*Click here for Part 1 of the 2010 Review*

Atlantis’s Retirement? The First Last Flight of OV-104:

As 2010 began, space enthusiasts grappled with the knowledge that this was the year in which all three Space Shuttle orbiters were scheduled to take their final flights to space. With STS-130 and STS-131 complete, attention turned to the upcoming STS-132/ULF-4 flight of Atlantis – a mission to deliver the Russian Mini-Research Module 1 (MRM-1) Rassvet to the International Space Station.

A bitter sweet moment, the flight of STS-132 was (and technically still is) the 32nd and final flight of orbiter Atlantis, a vehicle which entered into service for the world community on Oct. 3, 1985 with the launch of STS-51J.

Nearly 25-years later, NASA prepared Atlantis for one last mission, a mission that would see resounding success and, though unknown at the time, represent the 3rd and final Shuttle mission of 2010.

After returning from her previous flight (STS-129) in late-November 2009, Atlantis was processed through a multi-month OPF flow which included both standard and non-standard turnaround work.

Given Atlantis’s age – and the upcoming requirement to perform an Orbiter Modification Down Period (OMDP), a multi-step and intrusive inspection of Atlantis’s numerous systems – flow director Angie Brewer and the Atlantis team undertook the continued inspection of Atlantis’s spar structural fittings underneath her RCC (Reinforced Carbon-Carbon) WLE (Wing Leading Edge) panels.

While the need to perform a full-up OMDP was set aside by a program decision reached after a year-long investigation into the flight number/year requirements for OMDP, the decision was made to incorporate some of the less intrusive and necessary flight safety OMDP inspections during the standard flow turnarounds for Atlantis – a process which began in 2008 when Atlantis was rolled back from Pad-A following the multi-month delay to the Hubble Servicing Mission.

STS-132 Specific Articles: http://www.nasaspaceflight.com/tag/sts-132/

While all of Atlantis’s Spar Structural fittings were not inspected prior to STS-132, a majority inspection allowed NASA to cleared Atlantis for flight based on the extremely positive results from the spar fittings inspections performed both in her flow toward STS-129 and toward STS-132.

With these inspections in place, the Atlantis team completed OPF processing in early-April.

As day broke across the Kennedy Space Center on April 11, Atlantis was rolled from OPF-1 (her dedicated OPF) down a quarter-mile stretch of road toward the Vehicle Assembly Building.

Walked from the OPF by her processing team, technicians stopped Atlantis half-way down the transfer lane for a special photo op for all interested KSC employees and media officials present. The special photographic opportunity allowed KSC workers time to reflect on the nature of Atlantis’s numerous missions – of which a vast majority were dedicated to the pursuit of international interests – and the overwhelming history of the orbiter herself.

After a three hour stop, Atlantis was moved the rest of the way into the VAB and mated to her ET/SRB stack.

With Discovery touching down at the Kennedy Space on April 20 to end the STS-131 mission, and following three days of weather delays, Atlantis began her 3.4 mile trek to Launch Pad 39A just before midnight on April 20, arriving at Pad-A in the pre-dawn hours of April 21, leaving workers only 23-days (with only one contingency day) to process her for a targeted May 14 launch – a timeline that led NASA managers to state in no uncertain terms that they WOULD slip the launch date if needed to ensure that all necessary work was completed in a safe manner.

In the end, the requirement to slip the launch date proved highly unnecessary as Atlantis sailed through her pad flow with only one noteworthy issue encountered during hypergolic propellant loading in late-April.

With no issues on Atlantis, and quick understanding of Discovery’s Ku-Band antenna issue identified by ground processing teams, NASA managers officially cleared Atlantis for launch on May 14.

As the countdown began, no issues of note were reported with Atlantis and with a Program record low number of IPRs, only 46 IPRs to her name for the entire processing flow (Nov. 2009-May 2010), Atlantis lifted off right on time at 14:20 EDT on her very first launch attempt.

The amazingly clean nature of Atlantis’s STS-132 launch campaign led Russian Space Agency official Alexey Krasnov to state in the STS-132 Post-Launch News Conference that this entire launch flow was Atlantis’s way of screaming “use me again!”

After arriving on orbit, hand-held and orbiter ET umbilical well camera photographs revealed an extremely clean External Tank, paving the way for the clearance of Atlantis’s TPS (Thermal Protection System) for reentry.

During the course of Atlantis’s docked mission – her 11th trip to the International Space Station and her 18th overall docking to an orbital space station – her crew installed a new Space to Ground Antenna on the ISS, installed the MRM-1 to the ISS, and replaced six batteries on the P6 solar array truss of the Space Station.

Adding to the amazing nature of the STS-132 mission is the fact that all EVA objectives were accomplished even though additional EVA tasks were added to the crew’s work schedule in order to manually manipulate a cable on the OBSS (Orbiter Boom Sensor System) that was inhibiting the movement of one of the OBSS sensor packs necessary for complete inspection of the vehicle’s WLE and Nose Cap RCC.

But it wasn’t just the amazing and outstanding success story on orbit that highlighted the Atlantis mission, it was also the extraordinary work on the ground by the imagery analysis teams that shone through during the May flight.

In this manner, it was the extensive and prolonged imagery evaluations obtained on FD-2 and FD-3 (Flight Day 3) of the mission that allowed flight managers to press forward with a standard OBSS late-inspection of Atlantis’s TPS.

Initial thoughts of implementing a modified OBSS late-inspection to counter the images obtained or not obtained during the FD-2 inspections when the OBSS cable was snagged around the instrument platform were discarded thanks to the work performed on the ground.

After a week of docked operations, Atlantis and the ISS bid farewell on May 23rd. Three days later, Atlantis glided through the crystal clear Florida sky, dropping to runway 33 at the Kennedy Space Center to wrap up the STS-132 mission.

With completion of this mission, Atlantis crossed the 120 million mile mark in terms of miles travelled over her storied career.

With 18 space station dockings to her name, Atlantis holds the record (one she will keep for a very, very long time) for most dockings to a space station by a single vehicle.

An additional milestone for Atlantis included the honor of being the most international space vehicle in history, with 23 of her 32 missions dedicated to international pursuits.

In all, Atlantis has deployed two interplanetary probes, deployed 12 satellites, conducted 7 straight dockings with the Russian MIR space station, serviced the Hubble Telescope once, and conducted 11 International Space Station construction flights (including STS-132) in her 25 year career.

Her service is one that could not have been done without and is one that has paved the way for unprecedented international cooperation both now and for the future of space exploration.

But with Atlantis’s landing on May 26th, the question immediately arose as to what Atlantis’s future would hold. After being towed off the runway and back into her OPF, Atlantis began a sluggish processing flow toward the STS-335 LON (Launch On Need) rescue mission for the final planned Space Shuttle mission: STS-134 on sister Endeavour.

But even that role was in question in the first few weeks following the completion of STS-132 as internal NASA documents routinely placed Atlantis’s status as “Under Review” instead of in processing. At work here was more than just a simple uncertainty of Atlantis’s future, but an overall uncertainty of NASA’s future.

In the end, Atlantis would officially gain the role of LON vehicle for STS-134, a role she is currently in processing for in OPF-1. Carrying a target launch date of June 28, 2011, STS-335/Atlantis would ONLY launch with a four person crew (Commander Chris Ferguson, Pilot Doug Hurley, and Mission Specialists Rex Walheim and Sandy Magnus) to rescue Endeavour’s STS-134 crew in the event that Endeavour became disabled during the 134 flight; the mission would also deliver thousands of pounds of replacement supplies to the Station to make up for those used by the STS-134 crew.

STS-134/Endeavour or STS-133/Discovery: Which Mission Flies First?By the time Atlantis launched on STS-132, uncertainty was already building as to whether or not the STS-134 payload would be able to meet a target launch date in July 2010 because of an anomalous heating signature in the superconducting cryogenic magnet system that had been developed for the Alpha Magnetic Spectrometer 02 (AMS-02).

The anomalous signature was discovered during what was supposed to be final flight testing in the Netherlands and would have placed a higher demand on the cryogenic cooling system of AMS-02.

This discovery caused an initial delay to the delivery date of AMS-02 as teams worked to understand the issue. Then, as the timeline for the delays became clearer, NASA decided to swap the mission order of the final two planned Space Shuttle missions.

