The stunning lack of an In-Flight Anomaly Review for STS-135:

For over 30 years, NASA’s Space Shuttle Program relied on the all-powerful and iconic white Solid Rocket Boosters to help propel every single Shuttle mission toward Low Earth Orbit.

For the entire life of Space Shuttle Program, one thing was certain: there would be an In-Flight Anomaly (IFA) review for all Space Shuttle missions to review all vehicle performance indicators and ensure maximum safety for the future.

And that constant held from STS-1/Columbia (April 1981) to STS-134/Endeavour (June 2011). Notably, though, STS-135/Atlantis is missing from the complete list of IFA reviews.

Some people within the program claimed it was related to NASA leaderships’ desire to kill the Shuttle Program as quickly as possible, following the highly successful and triumphant mission of OV-104 Atlantis on STS-135 (8 July – 21 July 2011).

What’s more, the non-performance an IFA review following STS-135 directly contradicted numerous pre-flight reports and statements by Shuttle Program managers, that specifically noted that all post-flight reporting and IFA reviews would follow normal procedures for the last flight of the program.

Essentially, the express desire by Shuttle Program management and NASA itself going into STS-135 was to treat it as if it were just another flight of the Program – as if there would be another flight, which in some sense is true given the large quantity of Shuttle hardware that will still be flown on the Space Launch System (SLS) rocket.

But with the desire to terminate the program as quickly as possible came the 31 August 2011 “official” end to the Shuttle Program – and with it any chance of performing an IFA… something quite baffling when it is considered that numerous Shuttle hardware elements will be used for the Space Launch System rocket (e.g. the SRBs, Space Shuttle Main Engines, External Tank design, Main Propulsion System, etc…).

The directive not to perform an IFA was clearly issued following the successful return of Atlantis from STS-135 as indicated by the Mission Evaluation Room (MER) compilation of an actual IFA list (available for download on L2 – LINK) on 1 August 2011 for review at a later date.

Thus, the appearance of a detailed flight performance and IFA report for any element of STS-135/Atlantis is refreshing – though surprising. 

An inspiringly safe final SRB flight for the Shuttle Program:

Following the launch of STS-135/Atlantis on 8 July 2011, the launch vehicle’s twin SRBs were towed back to the Cape Canaveral for disassembly and post-flight inspection.

This process led to the creation of a detailed flight performance report of Shuttle Atlantis’s Solid Rocket Boosters on 18 August 2011 – not by NASA or Shuttle Program departments but by the contractor agency United Space Alliance (USA).

As noted by the USA Volume II – Solid Rocket Booster presentation for the Space Shuttle STS-135 Flight Evaluation Report (L2 LINK), “All Solid Rocket Booster subsystems performed nominally during launch countdown, flight, and recovery.”

With liftoff of the final Shuttle flight registered at 1129.03 EDT, the launch occurred on the first attempt with “No SRB LCC (Launch Commit Criteria) violations during the time period of SRB power up through launch. No exceedances of the Countdown Experience Base occurred this flight, and all SRB subsystems performed properly during prelaunch testing and launch countdown.”

But perhaps even more impressive than the clean pre-launch performance of the SRBs is the fact that “There were no SRB related In-Flight Anomalies (IFA) on this flight.”

SRB separation loads/events from the launch pad at liftoff:

Designed to bear the entire weight of the fully-fueled Shuttle launch vehicle on the Mobile Launch Platform (MLP), and thus representing the only place to securely bolt the SSV (Space Shuttle Vehicle) to the MLP, each SRB for the Space Shuttle was bolted to the MLP by four hold-down bolts with frangible nuts.

These frangible nuts had to separate prior to liftoff to allow for a clean launch of the SSV from the MLP. Thus, the nuts were designed to separate into two halves via a NASA Standard Detonator – with the fire command being sent to each frangible nut at approximately T-0.3 seconds.

This timing allowed the nuts to separate and fall into their designated receptacles where they were “caught” and prevented from recirculating in the aerodynamic environment around the vehicle induced at SRB ignition – thus preventing the frangible nuts from contacting the launching SSV stack and causing potential damage.

To verify the safety and continued functionality of this system, several post-flight and flight ascent data was collected on each Shuttle mission to verify a clean separation of the SRBs from the MLP and the eight hold-down bolts.

This verification process was performed for STS-135. As noted by the SRB flight performance report, “Post-flight inspection showed that all eight frangible nuts performed nominally, separating into two major halves. All four frangible nut major webs, and both minor webs, were identified in the debris from all eight blast containers.”

Furthermore, there were not stud hang-ups during liftoff, and all hold-down stud loads for STS-135 were well within family for the Space Shuttle Program – indicating a clean separation of the SRBs from the MLP at liftoff.

The maximum hold-down stud load for STS-135 was recorded on Post #2 with a value of 771.5 kips; likewise, the minimum stud load was recorded on Post- #5 just prior to SSME (Space Shuttle Main Engine) start with a value of 609.6 kips.

Both of these values were well within the maximum flight experience base of 841 kips (registered during the December 1988 launch of Atlantis on STS-27) and a historical maximum of 849 kips (registered during the STS-26/Discovery Return to Flight mission’s Flight Readiness Firing of the SSMEs).

Overall SRB ascent performance:

All ascent data points for both SRBs were well within family and consistent with previous nominal flights of the SRBs.

Both RSRM (Reusable Solid Rocket Motor) Ignition PICs (Pyro Initiator Controllers – the hardware that actually ignites the SRB propellant at T-0) met all performance requirements and functioned nominally.

All SRB rate Gyro performances were nominal, and correlated rate data from the Left and Right SRBs and the Orbiter’s rate gyro subsystems were within Shuttle specifications during powered ascent.

Moreover, “All reviewed measurements from the Operational Instrumentation performed properly throughout their respective mission phases for the launch,” notes the SRB performance report.

However, in terms of overall performance, of particular note were the Significant Event Times for STS-135′s SRBs.

While several of the manually initiated commands in the pre-launch timeframe deviated from their predicted time (an expected occurrence), of particular note were four flight event times that deviated ever so slightly from the pre-flight predictions.

The first was the actual time of ignition of the twin SRBs.

Pre-flight expectations showed a 0.006 second delay between the ignition command and the actual ignition of the twin SRBs.

Post-flight analysis of video from the launch pad revealed an actual 0.008 second delay between the ignition command (clocked from the SRB ignite command at T-0) and the actual, simultaneous ignition of the SRBs – a statistically insignificant 0.002 second difference.

Additionally, there was a 0.16 second difference in the time it took both the Left and Right SRBs to drop to a PC less than 50 indication – much better than the pre-flight prediction of a 0.3 second difference.

Likewise, there was a statistically irrelevant 0.2 second different in the safing of the Range Safety System (destruction system) between the two SRBs.

SRB nozzle null commands for SRB separation were nearly identical to each other and to pre-flight predictions; however, physical separation of the SRBs from the External Tank differed from the identical pre-flight prediction of MET (Mission Elapsed Time) 122.97 seconds. 

Physical separation of the Left SRB was registered at MET 123.08 seconds, with the Right SRB’s physical separation recorded at 123.12 seconds.

SRB separation performance:

Nevertheless, all SRB separation commands and performances were classed as nominal during STS-135.

Release of all structural attachments (8 total; 4 on each SRB – 3 on the aft attach bolts to the ET and one on the forward attach bolt to the ET) was completed within 30 milliseconds of the issuance of the separation command from orbiter Atlantis’s General Purpose Computers (GPCs).

Booster Separation Motor (BSM) – thrusters that push the SRBs away and clear from the ET – firing was nominal, with all 16 BSMs firing to completion.

SRB post-separation flight profile:

Both SRBs were tracked by ground-based radar assets from their separation from the ET to their loss of signal (LOS) due to the curvature of the Earth.

This LOS due to the curvature of the Earth nominally occurs at approximately T+340 seconds. But during STS-135, LOS for the Left SRB occurred at T+328 seconds, 12 seconds earlier than normal. Likewise, LOS with the Right SRB occurred at T+308 seconds, a full 32 seconds earlier than normal.

Post-flight review revealed this was due to a problem with the radar tracking site and not the SRBs’ post-separation flight profile.

Additionally, a temporary LOS was registered with the Left SRB at T+202 seconds. The signal was re-acquired at T+239 seconds. This LOS was traced to the same radar tracking site issue that resulted in the early, permanent LOS.

Radar tracking data of SRBs indicated a post-separation apogee altitude (highest altitude achieved) of 223,100 feet for the Left SRB at T+192 seconds and an apogee altitude of 223,200 feet for the Right SRB at T+192 seconds.

This deviated from the pre-flight prediction and Program nominal apogee of 226,836 feet by more than 3,636 feet.

Likewise, peak dynamic pressure on the Left SRB also deviated slightly from historical norms with a registered peak dynamic pressure of 1,500 pounds per square feet (psf) at T+309 seconds v. the historical norm of 1,456 psf at T+313.9 seconds.

Peak dynamic pressure for the Right SRB was not recorded due to the radar track site issue that led to an early LOS.

Nonetheless, both the peak dynamic pressure deviation and shallow apogee of the SRBs were “within the experience base of ascent trajectory planning and post-separation radar tracking.”

Drogue parachute deployments and associated loads were nominal, as was main parachute deployment, inflation, and associated loads.

Horizontal ribbon damage on five of the six main parachutes was reported during post-flight reviews; however, it was not noted during recovery operations if the damage was already present on the parachutes – indicated in-flight damage – or if the damage was caused during recovery operations.

Both SRB extension nozzle jettisons after main chute deploy and before water impact were nominal.

SRB splashdown:

With three fully inflated main parachutes each, both SRBs achieved nominal velocity for splashdown into the Atlantic Ocean.

Deriving splashdown times from “acceleration data recorded by the on-board data acquisition systems,” the Left SRB impacted the water at MET 398.98 seconds. The Right SRB followed with splashdown at MET 403.70 seconds.

Both SRBs hit the water at a relative speed of 76 ft/sec with a horizontal wind velocity measured at 30 ft/sec and seas at 4-6 ft at both splashdown locations.

Information from the Data Acquisition System (DAS) – a system installed in the parachute camera canister in the forward skirt of each SRB to record vehicle acceleration loads from just after liftoff to splashdown in the +/-125 G category – indicated a nominal +11.7 g water impact of both SRBs.

According to the SRB performance report, “This is within the range of normal SRB rigid body axial accelerations experienced for three fully open main parachutes.”

Likewise, post-splashdown cavity collapse occurred 1.17 seconds after splashdown in the Left SRB and 1.10 seconds after splashdown in the Right SRB.

Both cavity collapse times corresponded to in-family parameters from previous flight experience.

Interestingly, accelerometers in both SRBs did not record a “hard SRB splashdown” event that is nominally recorded approximately 3 seconds after water impact.

Thrust Vector Control system performance during flight:

For STS-135, all in-flight performance readings for the critical Thrust Vector Control (TVC) system indicated the proper positioning of all TVC actuators as commanded. 

As noted by the presentation, “During prelaunch and ascent, all actuators positioned as commanded. Actuator rates and duty cycles also correlated with the issued commands.”

All TVC actuator duty cycles correlated well the 134 flight experience base for the Right and Left SRBs, and all rock/tilt numbers fell well within the flight experience envelope.

