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STS-120 SRB cameras

Spectacular footage from six cameras mounted on shuttle Discovery's solid rocket boosters.

 Full coverage

Day 10 highlights

The astronauts getting equipment ready for the solar array repair spacewalk was the focus of activities on Flight Day 10.

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STS-120 day 9 highlights

This Halloween edition of the flight day highlights is complete with Clay Anderson's costume.

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STS-120 day 8 highlights

Moving the Port 6 truss to its permanent spot on the station and the ripped solar blanket are shown in the Flight Day 8 movie.

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STS-120 day 7 highlights

Juggling of the Port 6 solar array truss between the station and shuttle robotic arms highlighted work on Flight Day 7.

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STS-120 day 6 highlights

Spacewalk to detach Port 6 truss and discovery of debris in a solar array rotary joint are highlighted in the Flight Day 6 movie.

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STS-120 day 5 highlights

Highlights from Flight Day 5 see the astronauts enter into the newly-installed Harmony module.

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STS-120 day 4 highlights

The Flight Day 4 highlights movie shows Harmony's attachment to the station and the Discovery mission's first spacewalk.

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STS-120 day 3 highlights

This movie shows the highlights from Flight Day 3 as Discovery docked to the space station.

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STS-120 day 2 highlights

Flight Day 2 of Discovery's mission focused on heat shield inspections. This movie shows the day's highlights.

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STS-120 launch videos

Check out all angles of space shuttle Discovery's launch with our extensive video collection.

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STS-120 day 1 highlights

The highlights from shuttle Discovery's launch day are packaged into this movie.

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STS-120: Crew arrival

The space shuttle Discovery astronauts arrive at the Kennedy Space Center for their countdown to launch.

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STS-120: The programs

In advance of shuttle Discovery's STS-120 mission to the station, managers from both programs discuss the flight.

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STS-120: The mission

Discovery's trip to the station will install the Harmony module and move the P6 solar wing truss. The flight directors present a detailed overview of STS-120.

 Part 1 | Part 2

STS-120: Spacewalks

Five spacewalks are planned during Discovery's STS-120 assembly mission to the station. Lead spacewalk officer Dina Contella previews the EVAs.

 Full briefing
 EVA 1 summary
 EVA 2 summary
 EVA 3 summary
 EVA 4 summary
 EVA 5 summary

The Discovery crew

The Discovery astronauts, led by commander Pam Melroy, meet the press in the traditional pre-flight news conference.

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Flight controllers optimistic about successful repair
BY WILLIAM HARWOOD
STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION
Posted: November 2, 2007

The Discovery astronauts today reviewed plans for a dramatic solar array repair spacewalk early Saturday and appeared confident they have a good shot at fixing the mangled panel to keep space station assembly on track. Lead flight director Derek Hassmann said concern that spacewalker Scott Parazynski could get zapped by an unexpected electrical discharge while working near the charged array was misplaced and that the additional risk was minimal.


This artwork shows Scott Parazynski reaching the damage site. Credit: NASA
 
"As I left the control center today, I felt really, really good about where we are, about the robotics pieces of the procedures, about the spacewalking techniques, about the hardware, about our understanding of the area of damage, about our approaches to fixing that damage and also about the ground choreography and how the timeline's going to play out in mission control," he said. "I walked away from my shift today very, very impressed with the incredible amount of progress that's occurred over the last 24 hours."

Said lead spacewalk officer Dina Contella: "Having the extra day to prepare for this spacewalk has really been a good thing for the EVA team, we've really hammered flat a lot of the details. ... It's really been a huge, coordinated effort. The big picture really hasn't changed. it's just a matter of the details, really, getting (figured) out in the extra day that we had."

A successful repair is critical to NASA's plans for continuing space station assembly. At the Kennedy Space Center in Florida on Saturday, engineers are scheduled to move the shuttle Atlantis from its hangar to the Vehicle Assembly Building for attachment to a set of boosters and an external tank. Launch on the next space station assembly mission, a high-profile flight to deliver Europe's Columbus research module, is targeted for Dec. 6.

