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ISS Expedition 32 - US EVA-18 Updates
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Installation of MBSU-1 fails as Astronauts battle with stuck Bolts
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August 30, 2012 |
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International Space Station Expedition 32 Spacewalkers Suni Williams and Aki Hoshide along with Robotic Arm Operator Joe Acaba and Ground IV Crew Member Jack Fischer, completed a very challenging US EVA-18 on Thursday - finishing the first post-Shuttle Spacewalk under US supervision without achieving the primary objective, leaving the power system of the Space Station in a non-redundant condition.
This was the first pure Space Station EVA under US Supervision after the end of the Space Shuttle Program. Although the most recent US Spacewalk by Expedition 28 Astronauts Ron Garan and Mike Fossum in July 2011 was catalogued as stage EVA, the crew members of Atlantis Mission STS-135 were supporting the spacewalk. EVA-18 was the standard annual EVA that is planned for regular ISS maintenance and outfitting of the US Segment. The Spacewalk was focused on three primary tasks, the main operation being the replacement of a partially failed Main Bus Switching Unit. |
Photo: NASA
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MBSUs are large electrical power switching boxes that are a major component of the Station's power system. There are four MBSUs in use aboard the Space Station.
MBSU1 has experienced problems caused by radiation hits to its memory unit. These problems included re-sets and loss of telemetry, however, it was still transferring power as expected giving mission planners time to integrate the replacement task into an EVA and train it with a crew that was still on Earth at that time since no quick response or contingency EVA was required. A failure of the MBSU could have been tolerated by ISS, but would have left the Station in a non-redundant position which is generally avoided by Mission Managers. Replacing that MBSU with a spare unit that was located on External Stowage Platform 2 was planned to take 4.5 hours and extensive operations of Canadarm2, the Station's Robotic Arm. The other two tasks were the routing of power cables for the upcoming Russian Multi Purpose Laboratory Module and the replacement of a failed camera on the Station's Robotic Arm that stopped working recently. Also, time-permitting, the crew was prepared for several get-ahead tasks.
MBSU1 has experienced problems caused by radiation hits to its memory unit. These problems included re-sets and loss of telemetry, however, it was still transferring power as expected giving mission planners time to integrate the replacement task into an EVA and train it with a crew that was still on Earth at that time since no quick response or contingency EVA was required. A failure of the MBSU could have been tolerated by ISS, but would have left the Station in a non-redundant position which is generally avoided by Mission Managers. Replacing that MBSU with a spare unit that was located on External Stowage Platform 2 was planned to take 4.5 hours and extensive operations of Canadarm2, the Station's Robotic Arm. The other two tasks were the routing of power cables for the upcoming Russian Multi Purpose Laboratory Module and the replacement of a failed camera on the Station's Robotic Arm that stopped working recently. Also, time-permitting, the crew was prepared for several get-ahead tasks.
Click images to go to Crew Member Bio's
Photo: NASA
Photo: NASA
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Preparations for this EVA had been underway aboard the International Space Station for several weeks during which the crew prepared the Airlock, the two Extravehicular Mobility Units (EMUs) and their procedures for this spacewalk. They have trained the EVA inside the Neutral Buoyancy Laboratory several times, but new tasks were added once Williams and Hoshide departed for the Launch Site. These items were added in response to a number of camera failures that occurred in order to have the astronauts replace the most important cameras and retrieve others that have failed as well. The crew members completed extensive on-orbit training and procedure reviews as well as tagups with EVA Specialists on the ground to prepare for the EVA over the past several weeks. Luckily, Suni Williams brought plenty of EVA experience to the table in order to make it through the new tasks together with Aki Hoshide. Prior to the EVA, veteran Spacewalker Suni Williams already had performed four EVAs for a total of 29 hours and 17 minutes of EVA experience. Aki Hoshide was a spacewalk rookie becoming the third Japanese Astronaut to walk in space.