Nevertheless, there were six minor exceedances in the second-to-second experience base… four for the Left SRB and two for the Right SRB.

The first second-to-second exceedance for the Left SRB occurred at T+12.5 seconds. “The LH Position TVC Tilt Actuator Position B58H1151C exceeded the second-to-second High Experience Base. The experience base high value was 1.89 inches, and the actuator position was 2.71 inches,” notes the USA SRB flight performance report.

This 2.71 inch actuator position was still well within the overall Left SRB maximum flight experience envelope during the roll maneuver.

Likewise, the all the other instances of SRB TVC actuator duty cycles spiking above the second-to-second maximum flight experience base were still contained within the overall maximum flight experience envelope.

SRB Thermal Performance:

Thermal performance reviews for the two SRBs for STS-135 further indicated a very clean and safe flight, with the actual flight thermal environment being “less severe than the current Performance-Enhanced Space Shuttle ascent and 95 percentile descent design environments.”

Click here for recent SRB/RSRM Articles: http://www.nasaspaceflight.com/tag/srb/

No breach to the structural temperature limit exceedances were observed on the recovered SRBs, and all post-flight TPS (Thermal Protection System) conditions were well within family and consistent with previous nominal flights.

SRB in-flight debris environment:

A debris assessment review from ground cameras and on-board flight/engineering cameras from the SRBs and External Tank revealed a nominal performance and no major areas for concern.

In fact, only one squawk, 135-001, was written for “suspect ascent impacts in the RH ETA (External Tank Attach) Ring froth-pak foam,” notes the SRB performance report.

Post-flight analysis of the impact area revealed no foreign debris, and the impact areas themselves were consistent with previously-observed ice impacts to ETA ring froth-pak foam.

Moreover, all observed post-flight material loss was within flight experience and easily attributed to post-separation, splashdown, and recovery activities.

SRB onboard camera performance:

All four SRB engineer cameras and four Solid State Video Recorders (two per SRB) functioned nominally during first stage flight.

Likewise, ET-facing engineering cameras on the SRBs to monitor engineering targets of interest during SRB separation from the ET functioned as expected and collected good engineering images of the ET intertank panel during separation.

The camera feeds from the ET-facing cameras automatically switched to the parachute cameras 5mins 50seconds after liftoff. Nominal observation of the parachute deployment sequence was observed on both SRBs by the parachute engineering cameras (one per SRB).

An excellent final performance of exceptional hardware/propulsion element:

Overall, STS-135 appears to be the cleanest and safest flight of the ATK-produced Solid Rocket Boosters in the history of the Shuttle Program with ZERO In-Flight Anomalies indicated during preliminary post-flight inspections and only ONE squawk for damage that most likely was caused from ice from the External Tank, not the SRBs.

However, it is impossible to verify if this was, as suspected and indicated, the cleanest and most-successful flight of the Solid Rocket Boosters as no formal IFA review was held.

Nonetheless, the SRBs ended their service to the Shuttle Program as tried, true, and safe propulsive elements – thanks in great part to NASA’s and ATK’s intense desire to safely use the SRBs.

Obviously, this level of safe use changed significantly in 1986, finally morphing into what it always should have been.  But throughout the life of the Shuttle Program, continuous efforts were taken – at a different level of enthusiasm in the early days of the Program – to learn about and improve upon the SRB design.

This strategy and desire was greatly aided by the fact that 133 of the 135 SRB flight sets were recovered after launch, disassembled and painstakingly scrutinized for any defects or off-nominal indications.

Only two flight sets (4 SRBs total) throughout the life of the Program were not recovered: those on STS-51L/Challenger and those on STS-4/Columbia. The SRBs on STS-4/Columbia suffered parachute deployment failures and impacted the Atlantic Ocean at terminal velocity, shattering into multiple pieces and sinking to the bottom of the Atlantic.

Through this recovery and post-flight inspection process, safety levels continuous improved – even reaching the point of suspending Shuttle flight operations in the mid-1990s to address a partial burn-through of an inner O-ring on just one SRB.

And NASA’s use of SRBs is not over.  SRBs will continue to serve manned and unmanned launch endeavors for NASA as the Shuttle’s successor vehicle, the SLS rocket, makes use of twin 5-segment SRBs, verse the Shuttle’s 4-segment Solids, for its debut series of flights currently anticipated for the latter years of this decade.

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

(Images: L2′s STS-135, SRB, RSRM and IFA sections – all highly expansive collections of presentations, photos, video and data. Additional via NASA and Brian Papke - MaxQ Entertainment/NASASpaceFlight.com.)

(L2 and NSF are continuing to follow the orbiters through to their final resting places. To join L2, click here: http://www.nasaspaceflight.com/l2/)

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Heartbreak And Honor:

It was only last summer when Atlantis was busy in space, doing what she does best, on a mission that was being conducted by an orbiter which hadn’t even reached the half way point of her service life.

Rather than looking forward to her next mission, Atlantis had to endure numerous speeches – and on occasion the crocodile tears of those who pushed for the program’s end – citing the “bright” future for NASA, despite her successful landing being marked more noticeably by the thousands of pink slips that were handed out to the workforce that helped enable her safe return.

Atlantis’ mission even missed out on the regular report card of the In Flight Anomaly (IFA) review (L2 Link to all IFA presentations from recent missions) - a key component for a follow-on, as NASA opted to ensure a line was drawn under the Space Shuttle Program (SSP), visibly seen on at least two occasions by the sight of shuttle documentation literally being thrown into trash bins near the Launch Control Center (LCC).

At the same time, a team was working towards a reprieve for Atlantis and her younger sister Endeavour, as efforts were made to take control of the orbiter’s fate via a privately funded deal – as reported by this site – before that effort failed due to the amount of “re-purposing” work that had already taken place for the Space Launch System (SLS).

One former United Space Alliance (USA) engineer sarcastically noted that if some NASA leaders put the same amount of effort into advancing SLS’ progress, as they did to kill the Space Shuttle Program, “we’ll be on Mars before you know it.”

To most people, the retirement of the Shuttle was sealed via the loss of the flagship Columbia during STS-107. It is also claimed that any real viable reversal of the retirement decision – made during the now-defunct Vision for Space Exploration (VSE) – required full political and agency level support around three years before STS-135, due to the phased shutdown of critical contractor bases.

Thankfully, the main enduring memory will be how the Space Shuttle Program (SSP) covered itself in glory since Return To Flight, not only successfully completing the final role for the fleet – as seen via the completion of the giant space station which continues to fly over our heads – but also via a run of amazingly flawless missions, conducted by what was a hugely complex – and indeed risky – spaceship by design.

Taming the orbiters for their swansong missions – and returning each ship and their crews home safe – not only honored Columbia and her fallen crew, but also provided a wealth of experience and knowledge, all of which is being handed down to the follow on programs, both NASA and commercial, with a priority on crew safety.

Soon the public will be able to honor the three remaining orbiters in person, with Discovery, Endeavour and Atlantis all moving through their Transition and Retirement (T&R) operations.

Discovery has made the most progress, as was expected, now sporting the Replica Shuttle Main Engines (RSMEs) – given all flight SSMEs have since transitioned to the SLS program – while the tailcone has been installed around her aft, a required piece of hardware to allow for her final journey to Dulles Airport on top of the Shuttle Carrier Aircraft (SCA).

She will be rolled to the Shuttle Landing Facility (SLF) where she will be mated on top of the SCA in the coming months, with a final flight transiting her to the retirement destination of the world famous Smithsonian. She will also spend a short period greeting Enterprise on the runway, ahead of her trip to New York City.

Atlantis is yet to receive her RSMEs, and with missing Orbital Manuevering Pods (OMS) and Forward and Aft Reaction Control System (RCS) hardware, she did look less glamorous than usual during her roll to the VAB , where – upon arrival – she was greeted by Endeavour taking a peek at her older sister through a gap in the Transfer Aisle.

However, she wouldn’t of been aware of her shoddy appearance, following her final powerdown in late December of last year. The powerdown marked the end of her 26 year service to the United States and the world.

With Endeavour set to fly to the West Coast for her retirement, Atlantis at least gets to stay at her home port, taking center stage at a new facility which began ground breaking this week.

The retirement home will be hosted at the Kennedy Space Center Visitor Complex, with construction starting on a new 65,000-square-foot exhibit at the complex’s Space Shuttle Plaza.

“It is an honor to create the home for space shuttle Atlantis and to work with NASA to tell its story to the world,” said Jeremy Jacobs, chairman and chief executive officer of Delaware North Companies, which operates the visitor complex for NASA.

STS-135 commander Chris Ferguson was at the ground breaking, again showing his loyalty to the orbiter he brought home safe last year. The commander believes the public access to his ship will inspire future generations to step in his footsteps as an astronaut.

“It’s very fortunate we can celebrate this milestone, fortunate we had the foresight and the resources to preserve Atlantis to serve as a reminder of the limitless potential of the citizens of the United States of America, and inspire those who will come after us,” said Commander Ferguson.

“This coming Saturday does mark six months since the final landing of Atlantis out here, about three miles behind me,” said Ferguson.

“With that final landing, the shuttle program came to a conclusion after 30 years of discovery and exploration. At times we had to lick our wounds, at times there were joyous moments, but by the grace of God we concluded the program just the way we wanted to, very safely.”

However, the most apt words – at least from Atlantis’ standpoint – came from Janet Petro, deputy director of Kennedy Space Center, mirroring the affection shown towards the orbiters from the teams which often noted how the vehicles were like family members.

“For 30 years, the orbiters have been a part of our family. We’ve cared for them, we’ve protected them, and we’ve watched them soar. We’ve marveled at the similarities between them, and the differences that only ‘family’ could identify.

“Atlantis’ new home is beautifully designed to showcase her as the true engineering marvel that she is.”

To read about Atlantis from birth through to retirement, click here for the links:
http://forum.nasaspaceflight.com/index.php?topic=25785.0

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 NASA and L2 content.)

(L2 and NSF are continuing to follow the orbiters through their transitional period. To join L2, click here: http://www.nasaspaceflight.com/l2/)

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SSMEs Shipping Out:

The change of home from the Kennedy Space Center (KSC) to NASA’s Stennis Space Center (SSC) in south Mississippi is a natural transition for the 15 engines, not least because the SSMEs underwent testing at Stennis ahead of their flight roles with the orbiters.

However, it’s their future role of becoming part of the SLS test program which has breathed new life into the famous engines, some of which will actually gain the honor of going out in style, launching one last time with the SLS during the first few missions.

Their transition from KSC will take place one engine at a time, as they travel to Mississippi by truck. Once at SSC, the SSMEs will join SLS’ Upper Stage J-2X engine – which is being tested at the facility – allowing for all SLS engine assets to be in one location, leveraging the existing knowledge base, skills, infrastructure and personnel.

“The relocation of RS-25D engine assets represents a significant cost savings to the SLS Program by consolidating SLS engine assembly and test operations at a single facility,” said William Gerstenmaier, NASA’s associate administrator for Human Exploration and Operations Mission Directorate.

The relocation also frees up the Space Shuttle Main Engine Processing Facility at KSC, which became part of a commercial deal with Boeing – in collaboration with NASA and Space Florida – to being exclusively occupied  by the company, along with Orbiter Processing Facility 3 (OPF-3) and the Processing Control Center, as they ramp up operations for their CST-100 spacecraft.

