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.
—–
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, driven by L2′s fast exapanding SLS specific L2 section, which includes, presentations, videos, graphics and internal updates on the SLS and HLV, available on no other site. Other images via NASA.)

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

No related posts.

Discovery’s Final Months At KSC:

The veteran orbiter marked the beginning of the end for the orbiter’s role of conducting missions under the NASA call sign, when she returned from the highly successful STS-133 mission. Soon after, Discovery was placed into the Transition and Retirement (T&R) flow, which was always going to result in her being the first orbiter to leave the Kennedy Space Center (KSC) for one final time.

For that final trip, Discovery will be rolled to the Shuttle Landing Facility (SLF), hoisted up by the Mate/Demate Device (MDD), prior to being mated atop of the awaiting Shuttle Carrier Aircraft (SCA), which will fly Discovery to the Smithsonian’s National Air and Space Museum near Washington, D.C.

In fact, Discovery’s T&R flow schedule shows she will be coming to the end of preparations for the trip by the holiday break in late-December 2011,  Those schedules – which are subject to change – show that by January 3, 2012, Discovery will be “ready for ferry”.

Soon after, Discovery will be rolled out of her Orbiter Processing Facility (OPF-1) and into Vehicle Assembly Building (VAB) High Bay 4 (HB4) for storage. She will remain in storage until April 10, when she will be towed to the SLF and hoisted atop the SCA.

The non-official date – based on preliminary internal information – has Discovery departing KSC on April 12, 2012, just as her older sister Columbia did 31 years previously, during the very first Space Shuttle launch.

Discovery’s point of arrival, Dulles Airport, currently believe Discovery is due to arrive around April 16, as much as they do not have a confirmed date. The Smithsonian’s current orbiter, Enterprise, will be moved to a staging point just days ahead of Discovery’s arrival.

This means it may be possible that Discovery and Enterprise will be parked together on the tarmac at Udvar-Hazy for a short period of time for photos and video right after Discovery is wheels-down.

Discovery will be removed from the back of the SCA via cranes and lowered onto the ground at Dulles, a process which has already been practised at KSC’s SLF earlier in the year.

Shortly thereafter, Enterprise will be hoisted on top of the SCA in preparation for her ferry flight to JFK International Airport in New York.

Discovery will still sport her battle scars of re-entry on her Thermal Protection System (TPS) blankets. However, she will be missing some of the hardware she used during her operational life.

To her visitors, she will have a very similar appearance on the surface, but her Orbital Manuevering System (OMS) Pods and Forward Reaction Control System (FRCS) were near-gutted during safing operations at the White Sands facility in New Mexico.

She will also be sporting three RSMEs, as opposed to SSMEs, following the Program Requirements Control Board (PRCB) decision to protect all flight-able SSMEs for the SLS program.

The PRCB Change Request presentation (available on L2) noted direction from the Space Shuttle Program (SSP) to roadmap the ability to keep the engines, and replace them with replicas for when the retired vehicles go on display at their exhibitions.

“Directed by SSP to prepare an integrated approach for an alternative to using flight Space Shuttle Main Engines (SSMEs) on post SSP orbiter displays. To obtain authorization and funding to design, build, deliver, and install nine (9) Replica Shuttle Main Engines (RSMEs) to replace flight SSMEs on orbiters,” noted the presentation.

“To preserve the SSME flight engines for future use, NASA MSFC (Marshall Space Flight Center) / KSC (Kennedy Space Center) / JSC (Johnson Space Center) recommends a replica engine be provided utilizing existing inoperable nozzle assets and an adapter to simulate the SSME for display purposes.”

With the Shuttle Derived (SD) Heavy Lift Launch Vehicle (HLV) utilizing between three and five RS-25 engines on its core stage, the available stock of SSMEs (RS-25Ds) – comprising of three sets from each orbiter, a spare set of three and up to three others located outside of KSC – will be used during the testing and initial launches of the SLS, prior to the switch to the expendable RS-25E version of the engine in the 2020s.

For the orbiters going on display, SSME contractor Pratt & Whitney Rocketdyne (PWR) developed the RSME, of which nine have been fabricated for installation on the vehicles.

While a flight ready SSME consists of large amounts of plumbing, turbopumps and electronics, etc. The RSMEs simply consist of a scrap – but cosmetically repaired – nozzle, with an adaptor to install it into the aft of the retired orbiter.

The internal schedules showed the installation of the RSMEs was scheduled to take place in October, meaning they are behind on the timeline with this week’s completion of the task. However, there is a large amount of flexibility in the flow, given the aforementioned information that Discovery’s schedule allowed for four months between her “ready to ferry” date and her eventual departure from Florida.

With all three RSMEs now installed on Discovery, she is starting to return from her rather sorry looking appearance of a vehicle with no engines, no OMS Pods and no FRCS. This process was required to allow for the complete safing of the vehicle, due to the amount of hazardous substances her powered systems contained after returning from STS-133.

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

The T&R plans for Atlantis and Endeavour are currently under embargo, while the Johnson Space Center (JSC) – which missed out on a flown orbiter, are soon to expect delivery of the high-fidelity model which is being dismantled from its current home at the KSC Visitor Complex.

The model is scheduled to be moved to the Turn Basin at 7am (first motion) on Sunday, December 11, with the move requiring removal of light poles and other obstructions – work which will begin on December 9.

The replica External Tank and Solid Rocket Boosters (SRBs) which sat next to the orbiter at the display have also been dismantled and will be placed into temporary storage at KSC.

Ground breaking on a new exhibition facility – which is going to be the eventual home for Atlantis – is expected to start early in the new year.

(Images: Via L2 content and NASA.)

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

No related posts.

SLS Configurations:

The ongoing trades taking place at the Marshall Space Flight Center (MSFC) are a notable change from the Constellation Program (CxP) issue of making major configuration decisions years down the line, which – in the case of Ares – was well-known as one of the contributing factors to causing impacts to the entire vehicle.