The changes resulted in the moving of STS-134/Endeavour out of the July launch window and initially into the November launch window (a slot initially held by the STS-335 LON rescue flight). STS-133/Discovery remained in its previously planned mid-September launch window but moved head of STS-134 on the launch manifest. STS-335 was then initially penciled into a December launch window before quickly moving in 2011.

Furthermore, as President Obama’s plan to extend the operational lifetime of the International Space Station rose to prominence, the AMS-02 team, in conjunction with NASA, decided to replace the superconducting cryogenic magnet with a permanent magnet that will allow AMS-02 to remain operational through the intended end of the ISS program.

This decision, along with the desire to make the most use of Discovery’s docked time at the ISS on STS-133 led to a further realignment of the launch manifest, pushing Discovery/STS-133 to November 1 and Endeavour/STS-134 to February 27, 2011.

STS-134 was subsequently advanced by one day to February 26 before moving to April 1 as a result of continuing safety-conscious delays to the STS-133/Discovery mission.

With these delays, the Space Shuttle Program officially moved into 2011, a move that caused initial concerns over whether the program would have the money to execute a full-up flight in 2011 with the proposed FY2011 budget from President Obama.

However, NASA, ever diligent, created a plan to save money and create a monetary cushion to allow STS-134 to fly in the 2011 timeframe.

The Fight for NASA’s Future:

As the year began, NASA and space enthusiasts alike waited word from President Obama as to his vision for NASA’s future – a vision many had been waiting for for nearly a full calendar year.

On February 1, President Obama unveiled his FY2011 budget proposal… a proposal that included his vision for NASA – a vision that quickly garnered significant scrutiny and reactions from across the political spectrum.

While many expected the Ares I and Ares V rocket architecture to be scrapped in favor of a more direct Heavy Lift launch vehicle, the complete cancellation of the Constellation Program, delay of an initial design cycle on a Heavy Lift rocket until a date to be determined later, and a heavy reliance on commercial companies proved quite startling and surprising and would in fact come to dominate the debate on NASA’s future, and indeed the future of U.S.-based space exploration, within the American and International space communities as well as the U.S. Congress itself.

However, while these issues of manned U.S. space exploration were certainly the most controversial talking points of the President’s proposal, it is just as important to note the utmost and high support the President showed for the International Space Station, interplanetary robotic exploration missions (specifically designed as precursor missions for manned planetary exploration), and both land-based and space-based medical research – support which, to some, was equally surprising but highly welcomed.

A month and half after the release of the President’s proposal, President Obama visited the Kennedy Space Center/Cape Canaveral Air Force Station to attempt to rally support for his plan – done mainly through an address to select space center workers and a visit to the SpaceX facility.

However, by this time, it was clear that the President’s proposal was highly unpopular, demonstrated mainly by the compromises already in place – the most visible being the retention of the Constellation Program’s Orion crew capsule for extremely stripped-down use as a life-boat on the ISS and a 2015 “decision” date on a new Heavy Lift vehicle.

Not surprisingly, the address did little to rally support and by the end of July/beginning of August it was abundantly clear that Congress had other, more concrete and immediate approaches to NASA’s future – including immediate work on a new Heavy Lift launch vehicle for NASA, a stepped approach to the use of commercial companies for manned access to space (mainly to be considered only after the companies in question had proven their reliability and capability), and the inclusion of enough funds to transition STS-335 into a full-up mission (STS-135) to launch No Earlier Than June 1, 2011.

Nonetheless, both the Senate and House had, not surprisingly, different visions for this future.

To this end, both the House and Senate passed different bills initially. Since, under U.S. law, both bills would have required reconciliation into one bill – approved then by the House and Senate – before being sent to the President’s desk for approval or veto, a compromise in the bicameral legislature was proposed and submitted for review by the House Committee on Science and Technology.

The 168 page compromise bill, released by the House Committee on Science and Technology which is led by Rep. Bart Gordon from the state of Tennessee, stated: “In the 50 years since the establishment of NASA, the arena of space has evolved substantially.

As the uses and users of space continue to expand, the issues and operations in the regions closest to Earth have become increasingly complex, with a growing number of overlaps between civil, commercial, and national security activities. These developments present opportunities and challenges to the space activities of NASA and the United States.”

Nonetheless, the Senate refused to even consider the compromise bill, forcing the House to vote on and approve the Senate version since, as many House members stated, “a future for NASA, even a flawed one, is better than no future at all.”

But with all things political, the fight for NASA’s future would not end with the passage of and signing into law of the 2011 NASA Authorization Act. Since Congress could not pass the necessary funding bill for FY 2011 (Fiscal Year 2011) before the start of the FY on October 1 (a date which seems to surprise Congress each year), a Continuing Resolution – funding NASA at the previous FY’s level – was passed by the House and Senate.

This Continuing Resolution took NASA through mid-December, but greatly inhibited the agency’s ability to move forward on the initial designs of a new Heavy Lift Vehicle as well as officially adding the STS-135 mission to the launch manifest.

Since, during the lame-duck Congressional session in December, the Senate and House also failed to reach a compromise on the FY2011 budget, another Continuing Resolution was passed to fund the U.S. government and its agencies into March 2011 – thus leaving the new Congress, which convenes next week, to tackle the FY2011 budget.

Thus, as it currently stands for the Space Shuttle Program, STS-134/Endeavour will be the final Program flight. While many are confident that the Continuing Resolution to March 2011 will provide NASA the money needed to transition STS-335 into the full-up STS-135 mission, NASA has not made any leanings in that direction just yet.

The last official word from NASA was that the agency would make a decision by mid-January on whether or not to add STS-135 to the official manifest, though statements have been made by NASA officials that the agency could go as far at late-March before making the STS-135 decision.

(Images: Larry Sullivan, MaxQ Entertainment/NASASpaceflight.com, L2 Presentations, NASA.gov, US Congress).

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OBSS PTU Snag:

The OBSS and its sensor package are one of the unsung heroes of the Return To Flight (RTF) era, allowing for post-launch and pre-entry inspections of critical area of the orbiter’s Thermal Protection System (TPS).

Teamed with an arsenal of imagery footage and expert engineers with the Damage Assessment Team (DAT) in Houston, all post-Columbia missions have successfully returned with added – and justified – confidence in the health of the heatshield.

The evaluations into the TPS begins as soon as the shuttle launches, with ground-based cameras and radar tracking debris hazards, working in tandem with orbiter based assets, such as the ET cameras and crew photography footage of the tank – the main source of debris threats.

Flight Day 2 is highlighted by the first use of the OBSS during the mission, focusing on three primary areas; the nose cap and the port and starboard Wing Leading Edges (WLE) – ensuring the Reinforced Carbon Carbon (RCC) panels avoided damage during ascent.

STS-132′s FD2 inspections began without issue, with the OBSS unberthed, followed by the activation and calibration of the Laser Dynamic Range Imager (LDRI) on the boom’s sensor suite. A quick check for ice on the starboard T-0 umbilical was followed by a robotic translation to the start point for the starboard wing survey, which revealed an issue with the PTU.

“Background of Issue: During the beginning of STS-132 FD2 Inspection procedures, PTU readings and behavior were erratic and eventually lead to determination that it was not able to move the entire tilt range,” noted the PRCB presentation, available on L2.

Ground controllers asked the crew to reset the PTU in an effort to correct the issue, prior to the crew visually noticing a cable – known as the W601 cable – was snagged on the unit’s protruding reed sensor.

“All attempts to resolve were unsuccessful: Crew manipulation, ground control manipulation, change in PTU speed. PTU was unable to point to the tilt values required to support FD2 Inspection. A cable snag was confirmed by the crew viewing PTU motion from the Flight Deck windows.”

Despite losing the PTU’s full range of motion, most of the survey was completed, with a plan to utilize Flight Day 3′s R-bar Pitch Maneuver (RPM) – aided with additional ISS crewmembers, armed with cameras – to capture additional imagery footage for the DAT engineers.

Meanwhile, the Mission Management Team (MMT) asked KSC engineers to look into how the snag could have occurred, checking closeout photos of the OBSS PTU ahead of Payload Bay Door (PLBD) closure for flight, along with flight history and checks into replaced elements of the hardware.

“Cable Flight History: Sensor Pack 1 (SP1) with W601 Cable S/N (Serial Number) 1002 is the same unit that flew on STS-130. Prior to STS-132, SP1 assembly required a PTU change out – requires disconnect and re-connect of W601 cable (same cable, S/N 1002),” added the presentation.