“This enables the sharing of personnel, resources and practices across all engine projects, allows flexibility and responsiveness to the SLS program, and it is more affordable,” said Johnny Heflin, RS-25D core stage engine lead in the SLS Liquid Engines Office at Marshall.

“It also frees up the space, allowing Kennedy to move forward relative to commercial customers.”

SSME: End Of A Shuttle Era:

The RS-25s have an amazing flight record with the Space Shuttle – with only one engine suffering a problem during the entire 30 years of the program.

*To read about all three orbiters - from birth, processing, every single mission, through to retirement - click here for the links:
http://forum.nasaspaceflight.com/index.php?topic=25837.0*

That single issue occurred during STS-51F with Challenger, when one of two high pressure fuel turbopump turbine discharge temperature sensors for SSME-1 failed, leaving only one sensor active on the engine. Two minutes 12 seconds later, at Mission Elapsed Time 5mins 43secs, the second sensor failed, triggering the immediate shutdown of SSME-1.

The shutdown of SSME-1 significantly lowered the thrust profile for Challenger and triggered the only in-flight abort in Shuttle Program history: an Abort To Orbit (ATO) which allowed Challenger and her seven-member crew to reach a lower-than-planned but safe and stable orbit.

Nonetheless, before Challenger could complete her prolonged ascent (nearly 9mins 45secs in duration due to the lost thrust from SSME-1), an identical high pressure turbopump temperature sensor failure occurred in SSME-2.

Booster Systems Engineer Jenny M. Howard in Mission Control Houston acted immediately, instructing the crew to inhibit any further automatic SSME shutdowns based on readings from the remaining sensors. This quick action prevented the loss of another engine and a possible abort scenario far more risky or far worse than the already in-progress ATO.

When Challenger finally reached orbit, several aspects of the mission were retooled to account for the lower-than-planned orbital altitude.

Click here to read recent articles on the SSMEs: http://www.nasaspaceflight.com/tag/ssme/

As per the In Flight Anomaly (IFA) reports for the final three missions, all nine of the SSMEs performed admirably, as they assisted the orbiters for the ride uphill into orbit.

For STS-133, all three of Discovery’s SSMEs last flew with Atlantis during STS-129, although in different positions – after they required removing and re-installing in different positions, in order to allow a changeout of ME-1′s Low Pressure Oxidizer Turbo Pump (LPOTP) early in the flow.

Discovery flew with Main Engine 1 (ME-1) – serial number 2044, ME-2 – 2048 and ME-3 – 2058. All their related hardware was the same as that which flew with Atlantis, bar a couple of elements, such as a new nozzle for ME-1.

The only notable issue with the SSMEs occurred pre-launch, relating to a power issue with the redundant Main Engine Controller (MEC) on SSME 3.

The SSME controllers provides complete and continuous monitoring and control of engine operation. In addition, it performs maintenance and start preparation checks, and collects data for historical and maintenance purposes.

STS-133 Specific – Including ET Stringer Issue – Articles: http://www.nasaspaceflight.com/tag/sts-133/

The controller is an electronic package that contains five major sections; power supply section, input electronics section, output electronics sections, computer interface section, and digital computer unit.

Pressure, temperature, pump speed, flowrate, and position sensors supply the input signals. Output signals operate spark igniters, solenoid valves, and hydraulic actuators. The controller is dual redundant, which gives it normal, fail-operate, and fail-safe operational mode capability. The problem was specific to the redundant controller on ME-3.

Actions taken during troubleshooting included the installation of a breakout box and the testing of three single phase circuit breakers for SSMEC 3B on Panel L4. Although this inspection was limited by access, engineers pro-actively replaced all 18 SSMEC circuit breakers at the recommendation of management.

The problem soon became clear when CB 109 was inspected, with a clear observation of non-conductive debris on the hardware, a key candidate for the original problem seen with SSME 3′s redundant MEC.

After the troubleshooting was signed off at the Flight Readiness Review (FRR), all three engines – and controllers – performed without issue during ascent.

“Engine operation was nominal. ME-1 2044, ME-2 2048, ME-3 2058 – No SSME IFA Identified,” noted the STS-133 SSME IFA presentation (L2 Link to Presentation). “SSME observations are encompassed by previous flight and/or test experience and identified as no impact.

For STS-134, Endeavour’s ride into orbit was aided by a noisy trio that were no stranger to the aft of the youngest orbiter in the fleet, after pushing her uphill during STS-130.

The engines were installed for one final trip with Endeavour in the following positions on the orbiter: ME-1 – 2059, ME-2 – 2061, while 2057 was ME-3.

Only one item of interest made it into the FRR documentation for the SSMEs ahead of STS-134′s mission, referencing the incident when an ELSA (Life Support) bottle fell from the entrance level near the 50-2 door and hit Main Engine 2 (ME-2) during Vehicle Assembly Building (VAB) processing operations.

“STS-134 Endeavour ME 2 ELSA Bottle Damage Inspections: Issue: Possible handling damage to ME-2. Background: ELSA Bottle dropped from above ME-2 to heat shield adjacent to controller during VAB processing. Damage observed above and adjacent to engine,” noted the STS-134 SSME SSP FRR presentation (L2 Link to Presentation).

“Dent in Orbiter GN2 Line. Dent on edge of Heat Shield near ME-2 controller. Witness statements and damage indicate no engine impact. Assessment conducted around 4.5 Ft assuming possible engine contact.”

With this issue cleared, Endeavour launched on her final mission without incident and successfully completed her mission on June 1, 2011.

As what became a regular observation, the 14-15 IFA presentations per mission (all acquired by L2 –  link to presentation collection) reviewing the mission post flight included a very short SSME presentation, noting no anomalies (L2 Link to Presentation).

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

For STS-135, Atlantis’ engines were ME-1 – 2047, ME-2 – 2060 and ME-3 – 2045.

Again, the only incident of note came before the engines were fired up at launch, when IPR-49 (Interim Problem Report) noted a problem with the Main Fuel Valve (MFV) on SSME-3, spotted during a tanking test to check the integrity of the modified stringers on the stack’s External Tank (ET-138).

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.

The issue – the observation of a leak – was also covered in depth via the STS-135 SSP Flight Readiness Review (FRR) presentation for the SSMEs (L2 Link to Presentation), 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 related 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.

The MFV was replaced out at the pad and put through a series of leak checks. While those passed, the real test came during launch day, when the system was put through the cryogenic environment of tanking. Again, the skilled KSC and SSME engineers were shown to have successfully fixed the problem, as Atlantis launched for the final time without issue.

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

Now these stalwart engines – which includes the spare flight set: ME-1 – 2052 ME-2 – 2051 and ME-3 – 2054 – plus three others, are departing KSC once again – this time by road.

SSME To SLS Core:

Their potential role with the SLS was noted during the final flights of the Shuttle, as the 2010 Authorization Act reversed the FY2011 budget proposal which would not have seen any involvement of the RS-25s.

With a Shuttle Derived (SD) version of the Heavy Lift Launch Vehicle (HLV) consistently winning during trade studies, which once again pointed at a configuration which used RS-25s as the preference, the Program Requirements Control Board (PRCB) took action to protect the engines.

While NASA’s “White House-aligned” leadership continued to avoid pressing forward with the confirmation of the SD HLV SLS configuration, the PRCB stepped in to “preserve the SSME flight engines for future Agency use” (L2 Link to Presentation)- adding to a previous action to slow down the Transition and Retirement (T&R) of the contractor ability to manufacture flight spares for the RS-25s.

The PRCB also provided the approval for the orbiters to gain Replica Shuttle Main Engines (RSMEs) – previously scrapped nozzles installed via an adaptor – for when the vehicles retire to exhibitions, freeing up the flight flown SSMEs.

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

With the orbiters also donating large elements of their Main Propulsion System (MPS) – a heavily related collection of plumbing and lines – to the SLS program, a large amount of the HLV’s core guts will be from the orbiters for at least the testing/pathfinder stage, through to the opening launches.

The ongoing trades taking place at the Marshall Space Flight Center (MSFC) are also working through the core’s configuration for the three versions of the SLS, namely the Block I – 70mt, the Block IA – 100mt, and the Block II – 130mt vehicles.

Technically, SLS could launch with three, four or five RS-25s from the outset. However, with three engines on the core, and the automatic need for the core to be “stretched” – based on the five segment boosters on the configuration – using four engines would allow the vehicle to fly fully fueled in all configurations, saving the extra calculations/testing for an under-filled three engine core.

Per the meetings – as much as no decision has been made at this time ahead of the key Systems Requirements Review (SRR) and Systems Design Review (SDR) – it appears four engines on the first stage would be best prescribed for the SLS from the start, per sources.

SLS will naturally evolve after the opening flights of the Block I SLS, with SSME contractor Pratt & Whitney Rocketdyne (PWR) producing RS-25E engines for the rest of the SLS’ lifetime. The RS-25E – based on the reusable SSME (RS-25D) – is expendable and thus requires less long-life hardware items, in turn making it cheaper to produce.
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ISS cargo deliveries:

The year 2011 was a highly successful year in terms of cargo flights to the ISS, with January’s launch of Japan’s H-II Transfer Vehicle-2 (HTV-2), February’s launch of Europe’s Automated Transfer Vehicle-2 (ATV-2), and the successful launches of Space Shuttle missions STS-133, STS-134 and STS-135, as well as numerous Russian Progress flights.

The delivery and installation of the Permanent Multipurpose Module (PMM) to the ISS on STS-133 in February increased the amount of stowage space available on the station for cargo, which paved the way for STS-135 to deliver a massive stockpile of crew provisions to the station on the final Shuttle mission in July.

The stockpile of crew provisions from STS-135 will enable the station to make it to mid-2012 without any additional deliveries of cargo, and make it to 2013 when supplemented with deliveries of cargo from Europe’s ATV and Japan’s HTV. Thus, successful commercial and non-commercial resupply flights to the ISS are essential in order to maintain a crewed presence on the station throughout 2012.

The late-addition of STS-135 to the Shuttle’s manifest in order to shore up ISS’ supplies is already being seen as an excellent decision, given the delays of commercial resupply flights to the ISS and recent failures of Russian rockets.

Non-commercial cargo vehicles:

This year’s non-commercial cargo vehicle flights to the ISS will see two large deliveries made to the station by both Europe and Japan.

Europe’s ATV-3 spacecraft, named “Edoardo Amaldi”, is currently set to launch to the ISS atop an Ariane V rocket from the Kourou space center in French Guiana, on 9th March, and arrive at the ISS for a docking to the Service Module (AM) Aft port ten days later on 19th March. It is scheduled to undock from the ISS on 27th August.

ATV-3 will carry more “dry” cargo (i.e. internal items) than ATV-2 carried to the station in 2011, due to numerous internal structural modifications that have been made that will allow ATV to carry additional internal payload.

This will mean that less “wet” cargo (i.e. propellants) will be carried by ATV-3, however this will not be of big impact to the ISS since ATV-2 performed four “big boosts” of the ISS in 2011 that boosted the station’s altitude to a mean of around 400km, meaning less reboosts will be needed in future, and thus less requirements for propellants. (L2 Link)

The next large non-commercial delivery of ISS cargo will be via Japan’s HTV-3 spacecraft, currently scheduled to launch on 26th June atop an H-IIB rocket from the Tanegashima space center in Japan, arriving at the ISS five days later for a 1st July rendezvous, capture and berthing.

