Constellation transition – phased retirement plan for the SSME set

by Chris Bergin

NASA has drawn up the retirement plan for Space Shuttle Main Engine (SSME), which will become obsolete at the closure of the shuttle program in 2010.

NASA’s Transition Control Board (TCB) – a body that is tasked with redirection of agency assets to Constellation – has already started to remove engine production capabilities, with only four more new engines to be completed.

Huge amounts of VSE related insider news, presentations and videos – THE most comprehensive place to follow Ares/Orion development – are available for download on L2. See list at the end of this article.

All of this article is based on documented L2 information. For an overview of how L2 works, **click here for sample**




The workhorse of the shuttle fleet for over a quarter of a century, the engine has provided safe flight for the eight and a half minute ride to orbit since 1981, with only one major malfunction during its flight history – STS-51F (Engine number 1) – resulting in a safe Abort To Orbit (ATO).

Constructed at Pratt & Whitney’s Rocketdyne Division, each SSME is capable of achieving 400,000 lbs of thrust with an isp of 453 seconds in a vacuum, or 363 seconds at sea level. Costing around $40 million each, the engines are made up from up to 50,000 parts and could be reused around 20 times.

The engine was set to live on with the Ares I Upper Stage. However, problems with the requirement for air starting the engine with Ares I altered NASA’s direction towards the J-2X, with the Upper Stage eventually following the heritage of the Saturn IVB.

Other issues related to the removal of its reusability, with each engine only flying the one time, before being discarded as part of the Upper Stage, also reducing its viability for use as a set of five main engines on the Ares V first stage – which will now utilized five modified RS-68 engines.

The TCB had several factors to take into account, as they move towards a scaled reduction in production capability with the SSME. Their evaluations looked at several key areas of production, from retiring assets, to ‘spares and repairs’ impacts, should new hardware be required.

All the major elements that make up the engine are being phased out, ending with the shutdown of the A-2 Test Stand at the Stennis Space Center.

‘Present SSME Nozzle new production capability retirement and asset disposal decision,’ outlined the latest in a series of TCB presentations on the SSME, referencing the Nozzles, available on L2. ‘New production capability is defined as the ability to manufacture a new component which includes manufacturing equipment, tooling, materials, supplier base, and skills.

‘Plan is to retire / dispose of Nozzle new production capabilities after Last Need Date (LND) of 6/30/09, unit 5016: Last Need Date – The date at which a capability can be released by SSP without incurring unacceptable risk to mission execution as defined by the element / project managers Nozzle new fabrication and assembly process takes approximately 5 years to complete.

‘Nozzle resources, processes, assembly tooling, equipment and a portion of the suppliers will be maintained for mission spares purchase orders requirements and recycle capabilities.’

Four more engines are set to be completed, with the potential for an additional two spares, which the TCB are confident will be adequate for the remainder of the shuttle manifest.

‘Minimal SSME risk to complete remaining SSP flight manifest. Current inventory contains sufficient spares to meet planned SSP manifest. Assuming completion of units 5013, 5014, 5015, 5016,’ added the presentation.

‘Assembly equipment, tooling, spares, material, and suppliers to be retained to support recycle / repair efforts thru last flight supporting the SSP flight manifest. Minimum manufacturing capability will be retained for limited time to complete units 5017 and 5018 (if required). Support skills capability levels to be maintained to support recycle/repair efforts and to resolve potential anomalies that may arise.

‘Preliminary assessment of capability property items completed. Need to complete detailed Transition Property Assessments (TPA), prepare disposition paperwork, and turnover assets to DCMA for disposal.’

There will be an element of crossover to Constellation work for some SSME contractor work, with six of 53 companies – listed as capable of production – switching over to ‘Exploration’ activities. Also noted is the protection of Pratt & Whitney’s Rocketdyne Division resources during the phased reduction in new production shutdown.

‘PWR resources will not be impacted through retirement of the new production capability. Repair / Recycle utilizes the same personnel for fabrication and assembly operations. Personnel to be retained for recycle efforts, failure investigation and hardware replacement through last flight in 2010,’ added the presentation.

’53 Nozzle suppliers in 8 states have supported these capabilities and are on hiatus. Retirement / Close-out notification has not yet been issued, planned for 2nd Qtr GYF08. No supplier resources will be impacted with retirement of these capabilities.

‘Exploration will utilize 6 Nozzle suppliers. Supplier capability requirements identified and transition plan being developed by Exploration. Prior to disposition, assets required by Exploration will be transferred. Exploration suppliers identified and timely activation of suppliers ongoing.’

An interesting sidebar to the shutdown of SSME assets is noted at the end of the presentation, referencing engine facilities in California.

‘The Pacific Furnace located at Canoga Park CA. is used to braze the Nozzle assembly. This has been identified as being eligible for listing on the National Register of Historic Places.

‘Environmental hazards identified and will be handled in accordance with existing PWR Environmental Health and Safety (EH&S) procedures. The chemical milling equipment at supplier GKN Chemtronics located in El Cajon CA. will require special disposal handling if expected supplier purchase offer not approved.’