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 will allow the vehicle to fly fully fueled in all configurations saving the extra calculations/testing for an under-filled three engine core.

As such, it appears managers have already decided that using four engines on the first stage would be best prescribed for the SLS from the start.

Revealing details of the core stage discussions, a “face-to-face” outbrief in late September resulted in a highly detailed presentation (acquired by L2). The meeting involved SLS operations personnel and Mission Operations Directorate (MOD) departments.

In the presentation’s SLS Overview, the Launch Vehicle Blocks are shown in three configurations, namely Block I, Block IA and Block II – the latter of which is the fully evolved 130mt launch vehicle.

The Block I vehicle has two missions, opening with the flight to send an uncrewed Orion (MPCV) on a Circumlunar trip around the moon, followed by a crewed lunar orbit mission. While schedules are still being worked, managers are aiming to launch SLS-1 in 2017, followed by SLS-2 in 2019.

Block I uses a Core Stage Propulsion of LO2/LH2 with Four SSMEs (RS-25Ds) now sported by the configuration, an advance on the three RS-25Ds, as previously noted. Core Stage Tank design (structure, MPS (Main Propulsion System), avionics) will be used for all subsequent SLS flights. Tanks, MPS, and Engine interfaces will be sized for 130 mt vehicle.

Engineers are also in the final stages of completing the list of hardware that will be removed from the aft of the retired orbiters, ahead of being donated to the SLS test program and flight hardware.

As already well-known, these two Block I flights use the Ares Five-Segment configuration. These Solid Rocket Boosters (SRBs) will not be recovered from the Atlantic.

Also confirmed by the presentation, after first revealed by this site, the On-Orbit Stage will utilize the existing Delta-IV Upper Stage Interim Cryogenic Propulsion Stage (iCPS), driven by LO2/LH2. Also known as the kick-stage, this is a temporary measure ahead of SLS’ purpose built hardware.

“iCPS (Delta IV) will be used for two flights: Originally planned to be used with no s/w (software) mods. Current thinking is that s/w mods will be required. Requires Delta IV flight computer redesign. Will include the following four commands: Authority to Proceed. Engine Shutdown. Upload Burn Targets. State Vector Update,” added the presentation.

“Provides orbit insertion and trans-lunar injection burn. SLS will purchase two Delta-IV Upper Stages to enable Block 1 flights early. Will likely require Delta IV avionics redesign to meet mission risk constraints.”

Block IA will then take over, providing the mission configuration for the bulk of the 2020s, from SLS-1 to around SLS-13. This configuration will have the same appearance as the Block I, bar the Cargo version, which will debut after the Lunar missions.

The core will again utilize RS-25s, although it will first use up the stock of SSMEs (RS-25Ds), of which the presentation notes there are currently 14-15* in total. This figure includes the three sets of three donated by each of the Shuttle orbiters, and a spare set of three which were already held at the Kennedy Space Center (KSC) in the event of a pad changeout.

*Note, other L2 documentation state the number is 15 engines, plus two development engines, and an additional spare Line Replacement Unit (LRU).

Due to the core’s engine configuration, an advance on the four engines can be made – moving to the full utilization of five RS-25s on the core – as is noted by the overview of the Block IA, which acknowledges this version of the SLS will be when the program eventually moves on to the cheaper, expendable RS-25Es.

“Core Stage Propulsion Four-five expendable RS-25E. Develop expendable, cheaper version of SSME for on-ramp when the existing Shuttle inventory is used up (~14-15* full SSME’s),” noted the presentation, overviewing what will be a 100mt capable launch vehicle.

Most of that additional power will come via the debut of the new “advanced” boosters, which will be decided via a “competitive procurement”, resulting in either ATK winning through with a more powerful version of their Solids, or a switch to a liquid booster, likely to powered by RP-1 (Kerosene).

(Image taken from the amazing 220mb DM-2 Five Seg Motor Ground Test Video – available in L2).

“Advanced Booster: Composite SRBs or RP-based Liquid Boosters. Begin competitive procurement for SRB replacement. The trade space can include composite-case SRB’s or kerosene-based liquid boosters.”

With the Delta IV kick stage no longer required, the Block IA will be prepared to host the “Large On-Orbit Stage”, a new Cryo Prop Stage (CPS) driven by LO2/LH2, pointing to some flexibility of missions prior to the fully evolved SLS being ready.

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

“NASA designed on-orbit stage. Not part of SLS vehicle. Paid for by SLS Program. Enables Exploration missions,” added the presentation, which may be pointing more towards it being too early to know when the CPS will be used. “Utilizes Avionics independent from SLS.

“CPS (NASA) will be a new design: Will be used for Block IA+. Is being designed as a separate Project within SLS. Enables Exploration missions.”

Then comes the massive 130mt, fully evolved, Block II SLS, which will be a nature advancement on the Block IA configuration, with the only difference being the size of the vehicle, as it grows by nearly 80 feet – when compared to the Block IA cargo vehicle – to find space for the new Upper Stage.

Using three J-2X’s from the Constellation Program, development of the engines and stage will continue alongside the SLS work, prior to being held back until the Block II is ready to fly.

“Complete J-2X and put “on the shelf” for later use with SLS Block II. Move Integrated Stack avionics to this stage. This Upper Stage burns out prior to orbit insertion (ala Saturn V).”

This, as NASA have been claiming for some time now, will be the flagship launch vehicle that will send humans – and their supporting hardware – to Mars.

While less technical than the presentation used in the above content, a superb 48 page industry-level overview of the SLS has also been produced (and acquired by L2), which provides some of the first real mission capability overviews and industry base benefits for the SLS. This will form the basis of the next SLS article on this site.

(Images: Via L2 content, driven by L2′s new SLS specific L2 section, which includes, presentations, videos, graphics and internal updates on the SLS and HLV, available on no other site. Other images via NASA.)

