American Space Preeminence: Fwd: US EVA 28 astronauts repair station electrical system

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Date: October 16, 2014 8:30:19 AM CDT
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Subject: FW: US EVA 28 astronauts repair station electrical system

Astronauts race to reconfigure space station electrical system
"We're going to be doing the things we need to do on these EVAs to prep for moving some modules around," said Kenny Todd.

WASHINGTON, Oct. 15 (UPI) -- NASA astronauts Reid Wiseman and Barry Wilmore donned spacesuits and stepped outside the International Space Station on Wednesday morning to repair a broken component in one of the eight solar power channels that provide the station's NASA-built grid with electricity.
It was Wiseman's second spacewalk -- or what those in the business call extra-vehicular activity (EVA) -- and it was Wilmore's first. Their maintenance and repair duties were set to keep the two astronauts out of station for nearly 6 1/2 hours.
In addition to repairing the solar panel component, the two astronauts will begin prepping for the rearrangement of the station's docking systems -- a reorganization that will require some of the station's power circuits to be rewired.
"We're going to be doing the things we need to do on these EVAs to prep for moving some modules around," Kenny Todd, manager of space station integration operations back on Earth, said in a press conference preceding the mission. "All that is in preparation for being able to support future [commercial] crewed vehicles coming to station.
"We're trying to get out in front of that. We'll be prepping for moving modules; we'll be installing a new docking adapter system," Todd said. "All of that will be happening throughout the next several months onboard the station."
Wednesday's spacewalk is the 183rd time astronauts have stepped outside to work on the space station since it launched in 1998. The next crew of ISS astronauts will be making several extra spacewalks in the new year.
These trips will continue the work of Wiseman and Wilmore in readying ISS for future dockings by commercial spacecraft from Boeing and SpaceX. Those spacecraft will be used to ferry NASA's astronauts to and from the space station as soon as 2017.
© 2014 United Press International, Inc. All Rights Reserved.

Spacewalkers repair station electrical system
10/15/2014 03:42 PM
By WILLIAM HARWOOD
CBS News

Astronauts Reid Wiseman and Barry "Butch" Wilmore floated outside the International Space Station Wednesday and, after a bit of trouble with a balky bolt, replaced a broken voltage regulator in one of eight solar power channels to restore the lab's electrical grid to normal operation.

They then worked through a list of lower-priority tasks, removing a broken camera, installing a replacement at a different location and relocating a support mast and wireless transmitter assembly in preparation for spacewalks next year.

U.S. EVA-28 got underway at 8:16 a.m. EDT (GMT-4) Wednesday when Wiseman and Wilmore, floating in the Quest airlock compartment, switched their spacesuits to battery power.
Spacewalkers Reid Wiseman and Barry "Butch" Wilmore enjoyed a spectacular view of the Nile River and the Red Sea during a 260-mile-high pass over north Africa Wednesday. (Credit: NASA TV)

The primary goal of the 6-hour 34-minute spacewalk was to replace an electrical component known as a sequential shunt unit, or SSU, that failed earlier this year, knocking out one of the eight solar power channels in the station's NASA-built electrical grid.

The space station is equipped with eight 110-foot-long solar wings that provide power to eight distribution channels. Each array is equipped with a sequential shunt unit to regulate voltage as the station moves into and out of Earth's shadow. The SSU in power channel 3A failed May 8, forcing flight controllers to re-route power from channel 3B to keep a variety of components in operation.

The EVA timeline was set up to ensure that Wiseman and Wilmore could remove the faulty SSU during a night pass when the arrays were not generating power. A few moments before passing into orbital darkness, the spacewalkers were treated to a spectacular view of Egypt, the Nile river and the Red Sea passing by 260 miles below.

"I see Cairo, can't quite make out the pyramids, though," Wiseman observed.

Working in darkness at the far right side of the station's solar power truss, at the base of the channel 3A solar array, Wiseman was initially unable to drive open a bolt holding the faulty SSU in place.

Using a ratchet wrench and a bit of elbow grease, he successfully "broke torque" on the bolt and pulled the shorted SSU out of its mounting bracket. He then ran into problems bolting down the replacement.

"I still see nothing. No movement," Wilmore observed, watching an indicator that should have shown the SSU locking in place as Wiseman tightened the bolt needed to secure it.

"OK, let's keep track of the turns, try to find that sweet spot where the bolt will align with the receptacle," astronaut Ricky Arnold radioed from mission control in Houston.

