Discovery working payload installation issues – Green light for Agency FRR
The STS-133 flow has been slightly impacted by a delay relating to a problem with the Payload Ground Handling Mechanism (PGHM) at Pad 39A. However, Discovery remains on track the November 1 launch date, to be approved at the Agency Flight Readiness Review (FRR) – which will take place on October 25, following a “Go” from the SSP FRR this week.
STS-133 Pad Flow Latest:
Discovery herself is suffering from no issues during her pad flow, and continues to hold several days of contingency time based on a November 1 launch date.
The week’s milestones have been centered around numerous system checks, along with the arrival of Discovery’s STS-133 payload to the pad. Although the arrival was delayed by a day, due to a problem loading the Permanent Multi-purpose Module (PMM) into the payload cannister for the ride out to 39A, movie crews still managed to film scenes for the 2011 blockbuster Transformers 3.
Kennedy Space Center (KSC) workers note that a large amount of filming took place with Discovery in full view, given the Rotating Service Structure (RSS) had been opened for the arrival of the payload – a milestone which had been delayed 24 hours due to the loading cell problem.
“OV-103 / SRB BI-144 / RSRM 112 / ET-137 (Pad-A): The vehicle was powered up to support OMS/RCS (Orbital Maneuvering System/Reaction Control System) cross-feed checks, APU (Auxiliary Power Unit) decay checks, and MSBLS (Microwave Scan Beam Landing System) time/cycle test,” noted the NASA Test Director (NTD) processing update (L2).
“All were successfully completed, less APU decay checks, which are complete to date.”
“S0600 Vertical Payload Operations: The RSS was rotated to the park position to support payload arrival and installation operations. During system walkdown it was noticed that the MLP (Mobile Launch Platform) side 2 vacuum pump coupler was broken; the coupler has been R&R’d and the system is operational.”
With a quick resolution for the vacuum pump issue, the payload arrived at the pad in the early hours of Thursday and was transferred to the Payload Ground Handling Mechanism (PGHM) in the Payload Checkout Room (PCR).
“CTS (Call To Stations) for S0600 occurred at 0001 EDT. The payload arrived at 0201 EDT and lift to the PCR. Lift first motion occurred at 0546 EDT. The payload was transferred to the Payload Ground Handling Mechanism in the PCR. Canister lowering and RSS rotation (on the upcoming schedule).”
However, the operation to transfer the payload from the cannister to Discovery’s Payload Bay suffered a problem, relating to a failed hard drive on the control console that is responsible for the critical operation of handing over the payload to the orbiter.
“NEW PR (Problem Report): The transfer of the payload to the Payload Ground Handling Mechanism (PGHM) was delayed 24 hours because of a PGHM control console error. The issue has been isolated to a failed hard drive which was replaced,” the NTD noted.
“Canister lowering and transport back will be completed tonight (Friday). RSS rotation to mate will occur Saturday morning. Payload Bay door opening is now scheduled for Saturday morning. Payload installation into the Orbiter is scheduled for Monday morning.”
Engineers will continue to work through the weekend on payload operations. With around six days worth of contingency in the flow, no impact on the launch date is expected from this week’s delays.
STS-133 SSP FRR:
Over at the Johnson Space Center (JSC), the second most important Flight Readiness Review (FRR) for the mission was conducted by the Space Shuttle Program (SSP) on Wednesday. A second day’s worth of meetings wasn’t required, a sign of how smoothly the review proceeded.
The SSP FRR is the result of numerous departmental meetings, with all major hardware and mission reviews presenting to the SSP management. In total 27 presentations (Main and Backup) were produced for review by the managers (available on L2, with numerous articles to follow).
“All Orgs polled go to proceed to STS-133/ULF5 Agency FRR on 10/25,” flashed a memo (L2) on Wednesday evening, marking a successful review, as the mission presses forward to the final FRR later this month.
Normally the Agency FRR follows one week after the SSP FRR. However, scheduling conflicts with key managers who are involved with International Space Station meetings, resulted in the delay to just prior to the start of the launch countdown.
This is not expected to be a problem, due to the very “clean” nature of the SSP FRR, which raised only the one “action item” – relating to the frangible nut on the Solid Rocket Boosters (SRBs).
Although such a failure during a launch would result in a LOV/C (Loss Of Vehicle/Crew) scenario, the action item will gain the expected Flight Rationale in time for the Agency FRR at the Kennedy Space Center.
“The SSP FRR has concluded. All orgs polled Go to proceed to the Agency FRR on 10/25 in support of launch on November 1st,” noted the prefacing memo noting the green light gained at the SSP FRR.
“The review was very clean with no exceptions and only one action item issued related to an open SRB item for a frangible nut that failed Destructive Lot Acceptance Testing.
“Flight rationale is in work and is expected to be based on STS-133 and STS-134 boosters flying frangible nuts from a different lot that has passed testing and has flown since STS-125. An FRR action was issued to bring this item to a PRCB (Program Requirements Control Board) or noon board prior to the Agency FRR.”
STS-133 Specific Articles: https://www.nasaspaceflight.com/tag/sts-133/
Also gaining a mention was the failed Pump Module on the External Thermal Control System (ETCS) Loop A, which was recently replaced via several Stage EVAs. The failed unit is scheduled to be returned on Atlantis, via what remains a notional STS-135 mission, due to concerns relating to the appropriation of funding via the approved Senate Bill (article next week).
Pre-empting its return, managers have decided to add a task to EVA-2 on STS-133, requesting the space walkers to vent any remaining ammonia from the unit, in order to mitigate a potential flammability issue once the hardware is installed inside Atlantis’ Payload Bay for the return to Earth.
“STS-133/ULF5 is an 11+1+2 day mission with two scheduled EVAs, scheduled to launch on November 1st at an inplane time of 1540 central. The cargo complement includes the Permanent MPLM (PMM) and External Logistics Carrier 4 with a spare radiator and five open FRAMs,” continued the SSP FRR approval memo.
“The only significant open item is the analysis related to the pump module ammonia vent. The pump module is expected to have a small amount of ammonia (less than ~10 lbs). Analysis showed that if this ammonia was released in the payload bay, it exceeds flammability limits. Therefore, a task to vent the ammonia was added to EVA-2 in prep for return on STS-135 if that mission is flown.”
While the task to vent the ammonia is not deemed to be a problem for the EVA tasks, engineers need to check any venting does not find its way on to Discovery’s aft hardware or one of the ISS’ solar arrays. That analysis is currently being conducted, with a backup plan to add the task to a Stage EVA, when an orbiter is not docked to the orbital outpost.
“A potential concern with the vent is impingement on the Orbiter tail and OMS pods. The vent nozzle can be adjusted 30 degrees but then impingement is on a solar array. Analysis for both of these scenarios is underway,” added the notes.
“SSP suggested that a stage EVA be considered if there are concerns. The expectation is that this issue will be resolved prior to the Agency FRR.”
(Photos by Larry Sullivan, NASASpaceflight.com and MaxQ Entertainment. Payload Photo via L2. Graphics, STS-133FRR Presentations via L2).