HTV-3 will depart the ISS on 15th August. The HTV-3 mission was originally scheduled for the first quarter of 2012, but was pushed back to mid-2012 due to delays in hardware processing caused by the Japanese earthquake in 2011.

In additional to bringing a large volume of internal cargo to the station, HTV-3 will also carry two external payloads for the ISS – the Space Communication and Navigation (SCaN) testbed, which will be attached to ExPrESS Logistics Carrier-3 (ELC-3), and the Multi-mission Consolidated Equipment (MCE), a payload for the Japanese Exposed Facility (JEF). (L2 Link)

Five Russian Progress flights to the station are also planned in 2012 – Progress M-14M on 25th January, M-15M on 25th April, M-16M on 25th July, M-17M on 23rd October, and M-18M on 26th December. (L2 Link)

Progress flights, however, will be of particular interest to the ISS Program over the course of 2012 due to the multiple failures of Russian launch vehicles in 2011, including two third stages of Soyuz rockets – a Soyuz-U with Progress M-12M/44P on 24th August, and a Soyuz 2-1b with the Meridian satellite on 23rd December.

However, the Progress M-12M third stage failure was attributed to a problem in the RD-0110 engine, while the third stage failure of Meridian used a newer RD-0124 engine.

If any further Soyuz rockets fail in 2012, it will not only have implications for Progress cargo flights, but also Soyuz crewed flights, which could lead to a de-crewing of the station since the ISS partners now depend on the Soyuz for crewed access to the station.

As such, successful launches of both Progress and Soyuz spacecraft are vital for a continued crewed presence on the ISS throughout 2012.

Commercial cargo vehicles:

This year will also mark the first of two long-awaited commercial cargo vehicles visit the station – SpaceX’s Dragon, and Orbital’s Cygnus.

The first commercial spacecraft to attempt to reach the ISS will be SpaceX’s Dragon, which is currently scheduled to launch on the combined COTS-2/3 (C2/C3) mission atop a Falcon 9 rocket from Launch Complex-40 (LC-40) at Cape Canaveral Air Force Station (CCAFS) on 7th February.

Preliminary timelines show that COTS-2 objectives (rendezvous and communication tests) will be performed the day following launch, with COTS-3 objectives (rendezvous, capture & berthing) being performed two days after launch on 9th February. These timelines, however, are not confirmed at this time.
Following a two week stay at the ISS, during which some non-critical supplies will be transferred to the ISS, Dragon will be unberthed from the ISS on 23rd February, for a re-entry and splashdown off the coast of California. (L2 Link)

While Dragon was originally scheduled to reach the station in 2011, ongoing setbacks from the Progress M-12M launch failure and subsequent ISS crew impacts, ISS hardware and software upgrades, Dragon software testing, and Dragon flight review processes delayed the flight into 2012.

With the successful docking of Soyuz TMA-03M/29S to the ISS on 23rd December, which delivered US astronaut Don Pettit to the station, all crewmembers trained to capture and berth Dragon are now aboard the ISS.

ISS hardware and software upgrades, notably the Enhanced Processor & Integrated Communications (EPIC) and X2_R10 software transition, got underway aboard the ISS last week and will continue throughout this week, so far with success.

Dragon software testing and flight reviews are currently ongoing, as much a big hurdle – deployment of an ORBCOMM secondary payload – has now been removed from the C2/C3 mission so that SpaceX can concentrate on Dragon’s flight to the ISS, and not have to worry about ISS conjunction concerns from the ORBCOMM.

Assuming the C2/C3 mission is a success, SpaceX are schedule to fly at least one more Dragon to the ISS in 2012 as an operational resupply spacecraft.

The next commercial cargo craft to attempt to reach the ISS after Dragon will be Orbital’s Cygnus spacecraft, currently scheduled to launch No Earlier Than (NET) June due to ongoing delays with launch pad readiness. A hot-fire test and a test launch with a dummy payload of Cygnus’ Antares (formerly Taurus II) launch vehicle need to be performed prior to the Cygnus C1 mission.

Since ISS can make it only as far as 2013 without any commercial cargo deliveries (assuming successful deliveries of cargo by non-commercial vehicles), this means that at least one commercial resupply vehicle must successfully reach the ISS in 2012 in order to maintain a crewed presence in 2013.

The margin for failure of this year’s COTS vehicle test flights is tight, with sources noting that even with the stockpiles of supplies from STS-135, ISS will struggle to sustain a failure of any COTS vehicle to reach the station.

As such, retirement of the Space Shuttle and its large up/downmass before an operational commercial resupply capability was available has placed additional risk on the ISS, since test flights of new, and in the case of Orbital, untested launch vehicles and spacecraft are now on the critical path for sustained ISS operations.

Although the commercial vehicles in question have yet to reach the station at the start of the year in which they must become operational, the due diligence displayed thus far by both NASA and its commercial partners enables is an encouraging sign.

While the commercial resupply vehicles have been a long time coming, the end is now in sight for the COTS (Commercial Orbital Transportation Services) development program and the transition to the operational Commercial Resupply Services (CRS) program. Due to both the high risks and high payoffs involved, 2012 is likely to be the make-or-break year for COTS and CRS.

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2. NASA managers announce February 7 launch date for Dragon ISS missionIn what will be a highly historic mission, NASA managers...
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OV-103/Discovery – The final voyage of the veteran workhorse:

For the final year of the Space Shuttle Program, operations in 2011 began where all Shuttle missions have: in the Vehicle Assembly Building.

After enduring a rollback from LC-39A in late-December 2010, because of cracks on the stringers of her External Tank’s (ET) intertank structure, Space Shuttle orbiter Discovery, OV-103, spent the first month of 2011 in the VAB undergoing ET intertank repairs and strengthening activities while the various NASA centers conducted numerous simulations to nail down the cause of the ET stringer cracks. (L2 Link).

Discovery, the third operational Shuttle orbiter and fourth overall Shuttle orbiter constructed by NASA, was preparing for her 39th and final mission in November 2010 when the stringer crack issue presented itself during the mission’s first launch attempt on November 5, 2010.

Following the discovery of this issue, NASA mission managers refused to set a launch date for the flight in a concerted effort to allow the engineering analysis teams to have the time they needed to properly and safely address the issue without feeling a push toward launch fever. 

STS-133 Specific - Including ET Stringer Issue - Articles: http://www.nasaspaceflight.com/tag/sts-133/

On January 4, NASA identified the potential root cause for the stringer issue – a mottling on the stringers themselves.

As noted by an investigation report, “Some material used for the stringers was found to be ‘mottled,’ with a different surface appearance than the standard material. Testing revealed this mottled material had lower fracture toughness than the nominal material and exhibited unstable crack growth.

“All of the cracks found during tanking as well as cracks fixed during manufacturing were located on stringers made with this mottled material.”

Furthermore, engineers were finally able to recreate the stringer crack failure seen on Discovery’s ET using the stringers from the partially-built ET-139 at the Michoud Assembly Facility (MAF).

By January 6, the all-powerful Program Requirements Control Board (PRCB) had directed teams to proceed forward with the radius block modification on well over 100 of Discovery’s tank stringers – a decision that further emphasized the drive for safety and understanding over launch date pressure.

With that, Discovery’s launch date was penciled in for February 24 or 25 as negotiations began with other ISS partners – specifically ESA (the European Space Agency) which was planning to dock their ATV-2 vehicle to the ISS at the same time that Discovery would now be ready for launch.

After negotiations concluded, it was decided that ATV-2′s docking on the morning of February 24 would permit the launch of Discovery later that day – something that had previously been ruled out due to communication and on-orbit requirements of the two vehicles and the ISS crew.

But as repairs to Discovery’s stringers kicked into high gear and things looked to be settling out for the veteran space vehicle, STS-133/Discovery crewmember Tim Kopra was injured and had to be removed from the mission as a result.

Within three days, Steve Bowen was assigned to the mission as Tim Kopra’s replacement, and NASA, in making the crewmember switch announcement, made it clear that Bowen’s experience on the previous Shuttle mission, STS-132/Atlantis, meant that he would need only moderate refresher training to perform the EVA activities originally assigned to Kopra.

As a result, Discovery would keep her February 24 NET launch date, and Nicole Stott and Al Drew would split the Flight Engineering responsibilities for launch and entry that Kopra was originally assigned.

By the end of January, Discovery’s stringers were modified and reviews had cleared the vehicle to return to the launch pad.

On the night of January 31/February 1 – the 8th anniversary of the loss of sister Columbia – Discovery was returned to the launch pad for what would be the 20th post-Columbia mission.

By all would not be as smooth sailing as hoped. The GUCP once again showed its temperamental side by failing an ambient leak check at the pad. (L2 Link).

The GUCP was disassembled, inspected, its two-part flight seals replaced, and reassembled. Subsequent ambient leak checks revealed a healthy GUCP, and all pad activities continued on schedule.

On February 15, the Ariane 5 launch vehicle successfully delivered the ATV-2 ESA resupply vehicle for the ISS into orbit – paving the way for a 24 February docking of ATV-2 to ISS and subsequent launch of Discovery later that same day.

With all approvals in place, the three-day countdown began on Monday, February 21.

The countdown proceeded flawlessly, and fueling of Discovery’s External Tank yielded absolutely no issues with the modified stringers or the GUCP.

Following the successful docking of ATV-2 to the ISS on the morning of 24 February, final preparations continued, the crew boarded Discovery, and the Countdown reached T-9mins and holding.

And then… it happened: the Eastern Range suffered a computer anomaly that prevented them from seeing the necessary safety information readouts from Discovery.

As the Range team worked the issue, the minutes continued to tick toward the end of the day’s short launch window.

At T-9mins and holding, Launch Director Mike Leinbach and his team decided to pick up the count and then hold at T-5mins if the Range issue had not yet been resolved.

With concurrence from all involved, Discovery’s Commander, Steve Lindsey, told the millions watching to “get ready to witness the majesty and the power of the Shuttle Discovery as she lifts off one more time.”

The launch countdown picked up and was indeed held at T-5mins for just over 3mins as the Range continued to work the issue.

In a heart-pounded final seconds, the launch team moved, with esteem calm and professionalism, to resume the countdown in time once the Range issue was cleared.

In the end, the team successfully resumed the countdown with only 1 second of LOX drain back hold time – the limiting launch window factor that day – remaining before a scrub would have had to have been called for the day.

But that one second was all that was needed.

To thunderous applause, numerous tears, an on-hand spectator number reaching close to a quarter of million people, and under crystal clear skies, the Space Shuttle Discovery began the display she and her sisters were best known for when she gracefully lifted off from LC-39A at the Kennedy Space Center at 1653.24 EST and made one final reach for the stars.

A true tribute to America’s space workforce, Discovery executed a flawless ascent and safely, successfully, and with pride delivered her six-member crew and mission payload to LEO.

Discovery docked to the ISS for the final time on 26 February 2011.

With her docking, a historic milestone was reached for the ISS – a complete family moment with the ISS supporting all of its support vehicles: Shuttle, Soyuz, Progress, HTV, and ATV.

During the mission, Discovery delivered thousands of pounds of external spares via the Express Logistics Carrier ELC-4 and thousands of pounds of internal supplies for the Space Station via the newly minted Permanent Multipurpose Module (PMM) Leonardo – a former Multi-Purpose Logistics Module (MPLM).