Because of problems with the station's right-side solar array rotary joint, NASA needs to get the P6 array repaired and fully extended to provide the power necessary to support the attachment of Columbus next month as well as Japanese research modules scheduled for launch early next year.

"At this point, we've got problems on both ends of the truss, unfortunately," Hassmann said. "We've got the issues with the starboard truss, with the starboard solar array rotary joint, and now we've got this issue on the port side of the truss with the 4B solar array. ... We need to address one of these two problems before we proceed.

"Based on the discussions I've been involved in, we need to get the solar array addressed and fixed, fully deployed, structurally stable, available for power before we would proceed with 1E (the Columbus mission)."

Parazynski and astronaut Doug Wheelock plan to begin the dramatic spacewalk around 6:30 a.m., floating out of the station's Quest airlock module and making their way up onto the lab's main solar power truss. Parazynski will attach a foot restraint to a 50-foot boom carried by the station's robot arm and then lock his boots in place for a slow but spectacular 45-minute ride to the damaged array.

Wheelock, meanwhile, will make his way to the base of the P6-4B solar array on the far left end of the main power truss and provide verbal guidance cues for arm operators Stephanie Wilson and Dan Tani, working inside the Destiny laboratory module.

The P6-4B solar array is mounted on the far left end of the space station's main power truss, half a football field from the space station's pressurized modules. The robot arm alone cannot reach the damage site, even when positioned at a work site on the end of the power truss. But using the shuttle's heat shield inspection boom as an extension, the space crane can just barely get Parazynski into position.

On Thursday, mission managers said it would take Parazynski more than 30 minutes to reach the safety of the station's airlock in the event of a major spacesuit malfunction, primarily because of time needed to maneuver the robot arm. All NASA suits are equipped with a 30-minute supply of emergency oxygen and NASA has never before planned a station spacewalk that could put an astronaut in a position where he or she couldn't reach the airlock in a half hour.

But Contella said Friday engineers had refined their plans and that she believed Parazynski could get back to the Quest module before running out of air in any credible failure scenario.

After reaching the damage site, Parazynski, one of NASA's most experienced spacewalkers, first will inspect the mangled section of the 4B solar blanket to determine what might be needed to release an apparently snarled guidewire believed to have ripped open two blanket panel hinges during deployment Tuesday.

Before addressing the presumed snarl, the spacewalker will attach a homemade clip dubbed a cufflink, threading clasps on each end through reinforced holes above and below the rips in the blanket. That way, if the tension on the blanket changes because of work to free the snarl, it will not worsen the tears that are already there. Five such cufflinks will be installed across the 15-foot width of the blanket before any attempt is made to complete its extension.


Credit: NASA
 
If NASA is lucky, Parazynski will be able to simply move the guidewire to one side, freeing the snarl. If the tangle cannot be freed, he will cut the wire and Wheelock will use pliers at the base of the array to control its winding back onto a take-up reel.

"The problem would come is if we get there and we realize the snag either can't be cleared or maybe the snag has altered the guidewire, for example, in some way that we don't really want to do the deploy with the guide wire in that particular state, we don't think it's a good idea to have the damage as is for a deploy," Contella said.

"So if we get in either of those two cases, then we will cut the guidewire. So the idea is, Wheels would get ready at the bottom of the array. Remember, there's the take-up reel mechanism at the bottom and Wheels will have needle-nose pliers at the base and he'll get ready and basically grip the bottom part of the wire. And this is because we want to have a controlled intake as opposed to something that would accelerate and potentially end up with a big snarl at the base."

The spacewalk is timelined to last up to six hours and 30 minutes. But Hassmann and Contella said if Parazynski doesn't run into any major problems, the actual repair work could be completed in as little as a half hour. The astronauts inside the space station will attempt to redploy the repair panel as soon as Parazynski can be moved out of the way.

NASA expects to have good video coverage of the repair work, using cameras mounted on the space station and in the helmets of both spacewalkers. But Hassmann said video was not required. It will be up to Parazynski, the man on the scene, to determine the best course of action.

"We don't have fantastic photography of this area, we just don't have the capability to see exactly what's happening," Contella said. "So at that point, Scott's going to have to use his best judgment on what he thinks we're going to do."

