EVA-2: SARJ, Dextre, and ammonia coolant work:

After beginning their day at 2126 EDT, Endeavour’s flight crew got right to work preparing for the mission’s second EVA.

After a 50-minute hygiene break for Drew Feustel (EV-1) and Mike Finke (EV-2), the two returned to the ISS’ Quest Airlock for EVA preps, spacesuit purge, and spacesuit prebreathe activities.

Following Crew lock depressurization, Feustel and Finke took their EMUs (Extravehicular Mobility Units) to battery power - officially beginning EVA-2 for the STS-134 flight, marked at 1:05am Central Time.

After egressing the International Space Station, Feustel and Finke spent the first 30mins of the EVA performing EVA setup activities and translating out the P3/P4 truss. Once there, the spacewalking spent approximately 15mins performing re-routing operations on the P3/P4 truss.

At this point, Feustel and Finke went their separate ways, with Feustel beginning the hour-long process of filling the P5/P6 EAS jumper.

Meanwhile, Finke spent 20 minutes filling the Ammonia Tank Assembly before moving on to the one hour-long task of removing covers on the port SARJ (Solar Alpha Rotary Joint).

Click here for SARJ Articles: http://www.nasaspaceflight.com/tag/sarj/

This cover removal, for which Drew Feustel will join Mike Finke after he finishes his P5/P6 EAS jumper work, will precede lubrication activities of the SARJ itself - which is a large rotary wheel designed to turn the outer portions of the Station’s truss so that the eight solar array sets can track the sun and collect as much solar energy as possible to power the Station.

During cover removal, Finke noted at least two bolts flew off the cover when they were removed with his Pistol Grip Tool (PGT). Amazingly, Finke caught both bolts as they popped out. “The bolt flew off, I have it in my hand,” noted Finke, with Feustel responding with a “Wow!”

A loose washer was also observed, floating undernearth the cover. Efforts are being made to secure the washer, which – had it entered the SARJ mechanism – could have caused potential problems for moving hardware associated with the Race Ring.

As a result of the observations – which may point to the bolts and washers on the covers being worn down by removal – only half of the covers are being removed for what became partial lube task, and the PGT was used for only part of the cover removal, with the bolts then being removed by hand.

As first noted in mid-2007 on the starboard SARJ, evaluations into problems with the starboard SARJ began after vibrations and power fluctuations were noted by ground controllers and ISS crewmembers, which led to an inspection of the hardware during STS-120′s EVAs in October 2007.

With observations of metallic shavings - consisting of 1505 Nitride material - on the hardware, engineers concluded the debris was the result of grinding on the Race Rings.

With a similar issue then noted on the port SARJ, concerns grew with the starboard SARJ when Mike Fossum observed a depression, or pit, on the Race Ring during his EVA inspection on STS-124 in June 2008.

Plans were then created to replace the Trundle Bearings Assemblies (TBAs) and grease/lube the Race Ring during STS-126′s EVAs. The results were highly encouraging.

As noted by managers in an update after the STS-126 TBA replacement and Race Ring lubrication, “Status briefing on the initial quick look results of the Starboard SARJ rotations and disturbances seen after the ring was lubricated and the TBAs were changed out: The disturbances seen by starboard SARJ motion have greatly decreased based on the two orbits of autotrack that were performed immediately post R&R.

“The team requested an extended autotrack to obtain more data and determine if the disturbances drop even lower after a long period of operation and distribution of the grease due to rotation.”

Managers then created a forward plan to lubricate the Race Rings of both SARJs over Shuttle missions throughout 2009 and 2010 - with one of those planned flights (STS-134) eventually finding itself in 2011.

After cover removals are complete, Feustel was tasked with taking detailed photographs of the SARJ and collect samples for analysis once Endeavour returns to Earth. However, camera issues were noted, so it’s unknown how many useful photos were taken.

Following directly from the SARJ cover removals, Mike Finke was tasked with the first of two SARJ lubrication activities for the EVA. By now, the EVA was running late due to the bolt issue with the covers, leading to a “big picture” plan to extend the EVA by another hour - as both spacewalkers said they felt good to continue.

Meanwhile, Feustel left Finke to his work and move on to his EAS setup/vent operation. After this, Feustel turned his attention to cleanup operations for the ammonia vent tools.