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

Related posts:

1. Second Guessing NASA VSE Five Alternative Visions for Space Exploration. As concerns grow in...

Shuttle to SLS MPS:

The MPS relates to the powerhouse in the aft compartment of the vehicle, aiding the acceleration from lift-off of an orbiter to Main Engine Cutoff (MECO) – the phase of ascent referred to as “powered flight”.

As such, the Integrated MPS consists of the three Space Shuttle Main Engines (SSMEs), an external propellant tank (ET), a propellant management system used to transport fuel and oxidizer from the tank to the engines, and a multipurpose helium system.

For SLS, the External Tank will be translated into the core stage, becoming part of the in-line HLV. The second stage will ride on top of the core, with the Orion (Multi-Purpose Crew Vehicle) riding on top of the second stage on the crewed version of SLS, replaced by a payload on the cargo version.

Two Solid Rocket Boosters (SRBs) will be attached to either side of the core stage, not unlike the Shuttle stack, as much as these boosters will be larger five segment motors, potentially changing to a liquid version later in SLS’ lifetime.

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

As has been noted previously, SLS will utilize SSMEs – otherwise known as RS-25s. The stock of SSME (RS-25D) engines are currently being preserved at the Kennedy Space Center (KSC), after being donated by the Space Shuttle Program (SSP). There are at least three sets of three engines, removed from each orbiter, along with a spare set of three engines (12 engines in total).

Prior to the orbiters going on display at their respective exhibition sites, each vehicle will be fitted with three Replica Shuttle Main Engines (RSMEs) – made from previously scrapped nozzles and installed via an adaptor – which are being fabricated by SSME contractor Pratt & Whitney Rocketdyne (PWR).

Given the adaptor will be installed inside the SSME domes shields, visitors to the orbiters at their exhibitions won’t notice the difference, especially as the nozzles will be real hardware, repaired from their previous scrap designation.

The recommendation to preserve the flown SSMEs for future use was called for by NASA’s MSFC (Marshall Space Flight Center), KSC and JSC (Johnson Space Center), providing free engines for SLS to utilize on its opening flights.

All of the reusable engines will be destroyed when the unrecoverable core stage burns up in the designated disposal corridor, not unlike the shuttle ET.

As seen in the latest SLS documentation, the plan is to move to a cheaper, non-reusable version of the SSME – known as the RS-25E – once the RS-25D stock is exhausted by the SLS flights.

Now SLS managers have requested the use of the major plumbing inside the orbiter’s own MPS system, which is a natural match for the RS-25s.

“There has been a request to removed the entire MPS (Main Propulsion System) from the orbiters for SLS (Space Launch System),” noted KSC processing information (L2), adding such an operation would delay the shipping dates of the orbiters by over half a year.

“This would be six to nine month impact to the T&R (Transition and Retirement) schedule (for the orbiters).”

This effectively relates to the guts of the orbiters, specifically known as the Orbiter MPS.

The Orbiter MPS includes major hardware items such as the Propellant Management System (PMS).

The MPS PMS consists of manifolds, distribution lines, and valves that transport propellants from the tanks to the three main engines for combustion, and gases from the engines to the tank for pressurization.

The PMS is the lifeline of the integrated MPS. In addition to its primary function of feeding propellants from the External Tank to the engines during powered flight, the PMS also controls the loading of propellants before launch, the post-MECO propellant dump and vacuum inerting.

The removal of this hardware inside the aft compartments of the orbiters would involve disconnecting major hardware – such as the Propellant Feedline Manifolds, which consists of 17-inch and 12-inch piping – through the three spaces left vacant by the removed SSMEs.

Items which would be removed includes the feedlines – vacuum jacketed for H2, insulated for O2 – Fill and Drain (F&D) lines, recirculation lines (H2), and gaseous H2 and O2 lines – which are used to maintain pressure in the ET – via more well known items of hardware such as the Flow Control Valves (FCVs).

The FCVs were highlighted during an investigation into a small liberation from one of the valve’s poppet’s during STS-126.

Mitigation procedures – which included screening of flown valves post-flight at the frabricator Vacco - resulted in no further issues.

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

These are all natural elements of hardware which would provide both the SLS core and the SLS engines with the role they had previously enjoyed with the orbiter, such as the FCV-related Ullage Pressure System (UPS) – which deals with the volume in the LH2 and LO2 tanks not occupied by liquid propellant.

The ullage pressure system consists of the sensors, lines, and valves that are used to collect gaseous propellants (gaseous hydrogen and gaseous oxygen) from the three main engines; the system supplies the gaseous propellants to the External Tank to maintain propellant tank pressure during engine operation, as well as maintaining tank structural integrity.

Propellants must be supplied to the SSME with adequate head pressure for proper engine operation.

Also to be removed would be the MPS helium system, which consists of storage tanks, distribution lines, regulators, and valves that supply helium to the main engines and the MPS PMS.

The helium supply tanks consist of three large (17.3-cubic-foot) and seven small (4.7-cubic-foot) helium tanks known as Composite Overwrap Pressure Vessels (COPV). Each large tank is plumbed to two of the small tanks to form three clusters. Each cluster provides helium to one of the main engines. The remaining small tank is the pneumatic helium supply.

Although this would all result in a large amount of hardware being removed from the aft of the orbiters, visitors to the exhibitions would not have been able to see – or likely have any access – to the aft compartment, meaning their visual appearance will not be altered.

A final decision on proceeding with this work is expected later this year.

(Images: Via Larry Sullivan, Chris Gebhardt (MaxQ Entertainment/NASASpaceflight.com) orbiter engineering tour video (1000mb) available on L2, plus L2 content - driven by L2′s new SLS specific L2 section, which includes, presentations, videos, graphics and internal updates on the SLS and HLV available no where else on the internet).

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

Related posts:

1. Senate pass NASA bill for extra funding – shuttle extension goals The US Senate has passed the new NASA Authorization Bill...

