MAF:

Working under the motto of “Finish Strong”, the Michoud managers, engineers and technicians proved to be the unsung heroes of the final phase of the Space Shuttle Program (SSP).

Fighting back from the tragedy of Columbia’s loss, caused by a piece of hardware from one of their own External Tanks – as much as a series of events outside of their control contributed to the disaster – the MAF team and center became one of the focal points for the implementation of Return To Flight (RTF) modifications – L2 link.

Initially, this proved to be anything but smooth sailing, with the first tank to fly since Columbia’s launch liberating a large slice of its PAL (Protuberance Air Load) ramp during Discovery’s STS-114 ascent – resulting in further changes via the complex science of mitigating foam loss during the ride uphill.

Further finite modifications were made to the tank’s Thermal Protection System (TPS) as the fleet began to up the pace, itself a massive challenge, with each change to a highly refined system carefully studied and refined further.

One such example was the modifications made to the LH2 Ice Frost Ramps (IFRs), which were fine-tuned over a number of flights, based on their performance during actual launches. The LO2 IFRs were also monitored through to the end of the program.

These numerous changes, in tandem with an improving flight rate, resulted in additional challenges, such as achieving the delivery dates for the tanks based on the projected flight manifests created by the Flight Assignment Working Group (FAWG) – L2 Link.

Via the mix of ingenious management brainstorming at numerous Technical Interchange Meetings (TIMs), the dedication of the Michoud workforce working seven days a week and solid leadership from Lockheed Martin’s ET boss Wanda Sigur, refined delivery dates supported the desired manifest – as seen ahead of the flagship STS-125 mission to service the Hubble Space Telescope.

Click here for numerous ET news articles: http://www.nasaspaceflight.com/tag/et/

More importantly – not least in the case of Atlantis’ Hubble mission – the tanks started to enjoy a run of increasing success in the mitigation of foam liberation from the critical areas of the tank, resulting in mainly “clean” orbiters – no serious TPS damage caused by foam loss) – especially in the latter missions for the fleet.

Michoud even managed to add a tank to the manifest, namely ET-122, allowing for the addition of STS-135, a mission which has proved to be extremely vital for the International Space Station’s logistical health, especially during what has proven to be a problematic year for the Russians.

ET-122, damaged by Hurricane Katrina in 2005 when it was located in Cell-A of MAF’s Vehicle Assembly Building (VAB), required a large amount of work, both from a repair standpoint, but also via the requirement to implement the numerous RTF modifications.

And Katrina didn’t just damage the tank, but also displaced large amounts of the MAF workforce, some of whom were technically homeless at the time NASA needed them the most during the comeback from negative delivery dates.

Sadly, most of that workforce fell foul of NASA’s ongoing transition, as much as most saw it coming since the decision was made to retire the Shuttle fleet once ISS assembly was complete - although the since-cancelled Constellation Program (CxP) was a hammer blow to the facility. Just a handful of ET engineers remained at MAF by the end of August, with the rest of what is now a small workforce working on Orion and other contracts.

The official end of ET work at MAF resulted in the spare tanks – such as ET-94 – no longer being serviced by Lockheed Martin. They have been turned over to the ownership of Jacobs Technologies.

A number of workers might of been saved, had NASA administrator Charlie Bolden announced the Space Launch System (SLS) when lawmakers had requested it. MAF leaders had hoped for an end to the delays earlier this year, extending the period prior to the handing of WARN notices to a number of workers several times, before finally losing patience.

Now the SLS program is up and running, MAF are hoping to be involved in the resulting contracts, with one of the main contractors likely to be building the core stage, Boeing, already noted to have utilized the facility for their SLS-related Pathfinder tank. Meanwhile, other major weld tooling has been placed into storage.

MAF At The Movies:

Ironically, some of the remaining workforce found themselves with job sheets that had nothing to do with the space program, as they spent some of their days removing equipment to make space for a string of production companies to use the facility to film parts of their blockbuster films, per L2 information.

The first of which was GI Joe 2 (Retaliation) – which has now completed filming inside MAF, ahead of its summer 2012 release date.

This movie stars Bruce Willis – who is no stranger to space hardware, following his staring role in the blockbuster movie Armageddon, which filmed at numerous NASA centers, including the Johnson Space Center (JSC) and the Kennedy Space Center (KSC).

Universal Pictures will arrive in January to film two movies (the titles of which are being kept secret), while Disney and MGM are also in the process of negotiating the use of MAF’s 101 building for filming purposes.

Despite the major handover to Jacobs, Lockheed Martin still had control of final assembly position 3. However, current MAF employees have been told to clear out all equipment to make room for yet another studio. At this time all four final assembly positions, the entire VAB, and the 420 building at Michoud are now classed as movie sets.

It has also been noted that the BP oil company has also taken control of BLDG 451 – otherwise known as the LH2 proof test building – to store the blow out preventer that caused the Gulf oil spill in 2010.

It is hoped that sometime in 2012, MAF will see the work being carried out on the Orion which will fly on the Exploration Flight Test (EFT-1) being joined by work on commercial vehicles and the SLS, as opposed to providing a large indoor facility to Hollywood.

Please note: Clickable links with (L2) references point directly to cited L2 content. Such content is only available to L2 members (please ensure you are logged in). All other clickable links point to NSF articles and open content.

Images: Via L2 content. Other images via NASA.)

(L2 is – as it has been for the past several years – providing full exclusive SLS coverage, available no where else on the internet. To join L2, click here: http://www.nasaspaceflight.com/l2/)

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SLS Work:

August has been a relatively busy month for SLS, with NASA centers and contractors almost ignoring the delaying tactics in Washington DC, by pushing on with planning work surrounding the winning configuration of the Heavy Lift Launch Vehicle (HLV) – as much as NASA’s top brass continue to avoid announcing it.

At the Marshall Space Flight Center (MSFC), the new SLS DAC (Design Analysis Cycle) cycle officially started this month, a process which will take the vehicle design to the SRR (System Requirements Review)/Checkpoint Review in October.

Managers have already presented their teams with kickoff charts, showing what is now the well-known Shuttle Derived (SD) HLV, along with pointers towards a forward plan to develop the Upper Stage design simultaneously with the core stage.

While no Upper Stage hardware will be built at this stage, given the lack of funding, the current process of developing the US with the Core will provide an engineering advantage, given the integrated vehicle loads can be developed in a way which will allow the Core Stage to be designed for the appropriate Upper Stage from the outset.

With SLS concept development providing support of the SRR/SDR (System Design Review) and core stage procurement activities, the path is laid out for the SLS to progress to the PDR (Preliminary Design Review) stage. Once the core stage prime contract is awarded, the work will transition to more of an insight and vehicle integration role.

Boeing – who officially class themselves as “pursuing work on NASA’s Space Launch System to provide heavy lift capability for exploration beyond Low Earth Orbit” – have already completed testing their manufacturing processes via a sub-scale tank, known as the “Pathfinder”.

For SLS/HLV Articles, click here: http://www.nasaspaceflight.com/tag/hlv/

The Boeing team at MAF in New Orleans, class the Pathfinder as a “major milestone toward the future of space exploration”, adding the tank is a “key demonstration of NASA’s readiness to immediately transition into the Space Launch Systems (SLS) program”.

The Pathfinder Liquid Oxygen tank is a 5.5 meter diameter lightweight aluminum lithium design, demonstrating state of the art manufacturing and welding approaches developed as part of the Upper Stage Production Contract (USPC), allowing engineers to work on a 5.5m tank – per development on Ares I’s Upper Stage – via technologies and techniques will be applied to the 8.4m diameter SLS.

“State of the art production tools, developed by Boeing in partnership with NASA and the University of New Orleans National Center for Advanced Manufacturing, provided efficiencies not previously available at MAF for this type of manufacturing. The pathfinder is also representative of a Liquid Oxygen tank that is extensible to the Space Launch System,” noted a Boeing overview (available on L2).

“The use of a Liquid Oxygen tank originally designed for Upper Stage Production Contract enables an efficient transition of subsystems such as the Main Propulsion System and Thrust Vector Control from USPC to Space Launch Systems.

“Work on the Space Launch Systems enables Boeing to expand into a natural adjacency, leveraging decades of experience in manned space flight into possible future business.”

Interestingly, further evaluations have recently begun into the MPS which will ride with SLS, with the potential for the three retired Shuttle orbiters to donate their MPS’ for the opening three flights. (Another article will follow on this evaluation next week).

The lightweight aluminum-lithium design features a spun-formed dome, a gore panel dome, and a barrel welded together with two circumferential self-reacting welds. The team managed to complete the fabrication six weeks ahead of schedule.

“Preparing the Pathfinder for production (was) a major step toward production of the nation’s next generation human-rated launch systems,” said Steve Ernst, Boeing’s Exploration Launch Systems Manufacturing Development leader on the Boeing information

“The completed work is a balance between safety, reliability and cost forged by an innovative NASA-Boeing partnership that is paving the way for SLS.”

The information also notes how Boeing worked with NASA’s MSFC in developing the manufacturing processes, in order to prepare the Boeing engineers and technicians with the skills and techniques necessary to employ state of the art techniques for safe, reliable, and cost efficient production of future launch vehicles.

“(This was a) significant advancement of MAF activation by completing key training and certifications for task leaders and weld operators; establishing detailed approaches and processes for kitting, staging, and shipping and receiving; and emphasizing a significant focus on a healthy safety culture and process with the completion of job hazard analyses and lift plans.”

Boeing also confirmed that in order “to support Congressional direction to NASA for development of the Space Launch Systems”, Boeing prioritized work in its existing USPC and Instrument Unit Avionics contracts to work on items that advanced the technical baseline of technologies and manufacturing approaches for the new Heavy Lift Launch system.

“We recognized that we needed to identify opportunities to earn value for NASA and reduce risks associated with the transition to SLS,” added Rick Navarro, Boeing Michoud Site director.

“Working with NASA, this vision resulted in developing the concept to manufacture the Pathfinder tank which not only enabled the team to demonstrate technologies extensible to SLS, it also focused the team on establishing the necessary Boeing production infrastructure at Michoud to prepare for SLS production.

