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Astronauts begin day of construction in space BY WILLIAM HARWOOD STORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSION Posted: September 12, 2006 The Atlantis astronauts are gearing up to install a $372 million set of solar arrays on the international space station today, setting the stage for a complex spacewalk to make critical electrical connections. "We are really looking forward to this," Canadian astronaut Steve MacLean radioed mission control early today. "Should be spectacular." The first item on the agenda is the mechanical attachment of the 35,000-pound P3/P4 truss, launched aboard Atlantis and held overnight out over the shuttle's left wing on the end of the space station's Canadarm 2 space crane. Working at a robotics control station inside the Destiny laboratory module, MacLean and station flight engineer Jeff Williams began maneuvering P3/P4 into position for attachment to the left end of the station's unfinished solar array truss around 2 a.m. Once properly lined up and positioned, four motorized bolts on the end of the P1 truss segment will engage to lock the new truss element in place. "I'll maneuver the P3/P4 truss around up to the P1 truss, an operation that will take about 45 minutes, to the preinstall position nine centimeters away from the center of P1," MacLean said. "Then you have to wait for the rates to damp out, that takes about 30 minutes plus or minus five or 10 minutes probably, then we move in for the final install using the Canadian Space Vision System, which gives me the guidance data." The Space Vision System uses television cameras and powerful software to measure the precise locations of large black dots attached to the truss elements. The SVS software computes the relative positions of the markings to give MacLean very precise distance and orientation information. Temperature effects can cause distortions of up to five inches, MacLean said, and misalignments of 1 to 2 degrees. The SVS will help compensate for any such effects. "It'll take about an hour to get to the pre-install position there, and then we have to wait for an attitude change that we need in order to have the P3/P4 truss at a thermally viable position," MacLean said. "And then we install. Fergy (pilot Chris Ferguson) will come over and back me up with the Space Vision System and he will basically provide that data to me, and then using that data I will guide the P3/P4 truss in to the P1 Truss. And that'll be it. A good day." The actual attachment is automatic. Once P1 and P3 are in close proximity, four motorized bolts on P1 will drive into attachment fittings on P3, firmly locking the two truss elements together. Three of four bolts must engage to call the operation a success. At that point, astronauts Joe Tanner and Heidemarie Stefanyshyn-PiperPiper, now suited up in the station's Quest airlock module, will float out into space and begin the first of two back-to-back spacewalks to hook up and activate P3/P4. The spacewalk, the 70th devoted to space station assembly and maintenance since construction began in December 1998, is scheduled to begin at 5:15 a.m. The astronauts spent the night inside the Quest airlock at a reduced pressure of 10.2 pounds per square inch to help purge nitrogen from their bodies. The so-called camp out procedure was designed to shave about an hour off the time needed to prepare for today's spacewalk while helping ensure the astronauts don't get decompression sickness working in their 5-psi spacesuits. The primary goal of the outing is to remove launch restraints, to unfold and lock in place the boxes holding the stowed solar array panels and to connect 13 electrical umbilicals to provide station power to internal heaters. The power is needed to keep internal electrical components warm until the now-stowed arrays are unfurled Thursday. "Once three of four of those bolts are mated, we'll go ahead and send the crew EVA and perform the activities that we need to do to make the element survivable," said station flight director John McCullough. "All the power connections, the 13 umbilicals that need to be mated and all the activities to get ready for solar array deploy start on EVA-1. The power hookups all are completed by the end of EVA 1 and the element is completely survivable." The station's solar array truss currently consistes of three segments. S0, the center section, is mounted atop the Destiny laboaratory module. Segments S1 and P1 are attached to the right and left ends of S0 respectively. The P3/P4 segments will be bolted to P1 on the port, or left, side of the truss. There are no P2 or S2 segments. To get to the P1-P3/P4 worksite, Tanner and Piper will first exit the Quest airlock, using 55-foot-long safety tethers. Crossing over a spur to the S0 truss atop the Destiny module, the spacewalkers will move across the forward face of the truss to the port side and, reaching the end of their safety lines, hook up to a different 55-foot tether. Once at the P1/P3 