“Full pan and tilt range was confirmed post re-assembly during the STS-132 Pre-Installation Acceptance (PIA) testing with no issues of a cable snag. Installation procedures and close out photos were reviewed – no indication of incorrect installation. S/N 1002 Cable has flown on STS-130, STS-128, STS-125, STS-123/124, STS-115, STS-114.”

With the MMT noting their preference for the full use of the PTU to be restored, a cable tie plan was implemented on EVA-2 of the mission, freeing and holding back the snagged cable, and ultimately allowing for a nominal Late Inspections to be carried out without issue.

“In-Flight Resolution: During EVA2, the cable was physically removed from the snag point and an additional cable tie was installed to preclude the snag from reoccurring. Full PTU pan and tilt motion was restored and Late Inspection was performed nominally.

“Photos of flight hardware post STS-132. Red circles are area of snag occurred.”

Post Flight Troubleshooting:

Once Atlantis was back inside her Orbiter Processing Facility (OPF-1), engineers began a hands-on inspection of the PTU by removing the unit from the OBSS, part of the nominal procedures for preparing the PTU for its next flight, although this time including the enforced changeout of the troublesome cable.

“Troubleshooting Plan: Post flight activities – remove from vehicle, post flight functional of LDRI, manipulate Pan and Tilt to verify proper cable movement with added cable tie, cut added cable tie, manipulate SP1 assembly to attempt and recreate snag,” the presentation continued.

“Replace W601 Cable S/N 1002 with S/N 1005, confirm W601 cable S/N 1005 cable characteristics during full pan and tilt motion. Per Pre-Installation Acceptance procedure pan/tilt values. Per on-orbit operational pan/tilt values, determine if additional cable tie required, perform STS-133 Pre-flight PIA in prep for OPF testing.”

Implementing part one of the plan, engineers cut the cable tie installed during EVA-2, and attempted to perform the movement of the PTU with the old W601 cable that snagged during FD2 inspections. Just like it did on orbit, the cable snagged several times during ground testing.

“Performed troubleshooting on 6/16/10 in lab at KSC. Verified proper cable movement during PTU motion with cable tie attached. Cut added cable tie. Cable retained some memory of the added cable tie adjusted configuration thus cable had to be manually manipulated to re-create the pre-launch configuration,” noted the presentation.

“Cable laid flush against the PTU tilt ring at +102, -252 (pan, tilt). Moved PTU pan to +85 and the cable remained against the tilt ring. When the PTU was tilted up, it was observed that the cable snagged against the fixed electronic stop (Reed Sensor).

“It was concluded that the cable had to have been laying flat against the tilt ring at +102, -252, when the crew began panning and tilting in slow rate in order for the cable to snag. Able to recreate this scenario multiple times using W601 cable SN 1002.”

Engineers then replaced the old W601 cable with a new spare, re-performed the movement of the PTU, and successfully avoided the cable snagging during the tests.

“With successful recreation of the issue, W601 cable S/N 1002 was changed out with S/N 1005. Motion of PTU and cable characteristic was verified – values per PIA procedures, which include full range of motion, and on-orbit operational values.”

Forward Plan:

As to what caused the old cable to snag on the reed sensor during STS-132, and how can such a situation be avoided in the future, engineers checked to see if the W601 cable was somehow being pressed against the PTU after the Payload Bay Doors have been closed – in other words, if hardware was breaching into the space (envelope) of where the cable was positioned.

“Envelope Measurement History: Each of the three fully assembled SP1 units were measured for dynamic envelope to confirm clearance to the radiators and to any stowed payload,” added the presentation.

“Current Active Sensor Pack 1s: S/N 1003 with W601 cable S/N 1005. S/N 1007 with W601 cable S/N 1003. During this activity, it was noticed that each W601 cable has its own characteristics with respect to routing, translation and memory.”

With those findings – showing it may be an uncontrollable issue if left as-is – the Orbiter Project Office (OPO) will test the potential of added an additional cable tie, in order to guarantee the W601 cable avoids being pressed into a position that threatens it subsequently being snagged on the reed sensor.

“OPO has requested to assess the envelope measurement with the additional cable tie. Pending confirmation of positive envelope impacts, cable tie will remain in place for flight,” confirmed the conclusions to the presentation.

Testing on the viability of adding a new cable tie will take place during the week of July 26.

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STS-132 SRBs:

While Shuttle Derived Heavy Lift Launch Vehicle (SD HLV) options utilize the boosters that were set to live on via Ares I and Ares V, the need for “game changing” propulsion technologies has seen the solid’s stock weaken – with a potential drive towards all-liquid hydrocarbon vehicles.

Technically Ares lives on, with the US Congress holding the keys to approving the FY2011 proposal, which would result in the official cancellation of the Constellation Program – and while there will be at least two more shuttle missions, another solid will fire into life in Utah later this year, via the second firing of the five segment motor, known as DM-2.

Discussions are still taking place on adding one or two shuttle missions to the manifest, with the boosters for STS-335 (Launch On Need support for STS-134) already on site at KSC, potentially changing call signs to STS-135. However, as it stands, STS-134 will mark the final scheduled flight of the shuttle SRBs, when they will be tasked with aiding Endeavour’s two minute first stage ascent early next year.

Post flight IFA reviews are a key milestone for both the concluded mission, and the next scheduled flight – as their data provides the baseline for the Flight Readiness Reviews (FRRs). STS-133′s FRRs will enjoy smooth sailing from the standpoint of the SRBs, which performed admirably during Atlantis’ launch.

Only one IFA was recorded via the SRB IFA review – all 16 STS-132 IFA presentations available on L2 – relating to missing insulation from Forward Booster Separation Motor (BSM) Closeout – which is classed as an unacceptable debris hazard.

“RTV-133 Missing and Partially Debonded from Forward Booster Separation Motor (BSM) Closeout: Located on perimeter of upper right BSM – Size ~ 5 in long x ~ 1/4 in fillet bead. Unexpected debris source (not allowable),” noted the presentation, which added the loss of the insulation during ascent held no issue for the booster’s performance.

“Functions as environmental seal only. Not intended for thermal protection evaluation found heat effects and sooting not as severe as full flight but greater than adjacent area with intact RTV-133.”

Although its location is an unacceptable debris hazard, it is not clear if the material had enough mass to be a threat to the orbiter’s Thermal Protection System (TPS). However, no impact with the orbiter was noted, although an investigation is still ongoing as to the root cause of the liberation.

“Late ascent time of occurrence not ruled out – and also observed RTV-133 debonds associated with BSM closeout,” the presentation added. “IFA declared and Anomaly Resolution Team (ART-279) formed to investigate anomaly. Fault tree baselined and investigation ongoing.”

Squawks are minor issues which fail to be upgraded into a full IFA, with STS-132′s boosters listing nine – a low number – such items of interest in the review.

“132-002: System Tunnel Cover with Unknown Blue Material – No effect to hardware performance. 132-003: ET Attach Ring Forward Face Froth-Pak Foam Multiple Ascent Impact – No effect to system performance. 132-006: Range Safety System (RSS) Linear Shaped Charge (LSC) Connector Grease Intrusion – No effect to system performance,” listed the presentation.

“132-007 (x2): Corroded Coupling Nut on Aft Tunnel Cable Connectors – No effect to system performance. 132-008: Cracked Aft Beam on Frustum Aft Ring at -Y Isogrid Connection Point Splashdown time of occurrence. 132-009: Tape on Thrust Vector Control (TVC) Lower Frame – No effect to system performance.

“132-010: LH Rock and Tilt Auxiliary Power Unit (APU) Gearbox Quick Disconnect (QD) Cap O-rings Damaged Descent time of occurrence. 132-011: Shim Material Blistering on Hold Down Post (HDP) 1 No effect to system performance, Below Risk Assessment Mass.”

Squawk 132-002 provided a good example as to just how extensive the boosters are evaluated, even – in this case – before they launch, whist also showing how minor a squawk can be, with the blue material found to be nothing more than printer ink.

“Observed during L-1 day walkdown. Integrated SRB General Assembly Drawing Flag Note 0031 allows unavoidable processing material,” the presentation noted.

“Squawk generated to sample area, found material textured with multi-colored pattern. Compared to multiple sources Ball point pen, roller pen, laser printer ink and processing tap. Concluded most likely printer ink potentially transferred from Ground Operations processing tag. No effect to hardware performance.”

