STS-134: Endeavour set for February 28 rollover – ET-122 borescope checks

by Chris Bergin

Endeavour is set to depart from her Orbiter Processing Facility (OPF-2) on February 28, as milestones begin to align for her April 19 (No Earlier Than) launch to the International Space Station (ISS). With her External Tank (ET-122) and Solid Rocket Boosters (SRBs) mated, borescope inspections of ET-122’s stringers have been completed.

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Endeavour’s final mission is tasked with launching the AMS-02 (Alpha Magnetic Spectrometer-02) to the International Space Station (ISS), whilst carrying the Express Logistics Carrier 3 (ELC-3). Also riding with Endeavour are the Materials on International Space Station Experiment 8 (MISSE 8), an Orion Rendezvous Detailed Test Objective (DTO) kit, and a GLACIER freezer module for one of the Station’s science laboratories.

Endeavour will also return the MISSE 7a and 7b experiments to Earth as well as perform four Department of Defense payloads of opportunity: MAUI, SEITI, RAMBO-2, and SIMPLEX.

Furthermore, Endeavour and her six person crew will also be tasked with two Development Test Objectives – or DTOs. These include DTO 805, Crosswind Landing Performance, and DTO 703, Sensor Test for Orion Relative-Navigation Risk Mitigation (STORRM).

Given the numerous slips to her launch date, processing has continued on a smooth and relaxed path, with only one Interim Problem Report (IPR-20) continuing to be under evaluation.

Should Discovery launch at the opening of her STS-133 launch window, Endeavour will be making her final trip to the Vehicle Assembly Building (VAB) as her older sister is on orbit. The targeted launch date is April 19, 2011 with a window until May 2, 2011.

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“OV-105 (STS-134) Vehicle processing continues; there are no major concerns. They are working towards a rollover to the VAB on February 28,” noted KSC Integration (L2). “In VAB HB-3 (High Bay 3), ET-122 was mated to the SRB stack. Post-ops are currently in work and then will pick up with integrated closeouts.”

As previously reported, IPR-20 is related to a sensor on her LH (Left Hand) OMS (Orbital Maneuvering System) pod Main Engine Ignition (MEI), which is part of a sensor suite used to gain data on MEI Acoustic and SSME (Space Shuttle Main Engine) Ignition Overpressure (IOP) Environments.

Specific to an acoustic sensor called V08Y9704A – which failed to channelize during testing last year – troubleshooting has been ongoing since, with the latest effort to resolve the issue – by replacing a suspect component (low pass filter) – unsuccessful.

“IPR-0020, MEI troubleshooting installed a new low pass filter yesterday with no success. Engineering evaluation continues,” noted the NASA Test Director (NTD) report (L2), before recently updating with notes that a cable will be changed out as part of the troubleshooting effort. This latest effort is currently undergoing re-tests.

If – in the unlikely event – engineers are unable to resolve the issues with the sensor, no impact to the processing milestones would be suffered, given it is only part of a data gathering effort which is not specific to STS-134.

Other processing tasks inside OPF-2 are focusing on preparing Endeavour for her final short trip to the VAB, along with a retest of one of her Detailed Test Objective (DTO) payloads.

“OV-105 (OPF Bay 2): Hydraulics was brought up to support positioning elevons to full down position,” added the NTD report. “COM-456 STORRM retest is planned for today (Wednesday). MADS (Modular Auxiliary Data System) time and cycle testing is planned for today (Wednesday).”

STORRM is part of an effort to aid Orion’s docking to the ISS – given Relative Navigation sensors for Orion require special ‘reflectors’ on the PMA-2 docking target. STORRM may also aid future commercial spacecraft that are set to visit the station in future years.

The STORRM DTO opened with tasks during STS-131, which involved the crew taking close-out photographs of docking target on the ISS after hatch closure, following the installation of the reflectors by ISS crewmembers.

STS-134’s primary DTO tasks include the use of a laser system in TCS slot, with a recorder on sidewall. Data collection will be conducted during docking, undocking, and re-rendezvous.

With STS-135 flying with the final “new” tank (ET-138), Endeavour will be riding uphill with the older ET-122 – which was refurbished following damage sustained during Hurricane Katrina at the Michoud Assembly Facility (MAF) in New Orleans.

It remains unknown if ET-122 includes stringers which may suffer from the “mottled” material – which is part of the root cause as to why some of ET-137’s stringers cracked during November’s tanking/launch countdown – leading to scans and borescope inspections being carried out inside the VAB.

“SRB BI-145/RSRM 113/ET-122 (VAB HB-3): Borescopes from inside the intertank to detect mottled metal on ET-122 stringers is complete,” added the NTD report. “The data and results are being passed onto the respective engineering organizations for further analysis and discussions at the Program Requirements Control Board (PRCB).”

Should the inspections find any defected stringers, it is possible managers may call for radius blocks to be installed on the LO2/Intertank flange, a process which has been carried out as part of the mitigation drive on ET-137. Although it is possible no issues will be found on ET-122, given its 2000 construction date – potentially avoiding any suspect material stock being installed on the tank.

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Space Shuttle Program (SSP) managers have already said they are likely to conduct a Tanking Test ahead of STS-134’s launch, as a fail-safe to checking for any cracks on the stringers prior to the April 19 tanking for launch.

Meanwhile, processing on the mated tank and boosters is proceeding without issue, with the installation of “milk cans” around the aft connection points between the ET and SRBs.

“SRB BI-145/RSRM 113/ET-122 (VAB HB-3): Left hand and right hand forward skirt separation bolt ordnance installations are complete. Left hand and right hand lower strut closeouts are in work. Milk can work for left and right upper strut fairing installation continues. Milk cans for Left hand and right hand strut fairing installations are complete with RT-455 in cure.”

The only remaining question relating to STS-134 surrounds who will command Endeavour on her final mission. Understandably, very little is being said on whether the mission’s current commander – Mark Kelly – will be available for the mission due to the well-known personal issues.

“Because of Commander Mark E. Kelly’s personal situation, Rick Sturckow was named to train as backup Commander, so that the STS-134 crew could continue training,” noted the JSC Flight Crew department. “It is still in question whether Mark can come back and command that crew.”

(Further updates and articles will follow. Refer to live coverage threads linked above. L2 members refer to STS-134 live coverage sections for internal coverage, presentations, images and and updates from engineers and managers. Images used, and via L2 acquired PRCB presentations).

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