The addition of PMM Leonardo marked the final, permanent, pressurized module to be delivered to the ISS by the Space Shuttle fleet and NASA.

After nearly nine days of joint-docked operations, the ISS bid a final farewell to Orbiter Discovery after 13 missions to the orbital outpost.

On March 9, just before 12-noon, Discovery announced her triumphant return to the Kennedy Space Center before flying effortlessly over her Florida home and easing down onto Runway 15 at 11:58:14 EST.

By the time Discovery rolled to a stop on the Florida spaceport runway, she had achieved the distinction of having spent a cumulative total of 365 days (a full year) in space.

She was also the oldest-surviving Shuttle orbiter in the fleet upon completion of her final mission as well as the first Space Shuttle orbiter to successfully complete every single one of her missions – including all three Return to Flight missions following the losses of her big sisters Challenger and Columbia.

Discovery’s service to the human race began on 30 August 1984 with the launch of the STS-41D mission and ended on 9 March 2011 having lasted 26 years 6 months 6 days and 39 missions.

OV-105/Endeavour - An emotional high for the baby of the fleet:

For Endeavour, the 2011 calendar year began with direct knock-on effects from the on-going stringer crack issue of her sister Discovery’s ET.

The Space Shuttle Endeavour, the fifth and final space-worthy orbiter and sixth and final overall Space Shuttle orbiter constructed by NASA, began 2011 in her OPF-2 home as NASA hammered out a fix to the stringer issue on the External Tank.

Following the identification of root cause of the issue and implementation of the radius block modification, NASA made the decision to modify ET-122 – the External Tank Endeavour was to use on her final mission – despite the fact that ET-122 was an earlier-constructed tank than Discovery’s and was not constructed from the same material batch as Discovery’s mottled stringers were.

Nonetheless, the decision was made to ensure the highest safety factor for Endeavour and her returned-to-service ET.

In many ways, Endeavour’s final journey to space was a story of perseverance and rising above the odds.

Endeavour herself had always been a symbol of triumph from the throes of tragedy as her existence is owed entirely to the loss of Challenger, the sister she never knew.

Called upon for multiple important missions during her storied career, Endeavour was the Space Shuttle Orbiter that saved the Hubble Space Telescope in 1993 and the Orbiter that began construction of the International Space Station in December 1998 when she launched on the STS-88 mission to join the US’s “Unity” module with Russia’s Zarya module.

For Endeavour’s final mission, her Commander was none other than veteran Shuttle flier Mark E. Kelly – who, like his vehicle, was an amazing source of strength, hope, and inspiration throughout the early months of 2011 and throughout the STS-134 mission.

But the perseverance on STS-134 did not end with Endeavour or her crew.  Despite the fact that the STS-134 mission was the first of the final two missions to be added to the end of the Shuttle manifest (and the first of the final Shuttle missions whose flight was specifically mandated by Congress), her External Tank was a major source of pride for the NASA workforce.

Built in 2002, ET-122 was damaged during the landfall of Hurricane Katrina near the New Orleans MAF construction facility for the tanks. In fact, ET-122 was so damaged by the hurricane that it was completely removed from flight status.

Originally, Endeavour’s mission was supposed to use ET-138 – the final completed External Tank in the numerical sequence.

However, the addition of the STS-335 Launch On Need rescue mission for Endeavour mandated the need for another tank. Rather than complete fabrication and assembly of a new tank, ET-139, the MAF workforce was directed in November 2008 to restore ET-122 to flight status.

In addition to all the hurricane repair work that needed to be made, MAF workers also had to implement most of the RTF (Return To Flight) modifications mandated by NASA in the wake of the Columbia accident.

By early 2011, NASA decided to move ET-122 to STS-134/Endeavour’s mission so that Atlantis, if the STS-335 rescue mission was needed, could fly with a perfectly clean tank instead of the patched-up, but extremely safe, ET-122.

With Endeavour fitted with ET-122 and her SRB set, the entire stack arrived and LC-39A on March 10 with a target April 19 launch to the International Space Station.

With a rather traumatic opening week to her last visit to Pad-A, Endeavour’s flight managers were forced to review TPS damage zones on the baby of the Orbiter fleet after a tool was accidentally dropped from the RSS (Rotating Service Structure) and impacted Endeavour before landing on the zero-level deck of the MLP (Mobile Launch Platform).

The damage was very minor and no repairs were carried out on Endeavour.

At this time, as well, Endeavour was also cleared to proceed toward her April 19 launch date when Russian space officials confirmed that their Soyuz launch would only be slipping to April 4 and not deeper in April like originally thought.

But by the end of March, Russia and NASA were once again into negotiations on Endeavour’s launch date as a conflict between Russia’s Progress M-10M spacecraft and Endeavour’s missions arose.

Endeavour eventually lost the fight and was forced to move to an April 29 launch date – which she continued processing toward despite multiple rounds of adverse weather at the launch pad that triggered evaluations of the stack for storm damage.

Also at this time, NASA managers decided to cancel plans for a Soyuz fly-about of the docked Endeavour/ISS stack because of crew impact concerns should the Soyuz fail to re-dock to the ISS. (L2 Link).

By April 13, NASA formally extended Endeavour’s swan song mission by one day. With a newly extended mission, Endeavour entered what was thought to be her final launch countdown on April 26.

On launch day, as Endeavour’s crew prepared for their journey to the launch pad, an APU-1 heater issue presented itself. Initial attempts to troubleshoot the issue did not prove successful, and Launch Director Mike Leinbach scrubbed the April 29 launch attempt.

In the following week, the APU-1 heater issue was quickly traced to the Aft Load Control Assembly (ALCA-2) box. The ALCA-2 was Removed and Replaced, where a blown driver was subsequently focused on as the cause of the heater issue. (L2 Link).

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

With a new ALCA in place, Endeavour’s launch was retargeted for May 16.

For the final time, the countdown for the launch of Space Shuttle Endeavour began on Friday, May 13.

Thanks to the delay in the launch date, and agreements with Russia to undock the Soyuz TMA-20 for a nominal end of Soyuz mission landing during Endeavour’s docked mission, the formal plan to use the departing Soyuz to capture imagery of the docked Endeavour/ISS stack returned to mission planning.

On May 16, even though the weather looked borderline at best, all launch commit criteria aligned, leading to a final, unanimous “GO” for launch decision.

From the cockpit of Endeavour, Commander Mark Kelly said, “We endeavor to build a better life than the generation before and we endeavor to be a united nation. It is in our DNA to reach for the stars and explore. We must not stop.”

And mere minutes later, under overcast, grey, dreary skies, the Space Shuttle Endeavour roared to life for the 27th and final time as she thundered from the launch pad to begin her 25th and final voyage.

To many on the ground, including the launch team, Endeavour seemed to take just a little longer than normal to rise from the launch pad, turn, and begin her historic final mission to space – giving the 500,000 to 750,000 people in personal attendance the feeling of being able to see her for just a bit longer in all her glory.

Her launch was a moment of historical coincidence as well. Endeavour lifted off for the final time exactly 19 years to the day (May 16) after she landed to conclude her maiden voyage, the STS-49 mission in May 1992.

As she had 24 times before, Endeavour dutifully delivered her crew safely to orbit and performed a flawless docking to the ISS two days later.

Her mission marked the delivery of the premiere and exciting Alpha Magnetic Spectrometer to the ISS – an experiment designed to search for evidence of the existence of dark matter, anti-matter, and dark energy in our universe.

The mission also saw the delivery of ELC-3 – the final large delivery of external spares for the ISS – to the Station.

And, as we all remember and cherish, the mission also provided the stunning photography and video of Endeavour docked to the International Space Station from the vantage point of the departing Soyuz spacecraft. (L2 Link to 271 hi res flyaround photos)

But the greatest milestone of all came toward the end of Endeavour’s docked mission: US Assembly Complete of the International Space Station - achieved when Endeavour’s crew transferred and berthed Endeavour’s OBSS (Orbiter Boom Sensor System) to the orbiting outpost.

Thus, Endeavour was the orbiter that began and completed US assembly of the International Space Station.

(Animated image resized from hires/full screen version and sequence photo dumps on L2′s STS-134 Flight Day image section - several hundred megabytes strong – L2 Link.) 

After 11 days 17 hours 41 minutes of docked operations with the ISS, Endeavour bid a fond farewell to her orbital child.

Two days later, under the cover of darkness, Endeavour gallantly swooped down over her Florida home to end her career on 1 June 2011 at 0235 EDT.

To the very end, Endeavour was and always will be an iconic symbol of hope, a ship that inspires pride, awe, the quest for knowledge, and the determination to pick ourselves up and continue forward when adversity would rather us surrender.

After 19 years 24 days 6 hours and 55 minutes of service (May 7, 1992 at 1940 EDT to June 1, 2011 at 0235 EDT), Endeavour officially ended her tenure with the Space Shuttle Program. But she still remains our hope for a new tomorrow, an era when humans will regularly explore the space beyond the confines of our home world and push our boundaries of scientific knowledge and our quest of exploration.

OV-104/Atlantis - The Grand Finale of an American icon:

STS-135: The flight that wasn’t even manifested at the start of 2011.

Included in the NASA Authorization Act of 2011, which was signed into law on 11 October 2010, funding for the STS-135 mission remained in limbo while Congress remained incapable of reaching an agreement on the exact nature of the Fiscal Year 2011 calendar budget.

To this end, NASA continued procurement of mission hardware and software for the STS-335 contingency LON rescue mission which would have been used in the event that Endeavour became disabled during STS-134.

On 20 January 2011, NASA officially changed the mission designation number for STS-335 to STS-135 on internal documentation only (L2 Link), allowing teams to proceed with mission training and planning operations so that the continuing appropriations battle in Washington D.C. would not impact flight operations.

Finally, on 13 February 2011, NASA announced and confirmed that STS-135 would fly to the International Space Station regardless of whether or not appropriations from Congress materialized.

At this point, STS-135 became an officially manifested flight, making it one of the quickest missions to go from manifestation to liftoff in Shuttle Program history.

Undergoing a near one-year OPF-1 flow for STS-335/135, Space Shuttle orbiter Atlantis was mated to her ET/SRB stack.

Arriving at the launch pad at the same time as her sister Endeavour landed a few miles away to complete her last mission on June 1, Atlantis began a one month eight day pad flow.

On 15 June,  a tanking test was performed on the Atlantis/STS-135 stack to confirm a solid fix to Atlantis’s Tank’s stringers – which underwent the same modifications as Discovery’s and Endeavour’s tanks had.

The Tanking Test revealed a healthy tank and modified stringers while also revealing a hydrogen fuel valve issue in Main Engine #3 that, if it had occurred on launch day, would have resulted in a multi-day scrub.

Replacement of the valve was completed on 21 June, just one day after Atlantis’s payload was installed into her payload bay.

Despite a dismal weather forecast with only a 40 percent chance of acceptable weather, NASA launch managers decided to proceed with the launch attempt on 8 July.

Tanking operations began right on time at 0201 EDT and wrapped up three hours later with no issue.

In fact, Atlantis performed flawlessly during her countdown, with the only concern being the weather.

One hour before the scheduled liftoff, weather conditions improved and went GREEN, falling within Launch Commit Criteria rules. However, post-flight launch weather rules governing Return To Launch Site (RTLS) abort weather requirements could not be satisfied by the strict by-the-word standards.