"OK. Let me just talk about this, Ricky," Wiseman said. "The bolt is definitely in. If I pull up on this (SSU), it's not moving. I've got 9.9 turns (on the bolt), but we haven't seen any closure."

Arnold told the spacewalkers to back out the bolt, remove the box and inspect it for damage or any obstructions. Wilmore reported a possible broken thread at the base of the bolt, but he wasn't sure. After a bit of discussion, flight controllers told the spacewalkers to re-align the box and try again, putting more force into it than before.

This time around, again using the manual ratchet wrench, Wiseman was able to tighten the bolt all the way. A few moments later -- just two minutes or so from sunrise -- flight controllers tested the circuit and reported the replacement SSU was working normally.

"Woo hoo!" The spacewalks exclaimed.

The astronauts then pressed ahead with work to move a camera support mast from the lower side of the port-1 solar array truss segment to the top of the forward Harmony module. The relocation is required to clear a path for work next summer to robotically move a storage compartment from the bottom of the central Unity module to the forward-facing port of the left-side Tranquility module.

First, Wiseman had to remove and temporarily stow a camera on the stanchion that has a stuck zoom lens. The stanchion then was disconnected, carried by Wilmore to the upper side of the Harmony module for installation at camera port 11.

While that was going on, Wiseman disconnected a wireless transceiver assembly from the top of the left-side truss at camera port 8 so it could be attached to the stanchion installed atop Harmony by Wilmore. The transceiver is used to relay views from spacesuit helmet cameras.

But Wilmore ran into problems bolting down the stanchion. Free floating, he was unable to get enough force on an attachment bolt to get it to engage the mounting bracket.

"Over there, we couldn't get it off. Over here, we can't get it on," Wilmore said. "This is just a tough worksite."

Wiseman moved up to help and finally, after several attempts, Wilmore was able to drive the bolt home.

"It feels like it is in tight," he reported. "It's not going anywhehttp://www.geekwire.com/2014/amazon-slated-open-retail-store-next-week-san-francisco/re."

He then connected the wireless transceiver assembly, which will improve communications during a series of planned spacewalks next year to prepare forward ports for dockings by new commercial crew ferry craft.

Wiseman then carried the camera with the stuck zoom lens back to the airlock, retrieved a fresh camera and working together, the two spacewalkers installed it on the top of the left-side truss where the wireless transceiver had been located.

The spacewalk included a half hour for a variety of so-called "get-ahead" tasks that could be carried out if time was available, but flight controllers opted to end the excursion on time after the camera installation. After collecting their tools and other gear, the spacewalkers returned to the airlock and began repressurization procedures at 2:50 p.m.

It was the second in eight days for the U.S. crew after a spacewalk last Tuesday by Wiseman and Alexander Gerst to relocate a broken cooling pump, to replace a camera light and to install a component to provide backup power to the lab's robot arm transporter.

Overall, it was the 183rd spacewalk devoted to station assembly and maintenance since construction began in 1998, the sixth of seven EVAs planned for this year, the second for Wiseman and the first for Wilmore, a former shuttle pilot. With today's spacewalk, 119 astronauts and cosmonauts representing nine nations have logged 1,148 hours and 49 minutes of station EVA time, or 47.9 days.

The year's seventh and final planned spacewalk is scheduled for Oct. 22 when station commander Maxim Suraev and Alexander Samokutyaev plan to jettison no-longer-needed gear and carry out a detailed photo survey of the Russian segment's exterior.

NASA plans eight to 10 station spacewalks next year to prepare the lab for dockings by Boeing and SpaceX commercial crew ferry craft starting in 2017.

When the work is complete, the U.S. segment of the station will be able to accommodate two commercial crew vehicles and two U.S. cargo ships at the same time, giving NASA fully independent access to the orbiting laboratory for the first time since the shuttle's retirement in 2011.