STS-132′s RSRMs:

The performance of STS-132′s RSRM set 111 was classed as within specifications and overall ‘excellent’, although their inspection process takes slightly longer, and involves evaluations once the motors have returned to ATK’s base in Utah. So far, no IFAs have been declared, as engineers push forward towards their +180 days report.

“All RSRM countdown parameters were within LCC (Launch Commit Criteria/OMRS limits and within family,” opened the ATK presentation to the STS-132 IFA review (L2). “Overall performance of both RSRM motors and all ATK BSMs excellent and well within requirements.

“RSRM postflight hardware evaluation is ongoing: KSC – in work. Aft BSM and RH field joint assessments still to be performed. Utah – in work. Nozzle joint disassembly complete. No IFAs declared at this time.”

Only four squawks – two related to the same issue – were written, all of which have been reviewed and classed as no impact to the performance of the hardware.

“Overall performance of both STS-132 (RSRM-111) motors and ATK BSMs were excellent. Postflight evaluation is still in work. Four squawks have been written at this time. No IFAs declared at this time but additional postflight disassembly and evaluations are still in work,” added the introduction.

Two of the squawks were charged against the Left Hand (LH) Booster Separation Motor (BSM), relating to insulator-to-closure edge unbonds on serial numbers 232 and 233. Due to the lack of debris or motor performance concerns, this issue was not elevated to become an IFA.

The issue is also classed as likely to have occurred during splashdown in the Atlantic ocean, as opposed to during any phase of the powered ascent of first stage flight.

“Creation and growth of unbonds during post-operation heat soak and splashdown is expected,” noted the presentation. “No mechanism exists for creation of unbonds prior to post-operation heat soak.”

The third issue related to the Right Hand (RH) Nozzle Leak Check Barrier O-ring Groove on the Aft Edge Corner – which suffered from phenolic damage. No compromise to joint performance was noted.

“A small area of damage to the RH nozzle-to-case leak check barrier O-ring groove aft corner was observed at 308 degrees,” noted the presentation, which added the cause is still being investigated.

“Cause determination is still in work but loss is not expected to compromise thermal barrier capability of the leak check barrier O-ring or decrease the expected joint performance in the event of pressure reaching the leak check barrier O-ring.”

The final note on the IFA presentation referenced a blister on the insulation associated with the Right Hand Igniter Chamber. The blister was noted as a manufacturing defect with no impact to igniter performance.

“Unusually shaped feature (roughly 0.5” by 2”) was noted on the ID of the RH igniter chamber. Squawk was written to permit evaluation,” the presentation continued.

“A portion was excised which verified the observation was a blister and had no signs of thermal effects or sooting. Engineering allows blisters of this size in this region of the igniter.”

As with the orbiter and External Tank (ET) IFA reviews, the performance of the shuttle hardware has been highly impressive over recent years, at the very least ensuring the Space Shuttle Program (SSP) goes out on a high, or potentially vindicating the faith of lawmakers – should they approve funding to allow the program to continue through as far as 2012.

Proof the shuttle’s recent performance has been recognized by the engineering and political communities can also be seen via such extension debates, which now focus mainly on cost, as opposed to safety concerns.

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STS-133 Processing Latest:

Discovery continues to enjoy a busy processing flow, despite her STS-133 launch target moving out to the end of October (now confirmed as Nov 1), with her two latest Interim Problem Reports (IPRs) in the process of being closed.

“OV-103 (OPF Bay 3): Payload pre-mate and load testing for IPR-0025 (Remotely Operated Electrical Umbilical (ROEU) System) was completed, disposition is in work. IPR-0026 (ARPCS) update: Atmospheric Revitalization and Pressure Control System testing is complete,” noted the NASA Test Director (NTD) processing report (L2).

Work is being conducted throughout Discovery, including testing of her Orbiter Boom Sensor System (OBSS), which began on Wednesday.

“PRSD (Power Reactant Storage and Distributation) system testing was completed. Main landing gear seal R&R was completed. OBSS testing has begun.

“Additional WSB 3 (Water Spray Boiler) decay checks and WSB 1, 2, & 3 core fill is scheduled. WCS installation was completed Wednesday morning; functionality testing is scheduled for Thursday.”

Discovery’s three SSMEs were uninstalled last week – in order to allow ME-1 to be removed after its Low Pressure Oxidizer Turbo Pump (LPOTP) failed torque checks.

While work was ongoing to install a replacement LPOTP on ME-1, the Program Requirements Control Board (PRCB) approved a Change Request (CR) to swap the positions of two engines, allowing for their reinstallation without being delayed by the work on ME-1.

“Engine relief valve checks were completed Tuesday; post-ops are scheduled to complete Wednesday,” added the NTD. “LH/RH (Left Hand/Right Hand) translators were opened Tuesday in support of SSME installation which began on Wednesday.”

UPDATE: However, on Thursday – according to the NTD – the last of the three SSMEs was already being installed. Due to the new positions, only ME-1 would need to be removed, if the same issue repeats itself during testing. Previously, all three engines had to be uninstalled to allow for ME-1′s removal from its center position, due to interferences.

Meanwhile, in the Vehicle Assembly Building (VAB) High Bay 3 (HB-3), final torque and leak checks between the mated External Tank (ET-137) and the twin Solid Rocket Boosters (SRBs) are in the process of being completed this week.

“SRB BI-144 / RSRM 112 / ET-137 (VAB HB-3): Installations; complete less final torque. Perform final torque after leak checks are completed Thursday,” added the NTD report. “L/R SRB NSI Ordnance Installations are complete, closeouts are in work. L/R Heater Cable closeouts; L/R Heater Cables complete less RT-455 pull test results. Camera cable RT-455 in cure.”

STS-133 Specific Articles: http://www.nasaspaceflight.com/tag/sts-133/

STS-132 SSME Streaks:

Streaks in the engine plumes are not uncommon. However, the number of observations seen during Atlantis’ first stage ascent earned a mention in three presentations at the STS-132 IFA review – primarily on the Pratt and Whitney SSME presentation to PRCB-level managers.

“Numerous plume streaks between 23 – 54 seconds MET (Mission Elapsed Time). Do not correspond to any anomalous engine events,” noted the SSME IFA presentation for STS-132 – all 15 presentations available on L2.

The observations are not a safety issue, nor was there any loss of performance – backed up by the Mission Management Team (MMT) review of Atlantis’ ascent performance, which was deemed to be excellent. However, a root cause for the events are still being investigated.

“Photo Analysis of SSME Plume Streaks: Engine performance as predicted. No indication of event that would cause engine debris,” added the SSME IFA presentation. “MSFC (Marshall Space Flight Center) photographic analysis group reviewed video to determine most likely source of debris.

“11 of 217 events identified as possibly engine related (streaks appear to initiate at the nozzle rim). No streaks believed to be internal to the plume boundary.”

The source of the streaks – a number classed as twice as much as the previous record’ – may be found once Atlantis’ SSMEs undergo a detailed inspection later this month (July).

“Multiple Streaks Observed in SSME Plume Description: 217 streaks were observed in the SSME plumes. Normally get 20-40 streaks per flight, have seen up to 94 streaks,” added the Integration IFA review presentation (L2). “Engine detailed visual inspections will begin in July.”

Atlantis’ SSMEs are due to be removed shortly, with engineers currently working on uninstalling the SSME dome heat shields.

Atlantis continues to be processed as the STS-335 vehicle – Launch On Need (LON) support for STS-134. With the possibility STS-135 may be approved in the next 4-8 weeks, Atlantis – providing managers approve OV-104 for the mission – may still receive one more flight.

STS-132 Specific Articles: http://www.nasaspaceflight.com/tag/sts-132/

The performance of Atlantis’ engines – E2052, E2051 and E2047 – during what is currently her final mission was classed as nominal at the SSME IFA Review, with only a frayed Flow Recirculation Inhibitor (FRI) note added to the aforementioned observation of streaks in the SSME plumes.

“Issue: Degraded FRI found on Nozzle 5007 / E2051 post STS-132. Approximate 6” (25 degree) section frayed and extending into the flow path.”

FRI is filled ceramic fiber tube installed in the space between nozzle tubes and MCC wall at the G15 joint. The fact such a small observation was even listed in the IFA review is a testament to the inspection process, and historical performance of the engines.