On Thursday, the day of the Spacewalk, the USOS Crew had a nominal breakfast to get their day started before pressing into EVA Preparations. The two EV crew members put on their EMUs and completed normal checkouts and activation before utilizing the ISLE Pre-Breathe Protocol. ISLE is a relatively new pre-breathe technique. The acronym stands for In-Suit Light Exercise. Spacewalkers need to pre-breathe to flush Nitrogen out of their blood stream that could cause decompression sickness when the crew members are subjected to the lower pressure inside the EMUs. The 'bends' as this problem is also called, could lead to major complications during the spacewalk which is undesirable for obvious reasons. For ISLE, the two crew members pre-breathe pure Oxygen for 50 minutes and start the exercise protocol which required crew members to perform ten cycles of four minutes of exercise and one minute of rest. The exercise is essentially light flexing of the knees and arm movements that are sufficient to remove Nitrogen from the blood streams. ISLE had its debut on Space Shuttle Mission STS-134 and passed its evaluation and is now part of NASA's EVA repertoire. ISLE was executed properly while Joe Acaba was taking care of final Suit Preparations. Just before the start of the EVA, the two EV Crew Members moved to the Crew Lock portion of the Quest Airlock and Joe Acaba closed the hatch behind them. Thirty minutes of depressurization followed to set the stage for hatch opening. During Airlock Depress, final leak checks were performed before Mission Controllers gave to GO to start the EVA. Suni Williams opened the hatch to begin and the two spacewalkers started to re-configure their spacesuits to switch to internal consumables. The official start of US-based EVAs is the moment the two EMUs are switched to internal power which, for today's Spacewalk, occurred at 12:16 GMT which was perfectly on schedule in terms of the crew day's timeline. With the EVA in progress, the two Spacewalkers began to execute the set-up procedure. This task was budgeted for 45 minutes on the EVA Timeline. Suni Williams was first to exit the airlock and to get her tools ready for the EVA. Aki Hoshide, still inside the Quest Airlock at that time, handed tool bags and equipment to Suni that she installed outside the Airlock on one of the hand rails. |
Once all equipment was outside, Aki Hoshide also stepped outside to start the spacewalk. Initially, both crew members made sure their safety tethers and space suits were in the correct configuration before beginning their first tasks. Aki Hoshide started a translation adaptation exercise that was planned to take up to 15 minutes, but Aki felt comfortable in the EVA environment and completed the adaptation in just a few minutes. While that was in progress, Suni Williams turned around to face External Stowage Platform 2 where the spare MBSU was located. There, she broke torque on the two Bolts holding the unit in place on the Flight Releasable Attachment Mechanism on ESP-2. Aki assisted her for a moment when more than two hands were needed to handle the tools. Once that was complete, the spacewalkers parted ways. Suni Williams continued to configure the ESP-2 work site, removing Multilayer Insulation from the replacement unit and installing a Multi-Use End-Effector to be used later on for the temporary stowage of the removed MBSU.
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Aki Hoshide translated to the S0 Truss to set up the work site at the MBSU1 location. Once arriving at the MBSU, Hoshide gave Joe Acaba instructions to move Canadarm2 in a position close to him so that he could install an Articulating Portable Foot Restraint for later ingress.
Meanwhile, Suni Williams started the second task of the EVA which was the routing of the 413 power cable set. Two power cables had to be routed from the US-Russian Segment Interface to a distributing unit inside the S0 truss segment to provide a redundant power connection for the Russian Multipurpose Laboratory Module that is planned to arrive at ISS in 2013 or 2014. The cable task took about two hours as Suni Williams had to carefully route the cable it between a large number of other wires and connectors while she also had to maintain clearances to make sure no equipment was harmed. Once arriving at the S0 Truss, Williams opened Insulation Covers to climb into the large truss segment where she routed the 413 cable to a power distributor for installation. She used a pair of space scissors to cut the safety tether of the cap of the socket before plugging in the cable to finish the task. She egressed the truss, and performed a tool inventory. While she was busy routing the cable, Aki Hoshide ingressed the Foot Restraint to ride the arm for the remainder of the MBSU Operation. He was moved into position for break torque on the bolts holding it in place when the first signs of trouble emerged. When using the Pistol Grip Tool to remove the first of two Bolts, Aki found that the bolt was apparently stuck. Mission Control gave him different PGT settings to try and break torque with more force, but the bolt wouldn't come loose so that Hoshide needed to use a torque multiplier after several attempts did not work. Once the H-1 Bolt was done, he was re-positioned to remove the remaining bolt, he immediately ran into the same problem with H-2 being stuck. |
Image: NASA
Image: NASA
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Mission Controllers assessed the situation and instructed Hoshide to go back to H-1, do several more turns to confirm it is removed and go to H-2 afterwards to prevent it from jamming. After a struggle of about one hour, both bolts were loose and Aki Hoshide was able to pull the MBSU out of its slot and hold onto it for the move back to ESP-2.