However, the commitment clause for “Good Sense” allowed Launch Integration Manager Mike Moses to issue a formal waiver for the RTLS weather restrictions – giving all stations a GO status for launch – since the weather violation would have cleared by the time of an RTLS landing.

After Launch Director Mike Leinbach wished the crew “Good luck … on the final flight of this true American icon,” the countdown resumed and proceeded nominally from T-9mins to T-34seconds.

At T-34seconds, the Ground Launch Sequencer issued an automated hold at T-31seconds and inhibited Atlantis’s onboard computers from taking control of the countdown.

Prior to this, the final mission of the Space Shuttle to the ISS, the last time a Shuttle launch countdown was held at T-31secs was on the STS-88 mission – the very first Shuttle mission to ISS.

For Atlantis and STS-135, the hold was issued due to the failed indication of a complete retraction and latch of the Gaseous Oxygen vent arm.

The launch control team, one final time, demonstrated their extreme commitment to safety and professionalism as they calmly worked through the issue and used close circuit TV cameras at the launch pad to verify that the GOX vent arm was indeed fully retract and latched against the FSS (Fixed Service Structure) – thus confirming that the failed retraction and latching indication was a sensor error.

The glitch was ironic in many ways, as the GOX vent arm had never given the launch team an issue during the 150+ countdown retractions it was placed through during the life of the Program.

Furthermore, the GOX vent arm was a complete afterthought for the Shuttle Program and was only installed on the FSS after pad validation testing using test Shuttle Enterprise in 1979 revealed the need for the arm and vent system to prevent the build-up of dangerous ice at the top of the External Tank during the countdown.

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

With the issue resolved, the launch team released the hold, and Atlantis’s onboard computers took control of the vehicle and countdown. The time was 11:29:03.9 EDT on 8 July 2011.

In front of a world-wide audience and crowd of one million people at the Kennedy Space Center and surrounding cities and beaches, the Space Shuttle Atlantis came to life, majestically rose from her seaside launch pad, stretched her wings one final time, and went transonic as she punched through the cloud deck and disappeared from view – leaving only the sound of her engines as evidence of her flexing her muscles for the last time.

Atlantis, like her sisters, delivered her crew safely to orbit and docked to the ISS for the final time on 10 July 2011.

The mission saw the Atlantis crew deliver thousands of pounds of internal spares and supplies to the Station – stockpiling the outpost for several years to come.

The mission also delivered the Robotics Refueling Depot to the station, an external experiment deigned to help test robotic refueling technologies for future spacecraft and satellites.

On the final full day of docked operations, Atlantis Commander Chris Ferguson – at the farewell ceremony on the ISS – presented the ISS crew with a small American flag that was flown on the STS-1 mission by Shuttle Columbia on April 12-14, 1981.

The flag was fastened to the inner wall of the ISS and flanked by the STS-1 and STS-135 mission patches – a symbolic gesture signaling the end of the Shuttle program.

On July 19, Atlantis undocked from the ISS and performed a modified flyaround maneuver of the Space Station.

As she backed away from ISS for the last time, Atlantis silently slipped into the darkness of orbital night, the lights turning off on the historic program.

On July 21, Atlantis navigated her way through the fierce outer atmosphere of Earth, taking aim on the Kennedy Space Center for a pre-dawn landing on runway 15.

(Animation created from some of the 114 hi res photos (all available in L2) taken by Mike Fossum on the ISS)

Less than 10 minutes before landing, the ISS made a breath-taking visual pass directly over the Kennedy Space Center in a final salute to the Shuttle Program, heralding Atlantis’s arrival to her permanent home city.

At 05:57:54, Atlantis descended from the darkness and touched her wheels to the pavement at the Shuttle Landing Facility for an emotional finale to her legacy and the legacy of the Space Shuttle Program.

Upon “wheels stop,” the final Shuttle Commander thanked all the men and women who worked on the program and the vehicles over the preceding 30+ years. And in a touching moment, Commander Ferguson also thanked the five flight vehicles themselves for protecting their crews and enabling the expansion of our knowledge and quest for science.

Less than 30 minutes after landing, Atlantis fell silent for the final time.

It was over.
 
Final Reflections on a legend:

With that final Shuttle landing came a moment of joy, sadness, grief, prolonged contemplation, but above all PRIDE in an amazingly complex set of vehicles that inspired countless numbers around the world, flew more people to space than any other spacecraft thus far (and for many, many decades to come), and helped bridge the gap between nations and forge unprecedented alliances in space.

For 30 years, 3 months, 8 days, 22 hours and 57 minutes (April 12, 1981 at 0700EDT to July 21, 2011 at 0557 EDT), the five space-worthy Shuttle orbiters spent a combined total of 1,332 days 1 hour and 36 minutes in space, completing 21,152 orbits of Earth over 548.2 million miles.

All five Shuttle orbiters deployed a combined total of 66 satellites, completed 46 rendezvous with an orbital space station (9 to MIR and 37 to ISS), and carried a combined total of 827 crewmembers (some more than once) into space.

For the final breakdown:

Discovery (OV-103): 39 missions; 365days 12hrs 53mins in space; 5,830 orbits of Earth; 148.2 million miles travelled; 31 satellites deployed (including the Hubble Space Telescope); 14 space station dockings; 252 crewmembers.

Atlantis (OV-104): 33 missions; 305days 7hrs 47mins in space; 4,848 orbits of Earth; 125.9 million miles travelled; 14 satellites deployed; 19 space station dockings (a world-wide record she will keep for decades to come); 207 crewmembers.

Columbia (OV-102): 28 missions; 300days 17hours 41mins in space; 4,808 orbits of Earth; 125.5 million miles travelled; 8 satellites deployed; 160 crewmembers.

Endeavour (OV-105): 25 missions; 299days 3hrs 19mins in space; 4,671 orbits of Earth; 122.8 million miles travelled; 3 satellites deployed; 12 space station dockings and one space station rendezvous and grapple; 148 crewmembers.

Challenger (OV-099): 10 missions; 62days 7hrs 56mins in space; 995 orbits of Earth; 25.8 million miles travelled; 10 satellites deployed; 60 crewmembers.

And while the Shuttles’ missions are behind them, and their engines and APUs forever silent, we wish them and all who have flown aboard them, and all who have worked on them, and all who dedicated theirs lives to making them fly Godspeed in whatever the future may hold.

The Space Shuttle Program, the five orbiters, and their dedicated workforce leave behind an unprecedented legacy of achievement – and a legacy that must never be forgotten, a legacy where all were taught by example “To strive, to seek, to find, and not to yield.”

But moreover, the five Shuttle orbiters made a thousands-strong workforce incredibly proud.

To all of the NASA engineers, all of the astronauts, the entire NASA workforce (including those contractually employed by Pratt & Whitney, Boeing, ATK, Lockheed, USA), and all those whose names we never heard but nonetheless worked silently and many times without recognition in support of a program that you whole-heartedly believed in, we give you our resounding thanks and gratitude.

Without you, this program would not have been what it was.

The Shuttle program has come to an end, but the legacy of the program and those who worked and flew aboard the Shuttle, as well as those who will continue the dream of human space exploration, will forever carry on.

And so, for the final time, to Enterprise (1977-1985), Columbia (1981-2003), Challenger (1983-1986), Discovery (1984-2011), Atlantis (1985-2011), and Endeavour (1992-2011), you will always have our eternal thanks and gratitude for all that you have enabled the human race to learn and discover about not only the universe and our home planet, but also about ourselves and our ability to work together to achieve common and mutually-supportive objectives.

It was an incredible journey. And those of us who were a part of this great program, no matter how small a part, will never forget a single part of it or the Orbiters and people who made it all possible.

Thank you.

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.

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 Larry Sullivan and Brian Papke, MaxQ Entertainment/NASASpaceflight.com, L2 and L2 presentations and NASA. To join L2, click here: http://www.nasaspaceflight.com/l2/)

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Sleep Well, Atlantis:

The fourth operational orbiter of NASA’s fleet, Shuttle Atlantis was named, like her sisters, after previous Earth-bound vessels of exploration. However, unlike her three operational sisters to come before her, Atlantis was named after only one ship and is the only Shuttle orbiter named after a 20th century Earth-bound sailing ship.

Atlantis is also the only Shuttle orbiter named after an Earth-bound American research vessel. Specifically, the orbiter Atlantis takes her name from the 1930-1966 two-mastered boat that served as the primary research vessel for the Woods Hole Oceanographic Institute of Massachusetts.

Construction of the fourth and originally final Space Shuttle orbiter for NASA’s fleet began on January 29, 1979 when NASA awarded the contract to build OV-104 (Orbiting Vehicle 104) to Rockwell International.

Start of structural assembly of OV-104′s crew module began on March 30, 1980, before engineers at Palmdale began final assembly of OV-104′s constituent parts – a procedure which was complete on April 10, 1984. After an additional full year of end-to-end testing of all of her systems, construction was complete, and on April 6, 1985 the new Space Shuttle orbiter Atlantis was rolled out of her construction facility.

Three days after Shuttle Atlantis’ rollout ceremony at Palmdale, she was transported overland to Edwards Air Force Base, CA where final preparations were made for her cross-country ferry flight – culminating in delivery to the Kennedy Space Center on April 13, 1985: 4 years and one day after the very first Shuttle flight.

Atlantis’ first mission would be STS-51J, which launched on October 3, 1985. Her Department of Defence (DOD) mission involved her deploying a classified payload, before returning to Earth to landing at Edwards Air Force Base, California at 13:00.08 EDT on runway 23 on October 7.

Her final mission was the last flight of the Space Shuttle Program (SSP). Carried out flawlessly, STS-135 was a late addition to the manifest, allowing Atlantis the honor of closing out the program when she returned back to the Kennedy Space Center in July. (Animation created from some of the 114 hi res photos (all available in L2) taken by Mike Fossum on the ISS)

“It’s bittersweet as Atlantis comes home where she will forever stay. I couldn’t have more pride in this Space Shuttle team for your service to KSC, NASA, and America. What this team has accomplished over the past 30 years will be talked about and admired for generations to come,” noted KSC Director Bob Cabana in an emotional address to the workforce.

Work will continue on Atlantis, as she is prepared for going on display in a new facility at the visitor center, which will become her new home late in 2012, or early in 2013.

However, with the final task requiring a powered up status – the stowing of the Ku-Band antenna – Thursday morning saw the orbiter put to sleep for one final time.

The event – which engineers present at the time noted – was highly emotional, as the “Vehicle Powered” sign was turned off, as it has already been for Discovery, never to be lit again.

“Technicians in Orbiter Processing Facility-2 are scheduled to power down Atlantis for the final time Thursday. The shuttle’s Ku-band antenna also will be stowed for the last time. Wednesday, techs removed Atlantis’ airlock from the payload bay. The airlock is set to be transferred temporarily to Kennedy’s Space Station Processing Facility today,” noted a status report.

Atlantis had already had her Forward Reaction Control System (FRCS), OMS (Orbital Manuevering System) Pods and Space Shuttle Main Engines (SSMEs) removed earlier in what is called her Transition and Retirement (T&R) flow.

