY PLAY
VIDEO: PRE-LAUNCH INTERVIEW WITH DOUG HURLEY PLAY
VIDEO: PRE-LAUNCH INTERVIEW WITH CHRIS CASSIDY PLAY
VIDEO: PRE-LAUNCH INTERVIEW WITH JULIE PAYETTE PLAY
VIDEO: PRE-LAUNCH INTERVIEW WITH TOM MARSHBURN PLAY
VIDEO: PRE-LAUNCH INTERVIEW WITH DAVE WOLF PLAY

VIDEO: THE STS-127 MISSION PREVIEW MOVIE PLAY
VIDEO: THURSDAY'S PRE-LAUNCH NEWS CONFERENCE PLAY
VIDEO: JAPANESE SCIENCE FACILITIES ABOARD STATION PLAY
VIDEO: COUNTDOWN BEGINS TICKING FOR SATURDAY'S LAUNCH PLAY
VIDEO: LAUNCH COUNTDOWN PREVIEW BRIEFING PLAY
VIDEO: CREW ARRIVES JUST BEFORE MIDNIGHT PLAY | HI-DEF
VIDEO: GET TO KNOW ENDEAVOUR'S ASTRONAUTS PLAY

VIDEO: ASTRONAUTS PRACTICE EVACUATION OF SHUTTLE PLAY | HI-DEF
VIDEO: CREW BOARDS SHUTTLE FOR PRACTICE COUNT PLAY | HI-DEF
VIDEO: ASTRONAUTS SUIT UP FOR DRESS REHEARSAL PLAY | HI-DEF
VIDEO: CREW INSPECTS CARGO IN THE PAYLOAD BAY PLAY | HI-DEF
VIDEO: TRAINING SESSIONS AT LAUNCH PAD AND BUNKER PLAY | HI-DEF
VIDEO: INFORMAL CREW NEWS CONFERENCE AT LAUNCH PAD PLAY
VIDEO: ASTRONAUTS ARRIVE FOR PRACTICE COUNTDOWN PLAY

VIDEO: FLIGHT READINESS REVIEW SETS LAUNCH DATE PLAY

VIDEO: PAD 39A GANTRY ENCLOSES SHUTTLE PLAY | HI-DEF
VIDEO: ROLLAROUND MOVES ENDEAVOUR TO PAD 39A PLAY | HI-DEF
VIDEO: ENDEAVOUR IS HAULED OFF LAUNCH PAD 39B PLAY | HI-DEF
VIDEO: TIME-LAPSE OF SHUTTLE'S LAUNCH PAD SWITCH PLAY

VIDEO: SHUTTLE AND STATION PROGRAM UPDATE PLAY
VIDEO: THE STS-127 MISSION OVERVIEW BRIEFING PLAY
VIDEO: PREVIEW BRIEFING ON MISSION'S SPACEWALKS PLAY
VIDEO: THE ASTRONAUTS' PRE-FLIGHT NEWS BRIEFING PLAY

VIDEO: PAD 39B AND ITS LAST SPACE SHUTTLE PLAY | HI-DEF
VIDEO: ENDEAVOUR'S SUNRISE ARRIVAL AT PAD 39B PLAY | HI-DEF
VIDEO: MIDNIGHT ROLLOUT FROM ASSEMBLY BUILDING PLAY | HI-DEF
VIDEO: ENDEAVOUR HOISTED FOR ATTACHMENT TO TANK PLAY | HI-DEF
VIDEO: CRANE ROTATES ENDEAVOUR VERTICALLY PLAY | HI-DEF
VIDEO: ENDEAVOUR MOVES TO ASSEMBLY BUILDING PLAY | HI-DEF
VIDEO: ORION AND ARES ROCKET PROGRESS REPORT PLAY
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