In the end, she said, "it's a snag clear; it's not rocket science. So you want him to probably tell you what he thinks would be the best thing and then we'll just discuss it on the ground and make sure everybody sort of agrees that yeah, the solar array's not going to have some sort of adverse dynamics because of the way he wants to clear it, something like that."

During a news briefing Thursday, astronaut Dave Wolf downplayed the threat of a shock hazard, but told reporters it was possible, in theory, for an astronaut to get electrocuted in a worst-case short. Today, Hassmann downplayed those concerns saying "a number of things have to happen all at once for there even to be a small risk of any kind of electrical problem or shock hazard while Scott's out there doing his work."

"The thing to remember," he said, "is a pristine solar array, an undamaged solar array is completely isolated. The suit itself, obviously, is completely isolated. ... A spacewalking astronaut could put his hand on that solar array and there would be no risk of any kind of shock of any kind.

"What we do is, we think about the worse case scenarios and any possible way a shock hazard, any kind of electricity incident, could occur. And really what you have to do in your mind to make that happen is to find a metal piece on the suit, which in general is the rings around the gloves, the ring around the waist, the ring around the boots, and you'd have to take one of those metal rings and apply that to a hot part of the solar array. And in order to find a hot part of the solar array, you'd have to find a damaged portion.

"So if you could find that hot wire, a crew could put a metal portion of his suit, which is very limited, on the hot part and then he'd have to complete the circuit. So he'd have to find another part of his suit, the boot ring, for example, or the waist ring, and he'd have to apply that to another part of the solar array in order to complete that circuit in order to come anywhere close to any kind of shock hazard."


This artwork shows Scott Parazynski reaching the damage site. Credit: NASA
 
Each of the slats making up the folding solar blanket generates about 300 watts of power. The electricity cascades down a strip that runs from top to bottom along the left inboard edge of the panel near where the two rips are present. Control systems at the base of the array send a regulated 160 volts of direct current electricity into the station's power system. That output is converted to 124 volts for use by lab systems.

Playing it safe, Parazynski's tools were wrapped in non-conducting tape, as were the glove, boot and waist rings on his spacesuit.

The 17-ton P6 solar array truss segment was launched in 2000 to provide power during the initial stages of assembly. The lab's main power truss is now built and equipped with huge sets of solar panels on each end: starboard 4 (S4) on the right side and port 4 (P4) on the left. The outermost right side S6 arrays, scheduled for launch next fall, will be attached to a short spacer segment known as S5.

During two recent shuttle flights, astronauts retracted the two wings of the P6 array and disconnected it from the station's power system. Spacewalkers had problems retracting the 4B panel, however, encountering a frayed guidewire that repeatedly hung up on grommets during the retraction process.

On Tuesday, P6 was unbolted from its initial mounting point and moved to the far left end of the power truss and bolted to the P5 spacer segment. The first of its two solar array wings, known as P6-2B, extended a full 110 feet as required, but the crew aborted deployment of the 4B wing when one section of hinged blanket slats hung up, presumably due to a guide wire snag. Two seams between adjacent slats pulled open, resulting in separate tears, and the edges of several nearby slats were crumpled. The largest rip measured some two-and-a-half feet long.

Eighty percent deployed, the P6-4B array can generate 97 percent of the electricity of a fully extended wing. The station is not yet using power from the torn array, but engineers say tests confirm no major damage to its internal wiring.

The immediate concern is figuring out a way to fully extend the P6-4B wing to provide the necessary structural rigidity. With a partially deployed panel, none of the arrays on the left side of the main power truss can be rotated as required to track the sun without risking additional damage. As a result, the station's left-side solar alpha rotary joint, or SARJ, is locked in place until the damage is fixed.

Adding to NASA's problems, the station's right-side arrays also are locked in place because of unexpected metallic contamination inside the starboard SARJ. Parazynski and Doug Wheelock were in the process of gearing up Wednesday for a spacewalk to inspect the starboard SARJ Thursday when NASA managers decided to focus instead on fixing the P6-4B solar blanket.