“As a result, the team at Michoud found a way to start up operations and begin a functional production system.”

Boeing teams at the Kennedy Space Center also assisted the MAF Boeing team in establishing the necessary stock of production supplies for the production of the Pathfinder, while the the team at Boeing’s Huntington Beach operations played a key role in development and fabrication of tooling that was used for the Pathfinder.

Other Boeing sites such as San Antonio, Heath, and Charleston also assisted in defining and obtaining the necessary infrastructure to monitor production activities. A number of suppliers, stretching from the northeast United States to the west coast, also supported the Pathfinder effort.

The Pathfinder milestone comes at a time of painful transition for MAF, with WARN notices – extended several times in the hope NASA would finally push forward with its SLS contract awards – finally activated, resulting in the official end to ET operations at the facility.

Just a handful of ET engineers will remain at MAF after Friday, with the rest of what is now a small workforce working on Orion and other contracts.

The official end of ET work at MAF has resulted in the spare tanks – such as ET-94 – no longer being serviced by Lockheed Martin. They have been turned over to the ownership of Jacobs Technologies.

It is unknown what Jacobs will do with the ET hardware. However, their MSFOC group has begun unwrapping ET “major weld” tooling, placed into storage after the final ET was constructed.

These tools are the 5018 and 5019 (LO2 Weld and LH2 Weld) machines – which have been in preservation for a couple of years – and are the major weld fixtures for the LO2 tank and LH2 tanks (horizontal). Currently, the 5019 LH2 fixture has been unwrapped, with the LO2 5018 machine set to follow.

Once the tools are back in place, Lockheed and Boeing engineer will take measurements of the tools to evaluate their conversion from arc plasma welding to stir friction welding.

This also appears to be preparation work for the construction of SLS tank hardware.

(Images: Via MSFC, Boeing, MAF and L2 content - driven by L2′s new SLS specific L2 section, which includes, presentations, videos, graphics and internal updates on the SLS and HLV available no where else on the internet).

(L2 is – as it has been for the past several years – providing full exclusive future vehicle coverage, available no where else on the internet. To join L2, click here: http://www.nasaspaceflight.com/l2/)

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ET camera ascent performance (STS-135) and history:

As was the case 21-times before, the ET engineering camera on the LOX feedline of the External Tank functioned perfectly through pre-launch and launch activities during Space Shuttle Atlantis’ historic and sentimental journey to Low Earth Orbit on July 8.

During the launch of STS-135, the ET camera provided NASA managers and DAT (Damage Assessment Team) personnel with an early look at the tank’s performance as well as any areas of Atlantis’ TPS (Thermal Protection System) that might have been dinged by small foam liberations from the tank.

In all, the quick-look assessment enabled by the ET camera led to the understanding that this was one of the most - if not THE most - clean External Tanks in the history of the Shuttle Program: an in-flight tribute to the hard work and dedication of thousands of NASA engineers and the honorable workforce at the production facility in New Orleans, Louisiana.

This quick-look assessment of Atlantis’ TPS was confirmed on FD-2 and FD-3 of the STS-135 mission when it was revealed that Atlantis had sustained only one lower-surface TPS ding from ET debris.

But while the camera (a Sony XC-999) and its systems worked perfectly on every single one of the 22 post-Columbia Shuttle missions, the camera actually debuted on STS-112, providing images up to SRB separation when debris covered the camera lens and prevented further clear image downlink.

STS-135 Specific Articles: http://www.nasaspaceflight.com/tag/sts-135/

Moreover, the camera’s primary use on STS-112 - a mission by Atlantis in October 2002 - was for PAO launch coverage purposes and not for engineering assessment of the Tank’s TPS performance - an ironic use considering the rather significant foam liberation event that occurred on STS-112 and subsequent foam liberation event on STS-107/Columbia that ultimately made the camera mandatory for tank engineering assessment purposes.

Debuting in what would be its nominal configuration on the STS-114 Return To Flight mission by Shuttle orbiter Discovery in July 2005, the ET engineering camera was the first step in a scaled build-up of the Enhanced Launch Vehicle Imaging System, which eventually included four total cameras on the SRBs, an orbiter ET Umbilical Well camera for post-ET/Orbiter separation imagery, and a “lipstick” camera on the orbiters’ forward-facing pilot’s windows to capture LO2 Ice Frost Ramp foam liberations during ascent.

Over the course of their use by the Shuttle Program, the 22 post-Columbia ET engineering cameras proved their worth time and time again.

Using a 3.5 mm lens to provide a near 100-degree field of view, the cameras captured both amazing ascent footage and carried out their primary task of observing and timing any TPS foam liberations from the tank and any resulting impacts on the orbiter by offering a look at the vicinity of the tank’s bipod attachment area, the portion of the External Tank where the liquid hydrogen tank and intertank flange areas are adjoined, and a portion of the bottom side of the Orbiter.

The cameras themselves, from STS-114 through STS-135, were mounted inside the ET’s liquid oxygen (LOX) feedline fairing - a metal covering that protects the area where the fuel feedline penetrates the inter-tank structure and begins its journey down the exterior, orbiter-facing side of the ET.

Moreover, a section of the 1500 page INCO systems handbook - available for download on L2 - states, “The ET LO2 feedline fairing camera is powered and controlled automatically from the electronics package mounted on a support beam located between the LO2 and LH2 (Liquid Hydrogen) tanks.

“The camera’s field of view includes the bipod assembly region, Orbiter left and right wing (except as obstructed by the bipod strut), Orbiter -Z TPS beginning 12 inches forward of the bipod fitting and continuing aft. The camera captures images at the National Television System Committee (NTSC) frame rate of 30 frames per second (fps) and can see debris/divots that are 2.0 x 2.0 inches or larger at a distance of under 20 feet.”

Furthermore, each camera’s battery pack included 20 nickel-metal hydride batteries, which provided approximately 28 volts DC to the camera.

The batteries themselves were designed to function for about 70 minutes to allow for three launch attempts prior to recharging/replacing of the batteries. Nonetheless, the camera systems were designed to automatically switch the system off 15 minutes after liftoff - regardless of battery life potential.

To enable transmission of live images from the camera, each camera was attached to two “blade” S-Band antennas with a frequency range between 1.55 to 3.9 gigahertz.

Each S-Band antenna was about 2.5 inches long, transmitted a 10 watt signal to ground stations, and was located on the opposite side of the ET from the Orbiter - +/- 47.5-degrees to the side of the ET’s centerline.

During ascent, video from each camera was downlinked from the ET to several different NASA data receiving sites before being relayed for broadcast on NASA TV.

The last of these receiving ground stations along the Shuttle stack’s flight path was Wallops Flight Facility on the eastern shore of Virginia.

STS-135 ET camera mods and pre-launch single acquisition assessments:

While it was never a certainty that the extended transmission of video from the ET-138′s LOX feedline camera would prove fruitful, the effort to attempt to gain never-before-seen images of the External Tank after its separation of an Orbiter was undertaken by Michoud Assembly Facility (MAF) engineers at the request of the Space Shuttle Program.

According to the Extended STS-135 ET LO2 Feedline Video Transmission/Acquisition presentation, available on L2, “PRCB request to assess feasibility of leaving LO2 feedline camera on and recording the downlink TV signal for as long as possible until ET entry and/or breakup.”

To accommodate this request, a “best effort” was made to A) carry out a modification on ET-138’s camera without installing new hardware and B) secure acquisition stations along the ET flight path to “receive and record analog FM TV signals.”

The actual modification to the ET camera was made with relative ease in late-June by the “clipping” of a single wire in the EP to “disable the timing circuit” used to deactivate the camera 15 minutes after liftoff.

However, from the very beginning, the PRCB request presentation made it clear that actually obtaining video from the camera after the tank passed downrange of Wallops was going to be extremely troublesome.

“Two parts to the problem: Coordinate with countries regarding transmitting in airspace and Identify and secure receiving stations along ET flight path.”

To this end, by June 16, agreements had only been reached with the Department of Defense and Germany, and work had just begun to re-active the Diego Garcia (REEF) ground station and assess the potential use of “Navy ship-based assets.”

Additional ground stations in Dongara and Perth, Australia were evaluated but ultimately dismissed since they lay too far north of the ET’s projected flight path.

Furthermore, “A potential lead was pursued for a US Army base in Kuwait (Camp Arifjan), but they [were] not configured to receive analog FM TV from orbit,” noted the Signal Acquisition presentation.

Aircraft usage via the HYTHIRM project from the Langley Research Center were presented, but no aircraft were available for a July 8 launch.

Finally, teams looked at acquiring the camera’s transmissions via the TDRS (Tracking and Data Relay Satellite) network, but the satellites were not capable of being configured to receive an analog FM TV signal.

In all, part of the problem in planning to acquire the transmission from the ET was in the designed flight path of the ET over open ocean.

Specifically, each Shuttle mission’s ascent profile was specifically designed so that the bulk of the ETs flight paths were over the ocean.

More so, each Shuttle mission’s ascent profile was carefully designed to ensure that the ET would destructively reenter Earth’s atmosphere over the ocean and avoid, by a large degree, any populated land masses and heavy-use shipping lanes.

For the majority of the Shuttle Program, this resulted in the destructive disposal of the External Tanks over the Indian Ocean and the southern Pacific.

One notable and recent deviation from this was the disposal path for the ET from the STS-125/Atlantis mission to the Hubble Space Telescope in May 2009.  That disposal path tracked a few hundred miles southeast of the Hawaiian islands to a few hundred miles west of the western coast of Mexico.

But the flight and disposal paths were not the only thing that played against the odds for the STS-135 endeavor; the considerable lack of knowledge regarding the ET’s post-Orbiter separation attitude also factored into NASA’s effort.

As noted by the PRCB presentation, “There is no attitude control for the tank during entry. Shortly after Orbiter sep, the tank is regularly observed displaying a slow 3-axis random tumble.

“The unstable attitude is presumed to continue until Entry Interface and breakup.”

Thus, any TV reception of the tank would have been unpredictable and intermittent at best - as proved by a very, very brief and static-filled image received as the ET tumble over Europe about 25 minutes after launch.

