STS-134: Payload arrives at 39A – Managers aiming to avoid countdown drama

by Chris Bergin

Endeavour’s highly advanced payload arrived at Pad 39A on Monday evening, as STS-134 continues to track the April 19 launch date target with several contingency days to spare. Managers have also been discussing their Range Hold Coordination, following STS-133’s dramatic T-5 minute hold, which resulted in a restart with just two seconds to spare.

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Endeavour’s final pad flow has managed to proceed through the main Hypergolic Propellant Servicing – known as S0024 operations – without any incident of note, bar one minor Interim Problem Report (IPR), which is undergoing troubleshooting.

However, the main orbiter hyper loading tasks are complete, with the stage set for the loading of the Hydraulic Power Units (HPUs) on the Solid Rocket Boosters (SRBs) early next month.

“OV-105/SRB BI-145/RSRM 113/ET-122 (Pad-A): S0024 Hypergolic Propellant Servicing operations are complete to date. Oxidizer load was completed at 1553 EDT Friday,” noted the NASA Test Director (NTD) processing update report (L2).

“OMS/RCS (Orbital Manevering System/Reaction Control System) fuel load was completed at 0100 EDT Saturday, and APU (Auxiliary Power Unit) fuel load was completed at 0800 Saturday. Pad A was opened for controlled work on Saturday at 1430.”

The single issue – with IPRs commonplace during this stage of the pad flow – related to a leak on a Ground Support Equipment (GSE) cart, used for the APU fuel load. While troubleshooting is continuing, this issue did not delay the completion of S0024 operations over the weekend.

“New IPR-0031 to APU. System 1 PV tank decayed during interface leak check. Troubleshooting confirmed the leak was on the GSE cart. Engineering will upgrade to a GSE IPR for further troubleshooting. HPU load is currently scheduled for Monday, April 4.”

The main focus of the pad flow this week relates to the arrival of STS-134’s highly scientific physics payload, along with the ExPress Logistics Carrier3 (ELC3), which is packed with Orbital Replacement Units (ORUs) for the long-term benefit of the International Space Station (ISS).

The primary objective of the ISS ULF6 mission is to deliver the Alpha Magnetic Spectrometer-02 (AMS-02), which is a state-of-the-art particle physics detector constructed, tested and operated by an international team composed of 60 institutes from 16 countries and organized under United States Department of Energy (DOE) sponsorship.

The AMS-02 will use the unique environment of space to advance knowledge of the universe and lead to the understanding of the universe’s origin by searching for antimatter, dark matter and measuring cosmic rays.

The Experiment to Space Station (ExPress) Logistics Carrier3 (ELC3), will carry the Ammonia Tank Assembly (ATA), High Pressure Gas Tanks (HPGTs), Special Purpose Dexterous Manipulator (SPDM) Arm with ORU Tool Changeout Mechanism.

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Riding out to the pad inside the payload canister, preparations started with the retraction of the Rotating Service Structure (RSS), opening what is known as S0600 Payload Operations.

The payload canister was then lifted from the flatbed truck by the RSS hardware, transferring it into the Payload Checkout Room (PCR) for its eventual transfer to Endeavour’s Payload Bay.

“S0600 Payload Operations: RSS retracted 0915 Monday morning in preparation for payload delivery. CTS (Call To Stations) for payload transfer to Pad A is scheduled for 1800 Monday night,” listed Monday’s NTD sequence of events.

“The canister will be lifted to the PCR tonight and transferred in to the PGHM (Payload Ground Handling Mechanism) tomorrow (Tuesday). Payload installation into the orbiter is scheduled for Friday.”

Other items of interest noted by the NTD include the expected delivery of two waves of tankers to the pad complex on Tuesday. The tankers will be replenishing the LH2 storage tank, as preparations for launch continue to pick up the pace.

The latest report also notes no additional damage has been found on the vehicle, following last week’s dropped wrench incident.

“IPR-0026 (Dropped Wrench) update: Walk-downs of the ET (External Tank), SRB, and Orbiter are complete to date; no additional damage has been discovered,” confirmed the NTD.

This incident related to an engineer accidentally “dropping” an 8 inch wrench from near the top of the pad, causing some minor Thermal Protection System (TPS) damage to Endeavour’s belly, during FRCS (Forward Reaction Control System) fuel post QD (Quick Disconnect) connection operations.

The wrench was located, and the two areas of TPS damage are extremely minor. It is expected no repair work will be required, with the two areas documented in order for the Damage Assessment Team (DAT) to strike off their Region of Interest (ROI) list when the scuffs are noticed during Endeavour’s opening TPS inspections on orbit.

FRR – Range:

Very little has been said about what was an excellent turnaround of a problem with a USAF range safety system computer during STS-133’s countdown, given the system is under USAF control, though LRR documentation has revealed NASA managers are taking steps to ensure the procedures are fine-turned, in the event of a similar occurrence during the final two shuttle countdowns.

“Formal action assigned from the STS-133 Launch. Countdown Post- Test Briefing – in work. Range Hold Coordination – Reviewed process for identifying and communicating Range holds to the NTD and for Range hold switch implementation,” noted STS-134 LRR documentation (L2).

The fine-tuning relates to Range Operations (SRO) and NTD on the request to “place the hold switch in the proceed position,” per the transcript of the loop during the T-5 minute hold – a reserved three minute hold which was released with two seconds of drainback hold remaining in the launch window.

“Range holdfire switch activation procedure under review. Range anomaly reporting protocol under review. NTD face-to-face meeting with SROs and PIM,” added the LRR presentation, noting SROs will be present in Firing Room 4 (FR-4) during STS-134’s launch countdown simulation runs.

“SROs positioned in FR-4 bubble for STS-134 S0044 for situational awareness and problem reporting protocol awareness. Range is performing internal review of systems and processes for enhancements in identifying and communicating range readiness for launch.”

With the Flight Readiness Review (FRR) season in full swing for STS-134, departmental review meetings are all focusing towards the Space Shuttle Program (SSP) FRR, set to take place on March 31 – leading into the launch date-setting Agency level FRR a week later. The Mission Operations Directorate (MOD) FRR – 14 presentations on L2 – has already taken place.

“Space Shuttle Endeavour began the rollout from the Vehicle Assembly Building on the evening of March 10th and arrived at Launch Pad 39A early on the 11th. The MOD Flight Readiness Review was also conducted on March 10th and was an excellent review of MOD’s preparedness,” noted MOD’s “8th Floor News” (L2).

“The Shuttle Program FRR is scheduled for March 31st and the Agency FRR on April 7th.”

(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: and L2 Presentations).

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