While Canadarm2 was in motion, Suni Williams looked at the former location of the failed MBSU and reported metal-like shavings in the work area. Teams wanted Suni Williams to look at the back for the MBSU to assess the condition of the Bolts, so she had to translate back to ESP-2 to inspect the unit while Hoshide was still holding onto it. When looking at the bolt area, Suni also found metal shavings.
Mission Controllers started to discuss the issue while the removed MBSU was installed on the Multi-Use End-Effector to temporarily stow it on ESP-2. Having problems with stuck bolts or other connectors is not uncommon because this hardware is exposed to the space environment for an extended amount of time without being touched or maintained. Contributing factors to this type of issue are thermal properties that affect the material and possible foreign object debris that can prevent hardware from functioning nominally.
While Canadarm2 was in motion, Suni Williams looked at the former location of the failed MBSU and reported metal-like shavings in the work area. Teams wanted Suni Williams to look at the back for the MBSU to assess the condition of the Bolts, so she had to translate back to ESP-2 to inspect the unit while Hoshide was still holding onto it. When looking at the bolt area, Suni also found metal shavings.
Mission Controllers started to discuss the issue while the removed MBSU was installed on the Multi-Use End-Effector to temporarily stow it on ESP-2. Having problems with stuck bolts or other connectors is not uncommon because this hardware is exposed to the space environment for an extended amount of time without being touched or maintained. Contributing factors to this type of issue are thermal properties that affect the material and possible foreign object debris that can prevent hardware from functioning nominally.
Once the MBSU was secured, Aki Hoshide moved over to the spare unit to remove it from its slot by using the Pistol Grip Tool to remove H-1 and H-2. H-1 was removed without an issue, but the second bolt proved to be troublesome once again. Hoshide had to increase torque on the PGT to release the bolt and he eventually succeeded using the PGT in B1 Mode. He did a few extra turns to make sure the MBSU is removed properly before pulling it out of its slot and repeating the 25-minute journey to S0 aboard the robotic arm in the other direction.
Photo: NASA
Suni Williams using the Pistol Grip Tool
Photo Gallery: US EVA-18
Photo Gallery: US EVA-18
While Aki Hoshide was busy handling the spare MBSU, Suni Williams had time to take care of the second cable of her cable routing task. This shorter cable was dubbed 'Aki Cable' while the longer one was referred to as 'Suni Cable' reflecting a previous EVA design where each crew member routed one cable. This plan was changed because Suni's timeline had various gaps that needed to be filled with tasks such as the cable routing procedure. She worked in the Destiny Lab - Unity Node Area to route the cable and plug it into another connector. The two cables that were routed during Thursday's EVA will be left in place until the Russian Module is about ready to fly to ISS. One month before its arrival, Russian Spacewalkers will use the installed cables to finish the task to outfit the exterior of the Russian Segment for the arrival of MLM. At the end of Suni Williams' task, the two connectors of the cables were secured at Pressurized Mating Adapter 1 with the Aki Cable being temp stowed for another day.