Additionally, “It is presumed that after EI a plasma sheath will envelope the tank and either prevent or make very difficult any subsequent TV signal transmission and reception,” notes the PRCB presentation.

“A basic assumption has been made that any meaningful TV reception apparatus must be positioned upstream of EI.”

Because of the lack of knowledge of ET death dynamics, NASA was unable to confirm if a plasma blackout condition would interrupt TV transmission signals from the ET prior to its breakup.

Nonetheless, while clear live video was never obtained from Atlantis’ ET after it passed downrange from Wallops, the attempt to do so marked a tremendous effort on the part of NASA to document the tank’s reentry and “death.”

To read about Atlantis and her sisters – from birth, processing, every single mission, through to retirement, click here for the links:
http://forum.nasaspaceflight.com/index.php?topic=25837.0

Click here for the amazing MaxQ Entertainment STS-135 Mission Review Music Video:
http://forum.nasaspaceflight.com/index.php?topic=26178.0

(Images: Via L2 presentations and NASA.gov. Further articles on Atlantis will be produced during her down processing, driven by L2′s STS-135 Special Section which is continuing to folow the mission at MMT/MER level through to post flight IFA, surrounded by a wealth of FRR/PRCB/MER/MMT and SSP documentation/pressentations, videos, images and more.

(As with all recent missions, L2 is providing full exclusive level mission coverage, available no where else on the internet. To join L2, click here: http://www.nasaspaceflight.com/l2/)

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STS-135 Latest:

Following the completion of the final S0017 Terminal Countdown Demonstration Test (TCDT) for the Space Shuttle Program (SSP), STS-135′s flow is now officially into preparations for the Launch Countdown (S0007 operations), as Atlantis closes in on her July 8 launch date target.

A sign the launch date is getting closer is usually marked with waves of tankers heading to the pad, with Friday no exception as two convoys of LH2 tankers replenished the Liquid Hydrogen tank at the pad complex.

With Atlantis safely tucked away inside the Rotating Service Structure (RSS), a final walkdown of her payload was also carried out on Friday, while the Sensor Package 1 (SP1) was re-installed and retested on the end of the Orbiter Boom Sensor System (OBSS) after showing signs of a problem last week.

At the top of the stack, technicians have wrapped up their Non Destructive Evaluations (NDE) on the circumference of the LO2 and LH2 flanges at the top and bottom of the Intertank.

The X-Ray and Backscatter inspections checked the support beams – known as Stringers – ensuring they remained crack-free, following the recent Tanking Test, which was called for after STS-133′s ET-137 suffered from cracked stringers ahead of Discovery’s first launch attempt last year.

No issues were expected, given ET-138 had already been modified with radius blocks, a proven mitigation procedure to strengthen the Stringers as they endure the stresses of cryo temperatures and pressure cycles during tanking.

“ET NDE operations: NDE X-rays on the LH2 flange were completed and are in review. This completes the ET NDE x-rays barring any required re-shoots,” noted the NASA Test Director (NTD) report (L2). “No problems have been detected on the x-rays that have been analyzed to date.”

ET/Stringer Specific Articles: http://www.nasaspaceflight.com/tag/et/

Work will continue over the weekend to remove the NDE equipment from the pad, pending the confirmation all the required data has been gathered.

No notable Interim Problem Reports (IPRs) have been charged to Atlantis of late, with the latest – IPR-50, relating to a SSME-2 GN2 heater issue – only requiring a micro-switch adjustment and solder joint repair.

STS-135 Specific Articles: http://www.nasaspaceflight.com/tag/sts-135/

SSME-3 MFV Update:

The main IPR of interest – IPR-49, relating to the MFV on SSME-3 – is close to being resolved, as much as the real test will come on launch day when cryogenic propellant is once again rushed through the system. It was that environment during the Tanking Test which found the problem with the MFV, as outlined at the crew briefing provided by engineers during the TCDT.

“Problem: Engine 3 Main Fuel Valve leakage experienced during the ET tanking on 6/15/11. A contingency procedure was worked to isolate the fuel system (close all LH2 prevalves, LH2 recirculation iso valves and the LH2 hi-point bleed valve) that allowed us to continue with the tanking test,” noted the Crew Briefing presentation (available on L2).

The MFV is a ball valve with a 2.5-inch tubular flow passage and is flange-mounted between the high pressure fuel duct and nozzle diffuser. The valve controls the flow of fuel from the HPFTP (High Pressure Fuel Turbopump) to the coolant circuits and preburners.

Notably, a root cause of the leak is yet to be confirmed – something NASA engineers always prefer to have in the bag ahead of launch. It is hoped an obvious problem will be spotted by engineers at the MFV’s home in California, where the removed hardware was sent to this week, allowing for an overview to be provided at the L-1 Mission Management Team (MMT) meeting.

“Root Cause: Cause of valve leakage unknown until a failure analysis completed,” added the presentation. “Resolution: Valve removed, replaced and retested (but not under cryogenic conditions) before launch. An update on this issue will be given at the LCD L-1 briefing. Impact to this flight: None anticipated.”

The issue was also covered in depth via the STS-135 SSP Flight Readiness Review (FRR) presentation for the SSMEs, which covered how the issue was spotted during the Tanking Test, as it breached the Launch Commit Criteria (LCC) limitations. As a result, the issue would have scrubbed the launch day countdown, showing a bonus side-effect of finding the problem during the Tanking Test.

“Issue: STS-135, ME-3 (2045) Main Fuel Valve (MFV) skin temperatures indicated a MFV leak during the early stages of STS-135 tanking test. Temps violated minimum limit (LCC SSME-02). Tanking test continued with engines isolated from the fuel supply,” noted the FRR presentation.

The reference to the skin temperatures relates to sensors mounted to the outside wall of the downstream duct of the MFV to detect leakage during chill. Low temperatures are indicative of a MFV leak. The LCC limits are based on the vast flight experience of the Shuttle Program.

Although – as mentioned in the Crew Briefing presentation – no root cause has yet been found, a likely suspect failure path was presented to the SSP FRR.

“Most Probable Cause – MFV ball seal leak: Data appears real. Characteristics match previous ball seal leaks,” added the SSME FRR presentation for STS-135. “Scenarios assessed as unlikely: Liquid nitrogen dripping on sensors. Inconsistent with data characteristics and time in chill. Damaged instrumentation. Inconsistent with data characteristics and visual inspections.”

The FRR presentation also noted that there have been two other MFV leaks in the flight history of the Space Shuttle, listed as STS-2 – where metallic contamination found upon disassembly, and STS-73 – attributed to transient contamination (solid N2).

In addition to the above, 20 pre-start MFV leaks have observed during ground tests, half of which are attributed to solid N2 contamination, which is usually caused by an intermittent helium fuel system purge, allowing the solid N2 to form on the MFV.

By way of mitigation, a continuous purge was implemented into the procedures, meaning STS-135′s SSME-3 MFV issue is the first such leak since efforts were made to prevent sold N2 build up.

Almost immediately after the suspect leak was observed during the Tanking Test, engineers knew they would have to replace the MFV, resulting in a plan of action for work to take place at the pad.

“KSC Plan of Action: Ambient ball seal leak check completed – Zero leakage. Aft access Saturday, June 18. Detailed inspection in the area at KSC & Valve Room (on MFV and above MFV skin temp sensors). Valve removal midweek. Ship to Canoga, Californian for investigation,” added the FRR presentation.

“Borescope and visual inspection of fuel system. Replace with spare MFV. Perform standard system checkouts. Bubble soap leak checks. Valve and actuator functional tests. Helium signature and ball seal leak checks. FRTs Saturday, June 25. Helium Signature test Sunday, June 26.”

All work up to the weekend’s testing was completed on schedule, allowing for the Flight Readiness Test (FRT) to take place on Saturday, after the Dome Heat Shield around SSME-3 was re-installed.

“IPR 0049 SSME 3 Main Fuel Valve (MFV) R&R update: SSME 3 MFV electrical mates were completed. Heat shield installation is in work,” added the NTD report – with L2 updates noting the shield is now back in place. “MFV retest is scheduled for this weekend and will include SSME 3 FRT on Saturday and He Signature test on Sunday.”

UPDATE: Due to an unspecified hydraulic leak on the vehicle, the helium signature test has been delayed until at least 4am Monday. The issue is being tagged as IPR-53, pointing to two additional IPRs over the weekend. A full overview of the latest IPRs are expected via the NTD report on L2 around 7am Monday.

UPDATE 2: Leak was minor and SSME-3 MFV retests have been successfully completed.

These tests include the use of a mass spectrometer device, which will sniff for any helium leakage as the MFV is purged. Should no leak be detected, it is highly unlikely a leak will be suffered during launch day.

As such, the SSP FRR accepted the flight rationale for the engines to proceed to the Agency FRR at the Kennedy Space Center (KSC) on Tuesday, pending the successful conclusion of testing on the newly installed MFV.

SSME Specific Articles: http://www.nasaspaceflight.com/tag/ssme/

“Flight Rationale: LCC SSME-02 in place to protect for excessive MFV leakage. Safing procedures in place for hydrogen leak. SSME GN2 purge and helium fuel system purge dilute MFV leakage. Worst case impact is launch scrub. Pending results of valve and engine inspections. The Atlantis Main Engines are in a ready condition for STS-135.”

This article will be updated as information arrives on the weekend testing progress.

Fun Item:

Known by some of her engineers to be somewhat of a diva during some of her flows, with some of her dedicated workforce nicknaming her “Britney” (Spears) and others nicknaming her “the penguin”, both for seperate reasons which may become apparent when googling both names – Atlantis should now have a clear path for a managerial approval of the July 8 launch date.

She may also be on her best behaviour, after the Crew Briefing presentation noted Atlantis will be carrying an extra item into orbit next month, in the form of a man’s gold wedding band, which was listed as one of the items lost and unrecovered during her STS-135 flow.

Listed as one of five items on the “Lost, Not Found” pages of the Crew Briefing presentation, the gold wedding ring was noted as lost on the orbiter – in the Crew Module - back on March 7. Efforts to find the item have proven to be in vain and now will remain on board until Atlantis undergoes post-mission deservicing.

