STS-133 Launch Site Flow Review outlines Payload and TPS discussions

by Chris Gebhardt

As engineering preparations continue in earnest for the April 5 launch of Discovery, KSC engineers continue to work and plan for Discovery’s follow-up flight, the STS-133 mission currently scheduled to launch on September 16, 2010. Among these various preparations include payload processing milestone evaluations, MPLM to PMM configuration change proposals and challenges, and TPS work priorities.

Payload Evaluations:

In all, Discovery’s payload for the STS-133 mission will be the ELC-4 (ExPRESS Logistics Carrier 4) and the Permanent Multi-purpose Module (PMM) for the ISS (International Space Station).

For the ELC-4, the pallet was delivered to the Kennedy Space Center via a C-5 transport on August 15, 2009 for receiving inspection and preliminary processing work for the STS-133/ULF-5 (Utilization and Logistics Flight 5) flight.

Currently, ELC-4 processing tasks are ahead of the pre-planned timelines.

Moreover, the first of the two primary cargo elements to be attached to the ELC-4 – the ExPCA #4 (ExPRESS Pallet Controller Avionics 4) – was delivered to Kennedy on February 19 with the HRSR (Heat Rejection System Radiator) FSE (Flight Support Equipment) expected to arrive on April 1.

Processing of the ELC and its cargo elements will become an integrated effort on May 19 when the ExPCA is scheduled for installation onto ELC-4. Installation of the HRSR ORU (Orbital Replacement Unit) onto ELC-4 is currently scheduled for June 3.

While all further integrated ELC-4 testing is Under Review past that point, preliminary timelines indicated that integrated ops testing will begin on July 12 with “ELC4 Deck to Keel Mate” occurring in mid-July.

STS-133 Specific Articles:

Closeouts of the ELC and payload will also be completed by mid-July. CEIT (Crew Equipment Interface Test) and ICD walkdown have yet to be scheduled.

Final Weight and CG (Center of Gravity) measurements will take place in late-August with ELC-4 installation into the Payload Transport Canister also occurring in late-August.

While ELC-4 and its related cargo elements are currently either ahead of or right on their processing timelines to meet the NET (No Earlier Than) September 16, 2010 launch date of the STS-133 mission, the reconfiguration of the MPLM (Multi-Purpose Logistics Module) Leonardo – also referred to in the daily processing world of NASA as MPLM Flight Module 1 – is somewhat more problematic.

Final approvals of baseline configuration changes to MPLM Leonardo for reconfiguration into a PMM were approved at the SSPCB (Space Station Program Control Board) on March 2.

“PMM External Configuration (proposed): Modifications to include removal of +Y FRGF, removal of ROFU components, replacement of CBM seal, installation of new forward end cone MMOD shields, feed through seal replacement, visiting vehicle retro-reflector installation, and modification of MLI underneath MMOD shields to add Nextel/Kevlar ‘mattresses,'” notes the Launch Site Flow Review (LSFR) document for STS-131 – available for download on L2.

Currently, engineers have removed MPLM Donatello’s (Flight Module 3 – FM3) MLI (Multi-Layer Insulation) blankets and shipped them to TASI for modification for use on PMM Leonardo.

Nonetheless, processing timelines for Leonardo’s reconfiguration were already extremely tight given her role as the MLPM on STS-131 back when that mission was scheduled to launch on March 18.

Since STS-131 is now scheduled to launch on April 5th (pending final approval for flight on Friday during the SOMD “Agency” FRR), landing of Discovery will now occur under a nominal mission timeline on April 18.

Given a KSC landing for STS-131, MPLM Leonardo would be returned to the SSPFR (Space Station Processing Facility) on April 27 – the same day that external reconfigurations for PMM use are to begin.

Complete deintegration of MPLM Leonardo from STS-131 configuration would be complete by May 17 with “PMM Standalone Internal Modification ‘Window’ occurring from May 18-20.”

PMM testing would be completed by June 14 with PMM rack integration complete by July 12.

PMM closeouts are currently scheduled for late-August, as are final weight and CG measurements and installation into the Payload Transport Canister.

However, this timeline does not meet the STS-133 pad flow requirement to have the STS-133 payload to Pad-A’s Payload Changeout Room by August 11.

“PMM will not be ready for delivery to the Pad any earlier than the last week of August 2010. Current SSP baseline “payload to Pad” date is 11 August 2010,” notes the LSFR document.

Furthermore, the LSFR notes the multiple threats to the MPLM to PMM reconfiguration timelines.

“There are multiple threats to the MPLM to PMM conversion/processing campaign: Recent delay of the STS-131/19A launch (will STS-133/ULF5 launch slip correspondingly?), potential for further 19A launch delays, potential for an other than KSC 19A landing, significant number of ‘first time’ modification operations to be performed by ASI/TASI, potential for late cargo requirements, and workforce changes/turnover.”

In all, NASA is looking at several operations to smooth out these processing challenges, including some talk of switching the PMM from Leonardo to Raffaello (FM 2), though that is just talk and engineering evaluation at this time with no official word as to whether or not this is a serious consideration.

TPS Priorities:

For STS-133 processing, Discovery will undergo standard TPS (Thermal Protection System) processing along with several non-standard TPS turnaround tasks.

Among the standard work to be performed during Discovery’s flow is STS-131 flight damage repair, OMRS requirements, LRU access, and deferred work from previous turnaround flows.

Further, corrosion sampling will be performed on 10% of “total tile allocation” as well as putty repairs to RCC (Reinforced Carbon-Carbon) and Window DTA zones.

Nevertheless, the completion of several TPS upgrades remains for orbiter Discovery – upgrades that have been in work since RTF (Return for Flight).

TPS “Prioritized Opportunity: 1 thru 10 complete on OV-103” with 10 areas remaining, notes the LSFR document.

Of these areas, it is not expected or required that all work be completed on the 10 outstanding areas before the workhorse Orbiter takes her final flight.

Some of these TPS areas with pending upgrades include 39 of 40 tiles around the ET Door starboard sides and leading edge, 24 out of 24 tiles on the outboard aft portion of the MLGD (Main Landing Gear Door), 13 of 14 tile upgrades on the nose of Discovery, as well as 20 of 42 tiles on the vehicle’s Base Heat Shield Stinger.

Further areas of TPS upgrades include 22 of 40 “piano key” Body Flap Stub tiles, three zones of gap filler replacements in subset 2B along the MLGD edge, as well as the installation of BRI tiles along the MLGD (top priority and non completed to date), ET doors (23 tiles remaining), LESS panels (60 tiles remaining), and NLGD (Nose Landing Gear Door – 104 tiles remaining).

As such, Discovery’s processing flow will be balanced with mandatory TPS turnaround operations, TPS upgrade priority tasks, and all other processing work to ensure that Discovery is in the best condition for flight on the STS-133 mission.

L2 members : Documentation – from which the above article has quoted snippets – is available in full in the related L2 sections, now over 4500 gbs in size

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