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Afterwards, Suni Williams completed the installation of the removed MBSU in the stowage location on ESP-2 that was vacated when the spare unit was removed. Williams took advantage of the movable neck of the Multi-Use End-Effector to place the box in its slot and use the Pistol Grip Tool to try and turn those cranky bolts to install the unit. This time, H-2 was driven first and after 15.7 turns and three different PGT Settings, the bolt was in place. H-1 was torqued without a problem and the 107-Kilogram MBSU had found its new resting place on External Stowage Platform 2. Following that, Williams grabbed some contingency tools and made her way up to S0 to help Aki Hoshide with the installation of the new MBSU1. A needle-nose tool was used to remove some of the metal shavings around the Attachment Mechanism. For the installation, Williams moved to a viewing position to guide Aki Hoshide during the installation to make sure all connectors of the MBSU match their sockets and connect properly. Joe Acaba controlled the arm to precisely position the MBSU above its attachment location.
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Photo: NASA
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Working together, Aki Hoshide and Suni Williams guided the spare into position without a problem and the Pistol Grip Tool was utilized again. "We'll keep our fingers crossed," said IV Crew Member and Capcom Jack Fischer after teams went through all the trouble with the previous bolts. Coming out several turns short when the bolt got stuck, had Mission Controllers scratching their heads again working out a plan to use greater force with the PGT. Teams did not have any luck and the bolt came out five to six turns short causing a small gap between the electrical interface of the MBSU Systems which has to be fully connected for the switching box to function. As a last resort, Mission Controllers instructed the crew to retrieve a torque multiplier from the airlock. Suni Williams picked up the tool and, in addition, the PMA-Cover bag to bring it with her in case time would have permitted the installation of the cover.
After handing the torque multiplier to Hoshide, Suni was sent back to the Airlock to get more tools to resolve the issue that had already consumed three hours at that point. Hoshide removed the complete MBSU box again and was backed away from the truss. Suni Williams then used a can of pressurized Nitrogen Gas to remove any Foreign Object Debris from the connector and holes where the bolts needed to go. Another can was used to clean the electrical connectors. The next attempt to bolt the MBSU down brought no success.
Mission Control continued to work with the two crew members to try different scenarios to get that H-2 bolt in. Suni Williams was holding down the MBSU, keeping it level and wiggling it when being asked to while Aki Hoshide handled the Pistol Grip Tool that was alternated between different torque modes. The measurements that were taken did not come to fruition and eventually, after an additional hour, Mission Control came forward with a final plan using the maximum amount of torque that was allowable - making sure the bolt was not violating its limits and breaks. This final attempt looked promising to being with, but the bolt went in 9 turns and stopped. Hoshide tried again to use the PGT, but it 'torqued out' within one revolution.
At that point, the two EV crew members were at an EVA time of 7 hours and had to start closing out the work site, performing a tie-down of MBSU1 in location and closing out the different work sites such as the Robotic Arm and External Stowage Platform 1. Both crew members performed the required close-out tasks to leave all work sites in a stable configuration before moving back inside the airlock to wrap up the spacewalk.
The official end of the EVA came at 20:33 GMT, placing the EVA total at 8 hours and 17 minutes. This marked the 164th Spacewalk in support of ISS Assembly and Maintenance. With this EVA under her belt, Suni Williams is now up to 37 hours and 34 minutes of EVA time on five Spacewalks. This was Aki Hoshide's first time outside, his total now at 8 hours and 17 minutes. This EVA came in on place three of the all time-longest-spacewalk list.
With the EVA failing to achieve its primary objective, the International Space Station is now in a non-redundant configuration of its main power system which is a clear violation of flight rules - meaning that the installation of the MBSU has to be completed during a contingency EVA taking place as soon as possible. ISS can run on three Main Bus Switching Units, but it can not tolerate the failure of a second MBSU.
Loads from MBSU1's absence are currently being tackled by MBSU-4. Power distribution is being achieved via a Lab Truss Contingency Jumper and Secondary Power Distribution Assembly that were installed prior to the EVA. NASA has announced a news conference for later on Thursday to discuss the plan forward.
The latest information will be posted on this site and via the ISS101 Twitter Feed.
After handing the torque multiplier to Hoshide, Suni was sent back to the Airlock to get more tools to resolve the issue that had already consumed three hours at that point. Hoshide removed the complete MBSU box again and was backed away from the truss. Suni Williams then used a can of pressurized Nitrogen Gas to remove any Foreign Object Debris from the connector and holes where the bolts needed to go. Another can was used to clean the electrical connectors. The next attempt to bolt the MBSU down brought no success.
