As expected, the Endeavour astronauts will delay their fourth spacewalk, from Friday to Saturday, to protect against the possibility of an unprecedented heat shield repair. NASA's Mission Management Team met into the evening today, assessing test results and exploring various mission scenarios, but a final decision on whether or not to order a repair spacewalk was not expected until Thursday.

By delaying the shuttle crew's fourth spacewalk from Friday to Saturday, however, mission managers will have time to refine their plans if the MMT does, in fact, decide a tile repair is needed. In that case, the repair work would be carried out Saturday and a fifth spacewalk could be added Monday to complete the delayed station work. That scenario, if approved, likely would result in a two-day mission extension and a landing back at the Kennedy Space Center on Aug. 24.

If the tile repair is not needed, the astronauts would simply carry out the previously planned space station assembly spacewalk on Saturday and land as currently scheduled on Aug. 22.

"I'd like to give you some big picture words of what our plan forward is," astronaut Shannon Walker called from mission control to kick off a daily planning conference. "All the decisions have not been made yet, the MMT is actually still meeting as we speak, but one thing that has been decided is that EVA-4 will be on Saturday."

"Copy Shannon. And I hope everybody here is ready for this EVA, too, whatever it is," station commander Fyodor Yurchikhin replied.

"Yes, exactly. We do not know what the EVA will be," Walker said. "Obviously, it will either be TPS (thermal protection system) repair or the regular EVA-4. So what we have done is plan your day tomorrow as if it's going to be TPS repair, but stressing that no decision has been made either way."

"We copy," an astronaut said.

"OK, that being said, the plan is on board but don't go off and memorize it tonight because we're still working on it down here and it is not in synch with form 24 at all," Walker said. "But at the moment, you will see TPS-related activities on it."

Shuttle commander Scott Kelly then asked, "any word when the MMT's going to adjourn? Are they supposed to make a decision today on repair, or not repair?"

"Scott, we are hoping they are going to adjourn within the next hour or so, but actually we do not expect a decision today on whether or not we're going to repair or not repair," Walker replied.

"OK, thank you."

"At the moment, they don't have all the data they would like to make their decision," she continued.

"And no indication of which way they're leaning?" Kelly asked.

"Unfortunately, we have no idea which way the wind is blowing at the moment."

Additional coverage for subscribers:
VIDEO: PREVIEW OF SPACEWALK NO. 3 PLAY
VIDEO: THE FLIGHT DAY 7 HIGHLIGHTS MOVIE PLAY
VIDEO: FLIGHT DAY 7 MISSION STATUS BRIEFING PLAY
VIDEO: EDUCATIONAL EVENT WITH CHILDREN IN IDAHO PLAY
VIDEO: CREW INTERVIEW WITH ABC NEWS PLAY
VIDEO: CREW INTERVIEW WITH CBS NEWS PLAY
VIDEO: CREW INTERVIEW WITH CNN PLAY
VIDEO: CREW INTERVIEW WITH NBC NEWS PLAY
VIDEO: CREW INTERVIEW WITH FOX NEWS PLAY
VIDEO: STOWAGE PLATFORM ATTACHED TO THE STATION PLAY
VIDEO: THE PLATFORM IS RAISED OUT OF PAYLOAD BAY PLAY
VIDEO: SHUTTLE ARM GRAPPLES THE STOWAGE PLATFORM PLAY
VIDEO: STOWAGE PLATFORM INSTALLATION EXPLAINED PLAY

VIDEO: THE FLIGHT DAY 6 HIGHLIGHTS MOVIE PLAY
VIDEO: SHANNON GIVES UPDATE ON TILE DAMAGE ANALYSIS PLAY
VIDEO: FLIGHT DAY 6 MISSION STATUS BRIEFING PLAY
VIDEO: PREVIEW OF SPACEWALK NO. 2 PLAY
VIDEO: SPACEWALK NO. 2 BEGINS PLAY
VIDEO: SPACEWALKERS UNBOLT THE FAILED GYROSCOPE PLAY
VIDEO: THE FAILED GYRO IS REMOVED FROM THE STATION PLAY
VIDEO: NEW GYRO IS RETRIEVED FROM SHUTTLE PAYLOAD BAY PLAY
VIDEO: SPACEWALKERS BRING NEW GYRO UP TO THE STATION PLAY
VIDEO: THE NEW GYRO IS INSTALLED AND BOLTED DOWN PLAY
VIDEO: FAILED GYRO PUT ON STATION STOWAGE PLATFORM PLAY

VIDEO: THE FLIGHT DAY 5 HIGHLIGHTS MOVIE PLAY
VIDEO: HURRICANE FLOSSIE ON SUNDAY EVENING PLAY
VIDEO: CREW INSPECTIONS SHUTTLE TILE DAMAGE PLAY
VIDEO: INSPECTION BOOM FOR DAMAGE CHECK PLAY
VIDEO: FLIGHT DAY 5 MISSION STATUS BRIEFING PLAY