Engineers initially held out hope for a repair spacewalk Friday, but NASA managers decided early Thursday to wait until Saturday, giving engineers more time to fine-tune the plan.

Spaceflight Now Plus
Additional coverage for subscribers:
VIDEO: THE FLIGHT DAY 10 HIGHLIGHTS MOVIE PLAY
VIDEO: THURSDAY'S STATUS BRIEFING AND SPACEWALK PREVIEW PLAY

VIDEO: THE FLIGHT DAY 9 HIGHLIGHTS MOVIE PLAY
VIDEO: WEDNESDAY'S MISSION STATUS BRIEFING PLAY
VIDEO: CREW NEWS BRIEFING WITH U.S., ITALY, RUSSIA PLAY

VIDEO: THE FLIGHT DAY 8 HIGHLIGHTS MOVIE PLAY
VIDEO: TUESDAY'S MISSION STATUS BRIEFING PLAY
VIDEO: SOLAR ARRAY WING TEARS DURING DEPLOYMENT PLAY
VIDEO: FIRST SOLAR ARRAY IS SUCCESSFULLY UNFURLED PLAY
VIDEO: HOUSTON BEGINS SOLAR ARRAYS DEPLOY SEQUENCE PLAY
VIDEO: SPARE POWER SWITCHING UNIT INSTALLED PLAY
VIDEO: INSPECTIONS OF PORT-SIDE ROTARY JOINT PLAY
VIDEO: RADIATOR UNFOLDED FROM THE P6 TRUSS PLAY
VIDEO: THE ASTRONAUTS PAUSE FOR QUICK PHOTOS PLAY
VIDEO: SPACEWALKERS REMOVE SHROUDS FROM P6 BOXES PLAY
VIDEO: P6 TRUSS CAPTURED CLAW-LIKE INSTALL LATCH PLAY
VIDEO: SPACEWALKERS HELP GUIDE P6 TRUSS INTO PLACE PLAY
VIDEO: DOUG WHEELOCK EMERGES FROM AIRLOCK FOR EVA PLAY
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VIDEO: NARRATED ANIMATION OF P6 TRUSS INSTALLATION PLAY
VIDEO: PREVIEW OF TUESDAY'S SPACEWALK PLAY

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VIDEO: MONDAY'S MISSION STATUS BRIEFING PLAY
VIDEO: ANOTHER RADIATOR DEPLOYED FROM THE S1 TRUSS PLAY
VIDEO: RADIATOR DEPLOYED FROM STARBOARD 1 TRUSS PLAY
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VIDEO: CREW INTERVIEWED BY ABC NEWS PLAY
VIDEO: CREW INTERVIEWED BY NBC NEWS PLAY
VIDEO: CREW INTERVIEWED BY CNN PLAY
VIDEO: NARRATED ANIMATION OF RADIATOR DEPLOYS PLAY
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VIDEO: THE FLIGHT DAY 6 HIGHLIGHTS MOVIE PLAY
VIDEO: POST-SPACEWALK MISSION STATUS BRIEFING PLAY
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VIDEO: TANI COLLECTS SAMPLES OF DEBRIS IN ROTARY JOINT PLAY
VIDEO: TANI DISCOVERS UNKNOWN DEBRIS INSIDE ROTARY JOINT PLAY
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VIDEO: SPACEWALKERS UNBOLT THE PORT 6 TRUSS PLAY
VIDEO: NARRATED ANIMATION OF PORT 6 REMOVAL PLAY
VIDEO: PREVIEW OF SUNDAY'S SPACEWALK PLAY
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VIDEO: BIOGRAPHY MOVIE ON EXPEDITION 16 CREW PLAY
VIDEO: BIOGRAPHY ON NEW EXPEDITION 16 MEMBER DAN TANI PLAY

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VIDEO: CREW INTERVIEWED BY CBS NEWS PLAY
VIDEO: CREW INTERVIEWED BY FOX NEWS PLAY
VIDEO: CREW INTERVIEWED BY WHAM-TV PLAY
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VIDEO: POST-DOCKING MISSION STATUS BRIEFING PLAY
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VIDEO: REPLAY OF DOCKING FROM PAYLOAD BAY CAMERAS PLAY
VIDEO: SHUTTLE DISCOVERY DOCKS TO THE STATION PLAY
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VIDEO: SHUTTLE APPROACHES STATION FROM BELOW PLAY
VIDEO: NARRATED PREVIEW OF THE DOCKING PLAY