While the owner of the ring may have received an ear-bashing from his wife, the engineer can look forward to proudly announcing he was reunited with the space flown ring by Atlantis when she returns to her Orbiter Processing Facility (OPF)… providing she doesn’t take the opportunity to propose to another vehicle whilst on orbit.

(Images: Via L2 presentations and NASA.gov (KSC). Further articles on STS-135′s status in work, driven by L2′s fast expanding STS-135 Special Section which is already into the FRR content and live flow coverage, plus more. As with all recent missions, L2 is providing full exclusive level flow and mission coverage, available no where else on the internet. To join L2, click here: http://www.nasaspaceflight.com/l2/)

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STS-135 Pad Flow Latest:

The TCDT – otherwise known as S0017 operations – is a full scale dress rehearsal for the big day, allowing the STS-135 crew to conduct Emergency Egress Training, along with suiting up and ingressing Atlantis for a simulated countdown. The operations began at 7:30am local time on Wednesday, ending with a simulated countdown to T-0, marked at 11am local on Thursday.

Atlantis’ engineers also met with the crew at the TCDT L-1 meeting on Wednesday, briefing the astronauts on the health of their orbiter. The meeting discussed the brake fire from Endeavour’s landing on STS-134 – of which there are no real concerns – through to ongoing work with the Main Fuel Valve (MFV) replacement on SSME-3 (Space Shuttle Main Engine). 

The engineering teams also presented Commander Chris Ferguson and his crew with a large cardboard key to the orbiter with all the systems engineers signatures on it.

Meanwhile, teams are continuing to secure Atlantis’ payload, known as S0600 Vertical Payload Operations. This included work on the Orbiter Boom Sensor System (OBSS), which was observed to have an issue with a camera on Sensor Package 1.

“The Remotely Operated Electrical Umbilical (ROEU) mate/functional checkout and the Pico-Sat Solar Cell (PSSC) installation were completed,” noted the NASA Test Director (NTD) report (L2). OBSS Sensor Pack 1 and 2 update: During testing of OBSS Sensors, problem with camera on SP1. I Iris will open and close manually but will not respond in auto.

“Potential removal of SP1 and return to Flight Crew Lab to verify whether the Test controller box or the Camera that is discrepant. There is a spare camera on site if it is required.

“There was a galled nut plate discovered during the installation of the RMS Sideview Camera (RSC), and it has been repaired. As a result, the RMS side view camera and thermistor testing have been rescheduled to Friday.”

Technicians are also carrying out methodical inspections of ET-138′s flanges, scanning the Thermal Protection System (TPS) foam for signs of cracks in the underlying stringers. The checks are being carried out after last week’s Tanking Test, so as to ensure the radius block modifications have provided the expected protection against the problems suffered by sister tank ET-137.

“Supported the successful tanking test. Electrical, propulsion and thermal were all nominal performance. There is no evidence of any off-nominal structural performance at this time,” noted ET management on the Shuttle Standup/Integration Report (L2). “The Failure Investigation Team (FIT) inspection did not show any anomalies.”

So far, NDE (Non Destructive Evaluation) inspections – carried out via the use of X-Rays and Backscatter equipment – have found no issues with the LO2 flange, which is the main area of interest. Scans are now taking place on the lower LH2 flange on the Intertank, which are expected to wrap up by the end of the week.

“ET NDE operations: NDE X-rays are in work and will continue through the week. The NDE on the LO2 flange was completed,” added the NTD report. “The equipment and ET access platforms were re-positioned and NDE on the LH2 flange is in work. No problems have been detected on the x-rays that have been analyzed to date.”

While the Tanking Test found a problem with the MFV on SSME-3 (see left), with work continuing on installing a replacement valve, another smaller problem was found with an indicator on LO2 17 inch disconnect valve.

“Had a small valve problem during the tanking test on PD #1, which is the LO2 17” disconnect. It has two position indicators for the “Open” state. The “B” indicator did not come on. It was working last week. It was cycled a couple of times, but still did not work,” noted the Orbiter Project Office (OPO) on the Standup report.

“The team will troubleshoot the problem to try to recover the indication. If they cannot, LCC (Launch Commit Criteria) is one of two, so it would still be “GO” for launch.”

This issue, charged as IPR-45 (Interim Problem Report), now has a root cause, found by engineers out at Pad 39A during their investigations into the problem, while preparations are being made for the retests on SSME-3′s MFV (IPR-49).

“IPR 0045 PD1 LO2 17” disconnect open B indicator update: Troubleshooting revealed faulty wiring. R&R of the connector and associated wires in work,” added the NTD. “IPR 0049 SSME MFV R&R update: Replacement MFV installation was completed. The wire harness connector and associated wires were R&R and reconnected to the valve. The retest is scheduled for next Wednesday.

“MFV retest is currently scheduled for this weekend and will include SSME 3 FRT and He Signature test.”

STS-135 Specific Articles: http://www.nasaspaceflight.com/tag/sts-135/

ET Camera Mod:

As previously reported by this site, managers have approved a modification to the External Tank camera which is mounted inside the tank’s liquid oxygen (LOX) feedline fairing. The modification will allow for continuing footage of the tank, after separation from the orbiter, through to re-entry.

The modification involved the rewiring of the camera’s battery pack – specific to the G-Switch timer activation – allowing it to film from lift off, through ascent to MECO, but then allowed to continue operating through until the ET breaks up – depending on how long the camera survives as the tank re-enters.

This modification work has since been carried out at the pad during the continuing NDE inspections of ET-138′s stringers, with retests conducted on Thursday.

“PRCB request to assess feasibility of leaving LO2 feedline camera on and recording the downlink TV signal for as long as possible until ET entry and/or breakup,” outlined a Program Requirements Control Board (PRCB) presentation on the modification’s approval. “Receiving facilities must be able to receive and record analog FM TV signal.

“Two parts to the problem: Coordinate with countries regarding transmitting in airspace. Disable ET FL Camera timer that would otherwise turn the camera off at L+15 mins. Identify and secure receiving stations along ET flight path.”

Due to the lack of TDRS ability as an “overhead option” – given they are not configured to receive analog FM TV – a Special Temporary Agreement (STA) was submitted to National Telecommunications and Information Administration (NTIA) for 30 days beginning July 8 for European airspace transmission, with an agreement reached with DoDand Germans.

Work had also begun to re-activate Diego Garcia (REEF) ground station, while Navy ship-based assets are still being investigated. Aircraft options, such as the P3 Orion, were classed as unavailable.

With the aforementioned work in place, and the camera transmitting through until the tank’s destruction, the opportunity to gain first-of-its-kind imagery of a tank’s death plunge is now on the cards. However, it is questionable as to the quality of the footage.

“It is presumed that after EI (Entry Interface) a plasma sheath will envelope the tank and either prevent or make very difficult any subsequent TV signal transmission and reception,” noted the PRCB presentation. “A basic assumption has been made that any meaningful TV reception apparatus must be positioned upstream of EI.

“We have not yet been able to analytically confirm if a plasma blackout condition will present a TV reception problem prior to breakup.”

Another problem will be the tank’s tumble, given there is no attitude control for the tank during entry.

“Shortly after Orbiter sep, the tank is regularly observed displaying a slow 3-axis random tumble. The unstable attitude is presumed to continue until EI and breakup,” the presentation continued.

“Any TV reception will most likely be unpredictable and intermittent. It is unknown if the tank assumes a more stable aero attitude during entry. A fusion tool analysis has been requested using STS-134 crew handheld HD video to quantify tank tumble rates.”

From an engineering standpoint, the actual modification work on the ET camera was relatively simple, requiring only a single wire to be clipped in the electronics box to disable the timing circuit.

“Description of Change: Crit. 3 ET camera system electronics box modified to allow operational run time beyond currently designed run-time (15 minutes after g-switch activation),” noted STS-135′s ET-138 SSP FRR Presentation (all FRR presentations available on L2).

“Change requested by SSP to provide extended video of tank during re-entry / break-up. Change requires deactivating timer circuit by removing g-switch signal to logic board (g-switch wire clipped, insulated and taped). Camera operation now limited by battery life (~90 minutes).”

The approval for the modification came after the work was successfully demonstrated on a spare box at the Michoud Assembly Facility (MAF) in New Orleans.

“Rationale for Acceptance: Modification demonstrated on spare unit at MAF. G-switch verified operational prior to modification. Electronic box output verified beyond 15 minutes run time (>40 minutes before manually shut down),” added the FRR presentation.

“Electronics box lid to be re-installed per engineering requirements. RTV sealant applied to mating surface. New fasteners / loctite. Camera system open-loop functional test planned to re-verify system operation. Battery re-charged prior to launch.”

The FRR presentation also listed the expected problems with the footage, adding that technicians will attempt to record the video feed, as opposed to feeding it live to NASA TV, etc.

“Performance Expectations. Camera lens / visibility may be obscured due to TPS erosion during highheating re-entry environments. Real-time video coverage limited by ground tracking station availability. Majority of data expected to be recorded and not live feed.”

However, the PRCB presentation did add that the video of the footage will be made available, likely prior to an edit, similar to other videos recorded on orbit, prior to transmission on NASA TV.

In summary, the FRR approved the change – pending no dissent at the Agency FRR next week – with hope a good level of unique footage will be captured via the modified camera system.

“Camera System Modification Provides Robust Option to Provide Video. Coverage of ET During Re-entry,” summarized the ET-138 FRR presentation. “Modification Demonstrated on Spare Unit. Change will be Implemented via Field Engineering Change.”

(Images: Via L2 PRCB and FRR presentations. Further articles on STS-135′s status will be provided as information arrives, driven by L2′s fast expanding STS-135 Special Section which is already into the FRR content and live flow coverage, plus more. As with all recent missions, L2 is providing full exclusive level flow and mission coverage, available no where else on the internet. To join L2, click here: http://www.nasaspaceflight.com/l2/)

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STS-135 Latest:

Preparations in the flow towards the Tanking Test were all on track, ahead of what was set to be a 7am loading, including the final work on a small issues with observed moisture on an orbiter system, requiring the removal and replacement of a Window Cavity Conditioning System (WCCS) dessicant.