VIDEO: THE FLIGHT DAY 4 HIGHLIGHTS MOVIE PLAY
VIDEO: FLIGHT DAY 4 MISSION STATUS BRIEFING PLAY
VIDEO: SPACEWALK NO. 1 BEGINS PLAY
VIDEO: SPACEWALKERS REMOVE LAUNCH LOCKS ON S5 TRUSS PLAY
VIDEO: ROBOT ARM INSTALLS STARBOARD 5 TRUSS ON STATION PLAY
VIDEO: STARBOARD 5 TRUSS BOLTED TO THE SPACE STATION PLAY
VIDEO: TRUSS'S GRAPPLE FIXTURE REMOVED PLAY
VIDEO: PREVIEW OF SPACEWALK NO. 1 PLAY
VIDEO: STARBOARD 5 TRUSS INSTALLATION EXPLAINED PLAY

VIDEO: THE FLIGHT DAY 3 HIGHLIGHTS MOVIE PLAY
VIDEO: FLIGHT DAY 3 MISSION STATUS BRIEFING PLAY
VIDEO: STARBOARD 5 TRUSS PULLED OUT OF PAYLOAD BAY PLAY
VIDEO: TRUSS HANDED FROM SHUTTLE ARM TO STATION ARM PLAY
VIDEO: SHUTTLE ASTRONAUTS WELCOMED ABOARD STATION PLAY
VIDEO: SHUTTLE DOCKS TO THE STATION AS SEEN LIVE PLAY
VIDEO: ENDEAVOUR AND STATION FLY INTO ORBITAL SUNRISE PLAY
VIDEO: SHUTTLE DOES BACKFLIP BELOW THE STATION PLAY
VIDEO: ENDEAVOUR INTERCEPTS THE SPACE STATION PLAY
VIDEO: SHUTTLE TI BURN SEEN FROM STATION PLAY
VIDEO: ANIMATED PREVIEW OF DOCKING PLAY

VIDEO: FIRST IN-SPACE COMMENTS FROM BARBARA MORGAN PLAY
VIDEO: THE FLIGHT DAY 2 HIGHLIGHTS MOVIE PLAY
VIDEO: SHUTTLE INSPECTIONS EXPLAINED PLAY
VIDEO: FLIGHT DAY 2 MISSION STATUS BRIEFING PLAY
VIDEO: THE FULL LAUNCH EXPERIENCE PLAY
VIDEO: JETTISONED EXTERNAL TANK FALLS AWAY PLAY
VIDEO: THE FLIGHT DAY 1 HIGHLIGHTS MOVIE PLAY

VIDEO: LAUNCH REPLAY: EXTERNAL TANK CAMERA PLAY
VIDEO: LAUNCH REPLAY: UCS-23 WIDESCREEN PLAY
VIDEO: LAUNCH REPLAY: PLAYALINDA 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 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: LAUNCH REPLAY: WEST TOWER PLAY
VIDEO: LAUNCH REPLAY: PAD PERIMETER PLAY
VIDEO: LAUNCH REPLAY: COMPLEX 41 PLAY
VIDEO: LAUNCH REPLAY: KSC RUNWAY PLAY
VIDEO: LAUNCH REPLAY: PAD FRONT PLAY
VIDEO: LAUNCH REPLAY: CAMERA CS-1 PLAY
VIDEO: LAUNCH REPLAY: CAMERA CS-2 PLAY
VIDEO: LAUNCH REPLAY: CAMERA UCS-12 PLAY
VIDEO: LAUNCH REPLAY: PRESS SITE PLAY
VIDEO: LAUNCH REPLAY: VAB ROOF PLAY
VIDEO: LAUNCH REPLAY: BEACH TRACKER PLAY

VIDEO: ENDEAVOUR BLASTS OFF! PLAY
VIDEO: CREW'S LAUNCH MORNING PHOTO IN DINING ROOM PLAY
VIDEO: UPCLOSE FOOTAGE OF THE GANTRY ROLLBACK PLAY
VIDEO: TIME-LAPSE MOVIE OF GANTRY ROLLBACK PLAY
VIDEO: TUESDAY MORNING'S STATUS BRIEFING PLAY
VIDEO: STS-118 PRE-LAUNCH NEWS CONFERENCE PLAY
VIDEO: MONDAY MORNING'S STATUS BRIEFING PLAY
VIDEO: SUNDAY COUNTDOWN AND WEATHER UPDATE PLAY
VIDEO: CREW ARRIVES AT KENNEDY SPACE CENTER PLAY
VIDEO: COMMENTS FROM EACH OF THE ASTRONAUTS PLAY

VIDEO: PRE-FLIGHT INTERVIEW: SCOTT KELLY PLAY
VIDEO: PRE-FLIGHT INTERVIEW: CHARLIE HOBAUGH PLAY
VIDEO: PRE-FLIGHT INTERVIEW: TRACY CALDWELL PLAY
VIDEO: PRE-FLIGHT INTERVIEW: RICK MASTRACCHIO PLAY
VIDEO: PRE-FLIGHT INTERVIEW: DAVE WILLIAMS PLAY
VIDEO: PRE-FLIGHT INTERVIEW: BARBARA MORGAN PLAY
VIDEO: PRE-FLIGHT INTERVIEW: ALVIN DREW PLAY
MORE: STS-118 VIDEO COVERAGE
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