Finke completed the first SARJ lubing five minutes as Feustel worked the ammonia tool cleanup task. Finke then moved on to stow the P3/P4 jumpers - during which Feustel joined him for the remainder of the activity.

Feustel moved to the ATA and performed a venting operation while Finke tackled the S1 truss Radiator Grapple Bar Stow Beam operation.

While Finke was performing this 1hr 10min operation, Feustel installed a CLA cover on Dextre, or the Special Purpose Dexterous Manipulator. He then performed a lubing operation on Dextre with the aide of the Station’s Remote Manipulator System arm.

During the S1 Radiator Grapple Bar Stow Beam and Dextre operations, the port SARJ was rotated 200 degrees, a 45 minute operation.

After finishing their two previous activities, Finke and Feustel moved back to the port SARJ and perform the second lubrication of the joint for the EVA.

The two astronauts spent the final part of the EVA reinstalling the SARJ covers, cleaning up their worksite and tools, and translating back to the Quest Airlock to re-enter the ISS.

“That was an awesome EVA,” Commander Kelly noted, as the duo came to the end of their epic EVA, ahead of preparations to get the duo out of their spacesuits. Due to the length of the EVA, the crew moved into their pre-sleep shortly after they rejoin the rest of the crew.

Flight Day 8 will be mainly an off duty day. Monday will also mark the historic Soyuz “flyabout”, with the next article focusing on the once-in-a-lifetime event.

TPS Clearance Overview:

Following Endeavour’s brilliant ascent on Monday morning, information on the health OV-105′s Thermal Protection System (TPS) began pouring in from Endeavour’s computers, with the first indication of health coming from the Launch +12hrs (L+12 hours) Wing Leading Edge Impact Detection System (WLEIDS) report.

According to the L+12hrs WLEIDS executive summary (L2), “All WLEIDS ascent summary data was downloaded and down linked successfully. Ten (10) half second windows of detailed G time histories were downloaded in order to confirm the implication of cases above 1 Grms.

“In total, there are two indications; one Category IV indication on the starboard wing, and one Category III indication on the port wing. Both indications occurred on the 11/12 interface” - meaning they occurred at the interface region between Reinforced Carbon Carbon (RCC) Wing Leading Edge panels 11 and 12 on both the port and starboard wings.

Furthermore, “Overall, background levels for STS-134 (were) very similar to background levels of previous missions. No data anomalies (were) identified, and all (WLEIDS) units triggered on Main Engine Ignition within 0.13 seconds of each other.”

Both WLE impact indications met all six impact reportable criteria to be considered areas of interest/potential impact indications and not just normal RCC WLE settling “noises” created as the vehicle accelerates through Earth’s dense lower atmosphere.

Of the two potential impact indications, the largest was the indication from the starboard wing - which registered a Grms indication of 2.54 in Damage Likelihood Category IV.  Damage Likelihood Category IV is defined as a damage probability ratio between 1/200 and 1/100.

The second potential impact, the one on the port wing, registered on the WLEIDS with a Grms of 1.34 in Damage Likelihood Category III. This was a double transient event with the first transient falling in Damage Likelihood Category I: a damage probability ratio greater than 1/1000.

The second transient contained a damage probability between 1/500 and 1/200.

Flight Day 2′s (FD-2’s) inspection of the WLE via the Orbiter Boom Sensor System (OBSS) observed absolutely no areas of damage on the RCC at the locations identified as potential impacts sites by the WLEIDS.

The following day, on FD-3, Endeavour performed her customary R-bar Pitch Maneuver (RPM) to allow the crew on the International Space Station to photography her underbelly TPS. (Image used, 125mb “super belly” RPM photo stitch (L2))

Following this maneuver, the TPS Damage Assessment Team (DAT) released a preliminary report on the vehicle’s TPS health during FD-4. “Imagery review complete: ET doors verified closed. Five items on the lower surface have been evaluated - all QA completed. All lower surface tile (superficial) damages - four cleared by PDAT and one by comparison with OOIC.”

No gap filler protrusion were noted during RPM photography image review, and no upper surface discrepancies were identified either. FD-2 inspections confirmed that the T0 umbilical region of Endeavour suffered no damage during T0 umbilical release at liftoff.