OPF-1:

Eventually, Atlantis will depart OPF-2, as all three facilities are turned over to the 21st Century Space Launch Complex effort, which has already seen OPF-3 handed over to one of NASA’s Commercial Crew Development (CCDev) suitors – Boeing and their CST-100 spacecraft – after signing a 15 year lease via a NASA agreement with Space Florida, the State’s aerospace economic development agency.

OPF-1 was also the subject of a Program Requirements Control Board (PRCB) meeting this month, relating to the potential to provide an early turnover of the facility from its current role with the orbiter.

The meeting presentation noted the need to identify risks and schedule impacts of the early OPF-1 release schedule versus the baseline orbiter processing schedule, along with assessing the possibility and schedule improvement of accelerating Endeavour’s processing assuming early turn-over of OPF-1 is approved.

Such a turnover is directly related to the current “repurposing” efforts for the Space Launch System (SLS) and commercial entities, something which proved to be a major issue for the recent proposal to restart shuttle operations, which was concluded last week after a final meeting with NASA.

Endeavour – who is donating some of her Main Propulsion System (MPS) hardware to the SLS program – is also yet to receive her three Replica Shuttle Main Engines (RSMEs), required as she has also donated her three flight-proven SSMEs to SLS.

“OV-105 (Endeavour) schedule is independent of OPF Bay 1 early release. OV-105 schedule is based on SLS/RSME work,” noted the PRCB presentation, available to download on L2. “Only improvements to SLS timelines can accelerate 105′s dates. Add 3rd shift and/or weekends.”

Based on the requirement for the orbiters to provide some early assistance to the SLS teams, Transition and Retirement (T&R) flow timelines and projected “delivery” dates, the PRCB concluded they believe it is possible to vacant OPF-1 by July, 2012.

Click here for other T&R Articles: http://www.nasaspaceflight.com/tag/t&r/

“Early Release of OPF Bay 1 can be accomplished without adversely affecting T&R milestones,” added the presentation. “Given the current guidelines and work rules, Rev G (Early OPF Bay 1 assessment)reflects the earliest “Ready to Ferry” dates possible.

“T&R milestones/vehicle delivery dates will continue to be assessed and optimized to improve timelines. Additional risks of performing work in the VAB (Vehicle Assembly Building) can be mitigated and is within experience base.”

With only two OPFs being used by the orbiters, they will continue to take turns in spending a “vacation” in the VAB. The next switch is expected to take place in January.

To read about Atlantis from birth through to retirement, click here for the links:
http://forum.nasaspaceflight.com/index.php?topic=25785.0

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, Larry Sullivan, MaxQ Entertainment/NASASpaceflight.com and NASA.gov.)

(L2 and NSF are continuing to follow the orbiters through their transitional period. To join L2, click here: http://www.nasaspaceflight.com/l2/)

Related posts:

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Post-STS-135 OV-104 Nose Cap damage:

As part of the standard landing-day procedures, a quick assessment of orbiter Atlantis’s Thermal Protection System (TPS) was made after her successful return to the Kennedy Space Center after the 12-day capstone mission for the Space Shuttle Program.

During this runway TPS inspection, an unexpected damage site was found on Atlantis’s nose cap RCC (Reinforced Carbon-Carbon) panel where it adjoins the RCC chin strap.

As noted by the MOD (Mission Operations Directorate) presentation – available for download on L2 – “OV-104′s Nose Cap expansion seal on the R/H side was noted to have SiC damage during evaluation on the runway post landing.”

The damage was documented to be 0.3 inches in width and 1.3 inches in length.

Furthermore, “Carbon fibers were exposed and visible with a 7x hand lens. x30 – x100 magnification did not reveal oxidation of the carbon fibers.”

The presentation specifically notes that the damage to STS-135/Atlantis was completely unrelated to the identified root cause of the RCC spallation issue studied for the fleet’s Wing Leading Edge RCC panel joggle regions a few year ago.

Specifically, this SiC damage was of the same variety as noted on a previous flight of Atlantis – her STS-115 mission in September 2006 which marked her return to active duty following the resumption of Space Shuttle missions in July 2005.

Post-flight analysis and damage assessment for STS-135 indicates that the SiC coating did not liberate during flight but after Atlantis had touched down on runway 15.

While the liberated SiC coating could not be found on the runway and recovered for analysis, there was “no evidence of visible oxidation to the black carbon substrate” – evidence that supports a post-landing SiC liberation event.

The post-landing damage site was not in an area of the TPS that had been previously repaired, and all pre-flight Infrared Thermography images revealed no subsurface damages or flaws to the region during Atlantis’ OPF (Orbiter Processing Facility) flow toward STS-135.

In fact, the presentation notes that “Previous thermography of the area revealed ‘no blistering or anything that would have brought about a visual inspection.’”

Thus, it is believed that the damage was “due to mechanical loading induced by a minimum gap condition.”

The chin panel to nose cap gap was recorded pre-flight to be 0.010 inches, well inside the 0.016 – 0.086 inches requirement.

The post-flight measurements ranged from 0.010 inches to 0.020 inches.

Additionally, during post-flight gap measurements, “a piece of the seal easily liberated when accidently touched with a scale during gap measurement.”

The Leading Edge Structure Subsystem (LESS) Principal Review Team (PRT) found that the expansion seals in the nose-cap-to-chin-strap region likely shifted at some point in Atlantis’s processing after the initial measurements were taken or shifted during flight.

A review of Atlantis vehicle processing for this chin panel and RCC nose cap area showed documented work to remove and then re-install the chin strap during Atlantis’s OPF flow toward STS-132 – her penultimate flight.

The chin strap and RCC nose cap performed perfectly during STS-132.

The LESS PRT thus found that events during Atlantis’s reentry likely contributed and ultimately caused the SiC liberation.

During reentry on July 21, 2011, the chin panel to nose cap gap likely closed up due to RCC expansion from thermal effects, resulting in contact at this localized area that initiated a stress riser and caused a SiC coating crack.

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

Then, late in the reentry process, the “Type A sealant” likely started to solidify and fused the nose cap and chin panel together. At landing, the “heat soak” reached the STR and opened up the chin panel and nose cap gap.

When this happened, the “Type A sealant pulled the SiC chip away from the nose cap expansion seal causing the event.”

Therefore, the team concluded that the damage was the result of a minimum gap condition that existed between Atlantis’s nose cap RCC and chin strap RCC, and that the damage was “unrelated to the infamous WLE RCC Root cause spallation failure mode observed at the joggle region.”

The recommendation was then made to close the investigation with no change to the root cause team’s recommendations or SSP’s accepted risk.

The damage is not a concern or constraint for Atlantis’s display activities or “previous RCC root cause risk acceptance.”

The option does exist, however, to further study this issue for three to five years via current SSP funding.

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 presentation and L2 Photo Database.)

(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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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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Recalling Launch Day:

The retired USMC Colonel arrived at the spaceport expecting – as many did – for the weather to provide a stay of execution for what was to be the final shuttle launch.

Once the Mission Management Team (MMT) Tanking/Weather brief decided to give the conditions a chance to provide a break in the weather, Mr Cabana noted how the enormity of the occasion started to hit home.

“When I came to work (in the) morning prior to sunrise, I really didn’t think we were going to launch. I’m normally very optimistic about every launch attempt, but I really didn’t think the weather was going to cooperate,” he noted in a memo to the KSC teams (L2).

“I think part of it was that it finally hit me, the enormity of it all, that this was the last time we were going to launch a Space Shuttle at KSC. The end, that I said would soon be on us almost three years ago, was finally here, and it was hard to believe.”

With Atlantis’ External Tank (ET-138) fully loaded – notably without any of the issues which had challenged the talented KSC teams over recent years – the weather continued to show only a 40 percent chance of acceptable conditions at T-0.

However, as the countdown continued to tick down, and with Atlantis’ crew now onboard the vehicle, only the Return To Launch Site (RTLS) weather – a requirement for acceptable conditions in the event of a serious issue during the early stages of the launch resulted in a risky abort to  bring Atlantis around for a landing on the Shuttle Landing Facility (SLF) or bailout in the Atlantic – threatened to put pay to the attempt.

“As the next six hours toward launch progressed, it seemed more and more likely that the weather was going to cooperate, that we had a shot at getting Atlantis off, but it wasn’t a given even till the very end,” Cabana recalled.

“Even though launch weather was green, we couldn’t get a go forecast for RTLS, even with Rick Sturckow in the weather aircraft saying it was “a really, really big hole,” and he couldn’t see anything that was an issue.”

In the end, the teams in the Firing Room made a decision to issue a waiver and trust the observations of the STS-128 commander, allowing for the final hurdle to be cleared for launch – or so they thought, as a failed indication to confirm the full retraction of the GOX Vent Arm held the countdown at T-31 seconds, with only a short four minute window to resolve.

“Just to add a little more excitement to an already exciting event, the team flawlessly deals with a GLS (Ground Launch Sequencer) hold at 31 seconds, and gets Atlantis off with 58 seconds to spare,” added Mr Cabana, who continued by speaking about his emotions of the launch.

“No matter how many launches I have seen, I am always touched by it, and I am always anxious. I breathe a little easier 2 minutes and 5 seconds into the flight when the solid rocket motors fall away.

“I watch closely with our new cameras that enable us to monitor debris from the tank and can finally relax when MECO (Main Engine Cutoff) arrives with no anomalies.

“It is so much easier to fly it than to feel responsible for some of your closest friends as they ride that ball of flame into space.”

After Atlantis successfully made orbit, Mr Cabana had to face the teams responsible for the safe launch, knowing many of them had just come to the end of their careers.

“Recognizing the launch control team post-launch was an emotional event. It’s hard when you have the finest group of professionals anywhere, who have dedicated so much of their lives to the success of America’s space program, and you know many of them would be leaving the firing room for the last time.

“I would imagine that it was much the same after the last Apollo launch.  It will be awhile before we staff the firing room to send astronauts on a mission of exploration from Complex 39 again, but just as it happened after Apollo, it is going to happen after Shuttle also.

“I rode an emotional rollercoaster the rest of the day after launch.  There were tears and happiness, one following right after the other, on and off, as I talked with the team and hugged and shook hands with as many people as I could at the barbeque”

The overall feeling was one of pride for the workforce, who he feels – for the ones remaining at least – will be up for the challenge of the transition, based on their ability to overcome the challenges in their day to day jobs.

“Words cannot express the pride I have in all of you and how privileged I feel to be part of this team at this time in history. This is not easy, and we have challenges in front of us. However, there’s no doubt in my mind that we will be successful, because I know what you’re capable of when you’re given a challenge and a mission to accomplish. You have demonstrated it time and again,” he added.

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

“Thank you all for your tremendous dedication and sacrifice to ensuring these last Shuttle missions were executed better than ever before. You are absolutely the best, and it’s a privilege to serve you.”

Post Mission Address:

In a second address after Atlantis’ return to Earth last week, Mr Cabana looked back over the entire history of the Space Shuttle Program, echoing a point made by NASA administrator Charlie Bolden – that the Shuttle will be admired for hundreds of years to come.

“It’s bittersweet as Atlantis comes home where she will forever stay. I couldn’t have more pride in this Space Shuttle team for your service to KSC, NASA, and America. What this team has accomplished over the past 30 years will be talked about and admired for generations to come,” noted the four-time Shuttle astronaut.

“We have accomplished what no one else has been able to do. The Space Shuttle program has launched, recovered, and repaired satellites; conducted cutting-edge scientific and medical research; and built the largest structure in space, the International Space Station.