“The aft closeout and confidence checks for cryo load were successfully completed. Orbiter Crew Hatch gap measurements were completed, GUCP (Ground Umbilical Carrier Plate) QD (Quick Disconnect) leak checks were performed. Results were within spec,” noted the NASA Test Director (NTD) report (L2). “The WCCS carrier panel closeout was completed.”

PRSD (Power Reactant Storage and Distributation) GO2/GH2 Reactant gas load operations were also completed, followed by OMBUU (Orbiter Mid Body Umbilical Unit) demates.

However, operations took a seven hour hit at the T-14 hour point of the schedule towards the Tanking Test, as a lightning storm passed over the pad just a few hours prior to the scheduled retraction of the Rotating Service Structure (RSS).

The events were not as severe as the end of March lightning storm which passed over Endeavour ahead of STS-134′s launch.

As a result, the schedule for the test slipped to the right, with the start of the Tanking Test moving to NET (No Earlier Than) 11am local time – after the RSS was successfully retracted just after midnight.

“S0037 Tanking Test operations continued working a modified timeline driven by significant weather delays; Chief Engineer tagup – 0800. ET Tanking Weather Brief – 1030EDT. Cryo load is now scheduled to begin NET than Wednesday at 1100 EDT and run through early evening,” added the NTD.

“RSS rotation to park was delayed due to the significant weather that came through the area last evening. The Orbiter Weather Protection (OWP) and RSS have been retracted at this point to support tanking.”

However, just an hour prior to the scheduled start time for tanking, managers decided to delay again to 1pm local, before changing the schedule again to a 12:25 start.

With a GO for tanking from management, engineers pressed on with the start of tanking operations, which began with the use of the pumps to chilldown the transfer lines between the storage tanks and Atlantis’ Main Propulsion System (MPS), which is the path taken by the LOX and LH2. LOX Chilldown began at 12:25.

STS-135 Specific Articles: http://www.nasaspaceflight.com/tag/sts-135/

This was followed by the main stage of tanking, known as fast fill – ahead of around another two hours of loading to the point the tank reaches topping and stable replenish. Fast Fill on LH2 began at 13:06 local, followed by LOX fast fill at 13:31.

As with all recent tankings, several areas of interest will closely monitored, such as the low level and Engine Cut Off (ECO) sensors, which have performed as advertised since a successful resolution to what was a problem in part of the LH2 Feedthrough connector system, and leak detection monitoring around the GUCP.

However, the main focus will be via the numerous pad cameras, which will focus on the LO2 flange to check for any signs of cracks in the Thermal Protection System (TPS) foam, including infra-red footage which spotted the crack in ET-137′s flange during a GUCP related scrub on STS-133′s opening launch attempt countdown last year.

Once the tanking has been completed, the tank will undergo a pressurization cycle, further testing the strength of the stringer, prior to the call to drainback the tank. Once inert, Non Destructive Evaluations (NDE) will take place when the pad is reopened.

These visual and X-Ray/Backscatter scans of the tank will check the stringers for any hairline cracks on the support beams.

Late on Tuesday and early on Wednesday, the ERB met to discuss several lightning events at the pad during the storm, utilizing data from the array of instrumentation located on and near the pad itself. Thankfully, none of the stack’s systems appeared to suffer from any ill effects.

“Issues: An ERB was held last evening to discuss several close proximity lightning strikes that occurred at approximately 1930 yesterday. The data was gone over and discussed. No issues were identified but another meeting was scheduled for the morning – expected to clear the constraint for tanking test,” confirmed the NTD.

By the time of Wednesday morning’s NTD update, four new Interim Problem Reports (IPRs) were charged against the STS-135 flow, all of which were either successfully troubleshooted during the early hours, or will be worked after the Tanking Test.

“IPR 0045: LO2 17 inch disconnect Open Indicator B failed to pickup when cycled. A second cycle gave the same failure and the data path testing showed good health. The latch was properly configured to support tanking test but will need additional troubleshooting after S0037,” the NTD continued, noting the main three IPRs.

“IPR 0046: During system configuring, 9 fuel cell pump AC phase circuit breakers were found to be out of closed. The breakers were re-configured and none of the pumps were powered or commanded on. No damage to hardware and the constraint was cleared.

“IPR 0048 at approximately 0245EDT Wednesday, Power Feeder 606 to the pad had a failure at the C5 substation. This resulted in numerous losses and redundancy losses to Pad A.  Engineering is currently troubleshooting the failure and working to get the power leg restored but it is currently a constraint to Air to GN2 transition. This is currently a constraint to tanking this morning (since cleared).

UPDATE:

While the tank is currently showing no ill effects from the Tanking Test, engineering notes showed SSME-3′s MFV suffered from a small leak during tanking, becoming the latest Interim Problem Report (IPR).

“IPR-48: Exceeded Launch Commit Criteria (LCC) SSME MFV limit downstream temp of -130 degF. Indicative of ME3 (Main Engine 3) MPV leakage. MPS/SME isolated/slow leakage by closing the E3 prevalve,” the notes (L2) added.

While the closure of the prevalve allowed for the Tanking Test to continue, this condition on launch day would have resulted in a scrub, as was seen in a similar incident during a STS-73 launch attempt.

Already engineers are calling for the valve to be replaced, which should be complete by either the weekend or early next week. However, the launch date – currently July 8, will be assessed based on schedules related to the re-testing of the valve.

“Downstream issue out of this is that we will have to R&R the E3 MFV prior to STS-135 launch. (Pratt & Whitney) Rocketdyne assessing impact to scheduled launch date, may still be able to meet 7/8 date.”

Notably, Mission Management Team (MMT) chair Mike Moses specifically mentioned in the 134 post-landing presser that they had only “two days contingency” on paper, but that was only minimal work planned for the week following the Tanking Test – and that there’s more wiggle room in reality than on paper.

More will follow.

Meanwhile, following the completion of Aft skirt foaming operations on the Solid Rocket Boosters (SRBs), the curtain closeouts will pick up after the tanking test is complete.

Other notable events in the flow include the completion of Payload Ground Handling Mechanism (PGHM) final hydraulic leak checks, in preparation for payload installation later this week.

Payload delivery is currently planned to take place for late Thursday evening, around 2200EDT. Payload transfer to the PGHM is planned for Friday – however, any SSME related work may impact.

(Images: Via Larry Sullivan/MaxQ Entertainment and NASASpaceflight.com, L2 and nasa.gov. Further articles on STS-135′s status will be provided as information arrives, driven by L2′s new and fast expanding STS-135 Special Section.)

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STS-135 Latest:

Several processing tasks have been completed out at Pad 39A, along with one required element of troubleshooting – related to the removal and replacement of a Window Cavity Conditioning System (WCCS) dessicant, which was completed over the weekend.

“On OV-104 (Atlantis), on the pilot-side window cavity conditioning system, the desiccant beads showed that moisture had gotten into that system,” noted the Orbiter Project Office (OPO) on the Shuttle Standup/Integration report (L2). “The team will change out the beads and make sure the system is dry and leak-tight.”

This issue, as with all the other minor Interim Problem Reports (IPRs) charged against Atlantis during her pad flow, holds no impact to the current launch date target at this time.

“OV-104 (STS-135) Processing continues to go well going towards the launch on July 8, 2011. In work with the left-hand forward WCCS desiccant change out,” added Ground Operations via the Standup report going into the weekend.

“Removing the ET blank off plates. Will pick up with preps for tanking test and aft closeouts. Call to stations for the tanking test is next Monday at 20:30, with the actual tanking starting at 07:00 Wednesday morning. Payload to the Pad will follow tanking next Thursday.”

The Tanking Test is not expecting to reveal any problems with the stringers – specifically at the top end of the intertank around the LO2 flange – after full NDE (Non Destructive Evaluation) testing – inside the Vehicle Assembly Building (VAB) and the implementation of the radius blocks which strengthen the stringers.

The modification has shown its value, working without issue on STS-134′s ET-122, but also on ET-137 (STS-133), mitigating any further cracks in the stringers after the radius blocks were installed around the circumference of the LO2 flange following rollback to the VAB over the Christmas holidays.

With ET-138 heavily related to ET-137 – by way of production dates at the Michoud Assembly Facility (MAF) in New Orleans – it is possible ET-138 has some of the weaker stringers, found to be made from a “mottled” material stock.

However, with the radius blocks already installed, all the stringers are now likely to be strong enough to avoid cracking during the cryocycle of tanking and the pressurization of the tanks, even if some of the support beams suffer from the mottling effect.

The Tanking Test is a validation test, and a failsafe from a surprise during the actual launch day countdown, with Wednesday’s test a dress rehearsal for ET-138. As such, the tank’s portion of pad flow will almost mirror the tasks it will be put through during STS-135′s S0007 launch countdown next month.

“OV-104/SRB BI-146/RSRM 114/ET-138/MLP-3 (Pad A): S0037 tanking test preps began Thursday. The tanking test operations are scheduled to begin on 1st shift Monday with tanking on Wednesday,” added the NASA Test Director (NTD) report (L2).

“S1287, Orbiter aft closeouts (in work, continued through weekend) and the pre closeout snapshot was completed. The final confidence checks are scheduled for Monday 1st shift. ET purges and LO2 and LH2 system dewpoints completed. The GH2 and GO2 blank off plate removals were completed. The PV-13 (fill and drain) leak check was successfully completed.”

With the S0037 Tanking Test ops beginning with Call To Stations (CTS) at 20:30 local time on Monday, the opening tasks will include Power Reactant Storage and Distributation (PRSD) loading and Orbiter Mid Body Umbilical Unit (OMMUU) securing.

STS-135 Specific Articles: http://www.nasaspaceflight.com/tag/sts-135/

As would be the case for tanking during the actual launch countdown, the Rotating Service Structure (RSS) will be retracted at around 21:30 local time on Tuesday. Tanking will begin – pending acceptable weather – at 7am local on Wednesday, with the go to drain the tank expected at 12:30.

Once the tank has been drained and allowed to boil off to an inert state, technicians will perform NDE scans of the tank’s stringers to confirm no cracks have formed during the tanking test or subsequent drainback. This operation will be complete by 22:00 on Saturday, allowing for initial results to be presented to managers on Monday.