“FRI protects G15 Bellows Seal from overheating by reducing recirculation of hot gas into G15 cavity. FRI degradation is a normal wear issue with hot fire exposure. Function is maintained with fraying,” added the presentation, before noting hot fire experience for added confidence the issue held no safety concerns.

“Nozzle 2027 E0423 showed FRI damage after 1023 sec hot fire. FRI continued to provide protection and engine tested successfully to 4367 sec without damage to seal.”

FRI was only added to the SSMEs after STS-34, and a bellow seal will not fail during one flight – thus the issue was closed as no concern for safety of flight or performance.

No related posts.

STS-132′s ET-136 Review:

The performance of the foam Thermal Protection System (TPS) on the ETs – specifically the liberations that occur during the ride uphill – has been one of the key drivers for the successful and safe completion of the Shuttle manifest.

Noted as a science by former Space Shuttle Program (SSP) Wayne Hale, the protection against serious foam liberations – from critical areas, and at critical times of ascent – is the ultimate driver for protecting the orbiter’s heatshield. The result has been a run of orbiters returning to Earth with nothing more than cosmetic damage.

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STS-132 Re-entry/Landing:

Atlantis arrived back home in Florida with only nine reported issues in the Mission Evaluation Room (MER) – the last relating to the Flash Evaporation System (FES) during deorbit preparations. The FES provides cooling to orbiter systems when the Payload Bay Doors (PLBDs) – which include the radiators used on orbit – are closed.

“The FES in topping mode using the primary B controller shut down near the end of the radiator coldsoak for deorbit prep. The shutdown occurred about 46 minutes into the radiator coldsoak. The crew then restarted the FES topper using the primary B controller,” noted the post flight report to the MMT (L2). This resulted in a shutdown with the FES Freon outlet temperature failing to reach the control band.”

As part of the malfunctions handbook, the crew followed a procedure that has been used a couple of times on recent flights, known as a core flush – which is one solution for ice buildup in the FES. Contingency exists in the system if required.

“Subsequently, the crew restarted the FES using the primary A controller resulting in a successful seven minute operation, via a contingency procedure using a modified radiator bypass/FES checkout with core flush (on secondary controller) followed the primary A activation.

“In this contingency procedure, the FES is operated in secondary high load mode, followed by a core flush, then concluded with secondary topping operation. Ice and excess carryover were observed in the FES topping ducts during the core flush. The core flush stage of the procedure was performed twice because the initial core flush produced duct temperatures that indicated ice had not been completely flushed from the core.

“The second core flush produced duct temperature signatures that indicated a complete flush of the core. After completion of the contingency procedure, the FES configuration was switched to primary A controller in full up mode which prepares the orbiter for deorbit. Entry operations on the FES Pri A controller were nominal.”

STS-132 Specific Articles: http://www.nasaspaceflight.com/tag/sts-132/

With the FES issue resolved, both PLBDs were closed nominally by 146/03:49:08GMT [11/09:28:59 Mission Elapsed Time (MET)] in preparation for landing. A delayed closed indication on the starboard door has previously occurred several times in the past on multiple vehicles and is a known condition, thus was not a concern for entry.

The deorbit maneuver for the first landing opportunity at KSC, a dual-engine straight-feed firing, was started on orbit 186 at 146/11:41:59.2 GMT (11/17:21:51.2 MET) with shutdown at 146/11:45:05 GMT (11:17:24:57 MET). The burn was 185.6 sec in duration with a delta V of 333.6 ft/sec.

Atlantis’ Fuel Cells and Auxiliary Power Units (APUs) all performed as advertised, after holding a good level of reserve in case of weather related wave offs.

“All APU parameters were nominal on the final day on-orbit (FD13), during entry, and postlanding at KSC. APU 2 was the TIG-5 single APU start, APU 1 and 3 were started at EI-13,” added the MMT overview.

“The fuel cells generated 13.8 kW and 449 amps, average, and 3896 kWh of total electrical energy during the 282.48 hour mission. The fuel cells consumed 337 lb of hydrogen and 2673 lb of oxygen from the PRSD (Power Reactant Storage and Distributation) subsystem. The PRSD system also provided 234 lb of oxygen to the crew. The fuel cells produced 3009 lb of water. Approximately 44 lb of O2 was used for tank-to-tank transfer to ISS.

“The PRSD subsystem could have supported a 75 hour mission extension at the average mission power level of 13.8 kW based on the usable quantities remaining at landing. At an extension day average power level of 12.51 kW, it could have supported an 83 hour mission extension.”

Thanks to a timely gap in the Florida weather, the first landing attempt – mirroring the first launch attempt – was taken, in what was a fitting finale to Atlantis’ successful mission.

Pages of reports on the numerous orbiter systems – used during the transition from a spacecraft to an aircraft – all listed nominal performance, ahead of the wheels touching down on Runway 33 of the Shuttle Landing Facility (SLF).

“STS-132 Landing System performance nominal. MGTD (Main Gear): 146:12:48:08 (loss of WOW indication) NGTD (Nose Gear): 146:12:48:19 (loss of WOW indication) DC (Drag Chute) DEPLOY: 146:12:48:10.5 BRAKES ON: 146/12:48:45 (RHOB first indication over 250 psia),” added the MMT report.

“MLG TD Velocity: 195 KGS Brake Pressure nominal at averaging 400-500 psi throughout rollout, with the max brake pressure reached approximately 684 psi (LHI) DC JETTISON = 146:12:48:47 WHEEL STOP = 146:12:49:26 Total roll out time ~ 1 minute 18 seconds from MGTD Video of MLG tires, all had typical spin-up tire wear exposing tire tread cord.”

According to early Thermal Protection System (TPS) evaluations, Atlantis arrived back in excellent condition, with only a couple of gap fillers and, four missing putty repairs areas and some frayed blankets – which is all nominal, and confirmed the Damage Assessment Team (DAT) confidence in the healthy condition of Atlantis’ heatshield during on orbit inspections.

“Great effort on the flight, both the prep to get the vehicle ready and during the flight,” noted Shuttle manager John Casper on the latest Shuttle Standup/Integration report (L2).

“(Thanks to) the Ground Operations team for all their outstanding work to get Atlantis ready to fly, and now putting back in the OPF (Orbiter Processing Facility).”

Post STS-132/STS-335 Processing:

It takes around a week of operations to safe an orbiter in preparation for their next flow, with Atlantis set to be processed as the STS-335 vehicle in Launch On Need (LON) support of Endeavour’s STS-134 flight – although the final manifest running order is yet to be finalized – not least if STS-135 will be added, and which orbiter will fly the mission, with a June 2011 launch date preferred.

Following landing on the SLF, the Convoy engineers completed Atlantis’ total downgrade at 0953 EDT, ahead of tow operations to OPF-1, which began at 1244 EDT. This marked the start of OPF Roll In Operations.

“S0069 Integrated OPF Roll In operations: The vehicle was spotted in the OPF at 1604 EDT. Fuel cells were powered down at 2224 EDT. Jack & level was completed at 0054 EDT. T-0 and Horizontal drain/control venting is in work,” noted the opening STS-335 notes (L2) from the NASA Test Director (NTD).

“Cryo drain and tank inerting is complete. Orbiter power system validation and PLBD strongback installation (Friday). PLBD functional is scheduled for Tuesday.”

As is usual, Interim Problem Reports (IPRs) tend to include troubleshooting from issues recorded during the mission, with the heater failure on the L3D Reaction Control System (RCS) thruster debuting on the STS-335 flow as IPR 0002, one of four IPRs are listed by the NTD.

“New IPR 0002: Thruster L3D heater failed off. Troubleshooting plan is TBD (To Be Determined). New IPR 0003: SLF personnel reported audible leak at PD-17, LH2 high point bleed QD (Quick Disconnect). MPS (Main Propulsion System) reports leak rate is minimal and does not pose a safety/hazard concern. No action planned while on runway. Plan is to mate QD and perform leak check.

“New IPR 0004: O2 Tank 4 Midbody connection near Door 45 Leak exceeded allowable level. Problem was detected during preps for Cryo drain. It was determined to be a fuzz leak at the QD. It was determined to not be hazardous since the QD only passes GHe. Engineering suspects a possible nose seal issue and will inspect the QD at a later time. No constraint to continue with Cryo drain/inerting.”

Engineers will work on Atlantis on Saturday, prior to a two day break over Memorial Weekend, with only the requirement to establish Orbiter Aft access on the books.