interface, they will swap tethers again, switching to 85-foot safety lines. A key aspect of the spacewalk is the tight choreography between flight controllers, Tanner and Piper as the ground powers down one channel of the station's electrical system at a time to permit the astronauts to safely plug in the big umbilical cables that will route power and data to and from P3/P4. "The ground and the crew are very highly choreographed," McCullough said. "The ground has about 100 pages of ground procedures to execute in order to power down and safe connections for the EV crew to mate the 13 umbilicals. They're done on two different channels, so we have to power down one channel first, give them a go to hook up those umbilicals, then they give us a go and we power that channel back up again. We have to complete that before we can take down the next channel so we can maintain connectivity and power to the space station. "It takes about an hour and a half between the two sets of umbilicals and when that's complete, the second set of umbilicals will be given a go and they'll do that. In between that time, there are other activities for the crew to do to get prepared for solar array deploy on flight day six." For astronauts in the Destiny lab module, McCullough said in an interview, "a segment of the lights are going to go out that aren't on that channel. You want to be on the cooling loop system that's supplied by the other channel, so we switch over to that. You want to make sure your air circulation system is powered. ... We want to make sure we're switched over to the other side as much as possible." In one case, he said, the astronauts in the lab will use a jumper cable to keep avionics rack 2 going, which houses critical command and control computers that otherwise would get shut down during the P3/P4 powerup/powerdown cycle. Along with hooking up the umbilicals, Tanner and Piper will remove a variety of launch locks and restraints to prepare the solar arrays for deployment later in the mission and begin the process of preparing the massive solar alpha rotary joint, or SARJ, for operation. The rotary joint will permit the new arrays to rotate like a giant waterwheel to track the sun as the station circles the globe. "The solar alpha rotary joint is locked in place for launch," McCullough said. "It has 16 launch locks and a lot of braces that need to be installed to support rotation and we can't deploy the arrays until all of those things are completed." Tanner's call sign is EV-1 and he will wear a spacesuit with solid red stripes around the legs. Piper, wearing a suit with no markings, is EV-2. Here is an updated timeline of today's events (in EDT and mission elapsed time):
EDT DD HH MM EVENT
__________________________________________
12:15 AM 02 13 00 STS/ISS crew wakeup
12:45 AM 02 13 30 EVA-1: Hygiene break; prebreathe
01:00 AM 02 13 45 EVA-1: Airlock repress
01:30 AM 02 14 15 EVA-1: 10.2 depress
02:05 AM 02 14 50 EVA-1: Campout EVA preps
02:05 AM 02 14 50 SSRMS moves P3/4 to pre-install position
03:25 AM 02 16 10 SSRMS maneuver to "ready to latch" position
03:35 AM 02 16 20 EVA-1: Spacesuit purge
03:50 AM 02 16 35 EVA-1: Spacesuit prebreathe
03:55 AM 02 16 40 P1/P3 bolts engaged
04:40 AM 02 17 25 EVA-1: Crew lock depressurization
04:55 AM 02 17 40 SSRMS ungrapple
05:10 AM 02 17 55 SSRMS moves to viewing position
05:15 AM 02 18 00 EVA-1: Airlock egress; tool setup
05:50 AM 02 18 35 EVA-1: EV1: Connect P1/P3 lower cable tray
05:50 AM 02 18 35 EVA-1: EV2: Release aft solar array blanket box
restraint
06:50 AM 02 19 35 EVA-1: EV1: Release aft BGA restraint
06:50 AM 02 19 35 EVA-1: EV2: Release forward solar array blanket
box restraint
07:15 AM 02 20 00 ISS: EVA-2 tools configured
07:35 AM 02 20 20 EVA-1: EV1: Solar alpha rotary joint rotate
07:45 AM 02 20 30 EVA-1: EV1: Unstow aft solar array blanket box
restraint
07:50 AM 02 20 35 EVA-1: EV2: Release forward BGA restraint
08:15 AM 02 21 00 EVA-1: EV1: SARJ preps
08:15 AM 02 21 00 ISS: Expedition 13 departure preps
08:35 AM 02 21 20 EVA-1: EV2: unstow forward solar array blanket box
08:50 AM 02 21 35 EVA-1: EV1: Connect P1/P3 upper cable tray
09:05 AM 02 21 50 EVA-1: EV2: SARJ prep
10:05 AM 02 22 50 EVA-1: EV1: SARJ prep
10:55 AM 02 23 40 EVA-1: Cleanup
11:35 AM 03 00 20 EVA-1: Airlock ingress/repress
11:50 AM 03 00 35 12A post EVA-1
01:25 PM 03 02 10 EVA-2: Procedures review
02:40 PM 03 03 25 EVA-2: EV3/EV4 campout mask prebreathe
03:25 PM 03 04 10 EVA-2: Crew lock to 10.2 psi
03:45 PM 03 04 30 ISS crew sleep begins
04:15 PM 03 05 00 STS crew sleep begins (EV3/EV4 in airlock)
"On EVA 1 we start getting the P3/P4 element ready for solar array deploy," Piper said in a NASA interview. "That happens two days later. The first task [for] that is to hook up the umbilicals. Those are just the power cables and data cables so that the ground can start commanding all of the, the MDMs, the boxes that are on the elements and getting them ready for deploy. Actually one of Joe's tasks is to hook up the umbilicals.