However, the FD-4 presentation noted two areas of TPS underbelly damages that could not be cleared by the DAT and might require a Focused Inspection by Endeavour’s crew.

The first location was a multi-tile damage site on the inboard elevon with an estimated 3D damage depth of 0.3 +/-0.1 inches. The damage location itself was 6.52 inches in length x 2.32 inches in width +/-0.15 inches. Total tile thickness in this region is 1.636 inches.

This area, while initially a Focused Inspection candidate, was cleared for reentry by the DAT through an amazing series of analyses that proved that positive structural and thermal margins would be maintained in this region during entry.

Thus, the need to perform a Focused Inspection on this area was eliminated.

(Animated GIF created by NSF member Lee Jay Fingersh via the several hundred hi res RPM images available in L2).

The second area of damage that did eventually require a Focused Inspection was classed as a “large damage site.”

According the FD-4 TPS Subsystems Status presentation - available for download on L2 - “RPM Imagery: Visual indications of RTV (filler bar) and dark line (abrupt change in depth).”

The RPM imagery showed indications of “ledges/drop offs” in the TPS cavity with decreasing TPS tile thickness close to the edge of the tile.

STS-134 Specific Articles: http://www.nasaspaceflight.com/tag/sts-134/

Based on RPM imagery, the TPS tile damage depth was estimated at 0.6 inches +/- 0.1 inches with reduced confidence toward the tile edge.

This estimated damage depth corresponded nearly identically to the damage depth prediction on STS-118/Endeavour - the only other occurrence of deep tile damage on an orbiter post-Columbia.

On STS-118, RPM imagery yielded a predicted tile damage depth of 0.5 inches. Upon Focused Inspection of the area, the damage depth was revealed to be around 1.0 inch.

Due to these factors, the DAT and imagery support personnel were split on their interpretation of the RPM data. As such, the DAT formally recommended proceeding with a Focused Inspection of the “large damage site” on Endeavour.

Following the Focused Inspection on Saturday, the TPS DAT and Mission Management Team officially cleared Endeavour’s entire TPS for reentry.

(Extensive coverage is being provided on the news site, forum and L2 special sections – the latter of which is the world’s best front row seat to Shuttle missions. With specific and extensive flight day coverage, from interactive “one stop” FD live coverage in the open forum, to internal documentation, photos, videos and content in the specific L2 FD areas).

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ISS Extensions:

Previously due to be deorbited in around 2016, the ISS gained an extension to 2020 – pending the approval of the FY2011 budget proposal. It is understood there is little risk of the extension being reversed, should the US Congress decide to refine President Obama’s future plan for NASA.

As far as extending the ISS’ lifetime deep into the 2020s, the SSPCB minutes (available on L2) noted an “ISS Life Extension Internal Technical Integration effort” – a plan which will involve all ISS partners assessing the viability of safely operating the orbital outpost to at least 2025, pending Program-level approval.

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2. STS-126: EVA-1 opens major effort to repair SARJ on Station Spacewalkers Heidemarie Stefanyshyn-Piper (EV1), and Stephen Bowen (EV2) have completed...
3. Progress M-66 launches, heads for the International Space Station The Russian cargo ship Progress M-66/32P has launched from the...

NASA have continued to build plans to solve the SARJ issue on the Station – centering around an ambitious plan to replace the race ring on the starboard hardware that rotates solar arrays to track the sun, by installing SARJ XL on one of the 2010 shuttle flights.

Several flights – depending on requirements – will have the additional EVA tasks of cleaning and lubing the starboard SARJ. However, downstream plans continue to be modified, via the positive results gained after STS-126′s activities.

“After the STS-126 crew cleaned and lubricated the stbd SARJ, even though the race ring is damaged, the current required to rotate the joint was much lower than previously required,” noted an 8th Floor News update to MOD staff, acquired by L2.

“Because of this situation, there is higher confidence that this inboard race ring will be available for future operations.”

And future operations via use of the inner race ring on the SARJ, is deemed as capable of operation throughout the lifetime of the Station, in tandem with a mitigation plan involving the outer race ring.

“Lifetime analyses indicate that the inner race ring structure is good for the life of the Program. However, since the ring is damaged and may contribute to a somewhat higher degradation of the rolling equipment attached to the ring.

