Running 34 minutes ahead of schedule, astronauts Richard Linnehan and Michael Foreman switched their spacesuits to battery power at 7:49 p.m., kicking off a planned seven-hour spacewalk to attach two 11-foot-long arms to a Canadian maintenance robot being assembled at the international space station.

This is the 106th spacewalk devoted to station assembly and maintenance since construction began in 1998, the seventh so far this year and the second of five planned by the shuttle Endeavour's crew,. Linnehan, veteran of a 2002 Hubble Space Telescope repair mission, is making his fifth spacewalk while Foreman is making his first.

In the daily "execute package" of instructions uplinked to the shuttle-station complex, flight controllers jokingly paraphrased science fiction writer Isaac Asimov's three laws of robotics to fit the special purpose dexterous manipulator robot, known as Dextre for short.

"Optimus Prime, Gigantor and Robbie the Robot are here in MCC (mission control center) today, representing the Robot Actors Guild, to celebrate the launch of Dextre," the note said. "There was an embarrassing gaffe last month, during (shuttle flight) STS-122 when they came out to honor the wrong "Dex." (shuttle pilot Alan Poindexter)Ê

"We've incorporated a few new flight rules, now that we are about to have robotic EV's:

"1. Dextre may not injure a human being or, through inaction, allow a human being to come to harm.

"2. Dextre must obey orders given to it by human beings, except where such orders would conflict with the First Law.

"3. Dextre must protect its own existence as long as such protection does not conflict with the First or Second Law.

"The guild members bristled about these rules and, 'being held down by the man,' but figure that they can't be held back for long. 'First Dextre, next Data, then THE MATRIX!' declared Optimus at arrival at JSC."

It will take the astronauts a half hour or so to set up tethers and tools and to make their way to the forward face of the station's solar power truss where they will spend the next several hours attaching Dextre's arms.

Additional coverage for subscribers:
VIDEO: NARRATED PREVIEW OF SPACEWALK NO. 2 PLAY

VIDEO: THE FLIGHT DAY 5 HIGHLIGHTS MOVIE PLAY
VIDEO: SATURDAY MORNING MEDIA INTERVIEWS PLAY
VIDEO: STATION ARM GRAPPLES DEXTRE TO PROVIDE POWER PLAY
VIDEO: CEREMONY AT JAPANESE MODULE HATCH OPENING PLAY
VIDEO: SATURDAY'S MISSION STATUS BRIEFING PLAY
VIDEO: FRIDAY'S MISSION MANAGEMENT TEAM UPDATE PLAY

VIDEO: THURSDAY'S MISSION STATUS BRIEFING PLAY
VIDEO: THE FLIGHT DAY 4 HIGHLIGHTS MOVIE PLAY
VIDEO: NEW MODULE CONNECTED TO THE STATION PLAY
VIDEO: JAPANESE MODULE UNBERTHED FROM SHUTTLE PLAY
VIDEO: NARRATED PREVIEW OF SPACEWALK NO. 1 PLAY
VIDEO: THURSDAY'S MISSION MANAGEMENT TEAM UPDATE PLAY

VIDEO: THE FLIGHT DAY 3 HIGHLIGHTS MOVIE PLAY
VIDEO: DEXTRE PALLET MOVED FROM SHUTTLE TO STATION PLAY
VIDEO: THURSDAY'S MISSION STATUS BRIEFING PLAY
VIDEO: SHUTTLE ENDEAVOUR DOCKS TO SPACE STATION PLAY
VIDEO: ENDEAVOUR PERFORMS THE 360-DEGREE BACKFLIP PLAY
VIDEO: VIEWS OF THE SHUTTLE APPROACHING FROM BELOW PLAY
VIDEO: NARRATED ANIMATION OF PREVIEWING THE DOCKING PLAY
VIDEO: UPDATE FROM MISSION MANAGEMENT TEAM PLAY

VIDEO: THE FLIGHT DAY 2 HIGHLIGHTS MOVIE PLAY
VIDEO: WEDNESDAY'S MISSION STATUS BRIEFING PLAY
VIDEO: ANIMATION OF THE HEAT SHIELD INSPECTIONS PLAY
VIDEO: NARRATED TOUR OF ENDEAVOUR'S PAYLOAD BAY PLAY