VIDEO: THE FLIGHT DAY 2 HIGHLIGHTS MOVIE PLAY
VIDEO: BRIEFING ON LAUNCH IMAGERY AND TANK'S PERFORMANCE PLAY
VIDEO: WEDNESDAY'S MISSION STATUS BRIEFING PLAY
VIDEO: HEAT SHIELD INSPECTIONS EXPLAINED PLAY
VIDEO: THE FLIGHT DAY 1 HIGHLIGHTS MOVIE PLAY
VIDEO: INSIDE MISSION CONTROL DURING LAUNCH PLAY

VIDEO: DISCOVERY'S LAUNCH AS SEEN LIVE PLAY
VIDEO: EXTERNAL TANK CAMERA FROM LIFTOFF TO ORBIT PLAY
VIDEO: LAUNCH REPLAY: VAB ROOF PLAY
VIDEO: LAUNCH REPLAY: KSC RUNWAY PLAY
VIDEO: LAUNCH REPLAY: BEACH TRACKER PLAY
VIDEO: LAUNCH REPLAY: UCS-23 WIDESCREEN PLAY
VIDEO: LAUNCH REPLAY: PLAYALINDA WIDESCREEN PLAY
VIDEO: LAUNCH REPLAY: WEST TOWER PLAY
VIDEO: LAUNCH REPLAY: PRESS SITE 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: LAUNCH REPLAY: CAMERA UCS-12 PLAY
VIDEO: LAUNCH REPLAY: CAMERA UCS-15 PLAY
VIDEO: LAUNCH REPLAY: CAMERA CS-1 PLAY
VIDEO: LAUNCH REPLAY: CAMERA CS-2 PLAY
VIDEO: LAUNCH REPLAY: CAMERA CS-6 PLAY

VIDEO: THE CREW DEPARTS QUARTERS FOR THE PAD PLAY
VIDEO: ASTRONAUTS SUITS UP ON LAUNCH MORNING PLAY
VIDEO: A LOOK BACK AT SHUTTLE DISCOVERY'S HISTORY PLAY
VIDEO: PAD 39A'S ROTATING GANTRY MOVED BACK PLAY
VIDEO: INTERVIEW CLIPS WITH THE ASTRONAUTS PLAY
VIDEO: MONDAY MORNING'S STATUS BRIEFING PLAY
VIDEO: PRE-LAUNCH NEWS CONFERENCE PLAY
VIDEO: SUNDAY COUNTDOWN STATUS BRIEFING PLAY
VIDEO: SATURDAY COUNTDOWN STATUS BRIEFING PLAY
VIDEO: WATCH THE CREW'S ARRIVAL FOR LAUNCH PLAY
VIDEO: NEWS CONFERENCE AFTER FLIGHT READINESS REVIEW PLAY
VIDEO: SHUTTLE DISCOVERY ROLLS TO LAUNCH PAD 39A PLAY
VIDEO: CRANE HOISTS DISCOVERY FOR MATING TO TANK PLAY
VIDEO: DISCOVERY MOVED TO THE VEHICLE ASSEMBLY BUILDING PLAY
VIDEO: HYDRAULIC SEALS REPLACED ON LANDING GEAR STRUT PLAY
VIDEO: FUEL TANK ATTACHED TO SOLID ROCKET BOOSTERS PLAY
VIDEO: FOAM REMOVED FROM FUEL TANK FEEDLINE BRACKETS PLAY

VIDEO: STS-120 MISSION OVERVIEW BRIEFING PART 1 | PART 2
VIDEO: PREVIEW OF THE MISSION'S FIVE SPACEWALKS PLAY
VIDEO: DISCOVERY'S ASTRONAUTS MEET THE PRESS PLAY
VIDEO: BRIEFING ON SHUTTLE AND ISS PROGRAMS PLAY
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