Mission Control continued to work with the two crew members to try different scenarios to get that H-2 bolt in. Suni Williams was holding down the MBSU, keeping it level and wiggling it when being asked to while Aki Hoshide handled the Pistol Grip Tool that was alternated between different torque modes. The measurements that were taken did not come to fruition and eventually, after an additional hour, Mission Control came forward with a final plan using the maximum amount of torque that was allowable - making sure the bolt was not violating its limits and breaks. This final attempt looked promising to being with, but the bolt went in 9 turns and stopped. Hoshide tried again to use the PGT, but it 'torqued out' within one revolution.
At that point, the two EV crew members were at an EVA time of 7 hours and had to start closing out the work site, performing a tie-down of MBSU1 in location and closing out the different work sites such as the Robotic Arm and External Stowage Platform 1. Both crew members performed the required close-out tasks to leave all work sites in a stable configuration before moving back inside the airlock to wrap up the spacewalk.
The official end of the EVA came at 20:33 GMT, placing the EVA total at 8 hours and 17 minutes. This marked the 164th Spacewalk in support of ISS Assembly and Maintenance. With this EVA under her belt, Suni Williams is now up to 37 hours and 34 minutes of EVA time on five Spacewalks. This was Aki Hoshide's first time outside, his total now at 8 hours and 17 minutes. This EVA came in on place three of the all time-longest-spacewalk list.
With the EVA failing to achieve its primary objective, the International Space Station is now in a non-redundant configuration of its main power system which is a clear violation of flight rules - meaning that the installation of the MBSU has to be completed during a contingency EVA taking place as soon as possible. ISS can run on three Main Bus Switching Units, but it can not tolerate the failure of a second MBSU.
Loads from MBSU1's absence are currently being tackled by MBSU-4. Power distribution is being achieved via a Lab Truss Contingency Jumper and Secondary Power Distribution Assembly that were installed prior to the EVA. NASA has announced a news conference for later on Thursday to discuss the plan forward.
The latest information will be posted on this site and via the ISS101 Twitter Feed.
ISS Astronauts preparing for US Stage EVA - Spacewalk Preview |
August 23, 2012 |
Photo: NASA
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The crew of six aboard the International Space Station is getting ready for the second Spacewalk of Expedition 32 that is planned to occur just two weeks after the recent Russian EVA-31 was that was successfully completed by experienced Spacewalkers Gennady Padalka and Yuri Malenchenko on August 16. This is the first pure Space Station EVA under US Supervision after the end of the Space Shuttle Program. Although the most recent US Spacewalk by Expedition 28 Astronauts Ron Garan and Mike Fossum was catalogued as stage EVA, the crew members of Atlantis Mission STS-135 were supporting the spacewalk.
US EVA-18 is scheduled for August 30, 2012 and will be performed by veteran spacewalker Sunita Williams and spacewalking rookie Akihiko Hoshide. Hoshide will be the third Japanese Astronaut to walk in space. Suni Williams already has four EVAs under her belt for a total of 29 hours and 15 minutes - bringing significant experience for the challenging spacewalk planned for Expedition 32. |
The main challenge that two astronauts will be facing are new tasks that were added to the EVA Timeline after the crew finished training and became necessary after hardware failures aboard ISS occurred. The two EV Crew Members were unable to rehearse these tasks in the Neutral Buoyancy Laboratory in Houston during nominal training and needed to use on-orbit training sessions to prepare for the procedures.
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The main focus of the 18th US Stage EVA is the replacement of a partially failed Main Bus Switching Unit (MBSU-1) - a major component for the ISS electrical system (basically a large space-certified power switching box). The two other prime tasks for the crew are the routing of power cables in preparation for the arrival of the Russian Multipurpose Research Module in 2013/2014 and the removal&replacement of the failed Canadarm 2 Boom B camera. This is the new task that was recently added to the EVA Manifest. If time permits, Williams and Hoshide could address a total of four get-ahead tasks: the installation of protective covers on the currently unused Pressurized Mating Adapter 2, the removal of a camera on the Mobile Base System, the removal&replacement of a camera on the Japanese Experiment Module Exposed Facility, and troubleshooting of a possibly troublesome Power & Data Grapple Fixture ground wire on the Zarya Module.
