VAB integration between SLS and Orion outlined by SPIO
NASA’s Spacecraft and Payload Integration Office (SPIO) has outlined the complex process of integrating Orion on to the Space Launch System (SLS) stack during processing inside the Vehicle Assembly Building (VAB). The integration plan will be first put into action ahead of the opening SLS mission in 2017.
How To Mate Orion With SLS:
The VAB has been the focal point for mating NASA launch vehicles since the days of the Saturn through to the 30 year career of the Space Shuttle. The giant building’s role has been secured for decades to come, providing the role for SLS integration with its payloads.
Its four main Bays are being re-purposed not only to host SLS, but also any potential commercial launch vehicle – per its multi-user ambitions. However, only SLS has been confirmed as specifically requiring the iconic facility.
Building up the monster rocket will be no easy task, although some similarities with previous Space Shuttle stacking are likely to be employed – not least with the Solid Rocket Boosters (SRBs), arriving in segments by train from ATK’s Utah facility, prior to Booster Integration build up.
Once the twin five segment boosters have completed their stacking on the Mobile Launcher, the core stage – shipped in from the Michoud Assembly Facility (MAF) in New Orleans and offloaded at KSC’s turn basin – will be rolled into the Transfer Aisle and hoisted skywards by the VAB cranes that also boast an esteemed history.
Not unlike the mating operations between the boosters and the Shuttle’s External Tank, several days of mating, integration and closeouts will take place on the headless stack, prior to the integration with the spacecraft side of operations. That’s where SPIO come in.
“SPIO serves as the focal point for integrating payloads and spacecraft to the SLS vehicle. Adapters, propulsion stages, separations systems, and fairings are designed and procured as required to support SLS Program-allocated Design Reference Missions (DRMs),” notes the SPIO Concept Of Operations Presentation – acquired by L2.
As one would expect, integration is far more complex a task than simply placing Orion on top of the SLS launch vehicle. In reality, several elements of hardware will be required, collectively known as the Integrated Spacecraft and Payload Element (ISPE).
Built up from the top of the SLS core stage, the Launch Vehicle Stage Adapter (LVSA) will be the first element to be integrated to the stack, with a separation plane at the top of the LVSA – the mark between the first and second stages of the entire vehicle.
The next element will be the Interim Cryogenic Propulsion Stage (ICPS), currently set to be the Delta Cryogenic Second Stage (DCSS) for at least the first two flights of SLS. The MSA (Orion’s “MPCV”) Stage Adaptor will follow as the stack grows, prior to the integration of Orion – with its Service Module – and the Launch Abort System (LAS) to close out the entire stack.
The SPIO document provides an expansive overview of each element – and their integration paths – towards being added to the stack that will make up the SLS/Orion vehicle ahead of rollout to Pad 39B.
“The LVSA assembly includes the ICPS separation system, electrical and C&DH cable harnesses, diaphragm and the primary structure,” notes the document.
“The LVSA assembly mates to the Core Stage (CS) aft end and the ICPS forward end. The LVSA assembly supports cable routing from CS to ICPS, as well as provides structural support for launch and separation loads.”
Since the Core Stage and the Aft Skirt of the ICPS LH2 Tank are of different diameters, the LVSA will be required to conform the two different Outer Mold Line (OML) dimensions. These dimensions are clearly shown in graphical representations of the vehicle.
The LVSA will also provide human access necessary for mating cable harnesses that will pass between ICPS and CS. This access will be available in the VAB and at the Pad. The document notes the electrical and C&DH cable harnesses terminate on either side of the diaphragm via jumper connections.
During a processing flow, the LVSA assembly is transported to the integration bay where it is readied for integration with the Core Stage.
Next, the LVSA assembly and Core Stage mating flanges are verified to meet flatness and cleanliness requirements, and the components are electrically grounded prior to installation on the Core.
“Standard lifting Ground Support Equipment is attached to the facility crane and mated to the lifting interfaces of the LVSA,” the document adds. “Following completion of LVSA lifting preparations the assembly is hoisted off of its processing fixture/cart GSE to just above the Core Stage.
“At this time, the LVSA is clocked to the correct orientation and aligned for position, perpendicularity and parallelism to the CS with the use of Alignment GSE, and is lowered into place. The LVSA is mechanically secured to the CS, then all required electrical and C&DH interfaces are connected and verified. The LVSA assembly is now ready for mating with the ICPS.”
The ICPS is officially classed as “an existing commercial LO2/LH2-based upper stage that will be modified to meet NASA human rating requirements” – however, it is well-known the DCSS is the stage of choice for the opening SLS/Orion missions.
“The ICPS will be manufactured at the contractor’s facility, further prepared during offline operations, and subsequently delivered to the KSC integrated operations facility ready for stacking. The ICPS is integrated with the Orion via the MSA, which transitions the Outer Mold Line (OML) diameter of the ICPS to that of the Orion,” added the document.
“The ICPS contractor is responsible for the production tooling, electrical and mechanical GSE (Ground Support Equipment) design, fabrication and verification, as well as provision of transportation containment and pre/post shipment checkout procedures with SPIO oversight.”
The document also adds than the ICPS pyrotechnic separation system physically resides at the interface between the ICPS and the LVSA, and that this separation system is considered part of the LVSA assembly. The separation system is integrated into the LVSA assembly at the manufacturing facility prior to being transferred to KSC for integrated operations. It will also include a pyrotechnic Flight Termination System (FTS).
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As part of the processing flow, the ICPS is transported to the integration bay where it is readied for integration with the LVSA assembly. As with all the elements, the LVSA and ICPS mating flanges are verified to meet flatness and cleanliness requirements, and the components are electrically grounded prior to ICPS installation.
Once again, the hardware – this time the ICPS – is hoisted by the VAB crane, clocked to the correct orientation and aligned for position, perpendicularity and parallelism to the LVSA, and is lowered into place – ahead of being mechanically secured to the LVSA, followed by all required electrical interfaces being connected and verified.
The top end of the Integrated Spacecraft and Payload Element is the MSA, which also serves as a spacer between the exit plane of the Orion SM engine nozzle and the forward end of the ICPS LH2 tank. This interface ring is the first actual element of hardware that is being constructed for SLS, due to its requirement on the Exploration Flight Test -1 (EFT-1) vehicle.
“In order to isolate the environments between the Orion and the ICPS, a diaphragm is integrated into the design of the MSA,” the document adds. “The MSA is assembled at the manufacturing facility and the sub-Element delivered to KSC for integration operations.”
The same process for the Spacecraft Adaptor is noted for the LVSA and ICPS during the processing flow, providing commonality of operation and checkout procedures.
Orion – which will be processed for flight in the Operations & Checkout (O&C) building – will then be transported to the VAB Transfer Aisle in preparation to follow a similar process employed with the ISPE hardware, allowing for the completion of the stack once the LAS has topped off the vehicle.
A large amount of work will then take place on the entire stack, via Interface Verification Testing, Pyrotechnic Ordnance Integrated Operations and Vehicle Orientation GN&C Alignment, prior to the stack being readied for rollout operations.
Rollout and pad operations will be covered in a future article.
(Images: Via L2 content from L2’s SLS specific L2 section, which includes, presentations, videos, graphics and internal – interactive with actual SLS engineers – updates on the SLS and HLV, available on no other site. Other image via NASA)
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