© 2014 William Harwood/CBS News

US astronauts conduct spacewalk to repair ISS
A pair of American astronauts stepped outside the International Space Station Wednesday on a spacewalk to do repairs and upkeep at the orbiting outpost, NASA said
Washington (AFP) - A pair of American astronauts stepped outside the International Space Station Wednesday for a spacewalk to do repairs and upkeep at the orbiting outpost, NASA said.
Reid Wiseman and Barry "Butch" Wilmore finished their spacewalk after six hours and 34 minutes, right on schedule, the US space agency said.
Their first task was to replace a suitcase-sized power regulator for a solar array that had failed in May.
The operation required some careful coordination with the time when the space station passed under Earth's shadow, so that electricity was not being generated by the solar array.
Then, the astronauts set to their next task of moving equipment to make space for international docking adapters scheduled to be delivered to the complex in 2015.
These "will configure the station for future commercial crew vehicles and provide an additional berthing port for commercial cargo spacecraft," NASA said.
They also replaced an external TV camera that had lost its zoom capability with a new one.
Wednesday's spacewalk was the 183rd at the International Space Station, but was Wilmore's first.
It was the second outing for Wiseman, who along with flight engineer Alexander Gerst of the European Space Agency completed a six-hour spacewalk on October 7.

Copyright © 2014 Agence France Presse. All rights reserved.

Spacewalking astronauts begin preparing station for new space taxis
By Irene Klotz

View photo
NASA astronauts Reid Wiseman (R) and Barry Wilmore work inside the International Space Station on October …
By Irene Klotz
CAPE CANAVERAL Fla (Reuters) - A pair of spacewalking NASA astronauts hustled through an electrical repair job outside the International Space Station on Wednesday, then began work to prepare the outpost for new commercial space taxis.
Station flight engineers Reid Wiseman and Barry "Butch" Wilmore floated outside the station's airlock shortly after 8:15 a.m. EDT to begin a 6-1/2-hour spacewalk.
Their primary job was to replace a voltage regulator that failed in May, cutting out one of the station's eight power channels. The work needed to be done during a nighttime pass around Earth when the solar arrays are not generating power. The station, a $100 billion research complex, flies about 260 miles (420 km) above Earth.
After collecting their tools and making their way to the right-side exterior truss, the astronauts had just 35 minutes to unbolt the failed unit and install the replacement. The bolts, however, were not cooperative.
"The PGT (pistol grip tool) doesn't have enough power to turn it right now," Wiseman radioed to Mission Control in Houston. "I can feel it binding up."
Wiseman then switched to a ratchet wrench to unbolt the failed device, known as a sequential shunt unit, or SSU."Now it's time for Wiseman to apply a little muscle," NASA commentator Rob Navias said during a live broadcast on NASA TV.
That did the trick, clearing the spot for the new SSU. Wiseman again ran into problems installing the replacement, but as the minutes ticked down toward daylight, he was able to use the power tool and then the ratchet wrench to tighten the single bolt holding the SSU in place.
With less than two minutes before the station passed back into daylight, flight controllers tested the new unit and reported it was working properly, "Whoo-hoo," the spacewalkers radioed to Mission Control.
Wiseman and Wilmore then kicked off what is expected to be a yearlong NASA project to reconfigure the station for the arrival of privately owned and operated passenger spaceships. NASA hired Boeing and privately owned Space Exploration Technologies to begin flying crews to the station in 2017.
Preparing docking ports and other amenities for the new vehicles will take up to 10 more spacewalks next year, NASA officials said. Wiseman and Wilmore began the work by relocating a camera support mast, clearing a path for the station's robotic crane to move a storage module from the Unity to the Tranquility connection nodes next summer.
Wiseman and Wilmore also moved a wireless transmitter and installed a new camera.
Wednesday's spacewalk was the second for Wiseman and the first for Wilmore.
Two Russian crewmates plan another spacewalk on Oct. 22 to replace experiments, inspect and photograph the exterior of the Russian side of the station and take care of some maintenance.
(Reporting by Irene Klotz; Editing by Jonathan Oatis)

Copyright © 2014 Reuters Limited. All rights reserved.



Astronauts repair space station
Press Association

Press Association - Astronauts battled against troublesome bolts to effect repairs on the International Space Station