No related posts.

STS-132 Status:

The opening landing opportunity called for the deorbit burn to occur at 7:41am Eastern, resulting in a perfect landing on runway 33 at the Shuttle Landing Facility (SLF) at 8:48am.

The second – and final – opportunity would have been available one orbit later, with the deorbit burn at 9:17am for a landing at 10:22am. However, this was not required, along with EOM+1 (End Of Mission plus one day),  and “pick em” day on Friday, when the Edwards Air Force Base (Dryden Flight Research Facility) would have been brought into the mix.

Some level of troubleshooting was worked on the Flash Evaporator System (FES), which will control Atlantis’ temperatures after the Payload Bay Doors (PLBDs) are closed, removing the radiator’s ability to cool electronics and other systems on the orbiter. This issue was soon resolved, allowing for the closure of the PLBDs.

It’s been a smooth couple of days since undocking from the International Space Station (ISS), with Late Inspections enjoying a nominal survey – following the EVA work to free the Pan Tilt/Unit (PTU) on the Orbiter Boom Sensor System (OBSS).

With the Damage Assessment Team (DAT) working on both imagery and data taken during the inspections early in the mission – and the completion of coverage that had been missed via the lack of ability to angle the Laser Dynamic Range Imager (LDRI) over parts of the Wing Leading Edges (WLE) – engineers took just over a day to work through the hours of footage.

The results of the Late Inspections showed an extremely clean Atlantis, and a good argument for her being classed as the cleanest orbiter in at least recent history, with only 252 ROIs (Regions Of Interest) – areas that need any checks, such as scuffs and stains – a number which is the lowest since the use of the OBSS, and nearly half the number observed on STS-131.

“LESS/RCC team cleared all late inspection regions of interest. Level 1 review by PRT completed at 5:00 pm (5-24). Level 2 completed at 1:00 am. Final PRT Review completed at 6:52 am (5-25),” noted the DAT findings presentation (L2). “No ROI exhibited any damage characteristics. From all of the early/late inspection LDRI imagery LESS PRT is GO for entry.”

The robotic duo responsible for the survey – the OBSS on the end of the SRMS (Shuttle Remote Manipulator System) – were successfully reberthed in the Payload Bay for the return home, marking the end of their operations for the mission.

“On FD 11 (Flight Day 11), the OBSS and RMS were successfully berthed, latched, and stowed and are in a good configuration for payload bay door closure, entry, and landing,” noted the Mission Evaluation Room (MER) report on L2.

“OBSS BERTH and MRL LATCH. Did not receive the Aft MRL Latch 2 indication (known condition), no further action required. All other indications nominal. Good single motor drive time RMS BERTH and MRL LATCH – All indications nominal, good dual motor drive time.

“RMS MPM STOW – All indications nominal, good dual motor drive time. OBSS MPM STOW – All indications nominal, good dual motor drive time. The OBSS was stowed on the Stbd MPM by the SRMS. RMS Cradled and powered-down.”

Flight Day 12 involved checks to Atlantis Flight Control Surfaces (FCS), ahead of their use during Atlantis dive back into the atmosphere – which was successful from a hardware standpoint.

“FCS C/O (Check Out): All APU 1 (Auxiliary Power Unit) parameters were nominal during the FCS checkout run. APU 1 run time and fuel consumption are listed below,” added the MER report. “Start time: 145/07:47:03. Stop time: 145/07:45:21. Run time: 3:18. Fuel Used/Rate: 12 lbs; 3.64 lb/min.

“FD12 Performance: All APU parameters are nominal. All APU heaters are functioning nominally on the ‘B’ string. The GG heater lower set point shift – unique to OV-104 (Atlantis) position #1 since STS-81 – is evident after about six ‘B’ heater cycles, exactly the same as on the previous OV-104 mission, STS-129 (31). This heater signature was expected and will be noted in the MER trending database.”

STS-132 Specific Articles: http://www.nasaspaceflight.com/tag/sts-132/

During the FCS checks, Atlantis’ elevons and Rudder Speed Brake (RSB) were put through their paces, ahead of their use for landing, via the use of hydraulic actuators and valves.

“All Elevon Actuator Switching Valves and the RSB PDU Switching Valve were verified to configure to the proper positions (All Elevon Switching Valves to Standby 1 & the RSB PDU Switching Valve in Primary).  Priority valve cracking time was 0.393 seconds (spec ≤1 sec). The HYD System #1 bootstrap accumulator was 2336 psia prior APU #1 start and re-seat pressure was approximately 2832 psia (spec: GT 2675 psia).”

The Mission Management Team (MMT) were also presented with imagery analysis of what appears to be two Foreign Object Debris (FOD) leaving Atlantis during the FCS C/Os.

“(Object 1): Object estimated size: 0.46”. Appears to from bottom of FOV (Field Of View – assumed to emerge from inside Payload Bay). Distance from Camera B to sill of payload bay is 32 inches. 32 inch range (max) estimated to object. No extensive dynamic analysis produced,” noted a MMT presentation (L2).

“Object estimated size: 0.44” – Does not emerge into provided FOV from bottom, so there is not evidence as with the other FOD that it emerged from the PLB. However, it is first seen against the wing background (i.e. it’s much closer than the wingtip on first appearance. Estimate above assumes that it did come from PLB. 32 inch range (max) estimated to object.”

Both objects appear to be similar, but have not been identified. However, no concerns were raised by the MMT, and such debris events can occur during the vibrations of FCS checkouts.

“The Flight Controls System Checkout was performed. The procedure was completed with nominal results. The team is not working any issues,” confirmed the MER via their latest shift report, reviewing Flight Day 12′s activities. “Monitored FCS Checkout and RCS Hotfire. Two Foreign Object Debris (FOD) items were observed floating away from the Orbiter during FCS checkout.

“Imagery personnel recorded video of the FODs, and did not feel that they would pose a threat to the Orbiter TPS, since they were small (<1″), appeared to originate from the upper surface of the Orbiter and were floating away from the vehicle.”

Also included in the Flight Day 12 activities were the firing of Atlantis’ Reaction Control System (RCS) thrusters – including the L3D thruster with its failed heater, successfully mitigated via a passive thermal mitigation plan.

“38 of 38 primary thrusters have been fired. Thirteen (13) new Primary thrusters were fired since previous report,” noted the MER. “All thermal systems are performing nominally (except L3D thruster heater) and temperatures are within acceptable limits. The L3D temperatures are currently near 56F.”

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The Mission Management Team (MMT), with information from the DAT and OPO (Orbiter Project Office), officially cleared Atlantis’ TPS for reentry – following a long and arduous process of gathering all the necessary inspection data via Atlantis ‘Orbiter Boom Sensor System (OBSS), R-bar Pitch Maneuver (RPM) photography from ISS, and EVA (Extravehicular Activity) photography opportunities.

In all, the complete inspection of OV-104′s TPS revealed an extremely clean vehicle – aided in large part to the excellent performance of Atlantis’ External Tank which experienced very minor foam liberations during the May 14 launch of STS-132/ULF-4.

“Imagery review complete: 4 items in TIIMS were evaluated,” notes the short, 19-page comprehensive DAT presentation – available for download on L2.

In particular, the DAT identified one area of OMS (Orbital Maneuvering System) Pod blanket damage, two lower surface (underbelly) tile damage locations, and one AMES Gap filler protrusion.

Furthermore, no damage was identified at Atlantis’ port and starboard T0 umbilicals.

The presentation moreover notes the tremendously successful effort by Atlantis’crew to obtain all TPS imagery data in a timely manner given the OBSS’s PTU’s (Pan-Tilt Unit’s) inability to maneuver to the proper positions during initial TPS inspections on FD-2 because of an errant cable.

“Missed port imagery Upper LESS carrier panels 7-9 and Chine tiles, ~150 upper surface tiles.”

The errant cable was removed as an obstruction to the OBSS’s PTU during EVA-2 and all late-inspection imagery was obtained without issue on FD-11.

However, Station and EVA assets that were used to complete the necessary coverage of the TPS tiles by FD-5 of the mission, which resulted in a DAT and OPO recommendation to clear the TPS (save the RCC – Reinforced Carbon-Carbon – panels) for reentry.

STS-132 Specific Articles: http://www.nasaspaceflight.com/tag/sts-132/

Specific DAT TPS Clearance Review:

As is standard in the post-Columbia era, Atlantis’ R-bar Pitch Maneuver (RPM) just prior to docking with the International Space Station provided valuable data on the health of her underbelly TPS – specifically, verification of ET Umbilical door closure.