ET-138 Camera Modification Latest:

As previously reported, plans have been put together to modify the External Tank camera which will ride with Atlantis’ ET-138, allowing it to beam back video of the tank’s disintegration after parting ways with the orbiter at MECO (Main Engine Cut Off).

The modification, which is on the schedule to be carried out after the NDE scans of the LO2 flange following the tanking test, relates to the camera’s timer, which normally shuts down the camera not long after the tank and orbiter part ways.

The resulting video has the potential to capture the tank as it vents and re-enters on the other side of the planet, depending on how long the camera survives during the subsequent break up as it hits the atmosphere.

With the departmental Flight Readiness Reviews (FRRs) taking place ahead of the SSP level FRR later this month, more information is starting to filter through on the go-forward plan to allow the camera to continue providing imagery, with confirmation that the plan will involve the placing of assets downrange to provide additional communications ability after the usual Loss Of Signal (LOS) with ground stations at around T+15 minutes.

“On the ET feedline video camera, there has been discussion of leaving it on after ET separation and trying to get some assets in place down range to get the video during reentry,” noted one departments FRR notes (L2).

“The team is also looking at using aircraft to not only receive the video but also get some radar data as well as infra-red data for the breakup.”

The plan, which was taken to the Chief Engineer’s (CE’s) Review Board, may utilize a P3 Orion aircraft, and/or a Halo II aircraft – a modified Gulfstream IIB – which provided a stunning “de-convolved Visible Track” Video of STS-121′s re-entry (L2), as Discovery raced back to Earth between the Mach 10-8 period.

Any footage of the tank re-entering is extremely rare, with all recent footage mainly coming from the orbiter’s crew taking handheld video and photography, for the purpose of checking the condition of the tank’s Thermal Protection System (TPS) foam, allowing any potential liberations on the tank to be matched with potential impacts on the orbiter via the Damage Assessment Team (DAT) evaluations.

As with most mission related events, final approval is likely to be required at the SSP and Agency level FRRs.

(Images: Via L2 and nasa.gov. Further articles on STS-135′s status will be provided as information arrives, driven by L2′s new and fast expanding STS-135 Special Section.)

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STS-135 Processing Latest:

Although Atlantis has kicked up a couple of protests via a number of Interim Problem Reports (IPRs), none are classed as any concern for the launch date, or indeed the schedule of the Tanking Test – set to take place in the middle of this month.

Indeed, the pad flow has transitioned from S0009 Launch Pad Validation to S0024 Pre-launch propellant servicing tasks with all minor issues resolved, either at the pad, or via managerial decisions.

Items of interest center around IPR-39 to 44 – mainly relating to the loading of hypergolic fuel into the Solid Rocket Boosters (SRBs) Hydraulic Power Units (HPUs), which will be used to drive the Thrust Vector Control (TVC) system, allowing the nozzles on the boosters to aid the steering of the stack during first stage ascent.

“New IPR 135V-0042 was picked up by HPU during left SRB TVC rock system fill. The handle and stem of a GN2 regulator valve on the left SRB servicing cart came loose. Repair was completed and IPR will be upgraded to GSE (Ground Support Equipment) PR (Problem Report),” noted the NASA Test Director (NTD) processing reports (L2).

“New IPR 135V-0043 was picked up by HPU during left SRB TVC tilt system fill. After isolating the GSE from the vehicle, a vent valve was found out of configuration. The valve was repositioned, leak checks were successful, and tilt system fill resumed.”

Completed tasks in the flow include the Payload Bay Door torque tube installation, SSME (Space Shuttle Main Engines) and Aerosurface FRTs (Flight Readiness Tests). GO2/GH2 blank off plate installation in support of the Helium Signature Test (set for Saturday), S1287 Orbiter AFT closeouts and S0037 tanking test preparations.

Next week will involve the hypergolic loading of Atlantis’ Reaction Control System (RCS). Propellant loading of the orbiter’s Auxiliary Power Units (APUs), which will provide hydraulic power to numerous systems, such as the Flight Control Surfaces (FCS) and SSME gimbals, is already in work as of Wednesday.

“S0024 Pre-Launch Propellant Servicing preps continue. FRCS (Forward Reaction Control System) QD (Quick Disconnect) mates/leak checks in work. APS and APU QD mates/leak checks are scheduled over the weekend. Hyper Load is scheduled to begin early Monday morning with CTS (Call To Stations) at 0400 EDT,” added the NTD.

STS-135 Specific Articles: http://www.nasaspaceflight.com/tag/sts-135/

Good news has been reported on the lightning event, which was registered at the pad complex shortly after Atlantis arrived at Pad 39A, following rollout from the Vehicle Assembly Building (VAB). (Image from Pad 39B event, not 39A)

“The lightning strike detected within 0.32 nm of Pad A by CGLSS (Cloud to Ground Lightning Surveillance System) and within 0.87 nm by Strike Net will not be an issue for the vehicle. Engineering will perform only the GSE walkdowns. No ERB (Engineering Review Board) or further action will be required.”

Unrelated to the water intrusion observed – and cleaned up – on Atlantis after the storm, another potential “moisture issue” remains under investigation at an ERB level. The observation was made during the Window Contamination Control (WCCS) desiccant borescope inspection task, with indications are that moisture had intruded from an unknown source.

The WCCS is simple venting system which utilizes a pair of desiccant assemblies as part of its operation, plumbed into the windows through stainless steel tubing.

During each Orbiter Processing Facility (OPF) flow, the assemblies are purged with nitrogen, while the beads in the desiccant cartridges are checked. Every two to three flows, the desiccant cartridges are serviced with new desiccant material.

It is surprising that moisture could have made its way into the system, given the highly controlled environment inside the OPFs during servicing, so while the ERB review the status of the system, a plan has already been approved to replace the left hand outboard WCCS desiccant, with a desire to have the work completed ahead of the Tanking Test.

“The Window Contamination Control (WCCS) desiccant borescope inspections were completed and an ERB was held to discuss the findings,” noted the NTD. “The left hand outboard WCCS desiccant will have to be removed and replaced. Following S0024, the manifold and desiccant will be removed, purged and replaced. It is desirable to have repairs complete prior to next week’s Tanking Test.”

ET Camera Modification:

The External Tanks fly with a Sony XC-999 video camera, mounted inside the tank’s liquid oxygen (LOX) feedline fairing – a metal covering that protects the area where the fuel feedline penetrates the inter-tank – with the camera pointing down the tank.

The camera debuted for a one-off ride during STS-112′s launch, although this was implemented mainly for the purpose of PAO coverage, and was located higher on the tank – near the top of the intertank – prior to its full time integration with the tanks from STS-114 onwards, as part of the Return To Flight (RTF) requirements.

The 3.5 mm lens camera provides a field of view of about 100 degrees, offering a look at the vicinity of the tank’s bipod attachment area, a portion of the External Tank where the liquid hydrogen tank and intertank flange area are adjoined, and a portion of the bottom side of the Orbiter.

The camera has proved its worth over the years, capturing both amazing ascent footage – which is now a regular feature of the live NASA TV launch coverage – whilst carrying out its primary task of observing Thermal Protection System (TPS) foam liberations from the tank, capturing vital information on both the timing of any events, along with any resulting impacts on the orbiter.

The implementation of the camera was part of the build up of the Enhanced Launch Vehicle Imaging System (ELVIS), which includes cameras on the SRBs, the ET Umbilical Well of the orbiter, and most recently the ascent cameras placed on the orbiter’s “dashboard” which capture LO2 Ice Frost Ramp (IFR) foam liberations.

“The ET LO2 feedline fairing camera is powered and controlled automatically from the electronics package mounted on a support beam located between the LO2 and LH2 tanks,” noted the specific section on the system in the 1500 page INCO systems handbook (L2).

“The camera’s field of view includes the bipod assembly region, Orbiter left and right wing (except as obstructed by the bipod strut), Orbiter -Z TPS beginning 12 inches forward of the bipod fitting and continuing aft. The camera captures images at the National Television System Committee (NTSC) frame rate of 30 frames per second (fps) and can see debris/divots that are 2.0 x 2.0 inches or larger at a distance of under 20 feet.”

The camera’s battery pack includes 20 nickel-metal hydride batteries, which provides approximately 28 volts DC. Though the batteries will last for about 70 minutes – mainly to allow three launch attempts prior to the need to recharge/replace the batteries – the picture is usually lost not long after ET/Orbiter separation.

The camera has two ‘blade’ S-Band antennas – with a frequency range between 1.55 to 3.9 gigahertz, most often used for telemetry downlink.

Each is about 2.5 inches long, and will transmit a 10 watt signal to the ground stations. The antennas are located on the opposite side of the tank from the Orbiter about 45 degrees from the tank center line.

The complete camera system, weighing 32 pounds, activates approximately three minutes prior to launch and operates for about 15 minutes following liftoff.

The video is downlinked from the tank during flight to several different NASA data receiving sites, and then relayed for broadcast on NASA TV.

The last of these receiving ground stations is the Wallops Flight Facility, located on the ascent path, on the Virginia Eastern Shore.

Riding with the final ET on the final Shuttle mission, the camera is hoped to provide a star role during both Atlantis’ ascent and ET-138′s demise, after engineers noted a modification on the flow schedule (L2 information).

The modification will involve the rewiring of the camera’s battery pack – believed to be specific to the G-Switch timer activation – allowing it to film from lift off, through ascent to MECO, but then allowed to continue operating through until the ET breaks up – depending on how long the camera survives as the tank re-enters.

“The camera system provides the capability to RF downlink the ET camera video signal to ground stations from RF activation until G-switch timer activation at MET 15 minutes, which effectively turns off the transmitter (a G-switch is a mechanical device that senses acceleration in order to close its contacts),” the INCO handbook explains.

“However, the most critical portion of image gathering is prior to SRB separation, for debris transport analysis purposes, while imagery after SRB separation is only highly desirable (thus the reason for the switch’s shutdown task).”

Now, per schedule, a small team from the Michoud Assembly Facility (MAF) will carry out the modification during NDE (Non Destructive Evaluation) testing after the tanking test. The mod is in the flow for June 25.