The Ongoing SLS Delay:

As admitted by NASA Administrator Charlie Bolden, the decision on the configuration of the Space Launch System (SLS) was made on June 15, a decision based on the winning Design Reference Vehicle (DRM) out of the Marshall Space Flight Center (MSFC) hosted RAC (Requirements Analysis Cycle) study effort.

Memos on the decision, based around the utilization of a Shuttle Derived (SD) Heavy Lift Launch Vehicle (HLV) – as requested in the Authorization Act – soon circulated at the main NASA centers, with references to an official announcement to be made on July 8, the launch date for STS-135.

In a sign of how widespread the information was, Atlantis’ commander Chris Ferguson told the media to expect the announcement on the next vehicle to be made on launch day, following his arrival at the Shuttle Landing Facility (SLF) from Houston. His statement wasn’t retracted, nor was it corrected, by NASA Public Affairs.

July 8 came and went, as Atlantis launched on the final NASA shuttle mission – and most likely the last domestic manned mission for several years.

General Bolden was then called in front of a “Full Committee Hearing – A Review of NASA’s Space Launch System“, where lawmakers were given the chance to ask questions about the delay in pressing on with the SLS.

After a tough opening question, the General gave arguably his most impressive public performance to date, holding firm on why he was not able to reveal specifics on the vehicle’s configuration. His defence was related to industry restrictions and an ongoing independent cost analysis effort by Booz Allen.

That costing effort – which began on July 5 – is likely to be completed by mid-August, while an announcement on the configuration of the vehicle, is expected “soon”.

 An attempt to request NASA push on with making a public statement on the SLS configuration to the media – to coincide with Atlantis’ landing at the Kennedy Space Center – was turned down by NASA’s leadership.

The continued delays to the announcement are now causing numerous managers and workers – at least those remaining after the massive jobs losses shortly after Atlantis’ return – to question if the delay is based on politically-aligned tactics to kill the SLS.

As many are aware, a second round of job cuts are expected to be carried out soon at key SLS bases – such as the Michoud Assembly Facility (MAF) in New Orleans, where managers have attempted to delay and extend WARN notices in the hope of bridging the gap between Shuttle and SLS – again based on the raised hopes of the June configuration decision by General Bolden.

The continued delays have now resulted in MAF’s management losing patience, as August 26 was set as the date for all of the remaining workforce – a key SLS skill set – to be released.

In effect, those opposed to SLS – such as the architects of the FY2011 plan – only need to delay another month before they can cite the “difficulties and costs” of having to rehire workers to build a vehicle which could have been announced when the workforce was still in place.

SLS Configuration and Schedule:

The SLS configuration is – as expected -  based around a SD HLV, using “Shuttle” boosters, engines and external tank heritage. However, information – acquired in the new L2 SLS section – has provided the most recent and comprehensive overview on the specifics of what is a core vehicle from the onset.

Click here for recent SLS Articles:
http://www.nasaspaceflight.com/tag/hlv/

Initially, the call was to debut the SLS in 2016. As recently noted, the schedule for the opening flight has moved to December 2017 – although it now has an actual mission.

The mission will be lunar, with SLS-1 lofting Orion (MPCV) on an unmanned mission around the Moon.

Ironically, SpaceX recently noted – during their Falcon Heavy announcement – they are close to such a mission capability, far sooner than 2017.

SLS-1 will debut the vehicle in a 2.5 configuration, utilizing three Space Shuttle Main Engines (SSMEs) – otherwise known as RS-25Ds, donated by the Shuttle fleet – on an 8.4m diameter “External Tank” core, stretching 212 feet in length, with five segment Solid Rocket Boosters (SRBs).

It will also sport a 5m “kick stage” – which sources claim is a man rated version of the Boeing Delta IV upper stage. This stage was also listed as one of the candidates for the Sidemount SD HLV.

Nearly four years will pass before the next SLS launch in August 2021, known as SLS-2, a vehicle which is identical to SLS-1, with the only difference being an element of the mission, which would be a manned trip around the moon in the MPCV, prior to a west coast landing in the Pacific.

Although the manifest is very much “to be decided” – August, 2022 would be the next launch date, with SLS-3 again using the same configuration, as would SLS-4 one year later.

SLS-5, in August 2024, would be the debut of the Cargo SLS, with a new fairing and a vehicle hardware change possible – as the winner of the booster competition would debut with this HLV.

While ATK’s Reusable Solid Rocket Motor (RSRM) boosters may continue, should they win the competition, sources claim a likely switch to an RP-1/LOX booster – although an actual engine for such a booster has not been cited at this time.

Sources note the potential options for the liquid booster engine range from a TR-107, to a cluster of AJ-26-500s, to maybe even SpaceX’s Merlin 2. Based on such a manifest becoming a reality, such options would have well over a decade to provide such an option for the SLS.

SLS-6 – August 2025 – would return to the manned configuration, although no mission other than “exploration” – possibly as part of a Near Earth Object (NEO) mission – has been cited by the information.

SLS-7 – August 2026 – a Cargo SLS launch, would see one change to the vehicle, as the expendable SSME – known as the RS-25E – would be employed on the vehicle, taken over from the exhausted Shuttle SSME stock. Again, three engines would be required, as much as all of the SLS vehicles will be designed to have “space” for five engines.

With the manned and cargo SLS’ taking it in turns for the single mission per year role, SLS-11 – August, 2030 – would be the next change, as the five engine core is filled with the two extra RS-25Es, utilizing the full core power plant.

This configuration’s debut would be a cargo based mission, followed by a crewed mission one year later.

And then, in August of 2032, the evolved SLS is expected to debut (see image left), again based on the same 5xRS-25E driven core, but this time with a full Upper Stage, becoming the 130mt+ HLV. This debut (SLS-13) would be – as expected – based around a cargo mission.

Sources note the Upper Stage for the evolved SLS would utilize three J-2Xs, an engine which was originally set be involved with the since-cancelled Ares vehicles.

Other notes of interest claim the Ares Mobile Launcher (ML) has earned a reprieve, after it was initially claimed it would be cheaper to build a new launch platform, as opposed to carrying out expensive changes to the Fixed Service Structure (FSS) and Launch Mount – both of which were very specifically designed with the Ares I in mind.