Spacewalking astronauts have replaced a failed electrical unit at the International Space Station.
The space station had been operating since spring with only seven of its eight solar power channels.
The work by Reid Wiseman and Butch Wilmore - Nasa's second spacewalk in two weeks - brought the energy capability back up to 100%.
The spacewalkers encountered troublesome bolts but still managed to complete the job in the allotted time, with less than two minutes to spare.
The voltage regulator shorted out in May but could not be replaced until now because of a year-long hiatus in non-emergency spacewalks by Nasa.
The stoppage was caused by spacesuit problems, most notably a flooded helmet that nearly cost an astronaut's life in 2013.
Wiseman took part in the October 7 spacewalk that jump-started Nasa's outside maintenance, accompanied by a German astronaut. This time, Wiseman was joined by Wilmore, who made his first spacewalk.
To avoid an electric shock, the two spacewalkers waited until darkness before attempting to remove the old voltage regulator, so there would be no discharge.
They took in the view 260 miles below as they waited for the space station to fly into the night side of Earth.
"I see Cairo," Wiseman said. "Can't quite make out the pyramids, though."
As sunset fell over Kazakhstan and China, Wiseman began to undo the bolt holding down the bad regulator. His pistol grip tool failed to loosen the bolt. "I can feel it binding up," he said. A ratchet wrench - along with some muscle - did the trick.
Wiseman removed the 330lb regulator from its slot and, with Wilmore's help, popped in the new one. But once again, they ran into bolt trouble, this time in securing the new device.
The minutes ticked away as Mission Control debated how much longer to keep up the effort, before stopping for the next orbital sunrise. With less than 10 minutes remaining, flight controllers advised Wiseman to try tightening the bolt with the ratchet wrench. It worked.
Flight controllers immediately checked out the newly installed system, with less than three minutes to go. Success was declared with one minute and 45 seconds remaining.
The voltage regulator - officially called a sequential shunt unit or SSU - is needed to keep excess power from its designated solar wing, from overloading the station system. Power is regulated at about 160 volts.
After the May breakdown, Nasa transferred space station systems dependent on the failed power channel to a backup. No operations were hampered, but Nasa wanted that channel operating again for full capability and redundancy.
With their main job completed, the spacewalkers got started on moving camera and wireless radio systems. The relocations are needed to get ready for the eventual arrival of new commercial crew vehicles. That's still a few years away.
A Russian spacewalk, meanwhile, is on tap for next Wednesday.

Copyright © 2014 The Associated Press. All rights reserved.

NASA Astronauts Beat Clock, Wrap Up Spacewalk
By Miriam Kramer, Staff Writer   |   October 15, 2014 03:30pm ET

NASA astronauts Reid Wiseman and Barry Wilmore work outside the International Space Station during a spacewalk on Oct. 15, 2014.
Credit: NASA TV View full size image
Two NASA astronauts working outside the International Space Station raced against the clock during a spacewalk today (Oct. 15).
NASA's Reid Wiseman and Barry "Butch" Wilmore performed a 6.5-hour-long spacewalk that included one particularly tricky task that had to be started and completed when the orbiting outpost was in orbital night. Wilmore and Wiseman managed to remove and replace a power regulator that shorted out in May during the short amount of time when the station experienced night. (Space station crew members experience 16 sunsets and sunrises every day.)
"Whoop!" one of the astronauts exulted after the replacement regulator was installed. The regulator, which is used to regulate power from one of the station's solar arrays, needed to be changed out in order to restore the station to full power. [See photos of the Oct. 15 spacewalk]
Mission controllers watched a clock ticking down the time the astronauts had to complete the task. The spacewalk officially began at 8:16 a.m. EDT (1216 GMT) and ended 6 hours and 34 minutes later.
The two astronauts also removed a faulty camera from the outside of the station and installed a new one. Wilmore and Wiseman also moved some equipment to get ready for the eventual relocation of the station's Permanent Multipurpose Module (PMM) in 2015, NASA officials said.
Despite their hard day of work, the astronauts still had time to do a little sightseeing while outside the space station. They both got some good views of Earth during the spacewalk.
"That is amazing," one of the astronauts said when the spacewalkers spotted a possibly erupting volcano while flying above Earth.
"I see Cairo," Wiseman said during a pass over Egypt. "Can't quite make out the pyramids, though."
The PMM needs to be moved in order to make way for a pair of commercial crewed vehicles that could begin flying astronauts to the orbiting outpost as early as in 2017. Astronauts will also need to install a set of international docking adaptors that should fly to the station in 2015 for the commercial vehicles.
The two October spacewalks kick off a series of EVAs (extravehicular activities) designed to make way for the new private spaceships once they start delivering astronauts to the station. Last month, NASA awarded SpaceX and Boeing multibillion-dollar deals to develop their astronaut taxis, with the aim of getting at least one vehicle up and running by 2017.
"We're going to be doing the things we need to do on these EVAs to prep for moving some modules around," Kenny Todd, space station integration operations manager, said during a news conference before the spacewalks. "All that is in preparation for being able to support future [commercial] crewed vehicles coming to [the] station. We're trying to get out in front of that … We'll be prepping for moving modules; we'll be installing a new docking adapter system. All of that will be happening throughout the next several months on board the station."
This was the first spacewalk for Wilmore and the second for Wiseman. Wiseman ventured out on his first spacewalk on Oct. 7 with European Space Agency astronaut Alexander Gerst, who helped prepare the two spacewalking astronauts for their work today.
Three cosmonauts — Maxim Suraev, Alexander Samokutyaev and Elena Serova — who also work as part of the laboratory's Expedition 41 crew, join Gerst, Wiseman and Wilmore on the station. Samokutyaev and Suraev are scheduled to take a spacewalk next week, on Oct. 22.