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Image: NASA
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Also involved in the EVA will be Joe Acaba who is the IV Crew Member and Robotic Arm Operator. There will also be a ground IV Crew Member because Acaba will be busy driving the arm for the majority of the EVA. Astronaut Jack Fisher will be supporting and choreographing the spacewalk from Mission Control Houston. The EVA is expected to last six-and-a-half hours.
The two Astronauts will prepare for the Spacewalk inside the Quest Airlock, suiting up and using the ISLE-Pre-Breathe Protocol (In-Suit Light Exercise) to get ready to step outside. For more information on ISLE, visit our overview.
The two Astronauts will prepare for the Spacewalk inside the Quest Airlock, suiting up and using the ISLE-Pre-Breathe Protocol (In-Suit Light Exercise) to get ready to step outside. For more information on ISLE, visit our overview.
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After Airlock Depressurization and hatch opening, Suni Williams will be first to get out the door to begin equipment&tool set-ups. Aki Hoshide will be handing tool bags from inside the Airlock to Williams to quickly complete the nominal tool preparation task. When all tools are installed on a fish-stringer, Williams will turn around to face the External Stowage Platform near Quest where she will prepare a Multi-Use End-Effector - a tool needed to temporarily stow the failed MBSU. Then, she will release straps holding Multilayer Insulation that is protecting the spare MBSU on the stowage platform. The insulation is removed to expose the On-Orbit Spare MBSU to get it ready for installation. The MBSU Replacement unit is installed onto the ESP with a Flight Releasable Attachment Mechanism and Williams will break torque on the bolts holding the MBSU on the FRAM. Later, Williams will install a handle on the MBSU to allow Hoshide to grab onto it later in the EVA. When MBSU preparations are complete, Williams will retrieve a bundle of cable for the second task of the EVA and translate to the US Lab-Node 1 Interface where she will hook one end of the cable up to another cable and route it aft before temporarily stowing it to come back later in the spacewalk. While Williams is completing these procedures, Aki Hoshide has time on his schedule for a translation adaptation exercise which is common practice for EVA rookies. He will retrieve a tool bag and translate to the S0 Truss Segment of ISS where the failed MBSU is located. There are four MBSUs in use aboard the Space Station. MBSU1 has experienced problems caused by radiation hits to its memory unit. These problems included re-sets and loss of telemetry, however, it was still transferring power as expected giving mission planners time to integrate the replacement task into an EVA and train it with a crew that was still on Earth at that time since no quick response or contingency EVA was required.
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Image: NASA
Image: NASA
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At S0, Hoshide will set up the work site for the removal of the unit. He will break torque on the failed Switching Unit in preparation for its removal. Then, Hoshide will install scoops which he will later use as handling aides. Hoshide is going to install an Articulating Portable Foot Restraint on the Robotic Arm that will be moved into position prior to the EVA, before ingressing it to ride the arm for the MBSU operation. At that point, Mission Controllers will perform a power-down - power-up test on the MBSU to gather additional data on the problem it has been exhibiting. When that is complete, it will be powered down and Hoshide will release the MBSU and hold onto it while Canadarm 2 makes a pre-programmed translation back down. Joe Acaba will be monitoring the maneuver, ready to take action should any problems occur during arm motion.
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In the meantime, Williams will be working at the US-Russian Segment Interface installing the second Cable for MRM on a handrail before beginning to route that cable. It will be routed forward to the S0 Truss where it will be placed inside the truss. Around that time, Hoshide will have arrived at External Stowage Platform 2 after riding the Robotic Arm for several minutes. The failed MBSU will be temporarily installed on the MUD End-Effector that was prepared by Williams at the beginning of the EVA. Afterwards, Hoshide will be maneuvered in position to release the bolts of the spare MBSU. He will assume control over it and hold it while the Robotic Arm moves back to S0 for installation. While Hoshide is moving the MBSU, Suni Williams will already be at S0 filling the time until Hoshide arrives by climbing into the truss after removing covers and routing the MRM Cable to a power-panel where she will install it. She'll exit S0, put the cover back in place and assist Hoshide with the installation of the MBSU to make sure it is installed in the proper configuration.