The Ares ML – currently parked near the Vehicle Assembly Building (VAB) – was also going to be hooked up to the Roller Coaster Emergency Egress System (ESS), a massive structure which was to be built in-situ at Pad 39B. However, it is understood that despite a large amount of money being spent on the design phase, this concept has been scrapped and won’t return for the SLS.

Other efforts, such as the modifications and long-term life extension of at least one of the Crawler Transporters (CTs) to provide the ride for the SLS to the pad, are continuing.

As noted at the start of the article, sources have noted this schedule is preliminary, based on a poor funding forecast – a “worst case scenario” manifest, although no one was able to provide even a draft version of an improved schedule.

(Images: Via L2 content, driven by L2′s new SLS specific L2 section, which includes, presentations, videos, graphics and internal updates on the SLS and HLV.

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

Related posts:

1. Saving spaceship Orion – Zero Base Vehicle task complete NASA Constellation and Lockheed Martin engineers have completed the first...

STS-135 Latest:

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

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

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

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

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

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

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

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

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

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

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

SSME-3 MFV Update:

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Fun Item:

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

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

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

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

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

No related posts.

STS-135 Pad Flow Latest:

As managers prepare to meet at Tuesday’s Space Shuttle Program (SSP) Flight Readiness Review (FRR) in Houston – the second highest level review which leads into the Agency level FRR next week (full coverage in L2) – Atlantis has her game face on as pad flow work is conducted all around the STS-135 stack.

As part of her nominal flow, Atlantis received her payload on Monday, after it was transferred from the payload canister into the Payload Checkout Room (PCR), prior to being installed into her cargo bay.

However, the actual arrival of the payload at the pad – at the end of last week – provided its own challenge, following issues with the canister once it had risen into the Rotating Service Structure (RSS).

“S0600 Vertical Payload Operations: On Friday morning during standard Payload canister alignment for canister door opening, a loud popping noise was heard and one of four canister brackets attached to retract cables,” noted the NASA Test Director (NTD) report (L2).

The bracket in question is used in conjunction with the retract cable to pull the canister to the RSS after hoisting operations.

However, following an engineering evaluation, it was determined that it was safe for operations to proceed, allowing the Payload to be successfully transferred to the PGHM (Payload Ground Handling Mechanism) in the PCR. 

“Engineering processed a MR (Material Report) to use alternate locations in place of the broken bracket to allow for Payload Canister door closure and to let the canister back out to its nominal hanging angle prior to lowering,” added the NTD. “This bracket is not used during the actual canister lowering operation.

“The Payload community analyzed the effects of the failed bracket and determined that the Payload did not see any excessive loads. Canister lowering was completed late Friday night.”

With the RSS moved back into the mate position on Saturday morning, Atlantis’ Payload Bay Doors (PLBDs) were opened to allow what was to be the final payload installation on an orbiter. This was completed on Monday.

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

While this operation was continuing, technicians at the top of the stack began their Non Destructive Evaluations (NDE) of ET-138′s LO2 stringers.

The intertank support beams, which suffered from a number of cracks ahead of STS-133′s launch, have received the proven-mitigation procedure involving the installation of radius blocks, to provide extra strength to the stringers. However, given the close relation to STS-133′s tank, ET-138 underwent a tanking test to provide the required confidence ahead of launch.

“ET NDE operations: The ET/IT access kit was installed on Friday. NDE X-rays began Sunday morning. The adverse weather on Saturday along with an ET access platform alignment issue delayed the preps. NDE is scheduled to run through the week and into the weekend,” added the NTD report.

No obvious issues were observed by pad cameras (OTV) or the Final Inspection Team (FIT) during and after the tanking test, with the NDE inspections used to check under the Thermal Protection System (TPS) foam for any hairline cracks in the stringers themselves.

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

While engineers successfully moved the STS-135 stack out of the S0037 ET Tanking Test configuration, completing securing operations by Saturday night, an issue during the test – relating to a small leak on SSME-3 – is also being worked on Atlantis.

The issue, charged as IPR-48 (Interim Problem Report), saw a breach of the Launch Commit Criteria (LCC) on the SSME MFV limit downstream temperature, indicative of an MPV leakage on SSME-3. With the decision to close the prevalve to the engine, the tanking test was allowed to procedure on a nominal timeline.

As noted in one of the “SSME Bible” presentations (L2), the MFV is a ball valve with a 2.5-inch tubular flow passage and is flange-mounted between the high pressure fuel duct and nozzle diffuser. The valve controls the flow of fuel from the HPFTP (High Pressure Fuel Turbopump) to the coolant circuits and preburners.

The MFV has three moving components: a shaft/ball assembly, a cam follower, and a bellows/ball seal. The ball, cam, and shaft are connected to form a rigid throttling spool.

Redundant shaft seals, with an overboard drain cavity between them, prevent leakage along the shaft (actuator end) during engine operation. Inlet and outlet throttling sleeves align the flow to minimize turbulence and the resultant pressure loss.

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

During initial opening of the valve, the shaft rotates approximately 10 degrees and actuates the cam mechanism to lift the ball seal. After this initial rotation, the ball seal is fully retracted. During the final portion of valve motion the cam follower rides down ramps on the cams and allow the ball seal to be held against the ball by the spring load of the bellows.  
 
The MFV hydraulic actuator mounts to the valve housing and transmits rotary force to the shaft coupling. Dual shaft seals in both the valve and actuator, with vents between the seals, control leakage into the coupling cavity. The coupling cavity is protected against overpressurization by a burst diaphragm.

Ironically, this was a good issue to find during the Tanking Test, given it would have scrubbed the launch attempt on launch day, causing a several day delay to the mission.

Due to the signature of the problem, a decision was taken to replace the valve out at the pad almost immediately. However, engineers had to wait several days to get their hands on the hardware due to the requirement to inert the tank and reopen the pad.