“Lighting and viewing angles sufficient for assessment of forward edge,” notes the presentation. The paint stripe used to verify ET door closure was – as expected – not visible from RPM photography, confirming Atlantis’ computer data that the ET doors are closed and properly sealed for entry.

“Closure indicators not visible in imagery and no evidence of off nominal steps or thermal barrier protrusions [are present]. ET Doors are closed.”

Interestingly enough, all TPS damage locations for STS-132 are located on the port (or left-side) of Atlantis, with the two tile damage areas located on the port Nose Landing Gear Door (NLGD) and just outboard of the left-aft corner of the Port ET Umbilical door (and just inboard of the forward, starboard corner of the inboard Elevon), respectively.

For the damage location on the NLGD, the DAT summary notes that the tile in question is 1.7-inches thick with a missing “putty repair” of 1.2-inches in length, 0.6-inches in width, and 0.1-inches in depth.

Resulting damage dimensions are estimated at 1.89-inches in length and 0.49-inches in width with “photogrammetry determined depth [at] 0.2-inches.”

This damage area is of no concern for entry and was cleared using P-DAT.

The second tile damage location was similarly cleared using the Port Wing Tile Damage Analysis Tool, which includes the Peer Reviewed categories of Baseline Heating, Cavity Heating, Thermal Analysis, Tile Stress, and overall Stress.

These tools yielded “high” confidence in the damage analysis to the tile in question. Overall, this tile is 1.15-inches thick with photogrammetry damage estimated at 2.25-inches long, 0.97-inches wide, and 0.15-inches deep (+/- 0.05-inches).

However, clearance of this tile damage could not be had without consideration of the upstream AMES Gap filler which could affect the airflow and local heating environment around the damaged tile.

“Thermal analysis performed with STS-132 EOM M18 (Mach 18) heating due to upstream AMES gap filler,” notes the presentation.

For this protruding AMES Gap filler, “Thermal bounded by previous analysis that showed transition at M=18 (keq=.25) acceptable in this area,” notes the DAT summary.

Furthermore, a “Partial transition load comparison based on aeroheating heat loads” was performed as well.

A reference point to a previous analysis “which used partial transition load cases” developed for nonstandard processes was also used to clear the gap filler itself.

In all, the AMES Gap filler is protruding 0.24-inches (+/- 0.15-inches) in a non-reworked area of Atlantis Gap fillers located inboard of the Port Main Landing Gear Door (MLGD).

Since most of the Gap filler remains in the gap, liberation during reentry is not expected as ascent loads on the Gap filler are “several times higher than entry loads.”

Furthermore, considerable flight history with protruding Gap fillers is on file and was used to clear the Gap filler.

In fact, a chart of the historical Gap filler protrusions since Return to Flight in July 2005 showed three Gap filler protrusions with comparable or greater protrusion Height Maximums (Hmax); STS-124: Hmax= 0.23-inches; STS-120: Hmax= 0.29-inches; and STS-121: Hmax= 1.04-inches.

However, given the range of height uncertainty (+/-0.15-inches) with this particular Gap filler, it is possible that the Gap filler could trip the Boundary Layer at Mach 18 during reentry, creating a potential off-nominal heating effect on downstream areas of the vehicle, most notably the damage site of damaged TPS tile #2.

Therefore, while the Gap filler itself was cleared for entry, its affect on the lower surface aft TPS tile damage location had to be evaluated before that TPS tile damage site could be cleared for entry.

In all, it was determined that if the boundary layer is tripped at March 18 by the protruding Gap filler, the structural area directly below the damaged tile would see temperatures below 350˚F with just a small potential RTV overtemp: 2.79in2 normal flow.

Maximum structural temperature expected in the region is 246˚F, only 6˚F above the standard 240˚F baseline temperature.  Therefore, positive structural margin is maintained and no concern exists for the damaged TPS tile due to upstream affects from the protruding Gap filler.

Finally, the last area of Atlantis’ TPS to come under scrutiny from the DAT was a partially frayed outer layer on one FI blanket on the Port OMS pod.

The blanket in question is 1.6-inches thick and all blanket insulation remains intact – thus, thermal performance is maintained. Liberation is not expected due to previous experience with “frayed outer covers and loose patch repairs.”

Currently, it is believed that the blanket was damaged on the ground during final vehicle configuration for flight as the blanket is located next to a door that is removed each flow for access inside Atlantis.

In all, the extremely clean nature of Atlantis’ TPS tiles has led to the unanimous decision by the OPO and DAT to recommend the TPS tiles and blankets cleared for reentry.

Final clearance of the entire TPS (including the all-important RCC panels and nose cap) was approved earlier this morning by the MMT following a complete review of the RCC Wing Leading Edge panels and nose cap imagery from the OBSS late-inspections yesterday.

Thus, weather permitting, Atlantis has been cleared for her final landing at the Shuttle Landing Facility (SLF) Wednesday morning.

If all goes according to plan, Commander Ken Ham will ease Atlantis onto runway 33 (the southeast to northwest approach to the SLF) at the Kennedy Space Center at 0844 EDT, capping a near 12-day flight for Atlantis and the STS-132/ULF-4 mission.

Related posts:

1. Endeavour and her SCA piggyback ride arrive in Louisiana, via JSC flyoverThe Shuttle Carrier Aircraft (SCA) and Endeavour departed from Edwards...

L3D Thruster Heater Failure Overview:

Following a week of docked operations, orbiter Atlantis has completed her 11th and final docked mission to the International Space Station, capping an amazing career of 18 total dockings to MIR and the ISS (7 to MIR and 11 to ISS).

Currently, Atlantis will spend two more days in Low Earth Orbit, with the all-important late-inspection of the ship’s RCC (Reinforced Carbon-Carbon) WLE (Wing Leading Edge) panels and Nose Cap occurring on FD-11 (Monday). Then, on FD-12, Atlantis’ crew will begin preparing their ship for reentry by testing the various systems they will use for Entry, Descent, and Landing and reconfiguring Atlantis’ middeck for entry.

Finally, on FD-13 (Wednesday), Atlantis will – weather permitting – return to her home at the Kennedy Space Center with a mid-morning landing at the Shuttle Landing Facility.

However, Atlantis’ crew may have to place Atlantis into a slightly different orientation during certain portions of the post-undock timeline to accommodate the need to maintain thruster L3D’s temperature since that thruster’s heater has failed “off.”

According to the Mission Evaluation Room (MER), the L3D thruster heater failure is classified as MER-02 – or the second MER problem recorded during Atlantis’ STS-132/ULF-4 flight.

“Following initial thruster firings associated with ET Sep, both thruster L3D’s fuel and oxidizer injector temperatures reached 59 and 60 deg F, respectively, at ~135/20:08 GMT with no sign of thruster heater activation,” notes the MER presentation – available for download on L2.

Both the L2D and L4D thrusters – the adjacent thrusters – performed nominally with standard heater activation when their injector temperatures reached ~75 deg F.

For the L3D thruster, a temperature of ~60 deg F was maintained until FD-2 when, during the NC-3 course adjustment burn, the L3D thruster fired twice – thus raising the thruster temperature to 72 deg F.

“From the observed rate of temperature decline (approx. 1 deg/hr) the jet temperatures were not predicted to drop low enough to produce thruster leakage or trigger a Fail Leak RM alert overnight; therefore, no vehicle attitude or jet priority changes were performed prior to Crew Sleep,” notes the MER document.

During the on orbit overnight hours, the L3D thruster temperature dropped to 62 deg F and thermal analysis indicated that the thruster temperature would not drop to “leakage” temperatures. This, coupled with the standard thruster jet firings for rendezvous and docking, brought the thruster temperature to over 100 deg F.

The thruster temperature is important because, while the thruster valve design is certified for operations as low as 40 deg F, the thruster valves are known to leak at temperatures below 50 deg F.

“For a failed off heater, thermal analysis has shown that the valve temperature is ~ 5 deg F warmer than the injector temperature instrumentation,” notes the MER-02 problem report. Because of this finding, an OMRSD requirement was instated (back in the 1980s) to ensure that the thruster valve temperatures are maintained above 50 deg F during ground processing – a rule carried over into on orbit operations.