Copyright © 2014 TechMediaNetwork.com All rights reserved.

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For a nation that explores
October 16th, 2014

Space Station Replacements and Relocations Highlight Six-Hour EVA-28
By Ben Evans

Expedition 41 astronauts Reid Wiseman (top) and Barry "Butch" Wilmore (right) work at the zenith face of the Harmony node during yesterday's EVA-28. Photo Credit: NASA
Despite difficulties with stubborn bolts, Expedition 41 spacewalkers Reid Wiseman and Barry "Butch" Wilmore triumphantly concluded U.S. EVA-28 on Wednesday, 15 October, replacing a failed Sequential Shunt Unit (SSU) on the starboard truss of the International Space Station (ISS) and working to replace and relocate cameras and other equipment in anticipation of next year's arrival of International Docking Adapters (IDAs) and the movement of the Leonardo Permanent Multipurpose Module (PMM) for future Commercial Crew vehicles from 2017. With Wiseman designated "EV1", having red stripes on the legs of his Extravehicular Mobility Unit (EMU) suit for identification, and Wilmore as "EV2", clad in a pure-white ensemble, the duo spent six hours and 34 minutes outside the station on the 183rd spacewalk in support of ISS assembly and maintenance.
As described in AmericaSpace's EVA-28 preview article, this was the first U.S. spacewalk since November 2008 to feature an all-Navy team, with Wiseman currently a commander in the service and Wilmore a captain. Final preparations got underway early Wednesday, when the spacewalkers—assisted by Expedition 41 Commander Max Surayev and German astronaut Alexander Gerst—began 60 minutes of "pre-breathing" on masks, during which time the Quest airlock's inner "equipment lock" was depressed from its ambient 14.7 psi down to 10.2 psi. Upon completion of this protocol, Wiseman and Wilmore donned and purged their bulky EMUs and the airlock's atmosphere was repressurized to 14.7 psi.
This allowed them to enter a nominal pre-breathing regime, lasting about 50 minutes, followed by another 50 minutes of In-Suit Light Exercise (ISLE). The latter was first trialed on the STS-134 shuttle mission in May 2011 and involved the men flexing their knees for about four minutes, resting for one minute, then repeating over and over until the 50 minutes was up. The technique served to rapidly remove nitrogen from their bloodstreams and avoid an attack of the "bends".
Barry "Butch" Wilmore (left) and Reid Wiseman were the first all-Navy U.S. spacewalking duo since STS-126 in November 2008. Photo Credit: NASA
By 7:40 a.m. EDT, the fully-suited pair and their equipment—including the Simplified Aid for EVA Rescue (SAFER) units, affixed to the lower section of their life-sustaining backpacks—were transferred by Gerst from the equipment lock into Quest's outer "crew lock". Hatches between the two locks were closed and depressurization got briskly underway, reaching the 5 psi "hold point" for leak checks at about 7:55 a.m. With no issues, the depressurization continued until the crew lock reached a condition of near-vacuum and EVA-28 officially got underway at 8:16 a.m., when Wiseman and Wilmore transferred their suits' critical life-support utilities over to internal battery power. Interestingly, this was just one minute later than originally planned in the EVA-28 timeline.
Pushing open the outer hatch, Wiseman departed the airlock first, followed by Wilmore, who brought out the spare Sequential Shunt Unit (SSU) in an Orbital Replacement Unit (ORU) bag. Provided by Space Systems/Loral (SS/L), there are eight SSUs on the space station, responsible for regulating the incoming power from the eight Solar Array Wings (SAW) at an established "set point" of 160 volts, by shunting and unshunting 82 separate array "strings", to ensure a steady output across the ISS. Weighing 186 pounds (84 kg), each SSU can handle 38.5 kW of electrical power at an efficiency of 98.5 percent.
On 8 May 2014, the station lost its "3A" power channel, when the controlling SSU experienced an internal electrical short. Loads were immediately transferred to the 3B channel, with minimal loss of power, although the Optical Payload for Lasercomm Science (OPALS) and the Alpha Magnetic Spectrometer (AMS)-2 suffered from a temporary suspension of operations. The failure "was associated with a sharp temperature increase…and a high current difference between the two SSU circuits that was six times higher than normal," according to Spaceflight101 at the time. "These two indications point to a failure internal to the SSU that may not be recoverable by ground commanding."