“IPR 0049 SSME Main Fuel Valve (MFV) R&R update: Ball Seal Leak Checks were re-performed on Friday on the MFV to gather data on the valve after it was exposed to cryogenic temperatures,” added the NTD. “Aft access and SSME 3 heat shield and eyelid removals were completed on Saturday. MFV R&R work began on Monday.”

The actual work to carry out the replacement of the MFV on SSME-3 requires breaking into the propellant line.

While this involves a significant amount of work – and will likely require some extensive work on the insulation of the vacuum jacketed lines – the main challenge will be to conduct successful retests of the valve to have enough confidence the system will work as advertised on launch day.

“Retest requirements are still being evaluated, but will include hydraulic FRTs (Flight Readiness Test) and He (Helium) Signature test,” added the NTD report on what may become the key factor in making the launch date, as much as a nominal replacement and retest is expected to support July 8.

As noted by SSME experts (L2) the main problem with the valve suffering from even a small leak is that it could cause a significant enough change in the thermal conditioning of the engine downstream of the valve, which has the potential to disrupt engine ignition. Thus the swift decision to changeout the hardware.

“The ignition sequence, which happens over a 2.4 second time frame, has been fine-tuned to work as advertised  However, It is very dependent on known conditions of mixture ratio and density of the LOX and LH2 when the igniters are fired,” noted the expert comments.

*Click here to see a SSME Ignition in superslow 8mm footage*

“LH2 is very sensitive to the thermal characteristics of the plumbing once the MFV is opened. If that density has changed enough, due to the thermal conditioning of the plumbing between the MFV and the preburner where it is mixed with the LOX, it could prevent either ignition or stable ignition.

“Therefore rather than taking any chances of upsetting engine ignition, the MFV will be changed and helium leak tests performed to check it.”

UPDATE: The MFV is closed to being uninstalled on Tuesday, with retests planned for this weekend. The MFV will be shipped to Canoga Park in California for additional failure testing.

Meanwhile, Commander Chris Ferguson and his crew have arrived at the Kennedy Space Center (KSC) ahead of the TCDT.

Addressing the media, the commander acknowledged the historic nature of the final shuttle mission, but also confirmed that NASA will be announcing the decision on the Space Launch System (SLS) Heavy Lift Launch Vehicle (HLV) on launch day, as reported by this site.

“We’re incredibly proud to represent the final flight,” noted the commander. “A common question we get is what comes after the Shuttle Program? NASA has a big announcement, as I understand, planned for July 8. I think that is to do with what we call the HLV.”

SLS/HLV Specific Articles: http://www.nasaspaceflight.com/news/constellation/

The four person crew will spend until the end of this week working with the Kennedy team on the launch preparations, with the S0017 TCDT Call To Stations (CTS) is scheduled for Wednesday morning at 0730 local. T-0 for the dress rehearsal is scheduled for Thursday at 1100.

(Images: Via Larry Sullivan/MaxQ Entertainment and NASASpaceflight.com (Lead, Payload Canister, SSME wide and Crew Arrival, plus L2 (SSME MFV images) and nasa.gov (NDE). Further articles on STS-135′s status will be provided as information arrives, driven by L2′s new and fast expanding STS-135 Special Section which is already into the FRR content and live flow coverage, plus more.)

No related posts.

SLS Studies:

Months – if not years – of studies and reviews have surrounded the selection of NASA’s new Heavy Lift Launch Vehicle (HLV), only for the aforementioned studies to consistently provide a “winning configuration” known as the Shuttle Derived (SD) Heavy Lift Launch Vehicle (HLV).

While the very nature of a SD HLV being the “best choice” for NASA is a point of conjecture in numerous arenas, the studies never led to any firm decisions being taken at the NASA leadership, or more importantly at the political level.

With the President’s FY2011 budget proposal proving to be highly unpopular, the Senate’s Authorization Act changed NASA’s course and put its weight behind a Space Launch System (SLS) which utilized both Constellation (Ares) and Shuttle hardware.

This Act was based on consultations between lawmakers, space industry heads and NASA managers on the best approach for both supporting the International Space Station (ISS) in the second half of this decade, prior to evolving into the required HLV for Beyond Earth Orbit (BEO) missions.

However, the Act’s requirements appeared to be met by a level of disapproval from NASA leadership, as yet more studies were ordered, resulting in the Marshall Space Flight Center (MSFC) led review of potential launch vehicle configurations via three RAC (Requirements Analysis Cycle) teams.

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

As the RAC studies were continuing, a preliminary report into the SLS from NASA also highlighted budget and schedule concerns – much to the surprise of some RAC team members – although the report was embedded with caveats in finalizing their costings and evaluations on its own claims.

Internal Program-level Frustrations:

A final report to lawmakers is now well overdue, leading to frustrations surfacing from within NASA at even the management level. One of the more impassioned speeches came from Launch Director Mike Leinbach, who addressed his Firing Room workforce after the S0044 Launch Countdown Sim was completed.

Paraphrased highlights from the speech quickly became the subject of high praise from those who had worked the sim. However, a recording of what was actually said has since been acquired by this site, after the audio file spread throughout several NASA centers – again gaining nothing but praise for the highly respected manager - as it provided one of what is believed to be many examples of frustration from within NASA.

“For the final S0044 folks, what I’m about to say would not be appropriate on launch day, and this is our last chance to talk together,” noted Mr Leinbach over the recorded Launch Director loop (transcribed from an audio recording via L2).

“The end of the shuttle program is a tough thing to swallow and we’re all victims of poor policy out of Washington D.C., both at the NASA level and the executive branch of the government and it affects all of us – it affects most of you – severely.

“I’m embarrassed that we don’t have better guidance out of Washington DC. Throughout the history of the manned space flight program we’ve always had another program to transition into – from Mercury to Gemini, and to Apollo to the Apollo-Soyuz test program, to Skylab and then to the shuttle – we’ve always had something to transition into.