“The Program is seriously considering modifying the Stbd SARJ to provide a full redundant option where the joint can be rotated using the outer race ring.

“This would open up the option to operate the Stbd SARJ using the outboard race ring with the inboard race ring used as backup. This would require moving both of the Rotary Joint Motor Controllers (RJMC) outboard of the rotating joint.”

To enable this plan, an EVA task would be required on a future flight – or during an Expedition EVA – in order to create an installation location for the a second RJMC.

“The proposed solution includes developing two new interface boxes which would be installed at the current RJMC inboard location,” added the update. “This would provide a means for the S3 MDM to acquire joint resolver data from the inside of the rotary joint.”

It is not yet know if this would negate the need to fly SARJ XL to the station.

STS-119:

Meanwhile, when next orbiter due to arrive at the orbital outpost remains in the balance, as managers and engineers push forward on creating flight rationale for the Flow Control Valves (FCVs) in order to launch around March 12, just a few days prior to the Soyuz cut out.

Click here for NASASpaceflight.com articles on the FCV issue since STS-126.

Confidence is high that an engineering solution via testing will result in flight rationale being accepted at next month’s latest Flight Readiness Review (FRR). However, all elements that support the mission are having to work along the fluctuating timeline.

“As you all know, the Space Shuttle Program and our partners are working hard to develop a plan to go forward toward a launch,” noted Kwatsi Alibaruho from the Flight Director Office to MOD staff.

“That plan is coming together nicely, and our Shuttle Program Manager has been doing a great job articulating the status of the development of that plan to the community and to management as we progress.

“Officially, a launch date has not been set for STS-119 / ISS-15A; however, it’s obvious from the press releases and other information that folks are working toward a March 12, 2009 launch target.

“There is still a great deal of open work to close out before we can fix a launch target that everyone has high confidence in. There will be management reviews next week to assess our capability to meet March 12th or subsequent targets.

“Because so much of our work requires a significant lead time of several days to complete, we must be prepared to support our nearest possible launch target.”

Additional work required for the latest NET (No Earlier Than) launch date includes a switch from a Descending to Ascending Node landing.

The Ascending node entry path is usually preferred as it involves the orbiter return to track mainly over water, whereas a descending node entries occur much later in the flight day, and crosses over the heartland of the United States.

“I want the team to prepare for a March 12, 2009 launch. I know we have timeline work that needs to begin right away because for a March 12th launch opportunity, we will be landing on an Ascending Node, versus the Descending Landing we were doing for a 2/27/09 launch opportunity,” added Mr Alibaruho.

“I know there are also ISS Power, Thermal, and Attitude analyses that must begin at this time. Please proceed.

“In summary, that work that we must do to prepare for a 3/12/09 launch, we should do. If there is any work that can be deferred until the management reviews next week, I recommend you defer.”

L2 members: Documentation – from which the above article has quoted snippets – is available in full in the related L2 sections, now over 4000 gbs in size.

Related posts:

1. MMT outlines their extension day decision – EVA-4 finalizes SARJ tasks The Mission Management Team (MMT) has decided to extend STS-126...
2. STS-126: EVA-1 opens major effort to repair SARJ on Station Spacewalkers Heidemarie Stefanyshyn-Piper (EV1), and Stephen Bowen (EV2) have completed...
3. ISS prepares for arrival of STS-126 – STS-119 launch date advancement debate With STS-126 closing in on the start of S0007 –...

The latest information on the status of the repair was noted in a recent 8th Floor News internal update.

“Starboard SARJ TBA replacement and grease results: Status briefing on the initial quick look results of the Starboard SARJ rotations and disturbances seen after the ring was lubricated and the TBA’s were changed out,” noted the information on L2.

“The disturbances seen by starboard SARJ motion have greatly decreased based on the two orbits of autotrack that were performed immediately post R&R. The team requested an extended autotrack to obtain more data and determine if the disturbances drop even lower after a long period of operation and distribution of the grease due to rotation.”

These results are vital for the forward plan on ensuring the rotation of the giant Solar Arrays can be carried out without the situation worsening, but also on the required maintenance of the SARJ, which will require lubrication ahead of the current plan to install a replacement race ring called SARJ XL.

However, the results are so positive, SARJ XL may not even be required, as noted via the 8th Floor News information.