With the other seven power channels—1A, 1B, 2A, 2B, 3B, 4A and 4B—classified as fully functional, the ISS remained in a safe configuration, although the replacement of the failed SSU was important to hedge against the risk of future failures. Originally, this replacement task was planned for August 2014, during Expedition 40, although it was delayed until October and the early stages of Expedition 41 in the wake of problems with Long Life Batteries (LLBs) in the U.S. space suits.
Barry "Butch" Wilmore's helmet camera captured this perspective of crewmate Reid Wiseman tending to the SSU replacement task. Photo Credit: NASA
After closing the thermal cover of the Quest airlock, Wiseman and Wilmore pressed immediately into critical "buddy checks" of each other's suits and safety tethers. They then separated and headed for their first work site. Wiseman—making his second career spacewalk, following last week's EVA-27—assisted his first-time crewmate in moving along the Crew and Equipment Translation Aid (CETA) "spur". Wilmore started out first along Face 1 of the S-1 starboard truss segment, which he reached by 8:35 a.m., dropping the Green Hook from his tether bundle to enable him to safely venture further outboard along the expansive truss structure.
Meanwhile, Wiseman climbed up to the Starboard CETA Cart and transferred his crew lock bag, containing his tools, onto an Articulating Portable Foot Restraint (APFR). He released the bag/APFR "bundle" and attached it to his Body Restraint Tether (BRT). The latter was first tested aboard the shuttle in the mid-1990s and is designed to hold a spacewalker steady, whilst clamped to a handrail, and carries the benefit of freeing the hands to perform useful work. Serving as a "third hand", the BRT consists of a stack of balls, connected through the center by a cable, with a clamp on one end and a bayonet probe on the other, attaching to Wiseman's suit. He was thus able to bend and twist the BRT to the appropriate position, then "lock" it in place with a knob which tightens the cable.
Carrying his tools, Wiseman joined Wilmore out on the S-1 truss, where he too dropped his Green Hook. The two men then headed further outboard, past the S-3 Solar Alpha Rotary Joint (SARJ), until they reached the 3A solar array and the location of the failed SSU on the Beta Gimbal Platform, at the base of the Mast Canister Assembly on the S-4 truss element. Wilmore stowed the ORU bag containing the replacement SSU onto the nearby S-5 truss, whilst Wiseman installed the APFR and crew lock bag onto a Worksite Interface (WIF) socket. He removed his tools and installed them at the work site, then ingressed the APFR to take the lead role in the SSU changeout.
"Timing was a factor for the replacement of the Sequential Shunt Unit," NASA explained in an overview of EVA-28. "The spacewalkers needed to remove the failed, suitcase-sized unit and install its replacement while the station passed through the Earth's shadow and electricity was not being generated by the solar array." Pausing to await eclipse, the replacement effort kicked off in earnest at 9:44 a.m. Notwithstanding some difficulty in breaking torque on the SSU bolts, and with a touch of added muscle, Wiseman released and pulled out the failed unit by 9:57 a.m. and stowed it. Monitoring the progress of the spacewalk from Mission Control in Houston, Texas, was a team headed by Flight Director David Korth—who fulfilled a similar role in charge of the troubled EVA-23 in July 2013—and seated at the Capcom console were veteran spacewalkers Ricky Arnold and Doug "Wheels" Wheelock. By 10:10 a.m., the replacement SSU was in place and a few minutes later Mission Control's Station Power, ARticulation, Thermal and ANalysis (SPARTAN) console reported a satisfactory power-up of the new unit. It ran smoothly through its early checks during the remainder of EVA-28 and the 3A power channel was expected to be brought back online today (Thursday, 16 October).
Diagram of the myriad worksites for Wiseman and Wilmore during EVA-28, which covered both the starboard and port trusses. Image Credit: NASA
Following the completion of their first major task, Wiseman and Wilmore headed inboard along the truss, picking up their Green Hooks as they went along. Wilmore stowed the failed SSU at the Quest airlock and picked up a small ORU bag for his next task, after which the duo met at the Camera Port (CP)-7 site on the P-1 truss at 10:55 a.m. A few minutes later, Wiseman released the APFR tool stanchion and moved it further inboard to the central S-0 truss segment, which puts it out of the way in readiness for the Leonardo PMM relocation, which is anticipated to take place in July 2015.