“And we had that, and it got cancelled and now we don’t have anything, and I’m embarrassed that we don’t. Frankly, as a senior NASA manager, I’d like to apologize to you all that we don’t have that – so there you are. I love you all, I wish you all the best.

“We will press on through this flow and this launch in the way we always do. We’re going to play this game to the final out and then we’ll be done. I just wish you all the best, and again Godspeed to you all. Thank you.”

As the loop was opened, rapturous applause could be heard ringing around the Firing Room.

SLS Decision:

However, a follow-on vehicle is close to being officially announced, following an increased amount of activity at the executive level this week, resulting in a top level meeting between the SLS leadership and NASA administrator Charlie Bolden, which finally picked the configuration.

“SLS and GO briefed Bolden on a proposed SLS architecture with the following decisions made (finally),” noted one memo (L2). “8.4m core and Upper stage. RS-25s (Space Shuttle Main Engines) on core stage. J-2X on Upper Stage. 4 or 5 segment solid boosters for initial flights.”

While the boosters are highly likely to be five segment motors, the “initially” reference was explained, noting the evolved BEO SLS is yet to know if it will ride with SRBs or Liquid boosters.

“Competed boosters for evolved vehicle (between solid boosters and LOX/RP-1 (Kerolox) boosters),” added the memo. “RFP (Request For Proposals) to be quickly developed to provide data on competed boosters.”

However, ATK have been quick off the mark in informing NASA’s leadership they are ready to support, not just with the initial SLS, but also into the future, via the 130mt class vehicle.

According to source information, the Utah-based company – and home of the RSRM (Reusable Solid Rocket Motor) – have proposed a Firm Fixed Price (FFP) contract for 10 boosters, available between 2012-2015, whilst noting available assets that can support up to 11 SLS missions prior to asset depletion in 2020.

This is notable, given ATK are proposing the initial use of boosters in their expendable mode, thus eliminating several hundred million dollars worth of recovery and refurbishment costs. Sources also add that ATK’s approach from a “cost and schedule” standpoint has been highly impressive.

As far as ATK’s approach for the fully evolved SLS vehicle, source notes claim a future static test could be provided as a pathfinder test for an upgraded booster.

Such an upgraded booster may include recently proposed change to a HTPB (Hydroxyl-terminated polybutadiene) fueled solid in “composite over wrapped steel cases” thus allowing higher MEOP (Maximum Expected Operating Pressure) – to as much as 1500 psi.

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

KSC information has also noted that preliminary assessments will be used to find a use for the Ares I Mobile Launcher (ML), currently sat near the Vehicle Assembly Building (VAB) with no future role to play, following the cancellation of the Constellation Program (CxP) and thus its main customer, the Ares I.

Presentations on the 21st Century Launch Complex proposals (L2) – a stunning set of documents which include the “Point Of Departure” Architecture overviews (and will be the focus of upcoming articles) – also mirror the comments which point to the SLS joining forces with the Ares ML, as much evaluations are continuing into a need for the ML to play a role until the evolved SLS.

“Allocate ML for SLS. Modifications to support SLS architectures, with scarring for extensibility. Incorporate standardized interfaces, using mobile launcher to adapt to  vehicle requirement,” noted the Architectures Refinement Cycle 5.0 section of the latest presentation (in June) via L2.

It is also understood that Boeing will be the main contractor for the SLS vehicle, likely explaining their work at the Michoud Assembly Facility (MAF) on a small scale strongback core, as much as it is likely the first SLS test flight will utilize the stored Light Weight Tank (LWT) ET-94.

The role of Pratt & Whitney Rocketdyne (PWR) appears to be secure for at least the opening gambit of the SLS growth towards its 2016 IOC (Initial Operating Capability), with 12 RS-25Ds available for one-off roles with SLS flights, following their transition from the Space Shuttle Program (SSP).

It is not yet known if a transition to the expendable RS-25E will be made after the four sets of RS-25Ds have been used.

After being the long lead item for Ares I, the Upper Stage J-2X is continuing to make progress, after recently becoming housed in the A-2 Test Stand at the Stennis Space Center (SSC). Beginning in mid-June, the engine will undergo a series of 10 test firings that will last several months.

“An upper stage engine is essential to making space exploration outside low-Earth orbit a reality,” said Mike Kynard, manager of the J-2X upper stage engine project at NASA’s MSFC in a recent public statement.

“The J-2X goes beyond the limits of its historic predecessor and achieves higher thrust, performance, and reliability than the J2. We are thrilled to have the engine in the test stand to validate our assumptions about engine performance and reliability.”

It’s role with the SLS was one of the initial key requirements ordered by General Bolden, after he rejected the two-phase SLS approach.

(The progress on the SLS status will continue to be followed up over the coming weeks. L2 members, follow our exclusive SLS update coverage via the SLS and HLV tags. Images used:  Via L2 content and NASA.gov – plus Mr Leinbach photo via Brian Papke, MaxQ Entertainment/NASASpaceflight.com).

No related posts.

The HLV Centrepiece:

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

SLS Hardware – SRBs:

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

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

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

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

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

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

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

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

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

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

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

SLS Hardware – Core Engines:

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

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

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

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

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

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

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

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

SLS Hardware – Core Structure/Tank:

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

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

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

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

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

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

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

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

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

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

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

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

SLS – KSC:

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

No related posts.

STS-134 Latest:

Endeavour is snugly protected inside the Rotating Service Structure (RSS) at Pad 39A, although the top of her tank is exposed to the elements. While it is not confirmed hail actually hit the tank – for the second time in around a week – inspections have shown no additional areas of interest, following what was only minor damage from the previous storm.

“OV-105/SRB BI-145/RSRM 113/ET-122 (Pad-A): Tuesday’s bad weather generated reports of possible hail observed on OTV (TV Cameras) at the pad. Another iteration of S0018.100, Op 90 has been generated. (However,) Instrumentation did not have any corroborating evidence of hail at Pad-A,” noted the NASA Test Director (NTD) report (L2).