VIDEO: THE FLIGHT DAY 1 HIGHLIGHTS MOVIE PLAY
VIDEO: INSIDE MISSION CONTROL DURING LAUNCH PLAY
VIDEO: THE FULL LAUNCH EXPERIENCE PLAY
VIDEO: SHUTTLE ENDEAVOUR BLASTS OFF! PLAY
VIDEO: THE POST-LAUNCH NEWS CONFERENCE PLAY
VIDEO: HIGHLIGHTS FROM ENDEAVOUR'S LAUNCH CAMPAIGN PLAY
VIDEO: HIGHLIGHTS OF THE PAYLOADS' LAUNCH CAMPAIGN PLAY

VIDEO: LAUNCH REPLAY: VAB ROOF PLAY
VIDEO: LAUNCH REPLAY: PAD FRONT PLAY
VIDEO: LAUNCH REPLAY: PRESS SITE PLAY
VIDEO: LAUNCH REPLAY: WEST TOWER PLAY
VIDEO: LAUNCH REPLAY: PAD PERIMETER PLAY
VIDEO: LAUNCH REPLAY: UCS-23 WIDESCREEN PLAY
VIDEO: LAUNCH REPLAY: CAMERA 009 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 061 PLAY
VIDEO: LAUNCH REPLAY: CAMERA 063 PLAY
VIDEO: LAUNCH REPLAY: CAMERA 070 PLAY
VIDEO: LAUNCH REPLAY: CAMERA 071 PLAY
VIDEO: LAUNCH REPLAY: CAMERA CS-1 PLAY
VIDEO: LAUNCH REPLAY: CAMERA CS-2 PLAY
VIDEO: LAUNCH REPLAY: CAMERA CS-6 PLAY

VIDEO: FINAL PRE-LAUNCH POLLS GIVE "GO" FOR LIFTOFF PLAY
VIDEO: ENDEAVOUR'S CREW MODULE CLOSED FOR FLIGHT PLAY
VIDEO: ASTRONAUT DOI CLIMBS INTO HIS SEAT PLAY
VIDEO: PILOT JOHNSON CLIMBS INTO HIS SEAT PLAY
VIDEO: ASTRONAUT REISMAN CLIMBS INTO HIS SEAT PLAY
VIDEO: COMMANDER GORIE CLIMBS INTO HIS SEAT 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: TIME-LAPSE MOVIE OF SUNSET OVER PAD 39A PLAY
VIDEO: MORNING PREPARATIONS AT LAUNCH PAD 39A PLAY
VIDEO: PAD GANTRY RETRACTED FOR LAUNCH PLAY

VIDEO: OVERVIEW BRIEFING ON CANADA'S DEXTRE ROBOT PLAY
VIDEO: OVERVIEW BRIEFING ON JAPAN'S KIBO FACILITIES PLAY
VIDEO: SUNDAY'S COUNTDOWN STATUS BRIEFING PLAY
VIDEO: SATURDAY'S COUNTDOWN STATUS BRIEFING PLAY
VIDEO: CREW ARRIVES AT KENNEDY SPACE CENTER FOR LAUNCH PLAY
VIDEO: FRIDAY'S COUNTDOWN STATUS AND WEATHER BRIEFING PLAY

VIDEO: STS-123 ASTRONAUT BIOGRAPHY MOVIE PLAY
VIDEO: NARRATED SHORT FILM PREVIEW ENDEAVOUR'S FLIGHT PLAY

VIDEO: STS-123 MISSION OVERVIEW BRIEFING PLAY
VIDEO: BRIEFING ON THE SPACEWALKS PLAY
VIDEO: CREW'S PRE-FLIGHT BRIEFING PLAY
VIDEO: SHUTTLE AND ISS PROGRAM UPDATE PLAY

VIDEO: CREW INTERVIEW: COMMANDER DOM GORIE PLAY
VIDEO: CREW INTERVIEW: PILOT GREG JOHNSON PLAY
VIDEO: CREW INTERVIEW: MS1 BOB BEHNKEN PLAY
VIDEO: CREW INTERVIEW: MS2 MIKE FOREMAN PLAY
VIDEO: CREW INTERVIEW: MS3 TAKAO DOI PLAY
VIDEO: CREW INTERVIEW: MS4 RICK LINNEHAN PLAY

VIDEO: FLIGHT READINESS REVIEW NEWS BRIEFING PLAY
VIDEO: TCDT TRAINING HIGHLIGHTS PLAY
VIDEO: PRESS CHAT WITH CREW AT LAUNCH PAD PLAY
VIDEO: CREW ARRIVES AT KSC FOR PRACTICE COUNT PLAY
VIDEO: ENDEAVOUR ARRIVES AT PAD 39A PLAY | XL SIZE
VIDEO: SHUTTLE ROLLS TO THE VAB PLAY | XL SIZE
MORE: STS-123 VIDEO COVERAGE
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