However, no notes – at this time – have confirmed how the footage will be beamed back, given the ground station set up loses the ability for the camera to transmit to Wallops after MECO due to LOS (Loss Of Signal). It is likely a P3 Orion aircraft – or a ship in the required vicinity – will be utilized.

The video signal – which is frequency modulated on a 2272.5 MHz carrier and downlinked to ground stations – would need to be picked up as far as in an area near the Cook Islands, which is the disposal area for the tank after it re-enters.

As is usual, most of the tank is destroyed during entry, with only the chance of a few smaller pieces – such as attach points and aft orbiter connections – managing to make it down to the ocean surface.

Previously, only footage a few minutes after MECO has been seen – via handheld video taken by the orbiter’s crew on the flight deck. A video was also taken during STS-29, when ET-36′s re-entry over Indian Ocean was viewed by a US Navy Aircraft.

The prospect of footage from the tank itself – as it vents and starts to disintegrate – on the final ever shuttle mission, may not be up to the high standards of the Soyuz “Flyabout” footage of Endeavour and the ISS, but it would provide a potentially stunning viewpoint of the final Shuttle ET, prior to its demise.

(Images: Via L2 and nasa.gov. Further articles on STS-135′s status will be provided as information arrives, driven by L2′s new and fast expanding STS-135 Special Section.)

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The HLV Centrepiece:

The process to finalize the new path for NASA – following the cancellation of the Constellation Program (CxP) – remains under evaluation. The lack of a clear direction continues to burden the Agency, something which will continue to be the case even after the centerpiece rocket is revealed.

Although the ultimate goal for the Agency’s exploration plan is manned missions to Mars, no definitive roadmap has risen from the ashes of the Ares-based architecture, resulting in a path where a Heavy Lift vehicle is being designed before the missions it is set to cater for have been set in stone – something which often is pointed out as the wrong way around.

However, with the knowledge that very large payloads will need to be lofted uphill for the future goals, NASA teams are steadfast in their opinion that an HLV is required, a sentiment SpaceX – often championed as the exciting alternative and cheaper path for the United States to once again carry out manned BEO missions – agree with, as much as they embedded the caveat their agreement is specific to trips to Mars.

“Falcon Heavy should not be confused with the super heavy lift rocket program being debated by the U.S. Congress,” SpaceX officially cited when revealing their Falcon Heavy launch vehicle. “That vehicle is authorized to carry between 70-130 metric tons to orbit. SpaceX agrees with the need to develop a vehicle of that class as the best way to conduct a large number of human missions to Mars.”

Top level NASA meetings late last week (notes on L2′s SLS section) once again emphasized their agreement with the HLV requirement in the Authorization Act – which was based on NASA input during its drafting – noting that all findings concur there are no real savings in multiple smaller launches, which they claim also increase risk.

Such claims are often questioned, when citing alternatives such as EELVs and other commercial medium lift vehicles.

The main question for SLS at present relates to the configuration of the HLV, with the bulk of the RAC (Requirements Analysis Cycle) studies now concluded at the Marshall Space Flight Center (MSFC).

SLS Approach (all notes via L2′s SLS Section):

As previously reported by this site – and later by other media – a plan was created to fly a Block 0 SD (Shuttle Derived) HLV for four flights, starting in 2016, prior to an open competition to study the options for the evolved SLS which will carry out the BEO missions.

This approach was sent to NASA HQ late in May, only for it to be rejected by NASA administrator Charlie Bolden, who returned the plan to Marshall, tasking the teams to draw up baseline 70 MT vehicle which must fly by 2016 and must be able to evolve to 130 MT.

The order also noted the vehicle must be powered by LH2 (Liquid Hydrogen), powered by RS-25s (SSMEs) or RS-68s, while the Upper Stage must work under the assumption of using the J-2X hardware. However, the teams were allowed to trade on the boosters, between Solids and Liquids. Marshall were asked to send back their findings by June 1.

The result of what was sent back to NASA HQ was revealing, with high level meetings late this week noting the approach is now working with the clear requirement for a “staged evolution of a single large vehicle” – evolved to 130 MT. In other words, the initial 70 MT SLS will be the baseline/template for the 130 MT version.

This vehicle, which continues to be tagged as the Design Reference Vehicle (DRV) for the purpose of the final report to lawmakers, will enable use of core elements, “initially” – the notes claim – utilizing Solid Rocket Boosters to allow the SLS to provide back-up in the 2016-early 2017 time-frame for the ISS support assurance – as requested in the Authorization Act.

As such, the SD HLV RAC-1 option is still leading as the Design Reference Vehicle and is now undergoing a refinement on two areas, the core structure and the core engines, resulting in what would be more fairly described as a hybrid SD HLV, one which will grow within its own skin to evolve into a 130MT vehicle.

The meetings also noted the often-favored Kerolox (RP-1) option is not classed as a viable option, although it was claimed the RAC-2 option proved to be a worthy opponent of the SD HLV, by causing the re-examination of many of the key issues which challenged the leading DRV option.

The biggest challenge noted is the structuring of the procurement approach, along with the program management/oversight path, cited as where they expect to achieve the maximum savings, cost and sustainability, to a point NASA expect SLS to be “viable” under the rules of the Authorization Act – a key change to the preliminary report presented by NASA to lawmakers.

A definitive design and basic systems decision is expected before the end of June, even though these findings may lack the procurement and management strategy at that point. There is understood to be a hard deadline of July 8 – when Atlantis is scheduled to launch on the final Shuttle mission, STS-135.

SLS Hardware – SRBs:

With the allowances to examine Solid versus Liquid boosters on the SLS, the latest meetings would only commit to Solids being used “initially”, as much as sources expect they will win out as the long term solution for the evolved SLS.

A “non official” proposal of using liquid boosters on the HLV was created by a NSF forum member Nate Downes, which cites the liquid option as advantageous due to the simplicity of handling, superior impulse and the logistical advantages of pad fueling simplicity, which enables a wider range of missions for the same cost.

ATK appear to be fully aware their long-term role in SLS is not set in stone and have been busy providing costings and options to both the Marshall teams and “people in power” in Washington, DC.

While information on the latter is unlikely to see the light of day, L2′s SLS section acquired information on one example of a proposal to “boost” the capability of the SRBs over time, evolving the noisy duo which would aid the vehicle’s first stage flight, in tandem with the SLS’ evolution.

This example, provided to the RAC Team 1 at Marshall, proposes the change to a HTPB (Hydroxyl-terminated polybutadiene) fueled solid in “composite over wrapped steel cases” to allow higher MEOP (Maximum Expected Operating Pressure) – to as much as 1500 psi.

There are also proposals to use lighter weight nozzles with expansion ratios up to 12:1, although such a large scale change would require study at least at a Ground Support Equipment (GSE) level, given its relation to Launch Platform design.

Such challenges can be seen in a similar – yet not entirely related – change which was proposed for boosting Ares I’s capability three years ago.

“Extended Nozzle – Ares First Stage: Increase Ares I nozzle expansion ratio from 7.2 to 9.3,” noted a Constellation presentation acquired by L2 in 2008. “Justification: Provide 1200-1300 lb increase in overall vehicle payload capability.

According to that presentation, a larger 10.25 expansion ratio was preferred as “optimum” – though impacts to shipping, manufacturing, the TVC (Thrust Vector Control) hardware and the Mobile Launcher had to be considered in the approved ratio change.

“9.3 expansion ratio provides optimum performance with TVC attach constraints and manufacturing limitations,” cited the document.

ATK are continuing to make preparations for the DM-3 test of their five segment booster at their test facility in Utah.

SLS Hardware – Core Engines:

As has been proposed for some time now, the opening flights of the SLS are highly likely to utilize the existing four sets of Space Shuttle Main Engines (SSMEs) from the Shuttle Program – consisting of three sets from the last three flights of the shuttle and one spare set, all located at the Kennedy Space Center (KSC).

Click here for NASASpaceflight.com HLV/SLS- related news articles: http://www.nasaspaceflight.com/tag/hlv/

These RS-25Ds were also the centerpoint of the Block 0 SLS under the now-cancelled two-phased approach, which was to fly four times in support of the International Space Station and for opening Orion (MPCV) flights.

The current plan would result in a transition to RS-25Es, a cheaper and expendable version of the SSME, for the next evolution of the SLS.

As noted in a Program Requirements Control Board (PRCB) presentation last year, Pratt & Whitney Rocketdyne (PWR) were placed under an order to “delay the disposal and retain the capability” to manufacture new SSME-based engines.

“SSME New Production Strategic Capabilities (SCA) supports the manufacture of all current configuration major Block II engine components. New production line items consist of manufacturing tooling / equipment, raw materials, hardware details and sub-assemblies,” noted the PRCB presentation.

“Previously approved for retirement at NASA boards (2007/2008) – (overturned). Supports future launch vehicle architecture pending Agency decision.”

Although this is the leading option, the top-level meetings late last week confirmed some trades are continuing on the core structure and core engines, in order to ensure the best configuration for the “staged evolution of a single heavy launcher”.

SLS Hardware – Core Structure/Tank:

The core of the SLS first stage is where a large amount of refinement is taking place.

Firstly, the remaining ET specific workforce at the Michoud Assembly Facility (MAF), who – from managers and engineers – have spent most of their “remaining days” clearing out work stands and equipment from the 420 building to make room for the filming of a Hollywood movie, were expecting to get their 60 day WARN notices on May 26.

Lockheed Martin management informed these workers this was no longer the case, and will instead continue under a temporary funding request, due to what they cite as changes for the end date/funding for the ET program through to the start of a SLS program, which they project will be known this month.

Over at the Boeing side of MAF, managers have hired back previously released ET welders – badging them to Boeing from Lockheed – for the fabrication of what is known as the Pathfinder Tank – a scaled “strong back” tank.

Tooling is already in place to start this work and hardware is being moved into position.

Officially this is not an HLV/SLS project because this is being run as an “unsolicited” Boeing project, with a view for it to become part of the SLS program. However, the work is known to relate to the structural strength of the ET core on the first stage when stretched to a taller SLS configuration, along with modifications to the LH2 tank to support the SLS engine package.

