Floating in the space station's Quest airlock module, astronauts Michael Fossum and Ronald Garan switched their spacesuits to battery power at 12:22 p.m. to officially kick off a planned six-and-a-half-hour spacewalk. The spacewalk began 50 minutes behind schedule because of problems with a cable in Fossum's headset communications gear. After an equipment swap out, preparations continued normally.

"All right, boys, it's time to rock and roll," Discovery pilot Kenneth Ham radioed the spacewalkers as the excursion got under way.

This is the 110th spacewalk devoted to station assembly and maintenance since construction began in 1998, the 11th so far this year and the first of three planned by Fossum and Garan. Going into today's outing, astronauts from the United States, Russia, Japan, Canada, Germany, France and Sweden had logged 686 hours and four minutes of station spacewalk time.

The first item on the agenda today is to retrieve a shuttle heat shield inspection boom left on the station in March. The astronauts also will prepare the Japanese Kibo lab module for unberthing and then focus on the station's right-side solar alpha rotary joint, used to keep outboard solar panels pointed at the sun. Garan plans to re-install a bearing assembly while Fossum attempts to clean metallic contamination from a 10-foot-wide drive gear that has forced flight controllers to limit the joint's use.

Read our preview story.

Additional coverage for subscribers:
VIDEO: ANIMATION OF KIBO MODULE INSTALLATION PLAY
VIDEO: ANIMATION OF INSPECTION BOOM RETRIEVAL PLAY
VIDEO: NARRATED PREVIEW OF SPACEWALK NO. 1 PLAY
VIDEO: TUESDAY'S FLIGHT DIRECTOR INTERVIEW PLAY
VIDEO: THE FLIGHT DAY 3 HIGHLIGHTS MOVIE PLAY
VIDEO: CREW'S REMARKABLE CAMCORDER FOOTAGE FROM MONDAY PLAY
VIDEO: MONDAY'S MISSION STATUS BRIEFING PLAY
VIDEO: SHUTTLE CREW WELCOMED INTO STATION PLAY
VIDEO: DISCOVERY DOCKS TO SPACE STATION PLAY
VIDEO: SHUTTLE PERFORMS RENDEZVOUS BACKFLIP PLAY
VIDEO: THE FLIGHT DAY 2 HIGHLIGHTS MOVIE PLAY
VIDEO: CREW'S CAMCORDER FOOTAGE FROM FLIGHT DAY 2 PLAY
VIDEO: SUNDAY'S MISSION STATUS BRIEFING PLAY
VIDEO: THE FLIGHT DAY 1 HIGHLIGHTS MOVIE PLAY
VIDEO: EXTERNAL TANK SEEN AFTER SEPARATION PLAY
VIDEO: LAUNCH REPLAY: VAB ROOF PLAY
VIDEO: LAUNCH REPLAY: CAMERA CS-1 PLAY
VIDEO: LAUNCH REPLAY: CAMERA CS-2 PLAY
VIDEO: LAUNCH REPLAY: CAMERA CS-6 PLAY
VIDEO: LAUNCH REPLAY: FRONT CAMERA PLAY
VIDEO: LAUNCH REPLAY: BEACH TRACKER PLAY
VIDEO: LAUNCH REPLAY: PAD PERIMETER PLAY
VIDEO: LAUNCH REPLAY: UCS-12 TRACKER PLAY
VIDEO: LAUNCH REPLAY: UCS-23 TRACKER PLAY
VIDEO: LAUNCH REPLAY: PLAYALINDA BEACH PLAY
VIDEO: LAUNCH REPLAY: PATRICK AIR FORCE BASE PLAY
VIDEO: LAUNCH REPLAY: PRESS SITE PLAY
VIDEO: LAUNCH REPLAY: WEST TOWER PLAY
VIDEO: LAUNCH REPLAY: CAMERA 009 PLAY
VIDEO: LAUNCH REPLAY: CAMERA 041 PLAY
VIDEO: LAUNCH REPLAY: CAMERA 049 PLAY
VIDEO: LAUNCH REPLAY: CAMERA 050 PLAY
VIDEO: LAUNCH REPLAY: CAMERA 051 PLAY
VIDEO: LAUNCH REPLAY: CAMERA 054 PLAY
VIDEO: LAUNCH REPLAY: CAMERA 060 PLAY
VIDEO: LAUNCH REPLAY: CAMERA 061 PLAY
VIDEO: LAUNCH REPLAY: CAMERA 063 PLAY
VIDEO: LAUNCH REPLAY: CAMERA 070 PLAY
VIDEO: LAUNCH REPLAY: CAMERA 071 PLAY