"While he's doing that, I'm starting to remove the launch locks on the solar array blanket boxes. The solar arrays are folded up into what we call blanket boxes. The blanket boxes are attached to a mast canister, which is attached to the four-bar linkage, which is attached to the P4 structure. In order to get that all to fit inside the shuttle bay and also have it be safe for the vibrations of launch there are a number of launch locks and bolts that just hold it all together. "On EVA 1, I go out and start removing these bolts. The blanket boxes, instead of being out like you see them in all the pictures with the solar arrays deployed, are folded up together. They have big bolts that hold them together so I go out and I start removing all the bolts, first on the aft side and then I go to the forward side. Meanwhile, Joe's done with the umbilicals. He comes out and gets one of the solar arrays ... swings the four-bar out and then he climbs out onto the very end of the mast canister and swings the two blanket boxes out. "While he's doing that, I'm out on the forward one, and I do the same thing. Now the blanket boxes are pretty much ready for the ground to start commanding them as far as unlatching them and making sure that all the pins that hold them in are all deploy. That gets that ready for the solar array deploys. We're not quite ready to deploy the arrays yet because, in order to get the P3/P4 to fit inside the shuttle bay, we have to have the alpha joint rotated 180 degrees. In order to rotate it back to the zero position, there are two drive mechanisms that needed to be deployed, the DLAs (drive lock assemblies). We start working on those so that they can command the SARJ. That's pretty much what EVA 1 is. Tanner, his feet anchored in a foot restraint, will mate the first six umbilical cables working at the lower of two cable trays on P3. Piper, meanwhile, will be preparing the solar array wings for deployment, working from a foot restraint on P4 to access two sets of launch restraints, one inboard and one outboard, holding the blanket boxes in place. Tanner will assist once the first six umbilicals are connected, releasing two restraints securing one of two beta gimbal assemblies. The BGAs are used to control the pitch of the array wings once they are deployed. After the restraints are released, the blanket boxes and the canisters holding the telescoping masts that will extend the array blankets will be rolled into their deploy positions by manually pushing open the four-bar linkages. After stowing a massive keel pin that helped hold P3/P4 in place in the shuttle's cargo bay, Tanner will move to the mast canisters and rotate the 4A blanket boxes into position, swinging them through an arc of 90 degrees and locking them in place with a strut to hold them in position. Piper will rotate the 2A blanket boxes into place and release the restraints on the other BGA. Once both sets of blanket boxes are extended in the deploy position, Tanner and Piper will release latches allowing the mast canisters to open. Tanner then will move up to the top of P4 to mate seven umbilical cables while Piper removes thermal covers on the SARJ and repositions one of the two drive lock assembly motors so its gears engage. She also will engage four "stiffeners" needed to provide additional structural support. With the final set of electrical cables in place, Tanner will make his way up the Z1 truss atop the Unity module to remove a circuit interrupt device, or CID, as a get-ahead task for the next assembly mission. The CIDs act as circuit breakers in the station's electrical system. With CID-6 ion hand, Tanner will float back down the S0 truss and remove CID-8. After temporarily stowing the two CIDs, Tanner will rejoin Piper and reposition the other DLA to engage its gears. The two DLAs are redundant and either one can drive the rotary joint and the deployed solar arrays. Before returning to the airlock, Tanner and Piper will remove thermal shrouds around electrical components on the SARJ that are no longer needed. "The big challenge about that EVA is timing," Tanner told CBS News. "We have to go through our tasks fairly expeditiously, I've got to get that lower tray connected as quickly as I can because that starts a clock on the ground with that 100 pages John McCullough was talking about. They've got to execute many power ups and start talking to the boxes." Tanner was a good choice for STS-115. He and Atlantis commander Brent Jett flew together on an earlier station assembly mission to attach the P6 solar arrays atop the Z1 truss. "Deploying the arrays, we've done it before, we know how that should go. I think there's going to be a little bit of a problem on the four bar deploy. On (assembly mission) 4A, we had a problem of them not wanting to go at all and Carlos (Noriega) and I had to push pretty hard just to get them to move and even brought out a special tool to pull them as far as we could. And even with that, two of the latches when we left were not engaged. "I'm convinced we're not going to have that problem. It's not going to go too fast, it's going to go about two thirds of the way to full deployment but this time the finish will be as easy as pushing it the last little bit. So expect that to happen, I'm not worried about it." With spacewalk No. 1 complete, astronauts Dan Burbank and MacLean will spend the night inside Quest to prepare their bodies for a second spacewalk Wednesday. The objectives of the second excursion are to release 16 launch locks and six launch restraints to free the SARJ ring mechanism for rotation. Burbank and MacLean also will complete the installation of stiffeners to provide the necessary structural rigidity. If all goes well, the new solar arrays will be deployed Thursday, stretching 240 feet from tip to tip.
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STS-115 patch The official crew patch for the STS-115 mission of space shuttle Atlantis to resume orbital construction of the International Space Station. Choose your store:U.S. - U.K. - E.U. - Worldwide  |
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VIDEO:
TRUSS HANDED FROM SHUTTLE ARM TO STATION ARM 