“Team is developing a lube rig design that will be used to evaluate the life of a greased ring to determine how long it will be until team is concerned with roller tipping and when the ring should be relubricated,” added the 8th Floor.

“The Board also tasked the SARJ team with identifying a test or series of tests that will identify if the program can live with the existing degraded joint vs having to invest in the SARJ XL modification – which inserts a third race ring into the joint as a replacement for the currently spalled race ring.”

SARJ XL has already been checked over on the ground and is deemed good to fly if required. Should it take a ride to the ISS, it will fly on one of the final missions on the ‘current’ shuttle manifest, in 2010.

Related posts:

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The docked phase of the mission involved four spacewalks, all of which focused on the cleaning and lubrication of the starboard SARJ – with EVA-4 carrying out the same process on the port SARJ. With the starboard SARJ being the problem, it also saw its Trundle Bearing Assemblies (TBAs) replaced.

A two orbit Autotrack test was carried out on the starboard SARJ, following EVA-4, with initial data proving to be positive on the improvements to the rotating joint’s health – via less vibration and lower currents required to drive the motors.

“Port SARJ returned to autotrack operation post-EVA. Drive current levels slightly less after lubing,” noted Mission Management Team (MMT) documentation on L2.

“Starboard SARJ autotrack test performed; required significantly less current to drive: currents were 0.7 – 0.9A prior to lube, currents were 0.17A average and 0.35A peak after lube.”

While the data will take up to two months to fully analysis, managers are already hopeful of the possibility that the starboard SARJ won’t require renewed cleaning and lubrication on a regular basis. More so, a long term plan for the SARJ – which was mapped out during the summer – may not be required.

That plan involved several downstream missions including SARJ ‘clean and lube’ requirements, before the long-term solution of replacing the Race Ring – a plan known as SARJ XL – was initiated.

SARJ XL is classed as “an innovative scheme to potentially take the single spare race ring and insert it between the existing spalled inboard race ring, and the other spare ‘outboard’ race ring.”

At present, engineers are pressing ahead to launch SARJ XL on one of the CLF (Contingency Logistics Flight) missions in 2010, with that mission’s EVAs dedicated towards its installation.

“Trade Study: (ISS Manager) Mr. (Mike) Suffredini had asked about accelerating SARJ XL to ULF4 from ULF5 (ULF5 is the last mission in the “current” manifest). Due to various reasons, many due to hardware availability, the SSPCB directed the SARJ XL to stay on ULF5,” noted the latest news via a MOD memo, on L2, prior to the mission.

“However, (Mr Suffredini) did indicate that he wanted hardware delivery to stay in the same May 09 time period. If for some reason the assembly sequence slips, he wants the have other mission options (ie: hardware delivery should not slip with launch date). One option discussed is whether ULF4 (Russian MRM) may end up slipping with ULF5 taking its place in the sequence.

“Spare Race Ring Viability Inspection: Boeing looked at the ring that will be used for SARJ XL. Although there were several microscopic corrosion “features”, the ring was described as being pristine.”

Due to the complexity of the downstream manifest scheduling – which is already being pushed to into a full 2010 of shuttle flights, even before the now-likely shuttle extension kicks in – removing the need for SARJ XL has numerous benefits, ranging from cost savings to allowing other tasks to take priority on the CLF missions.

The best case scenario envisioned involves a requirement to “clean and lube” the starboard SARJ – and possibly its port counterpart as aging starts to take effect – once every year or so. Such tasks could be included during space station increments, as opposed to becoming shuttle mission EVA tasks.

Once the data from STS-126′s get-well tasks is fully analyzed, engineers will have a better understanding on both their ability to use autotrack on the starboard arrays, and the maintenance timeline. The potential deletion of SARJ XL can then be decided on.

Meanwhile, back on Flight Day 15 of STS-126, another key event is the required Late Inspections of Endeavour’s TPS (Thermal Protection System). The orbiter’s heatshield has already been deemed as completely clear of any notable damage via Flight Day 2 inspections, and Flight Day 3′s RPM imagery.

While the orbiter is protected by the Station during the docked phase – thus the likelihood of any damage is very small – one final inspection is important after docking, due to the contingency of returning to the ISS, should imagery find serious damage on the orbiter.