“ET Mechanical, Launch Site Support, NASA Safety, and MAF (Michoud Assembly Facility) representatives completed a walk-down with no new observations of damage on the ET found.”

Interestingly, work is still being completed on clearing the vehicle and pad from the initial storm last week, although the Engineering Review Board (ERB) are officially satisfied that ET-122 is safe to fly as-is – with the very minor damage not requiring any repair work.

“The ERB also concluded that the ET foam hail indentations will be ok to fly as-is, and dynamic loading on the SRB (Solid Rocket Booster) hold down posts should not be a concern,” the NTD report noted. “Ground Support Equipment (GSE) evaluations still remain to be completed, as well as the GUCP (Ground Umbilical Carrier Plate) alignment guide pin fit check.”

Processing has continued in a nominal fashion since the four additional – and since closed – Interim Problem Reports (IPRs) were generated during the Terminal Countdown Demonstration Test (TCDT).

S0024 HPU hydrazine loading operations have been completed, while the APU/HPU (Auxiliary and Hydraulic Power Unit) cart lowering and transport to the fuel farm is in work this week. S5009 Ordnance Installation has been rescheduled to April 18 following the change to the launch date to April 29, caused by an International Space Station (ISS) schedule and Dual Docked Operations (DDO) conflict with a Russian Progress resupply ship.

Several tankers of LH2 are expected at the pad complex on Friday, while preparations are continuing to push towards offline testing of STS-134′s primary payload, the Alpha Magnetic Spectrometer-2 (AMS-02), this weekend – providing work after Friday isn’t impacted by a potential government shutdown.

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

“S07134 AMS End-to-End Test was completed,” added the NTD report. “The AMS payload will be powered up to support off-line testing through the weekend.”

STS-134 SSME FRR:

Endeavour’s ride into orbit at the end of this month will be aided by her three Space Shuttle Main Engines (SSMEs). The noisy trio are no stranger to the aft of the youngest orbiter in the fleet, after pushing her uphill during STS-130. The engines were installed in the following positions on the orbiter: 2059 is ME-1, 2061 is ME-2, while 2057 is ME-3.

With the Space Shuttle Program (SSP) Flight Readiness Review (FRR) completed (15 presentations available on L2), documentation shows managers first overviewed the performance of Discovery’s SSMEs during STS-133 via the In Flight Anomaly (IFA) review at the Program Requirements Control Board (PRCB) meeting (14 presentations available on L2).

“Engine operation was nominal. ME-1 2044, ME-2 2048, ME-3 2058 – No SSME IFA Identified,” noted the STS-133 SSME IFA presentation, outlining the superb performance from the reliable workhorses which have ably supported the Space Shuttle Program since the 1980s. “All SSME observations are encompassed by previous flight and/or test experience and identified as no impact.

“One (minor) observation (believed to be related to the Oxidizer Preburner Oxidizer Valve (OPOV) – though full information is restricted) – was presented to the MMT (Mission Management Team) – no IFA recommended.”

Only one item of interest made it into the FRR documentation for the SSMEs, 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 SSME SSP FRR 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.

“Path limited to E2061 in vicinity of LPO Duct and Controller. No visible evidence of engine contact. Normal electrical pad checkouts conducted. Tactile test of controller harness verified connector integrity.

“Harness “wiggle checks” confirmed internal wire integrity. Potential controller housing impact analyzed. Calculated shock loads within typical vibration levels.”

The presentation continued by overviewing the flight rationale which was presented to managers at the SSP FRR.

“Flight Rationale: Engine hardware inspected and no external or internal damage evident. Electrical Harness Backshells visual and tactile manipulation. Protect sensitive internal wire crimps. Harness “wiggle checks” completed with no anomalies. Effective in finding/confirming electrical intermittents. Controller receptacle integrity confirmed by controller internal pressure check.

“Integrity of ducts, lines, etc. confirmed by visual inspections. Pad verified electrical functions and controller pressure. Harness installation precludes adverse loading or pinching of wiring. Conductors protected by at least three layers of insulation. Potential shock loads to controller housing within vibration experience. Critical functions are redundant.”

Once Endeavour returns home from her STS-134 mission, her engines will be removed and stored, potentially for use with the Space Launch System (SLS), should the ongoing RAC teams at the Marshall Space Flight Center (MSFC) continue to baseline a Shuttle Derived (SD) Heavy Lift Launch Vehicle (HLV) as the Design Reference Vehicle (DRV).

It was back in October of last year when a Program Requirements Control Board (PRCB) meeting recommended the orbiters should gain Replica Shuttle Main Engines (RSMEs) – previously scrapped nozzles installed via an adaptor – for when all three of the vehicles retire to exhibitions, thus protecting the flown SSMEs for potential reuse with the opening SLS flights.

NASA’s scheduled to announce the location of all three orbiter’s retirement homes next week.

The FRR presentation also referenced the readiness of six other SSMEs, three of which are installed on Atlantis for her STS-135 mission – a reference which relates to Atlantis also holding the role of the STS-335 Launch On Need (LON) vehicle, in the event of a highly unlikely need of a rescue scenario for Endeavour’s crew.

The other three engines are allocated to the spare set, in the event any or all of Endeavour’s SSMEs require changeout prior to launch.

“STS-135 Engines: ME-1 2047 ME-2 2060 ME-3 2045. Engines installed on Atlantis 7-9 December 2010. Engines reviewed and ready to support contingency if required,” the SSP FRR SSME presentation added. “Spare Engine set: ME-1 2052 ME-2 2051 ME-3 2054. Post-flight processing and checkouts complete. All current flight and ground test anomalies have been evaluated with respect to impact on Flight Engines.”

(Numerous articles will follow. L2 members refer to STS-134 coverage sections for internal coverage, presentations, images and and updates from engineers and managers. Images used: Larry Sullivan MaxQ Entertainment/NASASpaceflight.com and via L2 Presentations).

No related posts.