**Ride home through the fire, sparks and plasma of re-entry with Atlantis, Discovery and Endeavour. FIVE Stunning high quality 2hr, 355-400mb Camcorder and HUD videos – from payload bay closure – through re-entry with an astronaut held camcorder video – to post landing – several more videos showing landing from 90,000 ft also available and HUD videos from STA landings. Now includes HALO II Re-entry video, and re-entry videos from Gemini and Apollo (converted from 8mm)**

While 2010 is the current retirement date, discussions have been taking place about potentially adding up to six months of flying time to Shuttle, in order to help buffer what is currently a five year gap before Ares I comes on line for US manned access to the International Space Station (ISS) and primarily to aid any future pressure on the current manifest.

However, any extension – currently deemed unlikely due to funding requirements for Constellation – does not add further flights to the current manifest, which is targeted to end with the July, 2010, CLF (Contingency Logistic Flight) mission with Endeavour on STS-133.

Regardless, NASA has continued to improve the SSME, with recent additions including the AHMS (Advanced Health Monitoring System) and new knife edge seals on the High Pressure Oxidizer Turbopump (HPOTP) – which debuted on STS-120’s SSMEs. Further refinements to the powerpacks will be continually monitored for safe flight.

However, the beginning of the end for shuttle is already being actioned, with resources being phased down around the US, such as at the Michoud Assembly Facility (MAF), home of External Tank production, where the last ET is has already started (ET-137) fabrication as a flight spare.

The TCB is expected to confirm phased shutdown of MAF’s shuttle resources next Summer, though they will immediately transition to work on Ares I and eventually Ares V.

Selection of L2 Resources For Ares I, V and Constellation: 

Major changes to Orion (Graphical overview, presentations). Specifics embargoed to L2). Latest Mobile Launcher details. Orion/Ares I/Delta IV Heavy NEO Feasibility Study (Video). Constellation EVA Study Presentation. Superb Gene Kranz address to CxP workforce (Apollo to Orion feature) video. MOD ‘LEO to Mars’ presentations.

Superb Ares I Launch Ascent, Pad Abort Test CGI Videos (three). Integrated Stack (IS) Technical Interchange Meeting (TIM) notes – Nov 6 to Nov 15. The full ‘8th Floor News’ – Constellation Update (performance issues) – Nov 5. Ares I Mobile Launcher PMR.

‘Proposed’ Ares I SRBSF (Mini VAB) and graphic. LSAM (LDAC-1) Video and Images. Several Constellation All Hands Videos and Presentations. Ares I Pad Rollercoaster (Old and New presentation and slides – the very cool ‘CGI ride on the Ares pad coaster’ video. Ares I VAB ‘In-Line’ Stacking presentation slides.

Presentation of Ares/Orion impacts relating to Shuttle manifest acceleration. Ares I Interstage diagrams. Ares V Super Crawler. Ares I Launch Pad images (ML etc.) Hi Res images of Ares I-X Upper Stage. Orion 606-7 Data Updates. Updates Constellation launch schedule through to Orion 15. Orion Seat test photos. New ML Graphic and info. New Ares V graphic and baseline data. Large collection of hi res Orion paracute drop tests. SIX Part Series of Ares I Upper Stage Graphical Overviews. DAC-1C DDD Vast Slides on Vehicle Design. ATK First Stage Presentation. 39B Lightning Towers Slides. DAC-1C Departure points to DAC-2 Upper Stage Graphcs (Many Changes).

Orion/CEV Display Layout Presentation (40 pages). ATK figures on the 5-Seg Booster weight for CLV. Weather Shield (Rain Shield) for Orion on the pad. New Super hi-res images of Ares I. ATK Cutaway graphics of Ares I – perspective and axonometric. Ares I/Orion CxP 72031 Requirements Validation Matrix Information. CEV Paracute Assembly System (CPAS) Presentation.

Orion Launch Abort System (LAS) overview presentation. Changes to Ares I Upper Stage – expansive details and data. Ares I/Orion CxP 72031 Requirements Validation Matrix Information. CLV Umbilical Trade Matrix XLS. Vehicle interfaces for the DAC 1C version of Orion Ares. Ares I-X Test Flight Plan (full outline) Presentation. Ares I-X timeline and modification expanded info. Ares I Reference Trajectory. Boeing’s STS to Ares – Lessons Learned Presentation. CLV DAC-1C (Changes to CLV Upper Stage).

Ares I-X: Four Seg+Dummy ‘Tuna Can’ stage. Ascent Developmental Flight Test Presentation. CLV Pad 39B Handover Info and Latest. New images of CLV on top of new MLP and LUT. Lockheed Martin CEV/Orion Updates. ATK figures on the 5-Seg Booster weight for CLV.

90 Minute Video of Constellation all hands meeting. Escape System Trade Study Presentation. CEV-CLV Design Analysis Cycle Review (DAC-2) Presentation. Flight Design and Dynamics Division CEV update. CLV Mono-propellant RCS system. CEV pressurisation system review. CLV/CEV Configuration Images. The 2×3 Seg SRB Crew Launch Vehicle Option Presentation…plus more.

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