In such a scenario. the orbiter would be re-docked with the ISS, and her crew taking up residence on the ISS until Discovery could be launched on a rescue mission. Endeavour would undock ahead of Discovery’s arrival, where she would either be commanded through either a destructive – tail first – disposal re-entry, or RCO’ed through to landing.

Such LON (Launch On Need) scenarios are very unlikely, but NASA don’t take chances when it comes to the safe ability of an orbiter to re-enter since Return To Flight – since when the TPS inspections were included into shuttle missions, inclusions that involve the use of the OBSS (Orbiter Boom Sensor System).

The OBSS instrumentation package – which rides on the end of the 50 foot boom – consists of visual imaging equipment, the Laser Dynamic Range Imager (LDRI), and the Laser Camera System (LCS). The post-Columbia modification has sensors that can resolve at a resolution of few millimetres, and can scan at a rate of about 2.5 inches per second.

One small issue with the “tilt” direction of the camera suite on the OBSS was noted early in the mission, though this will not affect the ability to gain the required scans during Flight Day 15.

Classed as “OBSS ITVC Tilt Angle Offset”, the issue relates to the PTU (Pan Tilt Unit), which was noted to be offset by nine degrees in tilt and 1.5 degrees in pan. A similar issue was noted on STS-123.

“Bad PTU reset – incorrect reset could be caused either by operator error, or by a cable jam/snag,” noted one of several MMT presentations (L2) on the probable causes.

“2) Cable snag on cable tie – this is the first flight for the cable tie. The tie was incorporated in order to prevent a cable to sensor blanket snag that was observed in ground testing. Remote possibility with position of cable tie

“3) Hardware malfunction -Most unlikely cause since there isn’t any other reports of off-nominal PTU function.”

The bad reset was ruled out, following a failed solution via the reset that was carried out later in the mission as part of the troubleshooting.

“Performed Test 2 from 12:55 am to 2:13 am on Flight Day 12. Offset at -260 degrees tilt agrees with offset of ~9 degrees seen on FD2. Expect OBSS PTU behavior for Late Inspection to be similar to what was observed on Flight Day 2.”

However, with the issue known, Late Inspections can be carried out as planned, without any problems.

“Regardless of Troubleshooting: Additional Pan/Tilt resets will not pose additional risk to the hardware,” added one presentation. “Resets are performed numerous times on ground. Not a life cycle issue. Post Flight ground activities include an inspection and basic functional test.”

L2 members: All documentation – from which the above article has quoted snippets – is available in full in the related L2 sections, now over 4000 gbs in size.

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EVA-3 involved the changeout of the remaining five Trundle Bearing Assemblies (TBAs), the removal of the debris from the Race Ring, before greasing the metallic surfaces. One TBA task was outstanding.

The aim is to provide a temporary solution to the vibrations that were observed on the starboard SARJ, which will allow it to “autotrack” the sun and provide power to the ISS. A final solution will be carried out in 2010, via the installation of the SARJ XL replacement Race Ring. Due to the absense of the final TBA task, the autotrack test will have to wait until after EVA-4. 

Tasks to be completed on this EVA were laid out by the SSP EVA Flight Readiness Review (FRR), although the usual pattern of being ahead of the timeline by the spacewalkers has led to several refinements of the EVAs.

“EV1 starts with covers 20 and 21, and TBA 5 first, followed by DLA (Drive Lock Assembly) cleaning. Then works covers 22 and 1, and TBA 6 (to line up with EV2). Next, covers 2 and 3, with TBA 7,” noted the presentation.

“EV2 starts with covers 15 and 16, with TBA 2. Then covers 17 and 18, with TBA 3. Next, cover 19 and TBA 4.”

This EVA was the longest to be carried out on this mission, which became a topic of discussion at the FRR to ensure safety limits were maintained.

“One violation will occur as part of nominal mission plan for EVA duration greater than 6.5 hrs (Shuttle Crew Scheduling Constraints, Section 3.2.a governs allowable EVA duration),” noted the FRR presentation. “EVA3 duration planned for 7 hrs to complete Starboard SARJ cleaning.

“Each section of the S3 SARJ estimated to take 1:45 to clean, lube, and R&R the associated TBA. Currently performing 3:00 hrs SARJ maintenance on EVA1, 3:45 hrs on EVA2, and 6:00 hrs on EVA3. EVA duration is based on 6:00 hrs of SARJ tasks + 30 min egress/setup + 30 min of cleanup/ingress.”