“This last launch and landing of STS-135 is the culmination of a phenomenal program that includes three decades of space exploration, scientific discovery, international partnerships, and fulfilled dreams.”

Specific to the teams which have cared for all of the NASA orbiters, Mr Cabana spoke openly about how the iconic ships and their teams will be sorely missed – a refreshing attitude compared to the recent NASA PR exercise of endorsing a fast-talking youtuber to gleefully compare the end of the program to that of a sitcom cancellation, accompanied by NASA leaders grinning and waving into the camera.

“The people who dedicated so much of their lives to the orbiters, starting with Columbia and continuing with Challenger, Discovery, Atlantis, and Endeavour, are part of our family and will be greatly missed,” Mr Cabana wrote, as 1,500 of the KSC workforce were laid off at the end of last week.

“The Space Shuttle is an American icon and resonates in the heart and soul of every one of us. Leaving a legacy is part of what drives every man and woman involved in the space program, and we have the unique opportunity to pass on a one-of-a-kind heritage.

“We were given the responsibility of bringing the Space Shuttle program to a safe and successful close, and we finished strong, taking personal and professional pride in helping to preserve this remarkable inheritance for future generations.”

Mr Cabana did end on a positive note, putting his backing behind the United States to continue to use the inspiration of human space flight, which he is tasked with ensuring KSC is the lead center for such missions in the future.

“It is hard to believe the final mission, that I said almost three years ago would soon be upon us, is finally here. But more than the Space Shuttle, it is human space flight that inspires us and the future explorers of tomorrow.

“We will continue to lead in space exploration and be part of something much larger than ourselves. KSC has been, and will continue to be, the premier launch complex for sending humans and payloads to space.”

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

(Images: Via L2, MaxQ Entertainment (Larry Sullivan and Brian Papke) and NASA.gov/NASA TV. 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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Atlantis’ final moments off the ground:

Atlantis brought her crew home safely for one final time, landing on the Shuttle Landing Facility (SLF) runway 15 in the Florida pre-dawn hours, concluding a highly successful mission to provide a bufferzone for the International Space Station (ISS) during the gap between this mission and the start of commercial cargo supplies next year.

She landed – as became typical for the orbiters – with no additional Mission Evaluation Room (MER) items or “funnies”, despite having just bleed off all the massive energy of launch by driving through the atmosphere as a fireball.

“Atlantis has safely returned home following a very successful final mission. For the final time, Florida’s east coast was rocked by the double sonic booms announcing Atlantis’ arrival. Touchdown on runway 15 occurred at 0557:00 EDT with wheel stop at 0557:54 EDT,” noted the NASA Test Director (NTD) report, which is normally highly technical and focused on engineering and flow schedules.

“Atlantis flew a total of 4848 orbits of Earth for a total of 125,935,769 miles and spent 307 days in space. Welcome home Atlantis! Thank you for your service to our country’s Human Spaceflight Program.”

With no weather issues for landing, The Shuttle Flight Control Room (FCR) was polled and provided a go for the deorbit burn. A timeline of events for the Orbital Manuevering System (OMS) and Reaction Control System (RCS) were provided in the expansive MER Landing Report (L2)

“OMS Helium valves were configured for Deorbit burn at 202/08:45:12 GMT, and returned to post burn config at 202/08:54:13 GMT. Deorbit Burn (OMS-8) was accomplished using a dual-engine, straight-fed OMS burn. TIG (Time Of Ignition) was at 202:08:49:04.2 GMT. Cutoff was at 202:08:52:22.3 GMT resulting in a burn duration of 198.1 seconds with a delta-V of 333.1 fps. 

“OMS Helium configuration for the burn was Left: A-GPC, B-OP; Right: A-GPC, B-OP. System pressures, temperatures, and quantities were within expected limits.”

Following the burn, Commander Chris Ferguson sent down praise to the propulsion teams responsible for the OMS engines, which – as always – enjoyed an issue-free role on orbit.

“There were eight (8) maneuvers (including the OMS Assist burn during ascent) which used OMS engines this flight. Six of the maneuvers were dual engine burns, one maneuver was a single Left engine burn, and one maneuver was a single Right engine burn,” added the report.

“All burns were performed in straight-feed. The Left and Right engines were fired eight times each. Total burn times were 637.6 seconds for the Left engine and 636.8 seconds for the Right engine.”

With her nose pitched up, Atlantis was ready to begin the plunge towards Entry Interface. (Animation created from some of the 114 hi res photos (all available in L2) taken by Mike Fossum on the ISS)

As part of normal procedures, the Forward Reaction Control System (FRCS) dumped the spare fuel via four of the jets, which was timed at 202/09:07:13.5 GMT and lasted 32.64 seconds, dumping 398.2 lbs of the FRCS propellant.

With all three of her Auxiliary Power Units (APUs) in action – providing power to the orbiter’s hydraulic systems – nominal performance was noted as APU 1 sprang into action, prior to APU’s 2 and 3 following suit as Atlantis began the journey home.

“All APU parameters were nominal on the final day on-orbit (FD14), during entry, and post landing at KSC,” added the MER Landing Report. “APU 3 was the TIG-5 single APU start, APU 1 and 2 were started at EI-13. APU 3 ended with a run time of 1 hour 33 minutes, while APU 1 and both ran for 1 hour and 5 minutes.”

The report added all DPS (Data Processing System) hardware performed nominally during all phases of entry operations, in tandem with the Flight Software (FSW), which “performed flawless, bar typical GPC (General Purpose Computer) errors during rollout.” The GPCs, however, did not suffer from any of the issues two of the computers complained about on orbit.

While the mission was extended by one day – some achievement given Atlantis is the only orbiter unable to ‘stretch’ her Power Reactant Storage and Distributation (PRSD) consumable levels via the Station-to-Station Power Transfer System (SSPTS) – she landed with plenty of margin, had the mission required moving past EOM (End Of Mission) FD 14.

“The performance of the FC/PRSD systems during the mission was nominal,” added the MER report. “The fuel cells generated 13.6 kW and 442 amps, average, and 4159 kWh of total electrical energy during the 306.48 hour mission. The fuel cells consumed 360 lb of hydrogen and 2856 lb of oxygen from the PRSD subsystem.

“The PRSD system also provided 106 lb of oxygen to the crew. The fuel cells produced 3216 lb of water. Approximately 65 lb of O2 was used for stack repress while docked to ISS; there was no tank-to-tank transfer of oxygen to Space Station.”

Such was the performance of the three Fuel Cells, the report notes Atlantis landed with enough consumables for a three day mission extension – even via nominal power rates.

“The PRSD subsystem could have supported a 71 hour mission extension at the average mission power level of 13.6 kW based on the usable quantities remaining at landing. At an extension day average power level of 13.22 kW, it could have supported a 73 hour mission extension.”

With the Flight Control Surfaces (FCS) taking over from the RCS, as Atlantis started to feel the air over her airframe, her software guided her towards the Kennedy Space Center (KSC) without issue, prior to being commanded to a perfect landing on the SLF.

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

“STS-135 Landing System performance nominal based on quick look MER data retrieval. KSC Runway 15. Weather reported: No cross wind, with 1 knots tail wind. Winds at 330 deg at 1kt average with 2kt peak, landing on runway 15 which translate to a primarily tail wind condition,” the Landing Report noted.

“Events as shown below (times in GMT) This data is quick look, approximate values, for information only. MGTD (Main Gear Touch Down): 202:09:56:55. NGTD (Nose Gear Touch Down): 202:09:57:12. DC (Drag Chute) DEPLOY: 202:09:57:04. DC DISREEF: 202:09:57:10. DC JETTISON: 202:09:57:35.

“BRAKES ON: 202:09:57:19. MLG TD Velocity: 219 KGS. Brake Pressure onset was at 108 KGS. Brake Pressure nominal averaging 750-880 psi throughout rollout, with peak brake pressure 1100 psi. WHEEL STOP = 202:09:57:51. Total roll out time ~ 56 seconds from MGTD.”

While the MER reports are – like most internal mission reports – focused entirely on the performance of the vehicle, the landing summary included numerous departments signing off for the final time.

Some simply added a line of thanks, some joked about the last person leaving the MER to turn out the lights, but one – the the Electrical Power Distribution and Control (EPDC) console – summed up the emotion of the day.

“All monitored voltage and current measurements were nominal during all phases of de-orbit prep and entry,” noted the report, prior to the addition of the personal remarks. “I have spent a lot of time over the last few days reflecting on what I would say on this my last Shuttle Shift report, and I just don’t have the words to express the pride I feel as we close this era of manned space flight.

“It has truly been an honor and a privilege to work with this team both past and present. I like many of you can remember the Mercury, Gemini and Apollo days and wanting to participate in the space program when I grew up. Well, we have all lived that dream. We have shared in the triumphs and the tragedies and are the better for them.

“I will be forever indebted to you all for sharing this adventure with me. May God bless you and keep you all in your future endeavors. It has been quite a ride, EPDC console signing off.”

Ever the diva of the fleet, Atlantis did throw one problem at the teams whilst sat on the SLF, although the issue was very minor, related to a Valve Position Indicator (VPI).

“New IPR 0001: During runway switchlist, the left RCS manifold Iso valve 5 indicated closed block red (OPEN and CLOSE indicators ON) when the valve was opened,” noted the NTD report. “The valve closed indicator (VPI) later went OFF with no interaction. A slow indicator is suspected. Constraint set to V1158 VL5.”

With Atlantis hooked up to her cooling and purge systems at the SLF, the slow tow back to her Orbiter Processing Facility (OPF-2) – as much as Discovery was recently evicted from OPF-2 – began, with crowds gathered to welcome the orbiter back to the hanger.

Accompanied by the theme tune from Star Trek Voyager, Atlantis was parked up in front of her workforce, who waved flags and even received thanks from the STS-135 crew.

Atlantis was then towed inside OPF-2, where she underwent immediate safing operations, as is standard for a returning orbiter.

“OV-104 (OPF2): Atlantis was spotted in the OPF at 1540 EDT. Fuel Cell power down and ground power transfer was completed at 2141 EDT. Controlled venting is established and fuel cell cool down is in work,” added the NTD report on Friday.

“The remaining OPF support systems and vehicle systems will be configured for ground processing support. Residual cryo drain is planned to begin on second shift Friday (night). Weekend work: STS-135 securing and down mission processing. OMS/RCS flight cap removal.”

Although an order is still in place to “do no harm” to both Endeavour and Atlantis from the standpoint of down processing – via any 11th hour transition to a commercial shuttle operation in the future – the flow will mirror that of Discovery’s in her early weeks since returning from STS-133.

This will include the removal of her Space Shuttle Main Engines (SSMEs) which will be placed in storage for potential use on the Space Launch System (SLS) – as much as the proposed Heavy Lift Vehicle (HLV) is still stuck in a political swamp, after two opportunities to make a public announcement – on what is a chosen configuration – were delayed by the unknown persons of power in Washington, DC.

She will also lose her Forward Reaction Control System (FRCS) and OMS Pods, both of which will head to the Hypergolic Maintenance Facility (HMF) for deserving, prior to joining the game of musical OPFs, as the orbiters take it in turns to spend a vacation inside the Vehicle Assembly Building (VAB) due to ongoing work to covert OPF-3 for a commercial customer.

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

(Images: Via L2 content 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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