In a virtually flawless spacewalk, two astronauts wired the newly installed P6 solar power tower into the international space station's electrical system Tuesday. Troubleshooters on the ground, meanwhile, perfected plans for having the spacewalkers tighten up a loose solar array blanket during a third and final spacewalk Thursday.

NASA flight controllers briefed the shuttle Endeavour's crew late Tuesday evening on the still-evolving repair plan, setting the stage for a dramatic conclusion to an already action-packed flight.

"You all did a great job, get a good night's sleep," veteran spacewalker Jerry Ross radioed the crew from Houston after the discussion ended.

"Yeah, I think we will," replied Endeavour spacewalker Joseph Tanner. "We were pretty pumped up."

The proposed repair will be reviewed by NASA's mission management team Wednesday. But it is expected to be approved.

The $600 million P6 solar power tower was installed during the crew's first spacewalk Sunday. The array is made up of two huge wings and each wing is made up of two solar cell blankets. The blankets were folded up for launch.

When the starboard wing was deployed, it's central mast extended at a constant speed, pulling its two solar blankets out of their storage boxes. As they unfurled, however, panels making up the blankets tended to bunch up and suddenly pull free, causing the blankets to ripple back and forth in an unexpectedly dynamic fashion.

As a result, two cables intended to put up to 75 pounds of tension on one of the two blankets popped off their pulleys and take-up spools, leaving the blanket slacker than engineers would like.

Three other cables, which apply about one pound of force each to the blanket, worked normally, as did the tensioning cables in the other blanket making up the starboard solar wing.

The loose blanket's solar cells are working normally. But NASA managers want to rewind the tension cables to keep the blanket taut and to enable a future crew to retract the wings so the P6 array can be relocated.

The repair plan calls for Tanner and Noriega to anchor their feet in portable work platforms near the top of the P6's central truss, some 90 feet above Endeavour's cargo bay. The starboard P6 array wing will be rotated so the two tension cable pulleys and take-up spools are within reach.

The astronauts then will attempt to wind the loose cable back onto the take-up spools and pulleys. Engineers believe the cables are intact and that if Tanner and Noriega can just feed them back onto their spools, the tensioning system will work properly.

Working in a huge water tank used to simulate weightlessness, astronauts Michael Foale and John Grunsfeld spent the day practicing techniques for putting the tension cables back in place, working with a "tiger team" of engineers and flight controllers.

Astronaut David Wolf, meanwhile, was dispatched to Sunnyvale, Calif., where the arrays were built by Lockheed Martin, to test the procedure on prototypes of the actual flight hardware.

Videotape showing Wolf working with the tensioning system in Sunnyvale was uplinked to Tanner and Noriega late Tuesday using a videoconferencing system.

"We think it would best be done with two people, but what were you guys thinking?" Tanner asked.

"That is our current plan, to have one person have two hands on the drum and the other individual be in a good position to see and feed the cable onto the drum as the other individual slowly allows it to come back to its fully counterclockwise position," Ross replied.

"OK, because I'm thinking, you know, the one guy is holding the tension on the cable and if he can't get close enough to do that with the tool, with his hand, he could actually clip a tether, an adjustable tension equipment tether or something, and keep that tension on there while the other guy (does) the final positioning of the cable on the pulley and the reel," Tanner said. "The guy that has the loop pin (tool) is also the person who rotates the reel, winds it up, I guess is what you do, right? For two and a half turns?"

"Yeah, we're actually thinking that you, Joe, with a little bit longer reach, would be the one on the non-open side of the spool, you would be positioned so you could rotate and control the drum and we would have Carlos as the guy with the loop pin puller who would be feeding the cable onto the drum. And we would do one of these at a time."

"Right. OK, and can you get two people that close?"

"It was looked at in the water today with Mike Foale and John Grunsfeld and they think this is the best approach and they didn't have any problem with two people there at the work site," Ross said.

First, however, Tanner and Noriega will test the rotation of the take-up spools to make sure they are free to turn properly. If there is a jam, internal blanket box latches will be activated to free any stuck components.

"If we find that there are problems with the drum rotation, then we will probably, more than likely, open and close the latch mechanism for the tensioning device to see if we can free that internal, potential problem," Ross said.

The third spacewalk was originally scheduled to install an instrument called the floating potential probe to measure the space station's electrical environment. That job will still be done, but fixing the array blanket will be the first item on the agenda.

"We're going to go straight to the solar array activities," Ross radioed. "If we have to spend six hours doing that, that's what we'll do."

Tanner and Noriega successfully wired the P6 array into the space station's power system Tuesday during a six-hour 37-minute spacewalk. It was the 56th spacewalk in shuttle history, the 95th in U.S. space history and the 12th devoted to building the international space station.

Along with connecting the P6 array to the station's electrical bus, the spacewalkers also moved an S-band antenna from a temporary storage location to the top of the array; connected ammonia coolant lines between the station and radiators mounted on the side of the P6 truss; and hooked up jumpers that will allow power from P6 to flow into the Russian Zarya and Zvezda modules.

Station commander William Shepherd and his two crewmates - Yuri Gidzenko and Sergei Krikalev - worked inside the Unity module to make internal cable connections between P6 and the station. The crew resealed Unity to prevent condensation from building up while P6-powered heaters warmed the module up.

"Hopefully, we'll get you in ther permanently tomorrow," astronaut Joan Higginbotham radioed from Houston. "We're shooting for somewhere around lunch time, running around 1300 GMT."

During a final tagup with space station control, Shepherd voiced concern about his crew's work schedule, asking NASA managers to work with their Russian counterparts to defer tasks that are not absolutely essential.

Otherwise, he said, the station crew will not be ready to transfer supplies and equipment to and from the shuttle Friday - flight day nine - when the two crews are scheduled to meet face to face for the first time.

"What we need to do tomorrow, we need to organize the cargo that's going to go down on 4A (Endeavour) and I need to get on top of IMAX so we can get some shooting done," Shepherd said. "Then on Thursday, we need to try and lay stuff out in the node (Unity module), including the cargo, and set up IWIS (internal wireless instrumentation system).

"Unless we can park the things that are not essential for getting through 4A, we're not going to be ready for flight day nine."

"Shep we copy that and we concur strongly," replied Higginbotham. "We will do our best to get most of the things that are not 4A related and critical off of your timeline."

Earlier, Noriega carried out a detailed inspection of the power system's starboard solar wing, beaming down sharp color television images from cameras mounted on his space helmet.

Tanner reported both tension cables on the blanket in question had jumped off their guide pulleys at the base of one blanket.

"The outboard tension is not on the guide pulley, it's not going around that pulley," Tanner told flight controllers in Houston. "You see? From my angle, I can really see it. ... It probably means the inboard one isn't, either."

"I can't see that it's not on the reel," Noriega added, "but I can deduce it, because the arc of the cable is different from the arc of the pulley itself."

"We could put it back on that one pulley, but the other one is going to be a little work," Tanner said.

Ross then asked Noriega to move around the array's central mast to inspect the other blanket making up the starboard solar array wing.

"The guide wires look good, the tension wires have about the same amount of tautness," Noriega reported. "The tension bar looks in good shape as do the ribbon cables."

"OK, copy, and that goes for both the inboard and outboard systems?" Ross asked from mission control.

"That's affirmative."

"OK, guys, what you told us about the side that's not tensioned is about what the guys at Suynnyvale had expected to see and we think we've got, hopefully, a pretty good handle on it and can probably fix it."

"Great!"