The long duration EVA was based on four training runs in the Neutral Buoyancy Laboratory (NBL) at the Johnson Space Center (JSC), which pre-empted the need for a flight rule that could be assessed in real time during the spacewalk.

“Consistent with data from repeated (4) NBL runs. CR (Change Request) documents exception. Flight Rule written to govern real-time EVA duration strategy.”

The Mission Management Team (MMT) also became involved with ensuring the spacewalkers had enough contingency via the tools being used to lubricate the SARJ hardware over the remaining EVA timeline, following the loss of two grease guns during EVA-1.

Using typical NASA ingenuity, engineers noted the spacewalkers could modify another gun – which is carried on the orbiter in the case of a repair being required on the RCC panels.

The NOAX repair gun was developed as an option to fill any small holds or gouges on the orbiter TPS (Thermal Protection System), if its ever required.

The nearest this came to being used was during STS-118, when Endeavour suffered a gouge on her underbelly, before it was cleared to re-enter without any required work.

The decision held some negative impacts – if the gun is used – due to the removal of some of the contingency related to a NOAX based repair. However, with a clean orbiter, and the highly unlikely event of damage being caused ahead of Late Inspections (post undocking), the gun was always likely to remain unused in its TPS repair role. One gun will remain unused regardless.

“Two NOAX Flight Tubes flown on every mission and stored independently of Manual NOAX Guns and application hardware. Supports early and late mission RCC Repair (Crit 1 task). Flight NOAX tubes are integrated IVA prior to Airlock egress; flight NOAX tubes cannot be integrated into NOAX gun EVA,” noted the MMT presentation on the decision.

“SARJ grease gun design was based on the NOAX manual gun design. Three modifications were made to the NOAX manual gun. 3/8” aluminum nozzle (NOAX) vs. 1/8” Teflon (SARJ). Zip tie added to SARJ Gun handle to minimize hand travel. Thermal cover on SARJ straight nozzle different than NOAX straight nozzle.

“Background: One of two Manual NOAX Guns and one NOAX nozzle proposed for possible use during SARJ EVA-3 and EVA-4. NOAX nozzle design is slightly different but can be configured for use on SARJ EVA.

“Concerns: NOAX nozzle not reusable for RCC Repair if used for SARJ EVA. Nozzle requires IVA disassembly and cleaning prior to use for NOAX repair. Risk of grease transfer/contamination on Manual Guns if gun is used later for NOAX repair

“Unknown effect of material incompatibility between NOAX and Braycote. Requires Dual Glove Box and arc-jet testing (5-6 days) to characterize effect. Risk of no redundancy for implementing a NOAX Repair during late mission contingency. Contaminated gun could be used as back-up.”

The MMT reviewed the request to use the TPS NOAX dispensing tool for EVAs 3 and 4 to assist with the lubrication of the port and starboard SARJ and decided to allow it to be placed in the crew lock area of the Quest airlock, ready to be used if required.

That gun may still be able to be used as a backup on a TPS repair, if absolutely required by replacing the cartridge.

“The MMT recognizes that there is a very low probability that the tool will be required for the contingency scenario of dispensing NOAX,” noted the MMT. “It was also observed that the tool could be cleaned up after it was used for SARJ lubrication and ready to serve as the backup to the prime NOAX dispensing tool, if needed.

“Since one of the primary objectives of this mission was to stabilize and restore the SARJ to fully functional status, the MMT concurred with the request to use the backup NOAX dispensing tool for EVAs 3 and 4.”

L2 members: All documentation – from which the above article has quoted snippets – is available in full in the related L2 sections, now over 4000 gbs in size.

Related posts:

1. STS-126: EVA-1 opens major effort to repair SARJ on Station Spacewalkers Heidemarie Stefanyshyn-Piper (EV1), and Stephen Bowen (EV2) have completed...
2. MMT outlines their extension day decision – EVA-4 finalizes SARJ tasks The Mission Management Team (MMT) has decided to extend STS-126...

An issue was worked ahead of the EVA, with issues noted with the Pan Tilt Unit (PTU) camera on the joint of the SRMS/OBSS (Shuttle Remote Manipulator/Orbiter Boom Sensor System). The camera is used to observe – among other items – EVAs and Late Inspections.