STS-132 Specific Articles: http://www.nasaspaceflight.com/tag/sts-132/

Potential L3D Thruster Forward Actions:

For the thruster on Atlantis, the document notes that the next worst case failure would be a ‘Fail Leak.’ “Sufficient redundancy exists – two other thrusters on the same side and direction (L2D & L4D) – such that no special procedures are required.”

Nonetheless, should a leak occur, the propellant loss or contamination could be staved by closing the L3 manifold isolation valves.

“Per flight rule C2-2C, the manifold would be closed immediately regardless of the injector temperatures if the jet is suspected to be leaking due to contamination concerns.”

Closure of the manifold would result in the loss of the L3L and L3A thrusters as well as the L3D thruster; however, two redundant thrusters would still be available in each of the affected directions.

Failure of the L3D thruster during the docked portion of the mission was negated due to the mated beta angle which prevented the L3D thruster temperature from dropping below approximately 50 deg F.

However, a greater degree of uncertainty exists in the post-undocking timeframe. “Drain panel heater cycling, which warms L3D injectors about 4F per cycle, is expected in the post undocking -ZLV -XVV attitudes, but the exact duty cycle is hard to predict due to several attitude changes,” notes the MER document.

Due to these uncertainties, temperatures as low as 40 deg F could be had in the post-undocking timeframe.

However, “Thruster temperature can be maintained with the nominal thermal environment, thruster firings, and attitude changes.”

Additionally, non-nominal thruster firings and attitude changes could be employed to maintain thruster temperatures. But, should these thruster firings and attitude controls fail to maintain thruster temperature, the thruster could be declared failed.

If this were to happen, there would be no serious impact to the remainder of Atlantis’ mission and a Nominal End of Mission (NEOM) would be carried out thanks to the redundancy provided by other thrusters.

Therefore, since a loss of the L3D thruster would still result in a NEOM, the MER problem report indicates that any off-nominal thruster firing or orbiter attitude change to maintain thruster temperature would likely be declared unnecessary by the Flight Control team.

This thought of declaring specific action to maintain thruster temperature as unnecessary was confirmed by the MOD (Mission Operations Directorate) and PROP (Propellant) console in Mission Control in a FD-8 presentation by OMS/RCS – also available for download on L2.

“Recommendations: Place thruster in last priority after [ISS] flyaround and take no further actions since predictions are that L3D will remain above 47 deg F.”

However, “Due to analysis uncertainty, it is prudent to determine alternate attitude(s) that could be used if updated analysis predicts lower temps or if actual behavior varies from predicted”

However, a change to the nominal post-undock attitudes would mean an increase in potential MMOD (Micro-Meteoroid Orbiting Debris) risk.

According to the FD-8 OMS/RCS report, “Vehicle attitude changes to place L3D in warmer Environment [would result in] increased MMOD risk.”

The increased risk would translate to approximately 5%, from 1:379 to 1:361 – still well within the acceptable risk matrix for the SSP (Space Shuttle Program).

Furthermore, full data readings on the health of the L3D and other shutdown thrusters would be maintained through EOM (End of Mission) since the thruster’s instrumentation is not affected by the heater failure.

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Atlantis Status:

Her final hours with the orbital outpost have earned praise from engineers, managers and astronauts alike, most of whom have moved away from the politically correct “it” to the traditionally correct “her” when speaking directly of the famous spacecraft.

While the current NASA administrator is himself a veteran shuttle Commander, his comment that people will have forgotten how humans used to travel into space in 10 years time appears to have no basis in reality, if the tributes for the orbiter’s swansong mission – which continue to flood in from public and officials alike – are anything to go by.

Ironically, STS-132 (swapped with Discovery) - and STS-129 - weren’t originally manifested to Atlantis, with the previous plan to retire – or at least mothball – the orbiter after STS-125′s visit to service the Hubble Space Telescope.

Another stay of execution remains on the cards via STS-135, although that mission – if approved – may be handed to Discovery (article next week).

General Bolden, at least, remains less than enthusiastic about any plan that does not end the Shuttle Program as soon as possible, as he continues to champion the deeply unpopular proposal outlined in President Obama’s FY2011 budget.

For her part, Atlantis remains unfazed by her fate, and continues to behave impeccably on orbit, with only a small number of minor issues charged against the vehicle at the Mission Evaluation Room (MER), highlighted by the snagged cable on the Orbiter Boom Sensor System (OBSS) Pan/Tilt Unit (PTU).

“As far as the current mission goes, there was a little bit of bad luck,” noted SSP (Space Shuttle Program) manager John Shannon on the Shuttle Standup/Integration report (L2) – in reviewing the first part of the mission. “It was just very strange how that cable got routed right between the connector and the little stanchion piece that kept it from tilting up on our inspection.”

STS-132 Specific Articles: http://www.nasaspaceflight.com/tag/sts-132/

While the unit is now able to translate through the required movements that will allow for the Laser Dynamic Range Imager (LDRI) to finally complete a full scan of Atlantis’ RCC panels, Mr Shannon praised the teams for utilizing a variety of assets to allow for the clearance of the vehicle’s Thermal Protection System (TPS) for entry.

“The team has done an amazing job of looking at options and alternative ways of getting inspection data. The RPM looked like it went really well. Overall, it looks like a really clean vehicle. There (were) really (no) reasons to suspect any damage to the vehicle. We will go do the risk trades to get as much inspection data as possible before undocking.”

Those discussions on whether to carry out a docked inspection during these late docked days on Station resulted in a decision to press ahead with a nominal Late Inspection plan – which will take place on Flight Day 11.

Although the discussions took several days to conclude, the process of clearing Atlantis from any TPS concerns was typically methodical, and carried out at a pace that ensured the Damage Assessment Team (DAT) presented their recommendations only when they were ready to do so.

All but one of the Atlantis’ array of thrusters will be available for undocking, following an issue with the L3D RCS (Reaction Control System) thruster’s heater shortly after entering orbit. However, concerns the thruster may start to leak – itself not a major impact – have been allayed by good temperature management whilst on orbit.

“All passive thermal temperatures are within acceptable range and all thermal systems are performing nominally except the L3D RCS thruster heater, which is failed off,” noted the MER (L2). “Current docked attitude is maintaining L3D temperatures within limits.

“No heater cycles have been observed on this thruster. The lowest injector temperatures observed during this shift were 71.7 deg F for fuel and 72.7 deg F for oxidizer.” A full overview of the L3D management plan for post docking will be published in the next article.

“25 of 38 primary thrusters have been fired. No new Primary thrusters were fired since previous report,” with all 38 thrusters set for a two pulse test on EOM-1 (End Of Mission minus one day) during pre-entry checkouts of Atlantis’ systems.

Atlantis’ three Auxiliary Power Units (APUs) and Fuel Cells all continue to show good health, bar a small issue with Fuel Cell 3 noted via its monitoring hardware - although the FC continues to operate nominally.

“All APU on-orbit parameters are nominal. All APU heaters are operating on the ‘A’ circuit. Subsystem performance is nominal. The PRSD (Power Reactant Storage and Distributation) O2/H2 manifold 2 isolation valves were cycled closed for crew sleep and reopened (prior to crew wake up).

“Fuel Cell 3, s/n 118, O2 flow meter indication continues to be erratic. It did indicate an increase in flow at the beginning of the fuel cell purge and a decrease at the end of the purge, verifying proper purge valve operation.”

According to the flight plan, the undocking late in the crew day will not allow for a water dump – as per usual – pending any change of plan by the Mission Management Team (MMT). However, Atlantis has enough spare capacity to allow the dump to occur on Flight Day 11 if required.

“Life Support Subsystem is operating nominal, working no issues. Total GN2 = 294.1 lbs. Total Supply water = 391.4 lbs (large transfer to ISS). Total waste water = 58.6 percent (100 lbs),” noted the MER’s most recent status report.

Nominal performance is mirrored throughout the system report, which has become the norm on most recent flights, though under appreciated given the complexity of the vehicle.

“A review of the GPS Data during this period confirmed that the GPS was operating nominally. The GPS team is not working on any issues or funnies,” added examples of the MER status overview. “The Flight Control System is operating nominally. All communications subsystems are performing well. The DPS (Data Processing System) HW (Hardware) team is not working any issues at this time.”

Atlantis is due to undock from the ISS at 10:22am Central Time, prior to a one lap flyaround of the Station, and the main separation burn at 12:05pm Central.

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