STS-131 mated as “schedule crunch” pressures downstream launch manifest

by Chris Bergin

Discovery and External Tank ET-135 have completed mating operations with no issues reported, as STS-131 continues to enjoy a smooth flow towards rollout next week. Meanwhile, STS-132’s ET-136 is due to arrive at the Kennedy Space Center (KSC) early next week, as managers discuss the “schedule crunch” of the final three “scheduled” shuttle missions.

STS-131 Processing Latest:

ET/Orbiter mate operations are conducted over two to three days, as engineers work on the precise tensions for the mating of the LH2 and LO2 studs on either side of aft part of the tank with the orbiter. This process can sometimes be problematic, though STS-131’s mating operations were completed without a hitch.

“OV-103 / ET-135 / SRB BI-142 / RSRM 110 (VAB HB-3) Orbiter/ET Mate operations: ET Separation Camera installation is complete. LH2 and LO2 Stud closeouts are complete. LH2 and LO2 monoball installation/electrical mates and closeouts are complete,” noted NASA Test Director (NTD) end of week processing information on L2.

“LH2 and LO2 purge curtain installation continues. LH2 and LO2 main sep container installation, umbilical closeout lids, and flight strut installation completed.”

In tandem with the mating operations, preparations were started on Friday for the Shuttle Interface Test – where engineers check the associated interfaces between the mated hardware that makes up the shuttle stack.

“Shuttle Interface Test operations: Preps were kicked off Thursday and continued through 3rd shift Friday (Saturday morning). Call-To-Stations 0900 EST Friday morning. Weekend Work: Orbiter/ET mate operations, Shuttle Interface Testing, and preps associated with the SSV (Space Shuttle Vehicle) move to Pad-A.”

Currently, STS-131 is set to depart the Vehicle Assembly Building (VAB) at just after midnight on Tuesday morning, for arrival at Pad 39A just after dawn. Preparations for launch at the pad complex have already begun.

“Call-to-stations for rollout to Pad A is scheduled for Monday at 2000 EST; first motion is scheduled for 0001 EST on Tuesday,” added the NTD report. “Pad-A: LOX Storage Tank replenishment was completed as scheduled yesterday; four waves (five tankers each) were delivered. UPDATE: Rollout delayed 24 hours due to unacceptable weather.

“APU (Auxiliary Power Unit) Fuel Cart transfer/lift from the Fuel Farm to the 135′-level is inwork. LH2 Storage Tank replenishment Friday; two waves (five tankers each) are scheduled for delivery.”

Should Discovery rollout early in the week, over a week’s worth of contingency exists in the flow to support the realigned April 5 launch date – which was delayed from March due to unacceptable temperatures for Discovery’s rollover from her Orbiter Processing Facility (OPF) to the VAB, along with a Dual Docked Operations (DDO) constraint with a Russian Soyuz.

STS-131 Specific Articles:

“The STS-131/19A launch date move to April 5 was avoid any further issues with the abnormal cold spell the KSC team has been dealing with. After much discussion and several options, this was chosen as the most prudent and safest approach,” added Space Shuttle Program (SSP) manager John Shannon on a recent Shuttle Standup/Integration report (L2).

Mr Shannon also noted that April 5 will allow for enough time for the preparations to take place for the following mission – STS-132.

“The date of April 5 was chosen to ease the approach into the STS-132/ULF4 mission – even though this will force many to travel to KSC on Easter Sunday. The team agreed that this date was best, rather than a later date, to avoid scheduling conflicts with the follow-on mission.

“This new launch date allows the SSP two weeks after its FRR (Flight Readiness Review) to work any issues that may arise, prior to the Agency FRR.”

STS-132 Processing Latest:

With the current manifest showing four mission prior to the end of summer, a “schedule crunch” may result in some realignment – which was expected, and moreover allowed for – with funding allowing for a manifest stretch as far as the first quarter of 2011, should it be required.

“There was discussion concerning STS-132/ULF4, because it may be put into a schedule crunch with the follow-on mission,” added Mr Shannon. “For now, it will remain at the current launch date of May 14. This will allow for the integration work that remains to be completed for STS-133/ULF5 and STS-134/ULF6.

“From a processing standpoint, everything is going great. The entire team is doing the right stuff and making the right decisions. The last two flights have been some of the best in the history of the SSP and it has been a joy to watch the team execute this mission.”

As noted by Mr Shannon, all three orbiters are enjoying a smooth processing flow, with Endeavour easing through what is currently her final flow with STS-134 – following her recent return from the highly successful STS-130 mission to the International Space Station (ISS).

Atlantis, meanwhile recently completed the milestone of SSME (Space Shuttle Main Engine) installation – with only a few minor issue recently noted, one relating to a thruster quantity gauge and another relating to a cable that was replaced after payload premate operations.

“Orbiter: OV-104 (OPF Bay 1): IPR (Interim Problem Report)-13 (electrical connector pin resistance reading infinite): problem was isolated to a defective cable and the recessed pin was repaired. Payload premate testing is complete including the retest of the IPR-0013,” noted NTD processing information.

“OMS/RCS redundant electrical circuit verification is complete. Picked up a PR (Problem Report) on the Panel O3 OMS/RCS quantity gauge display; the ‘ones’ digit is not visible. Pre-ops supporting WCS (Waste Containment System) Functional were completed; WCS Functional is scheduled to begin.

“SSME to orbiter electrical interface connector mate operations are complete. SSME/MPS (Main Propulsion System) integrated testing picked up Thursday and continues.

“OBSS (Orbiter Boom Sensor System) End Effector premate test began Thursday. OBSS thermistor interface test and the OBSS Keep Alive Test are complete. Assembly power converter unit (APCU) IVT is began Friday. Weekend Work: TPS (Thermal Protection System) work in various locations.”

As STS-132 processing ramps up, stacking of STS-132’s Solid Rocket Boosters (SRBs) is scheduled to begin on March 3. The boosters will begin to rise from the Mobile Launch Platform (MLP) in High Bay 1 of the VAB.

Meanwhile, ET-136 is scheduled to arrive on Monday or Tuesday of next week, following its departure from the Michoud Assembly Facility (MAF) in New Orleans. The tank is on a five day journey inside the Pegasus barge, towed by the Liberty Star.

“BI-143 / RSRM 111 (Surge 1): The team continues to work toward stacking operations to begin 3/3 in VAB HB-1,” confirmed processing information. “ET-136 (Liberty Star/Pegasus): ET-136 is en route aboard the Pegasus barge; arrival at Port Canaveral will be either Monday or Tuesday next week.”

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

Related Articles