“Targets 1, 2 and 3 are near the pan limit for the PTU. Target 1 is also near the tilt limit. Target 2 is at the tilt and pan limit. Target 4 is not near the pan/tilt limits, but is also not at the preferred higher tilt values (only at -118 degrees),” noted the error report.

“The OBSS/SRMS remains in the MPLM viewing position. OBSS personnel continued to evaluate potential OBSS PTU viewing opportunities to further troubleshoot the tilt discrepancy noted during the Flight Day 2 survey. OBSS personnel are coordinating with EV personnel on possible tests that could be done to further troubleshoot this discrepancy.

“We have begun looking at camera views that could be used to view the OBSS ITVC in the SARJ Cleaning, MPLM viewing, and Undock positions. So far, the Undock position seems to have the best viewing opportunities, but it is also very close to Late Inspection.

“We will continue to look at possible targets at which to point the camera in the different positions that could be used to help determine any offset in the PTU.”

Prior to the start of EVA-1, the PTV was put through a test, and appeared to work as required. Further evaluations will follow over the coming days. Engineers already believe they have a candidate for the issue.

“It was also noted that there are ties on the PTU cables for this flight, where on STS-122 there were no ties, and the cable moved freely during the pan/tilt reset manuever. It is not clear whether this tie could be impeding the PTU movement.

“(EV) verified that this tie was added due to concerns that the free moving cables could get caught during manuevers (this was witnessed during ground testing) and cause drag issues on the PTU.

“Ground testing indicated that the ties did not impede the PTU range of motion; however, (EV) said it is possible that shifting caused during ascent could have caused some cable movement. Further testing would be needed to determine if the cable ties are a factor.”

Flight Day 5 saw the spacewalkers perform the first of four planned EVAs, which involved the transfer the Nitrogen Tank Assembly from ISS to the payload bay, the transfer a spare part for the External Thermal Control System to ISS, and begin work on the Starboard Solar Alpha Rotary Joint (SARJ).

“EV1 starts by pulling off cover 8 and TBA 10. Cleans and installs TBA, cover 8. Removes covers 9 and 10 and TBA 11, cleans, LEAVE TBA 11 OUT, and reinstalls covers. Continues with single cover cleaning under C11. May remove SLR 4A,” outlined the associated SSP FRR (Flight Readiness Review) presentation.

“EV2: Starts with removing covers 22 and 1, and TBA 6. Cleans, installs 6, reinstalls covers 1 and 22. If time available, works from cover 2 (TBA 7) zenith, making sure to time TBA R&Rs appropriately with EV1. May remove SLR 4A.”

This work will continue over the course of the remaining EVAs, with the second on Thursday, the third on Saturday, and the fourth and final EVA will be conducted on Monday.

This mission also includes the transfer, installation, and activation of several systems to support six person crew, such as the Water Recovery System, a second toilet system, new galley components, two new food warmers, a food refrigerator, two separate sleeping quarters and a resistance exercise device.

During EVA-1, the starboard SARJ was successfully cleaned and lubricated in the required locations for this spacewalk, while several Trundle Bearing Assemblies were also replaced. The spacewalkers used special tools to carry out the task, including a grease gun and a scrapper.

It appears that one of the grease guns used by Stefanyshyn-Piper leaked grease into her tool bag. While efforts were made to clean excess grease from her EMU gloves, a tool kit liberated from the bag, before floating away into space.

Stefanyshyn-Piper – although she can’t be blamed due to the grease incident before the bag floated away – apologized upon arriving back into the airlock after the near-seven hour EVA. However, controllers on the ground immediately praised the duo for their hard work.

EVA 2 will involve the relocation of the 2 CETA carts from the starboard side of the truss to the port side in preparation for SSRMS install of the S6 set of solar arrays on 15A. SARJ cleaning will continue, while the snare cables of the A side of the SSRMS will be lubricated to help ensure that the snares are completely out of the capture path for future HTV operations.

L2 members: All documentation – from which the above article has quoted snippets – is available in full in the related L2 sections, now over 4000 gbs in size.

Related posts:

1. MMT outlines their extension day decision – EVA-4 finalizes SARJ tasks The Mission Management Team (MMT) has decided to extend STS-126...