This work on the Pathfinder Tank is being staged in the RWT (Robotic Weld Tool) area. The tooling/form/jig to hold the components together for the weld is being set up, as training for the operators is conducted ahead of the actual prototype being fabricated.

The key information about the Pathfinder relates to the domes being worked, which are classed as spun aluminum – single piece dome – versus the paneled dome used to produce the Shuttle ET.

Eventually, the fabrication will lead to a small scale LH2 tank, using the single piece (spun) dome, which will be used to show it is able to cope with SLS’ load requirements.

The Lockheed MAF planning group have also been told to start writing procedures to bring the MAF VAB (Vehicle Assembly Building) back on line in the event of starting production again – showing a major move to a running start at the time of a SLS decision point.

Currently, the LWT ET-94 remains vertical in the MAF VAB. ET-139 is in situ after the Stringer investigation work, while parts for ET-140 and ET-141 remain in storage.

MAF source information notes they have enough material for two new tanks already on site, but they will have to start up the smelter if they want to make more components.

SLS – KSC:

With the painful job losses continuing to be suffered at the Florida Spaceport, Director Bob Cabana addressed his workforce last week, announcing a Center Director forum in the summer, as he aims to transition the center into the focal point for hosting government and commercial launch service providers.

Mr. Cabana also noted that NASA’s future architecture is emerging, and that he expects a decision “this summer” on the configuration of the SLS, citing KSC has a lot of important work over the coming months and years.

Ironically, KSC has already made a decision relating to hosting a HLV at the spaceport, after the entire Crawler Transporter group – which was already under layoff notice – was told they are keeping their jobs via KSC allocating funding for them to work man hour/material/project estimates for upgrading the famous Crawlers for SLS.

The group was told that NASA Ames had finished design on new Jacking, Equalization and Leveling System Cylinders (16/CT) and bearings, as well as work on new Rollers (88/CT, over 2000lbs/roller, heavy duty, mombo rollers and bearings/bushings) for the belts/shoes.

New GenSets for more AC Power to support the increased demands are in the pipeline too. These upgrade modifications will begin in about four to six month’s time.

Initial testing was completed last year on one area of crawlerway just outside of Pad 39B, via a strange looking contraption which aimed to test the impact of over 25 million pounds on the rock surface of the track.

The findings of the testing, which was conducted by NASA, the United Space Alliance (USA), Architect and Engineering firm Jones Edmunds and Associates (JEA) and a couple of additional contractors, was classed as positive.

No references have been made into the use of the Ares I Mobile Launcher (ML), which remains sat next to the VAB, with a launch mount which is highly specific to the Ares I vehicle.

All This Has Happened Before – Will It Happen Again?:

The saga revolving around NASA’s next Heavy Lift Launch Vehicle has been ongoing for years. Winning trade studies and being a leading option does not provide any certainty such a vehicle will ever see “hammers on aluminum”, as seen just prior to the FY2011 Budget Proposal announcement.

In the weeks leading up to the FY2011 announcement, General Bolden himself tasked a special team to conduct a study into the HLV options, which resulted in the Sidemount HLV and RP-1 (Kerolox) vehicles losing out to the in-line SD HLV.

“HLV study summary from (Mr. Jeff) Hanley – Sidemount doesn’t buy anything and takes hit on safety. A couple of (winning) versions of In-line going to (Mr.) Bolden,” noted one memo surrounding the study at the time. MAF also noted they were all set to implement the plan.

However, the end result was a complete omission from the FY2011 announcement, which focused on a five year study into “game-changing” propulsion, effectively mothballing the HLV bar a small team, before the lawmakers reversed the decision via their Authorization Act.

The coming weeks will prove to be critical for this latest approach to providing NASA with the blueprints for a new HLV.

(The progress on the SLS status will continue to be followed up over the coming weeks. L2 members, follow our exclusive SLS update coverage via the SLS and HLV tags. Images used:  Via L2 content and NASA.gov).

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STS-134 LAUNCH DAY Latest:

With all of the recent Interim Problem Reports (IPRs) from the first two days of the S0007 Launch Countdown operations resolved, Endeavour pushed towards her key event of RSS retraction, which was scheduled for around 7:30pm local time on Thursday evening.

However, a spectacular light show from severe storm weather – containing rain, winds, lightning and hail – the latter of which appears to have stayed away from the Pad 39A region, delayed the operation, thankfully resulting in no notable damage to the stack – per initial reports.

Eventually, the RSS retraction was completed by 12:32am local time, revealing Endeavour for what may be her final starring role on a launch pad.

The first major task for Endeavour’s launch day was the meeting of the MMT, which reviewed the overnight storm events, plus the upcoming weather for morning, prior to making a decision on whether to proceed with tanking the Shuttle’s ET-122.

A go was given by the MMT, allowing engineers to start the pumps to chilldown the transfer lines between the storage tanks and Endeavour’s Main Propulsion System (MPS), which is the path taken by the LOX and LH2. Slow fill and fast fill soon followed, prior to a smooth completion of tanking operations.

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

As with all recent tanking, several areas of interest were closely monitored, such as the low level and Engine Cut Off (ECO) sensors, which have performed as advertised since a successful resolution to what was a problem in part of the LH2 Feedthrough connector system.

As the three hour tanking process continued, sensors were sniffing around the top of the tank for any indicators of a leak from the Ground Umbilical Carrier Plate (GUCP), which has been problematic during a number of countdowns, such as STS-119, STS-127 and the previous mission, STS-133.

With tanking complete, cameras around the pad – including infra-red systems – will keep a close eye on the flange area between the Intertank and LO2 tank, ensuring no observations of cracks are found in the Thermal Protection System (TPS) foam, which would be an indication of a cracked stringer.

This is also unlikely to occur, following the STS-133 event, with mitigation in place via the installation of radius blocks around the circumference of the flange, which worked well on Discovery’s ET-137.

Atlantis’ ET-138 tank also sports the stringer modifications, given its close relation to Discovery’s tank, although ET-122′s modifications are only installed as a contingency, given this tank is much older than most of the recent tanks to launch.

ET-122 wasn’t fabricated during the period where suspect “mottled” materials were used on the production of the stringers.

Numerous key events will follow after tanking, including the checks on the tank by the Final Inspection Team (FIT), who will check for ice build up on the tank, prior to the crew making their way to the pad to ingress Endeavour.

UPDATES DURING COUNTDOWN:

With the actual tanking process starting on time and suffering from no issues as fast fill continued, the NASA Test Director (NTD) noted one of the latest Interim Problem Reports (IPRs) to be charged against Endeavour on Friday morning. The issue related to the orbiter’s power-generating Fuel Cells.

“IPR 0052: During Fuel Cell Pulse Purging, data indicates pin sharing on both sides of Fuel Cell 3 Sub-Stack 2 pins. The observed data did not precisely fit the standard MR (Material Review) disposition,” noted the NTD report (L2). 

“Performance will be monitored during and after Fuel Cell start to see that data falls into expected values and if that occurs,  the standard MR rationale will apply. Constraint: 16-1154 resume count at T-9.”

Another issue (IPR-53) was then listed during early tanking – as much as it wasn’t related to the loading of prop into the tank. This issue is being classed as “Right OMS fuel tank LCC (Launch Commit Criteria) OMS05 violation pressure limit.”

Meetings are taking place on a course of action, with notes this condition has not been seen before at this stage of the countdown. There is potential a LCC waiver can be added to remove the constraint.

However, a forward plan was approved to interconnect the crossfeed lines between the two OMS tanks to try and equalize the pressure, which brought the pressure back within LCC limits.

“IPR 0053 Update – Propellant transfer successful. All parameters within spec for OMS-05,” confirmed L2 acquired information.

The other main problem related to an Auxiliary Power Unit (APU) heater unit (IPR-54 – changed from the initial IPR-55), which was seen to be  trending low and required further investigation. This issue has caused the SCRUB after it was deemed to be a hard failure.

“Auxilary Power Unit 1 Fuel Test Line Temp V46T0183A1 is 44 deg f s/b 45 deg F or above. Violates LCC APU-14,” was the official internal note posted for the issue (acquired by L2 at 10am Eastern). 

“System: APU 1 Fuel Service Line Temp V46T0184A1 is also trending down. A preplanned procedure exists to verify heater function. Requires cockpit access.”

With acccess acquired by techs at the pad, it was thought the flicking of a number of related switches would allow for the problem to be cleared.

“Auxilary Power Unit switched to the A heater string via ground command and the temperature is now trending up,” added L2 information. ”Still need to verify heater B function via cockpit switch.”

However, the call came back to the Launch Control Center that the problem was engineering-related, on an LCA (Load Control Assembly) resulting in the decision to scrub for between three to five days, as a forward plan is built on repairing the hardware.

ET-122 is currently being drained, per scrub requirements.

For live play by play coverage, follow the live event pages here:
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As noted, ET-122 is an older tank, refurbished after the damage it sustained during Hurricane Katrina, modified with the numerous and successfully proven Return To Flight (RTF) modifications, and returned to the flight manifest for a star role with one of the final flights of the Space Shuttle.

Originally set to fly on the final mission with Atlantis on STS-135, managers decided – due to the lack of a Shuttle Launch On Need (LON) for the final flight – to reserve the newer ET-138 to fly last, promoting ET-122 to fly with Endeavour.

As as result of the tank’s eventful history, modifications and improvements, the Flight Readiness Review (FRR) for ET-122 was one of the largest reviews for a tank since the fleet returned to service since the tragic loss of Columbia during STS-107′s return.

External Tank 122 was delivered as completed tank in November 2002 and stored at the Michoud Assembly Facility (MAF) and was actually undergoing the RTF modifications when the tank was exposed to weather-related environments during Hurricane Katrina while inside the VAB at the New Orleans Facility.

“Damage limited to tank outer surface damage from roof material (concrete debris / chips) and rain water,” noted the FRR presentation. “TPS debris minimization changes implemented at debris critical locations.”

The areas of repair are obvious to see, with numerous lighter patches around the tank, none of which will prove to be a debris hazard during ascent.

(All images via L2, with addition to Larry Sullivan of MaxQ Entertainment/NASASpaceflight.com. 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 launches and missions, breaking every major event over the last 10 missions before any other site, including NASA sites/TV).

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