VIDEO: LIFTOFF OF DISCOVERY WITH KIBO LAB! PLAY
VIDEO: ONBOARD CAMERA FOOTAGE OF TANK FOAM FALLING PLAY
VIDEO: INSIDE MISSION CONTROL DURING LAUNCH PLAY
VIDEO: POST-LAUNCH NEWS CONFERENCE PLAY

VIDEO: FINAL PRE-LAUNCH POLLS GIVE "GO" FOR LIFTOFF PLAY
VIDEO: ASTRONAUTS ARRIVE AT LAUNCH PAD 39A PLAY
VIDEO: CREW DEPARTS QUARTERS FOR LAUNCH PAD PLAY
VIDEO: ASTRONAUTS DON SPACESUITS FOR LAUNCH PLAY
VIDEO: NARRATED RECAP OF KIBO LAB'S PRE-FLIGHT CAMPAIGN PLAY
VIDEO: NARRATED RECAP OF DISCOVERY'S PRE-FLIGHT CAMPAIGN PLAY
VIDEO: LAUNCH PAD GANTRY RETRACTED FRIDAY NIGHT PLAY
VIDEO: TIME-LAPSE OF GANTRY ROLLBACK PLAY
VIDEO: FRIDAY'S COUNTDOWN STATUS BRIEFING PLAY
VIDEO: PRE-LAUNCH NEWS CONFERENCE PLAY
VIDEO: BRIEFING ON KIBO LABORATORY FACILITY PLAY
VIDEO: ASTRONAUTS ARRIVE AT THE CAPE FOR LAUNCH PLAY
VIDEO: WEDNESDAY'S COUNTDOWN AND WEATHER BRIEFING PLAY
VIDEO: NARRATED MISSION PREVIEW MOVIE PLAY

VIDEO: NEWS BRIEFING FOLLOWING FLIGHT READINESS REVIEW PLAY

VIDEO: INTERVIEW WITH COMMANDER MARK KELLY PLAY
VIDEO: INTERVIEW WITH PILOT KEN HAM PLAY
VIDEO: INTERVIEW WITH MS1 KAREN NYBERG PLAY
VIDEO: INTERVIEW WITH MS2 RON GARAN PLAY
VIDEO: INTERVIEW WITH MS3 MIKE FOSSUM PLAY
VIDEO: INTERVIEW WITH MS4 AKIHIKO HOSHIDE PLAY

VIDEO: ASTRONAUTS PRACTICE EVACUATION OF SHUTTLE PLAY
VIDEO: CREW BOARDS DISCOVERY FOR PRACTICE COUNTDOWN PLAY
VIDEO: TRAINING SESSIONS AT LAUNCH PAD AND BUNKER PLAY
VIDEO: CREW NEWS CONFERENCE AT LAUNCH PAD 39A PLAY
VIDEO: ASTRONAUTS ARRIVE FOR PRACTICE COUNTDOWN PLAY

VIDEO: TIME-LAPSE OF GANTRY ENCLOSING DISCOVERY PLAY
VIDEO: PAD'S ORBITER ACCESS ARM SWUNG INTO POSITION PLAY
VIDEO: TIME-LAPSE OF CRAWLER RETREATING AFTER ROLLOUT PLAY
VIDEO: SHUTTLE DISCOVERY ROLLED TO PAD 39A PLAY

VIDEO: SHUTTLE AND STATION PROGRAM BRIEFING PLAY
VIDEO: STS-124 MISSION OVERVIEW PART 1 | PART 2
VIDEO: PREVIEW BRIEFING ON MISSION'S SPACEWALKS PLAY
VIDEO: THE ASTRONAUTS' PRE-FLIGHT NEWS BRIEFING PLAY

VIDEO: KIBO LABORATORY TRAVELS TO THE LAUNCH PAD PLAY
VIDEO: TRANSPORT CANISTER WITH KIBO ROTATED UPRIGHT PLAY
VIDEO: CRANE PLACES KIBO MODULE INTO TRANSPORT CANISTER PLAY

VIDEO: DISCOVERY HOISTED FOR ATTACHMENT TO FUEL TANK PLAY
VIDEO: THE SHUTTLE MOVES TO THE VEHICLE ASSEMBLY BUILDING PLAY
MORE: STS-124 VIDEO COVERAGE
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