Returning to CP-7, Wilmore unbolted and removed the failed camera group—which has suffered a broken zoom feature—and handed it to Wiseman. By 11:30 a.m., its electrical connectors had been removed and protective caps installed and the astronauts moved the CP-7 stanchion to its new location on the space-facing "end" of the Harmony node (known as "zenith-aft"), at the junction with the U.S. Destiny laboratory module, where the CP-11 camera group is situated. Wilmore installed the stanchion at CP-11 and mated the electrical connectors.
Meanwhile, Wiseman headed "port-zenith" to the CP-8 camera group, where he released a trio of bolts of the Wireless Video System External Transceiver Assembly (WETA), removed the unit and attached it to his BRT for transportation to its new home. Rejoining Wilmore at about 12:15 p.m., as the space station passed high over South America, the two men were astonished to witness a Bolivian volcano in the process of erupting. There was precious little time to admire the view, however, and as Wilmore toiled to install the WETA at CP-11, Wiseman translated back to the Quest airlock to stow the CP-7 camera group and collect a replacement unit in a large ORU bag.
Despite difficulties with the torqueing of bolts, EVA-28 ran smoothly and all assigned tasks were successfully completed. Photo Credit: NASA
Wilmore completed his task of securing electrical connectors to provide power to the WETA by 1:20 p.m., as the ISS passed into a spectacular orbital sunrise, high above the Tasman Sea. A little after 2:00 p.m., a good signal was received from the newly relocated WETA. Elsewhere, Wiseman brought the replacement camera group and installed it at the CP-8 location, on the port-side truss, then paused to check the alignment of the lens cover and ensured that it was square.
In spite of some discussion of adding several "get-ahead" tasks to EVA-28, it was ultimately decided to "declare victory" for the day and the duo cleaned up their respective work sites and headed back to the airlock. The spacewalk ended at 2:50 p.m. EDT, after six hours and 34 minutes. With its conclusion, EVA-28 gives Wiseman a total of 12 hours and 47 minutes of EVA time in two excursions, placing him in 119th place in the list of the world's most experienced spacewalkers. Putting this into context, in terms of EVA time, Wiseman is now slightly behind U.S. astronaut Al Drew and just ahead of Apollo 12 and Skylab astronaut Charles "Pete" Conrad. Having now executed his first EVA, Wilmore now sits at 163rd on the list, out of 210 total spacewalkers. This places him just behind U.S. astronaut Nicole Stott and slightly ahead of his Expedition 41 crewmate Aleksandr Samokutyayev.
Aside from the replacement of the failed SSU, EVA-28's relocation of external cameras will prove critical for next year's scheduled arrival of the first International Docking Adapters (IDAs) for the long-awaited Commercial Crew vehicles. According to Space Station Integration Operations Manager Kenny Todd, these EVAs mark the beginning of a salvo of spacewalks which will run into the spring and summer of 2015. Mr. Todd stressed that the two contingency EVAs last December and also a third unplanned spacewalk in April 2014 by Expedition 39's Rick Mastracchio and Steve Swanson "had left some things out there that we knew we wanted put back in proper order". He added that there was an urgent need to tend to power-related issues and improve the station's fault-tolerant capability, ahead of several more complex EVAs next year.
Current plans call for two U.S. spacewalks in January 2015, two others in April and June and a further pair in August to route cables and utilities in support of the relocation of the Leonardo Permanent Multipurpose Module (PMM) and the Pressurized Mating Adapter (PMA)-3. This will lay the groundwork for the delivery of two International Docking Adapters (IDAs) in support of Boeing's CST-100 and SpaceX's Dragon V2 Commercial Crew vehicles. The Leonardo PMM will be robotically transferred in July 2015 from the nadir port of the Unity node to the forward port of the Tranquility node, whilst PMA-3 will be moved in the late August timeframe from its current berth on Tranquility to the zenith port of the Harmony node for Commercial Crew operations.

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