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Image: NASA
MRM Cable Installation Panel
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Once Hoshide has installed the unit by driving bolts, Williams will leave for another task and Hoshide will clean up the work site. Mission Control activates the MBSU and performs initial checkouts to make sure it passes power and is commandable from the ground. The entire MBSU Operation is budgeted with up to 4.5 hours of EVA time.
Should the EVA be on its timeline at that point, Aki would continue to ride the arm to move over to its Mobile Base System where he would release one bolt to retrieve a failed MBS Camera that he would take with him to place it back inside the Airlock for return to the ground. Following that, Hoshide would egress the arm while Williams is installing the failed MBSU on the Attachment System that was previously occupied by the spare on ESP-2. Williams will take the scoops off, configure the MUD End Effector and re-install the Multilayer Insulation on the MBSU to clean up the site. Candarm 2 will be reconfigured by Aki Hoshide, removing the Foot Restraint from the arm at the S0 work site where he will re-install it to ingress it once again - this time at a stationary position to access the Robotic Arm that would be moved into the correct position. Hoshide will remove the Boom Camera on Candarm2 and replace it with a spare Camera Light Pan/Tilt Assembly that was brought outside on the EVA. He will make necessary connections before teams on the ground will test the new camera.
Should the EVA be on its timeline at that point, Aki would continue to ride the arm to move over to its Mobile Base System where he would release one bolt to retrieve a failed MBS Camera that he would take with him to place it back inside the Airlock for return to the ground. Following that, Hoshide would egress the arm while Williams is installing the failed MBSU on the Attachment System that was previously occupied by the spare on ESP-2. Williams will take the scoops off, configure the MUD End Effector and re-install the Multilayer Insulation on the MBSU to clean up the site. Candarm 2 will be reconfigured by Aki Hoshide, removing the Foot Restraint from the arm at the S0 work site where he will re-install it to ingress it once again - this time at a stationary position to access the Robotic Arm that would be moved into the correct position. Hoshide will remove the Boom Camera on Candarm2 and replace it with a spare Camera Light Pan/Tilt Assembly that was brought outside on the EVA. He will make necessary connections before teams on the ground will test the new camera.
Image: NASA
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Image: NASA
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When this task is complete, all primary operations of the EVA will have been checked off the list, giving the crew members the opportunity of starting get-ahead tasks should additional time be available. The first of these tasks is the installation of protective covers on Pressurized Mating Adapter 2. PMA-2 is attached to the Harmony Module of ISS and was used for Shuttle Dockings to the station. With no active vehicles flying that have the ability to dock with PMAs, the systems are not required to be accessible, but teams want to keep the hardware in the best condition possible for future use for different visiting vehicles. The cover protects the inside of the adapter from sun exposure and temperature changes as well as space debris. A similar cover was installed over PMA-3 during the STS-135 Spacewalk. Another get-ahead task is the installation of a new camera assembly on the Kibo Module's Exposed Facility after removing a failed one.
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Photo: NASA
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Photo: NASA
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Photo: NASA
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Troubleshooting of a possible protruding grounding wire at the Zarya Power & Data Grapple Fixture is the final get-ahead task of this EVA.
When all tasks are complete or the EVA time is up, the two Astronauts will close-out the spacewalk with tool reconfigurations, a tool inventory and Airlock Ingress followed by hatch closure to finish what is hoped to be a successful Spacewalk.
Live EVA coverage and updates will be available at Spaceflight101.com.
When all tasks are complete or the EVA time is up, the two Astronauts will close-out the spacewalk with tool reconfigurations, a tool inventory and Airlock Ingress followed by hatch closure to finish what is hoped to be a successful Spacewalk.
Live EVA coverage and updates will be available at Spaceflight101.com.
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