As engineers and flight planners around NASA narrow in on the final stretch of the launch campaign for the STS-134 mission, flight engineers are in the process of reviewing a series of special topics, new operations, and weather support issues. Among the various items currently under final review/assessment are the 5th flight of the Boundary Layer Transition Detailed Test Objective, weather support equipment for launch, and new ops on Shuttle and ISS.
Following her return in February 2010 from the highly successful STS-130 mission, Endeavour’s extended OPF (Orbiter Processing Facility) flow for the ULF-6/STS-134 mission included a slight reconfiguration of her TPS (Thermal Protection System) tiles.
Officially baselined for inclusion on STS-134 at the June 24, 2010 Program Requirement Control Board (PRCB), this TPS reconfiguration was done to enable the execution of a 5th Boundary Layer Transition (BLT) DTO (Detailed Test Objective) – a DTO that was originally only intended and planned to fly aboard sister orbiter Discovery.
To accomplish this DTO, Endeavour has been mounted with a protuberance tile bearing a 0.5-inch high “bump” in the otherwise smooth surface the tile and numerous temperature sensors and thermocouples downstream of the protuberance.
These sensors and thermocouples will be used during atmospheric reentry to gather data on the protuberance’s affect on the local airstream and its subsequent affects on heating and turbulence on the downstream portion of the vehicle.
With a height of 0.5 inches, the protuberance is expected to trip the boundary layer at ~Mach 19.5.
With this in mind, Endeavour’s deorbit and reentry track will be aligned to prohibit a roll reversal during the boundary trip region at ~Mach 19.5. “Additional crossrange limits [will be] calculated to avoid roll reversals prior Mach 16 to improve data gathering,” notes the Flight Director’s Overview presentation to the STS-134 MOD FRR (Mission Operations Directorate Flight Readiness Review) – available for download on L2.
In addition to final discussions about the BLT DTO, mission planners/engineers are also tracking the management of APU (Auxiliary Power Unit) Auto Shutdown Inhibit.
As stated in the Flight Director’s Overview presentation, “Hot restart failure mode could be catastrophic if APU Auto Shutdown switch positioned in Inhibit.”
Since current flight rules do not account for this possibility when “configuring the Auto Shutdown switch after a diagnostic restart,” the specific Flight Rules for STS-134 will be annexed for PCN-1 to provide safeguards against this scenario.
Lastly, the final item addressed by the MOD FRR pertaining to the ascent phase of STS-134’s flight dealt with a possible upgrade to National Weather Service (NWS) hardware and weather balloon data issues at Moron, Spain for STS-133.
In terms of hardware upgrades, the MOD FRR presentation noted that the NWS may be required to install the AWIPS-II workstation prior to the scheduled launch of STS-134. A final decision on whether or not this would occur was expected on March 10.
Moreover, the Spaceflight Meteorology Group (SMG) is looking into issues experienced at the Transoceanic Abort Landing (TAL) site of Moron, Spain during both the Nov. 2010 and Feb. 2011 launch attempts for STS-133/Discovery.
“Moron Wx Team not able to dial in upper air balloons or surface observations,” notes the Flight Director’s Overview MOD FRR presentation.
The Moron observers were ultimately able to email the necessary data to the SMG, a certified backup procedure. Nonetheless, SMG is looking into the issue and understands that this might be an issue during STS-134 as well.
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Likewise, the Moron radar may be intermittent during the STS-134 launch period as the Spanish Weather Service is in the process of restoring UPS for the radar at Sevilla.
The Spanish Weather Service is working to have the UPS installed prior to the launch of STS-134.
Shuttle & ISS New Operations:
As with all Space Shuttle/ISS missions, several new operations will be debuted on STS-134/ULF6, including the flight of STORRM (Sensor Test for Orion Rel-Nav Risk Mitigation) on Endeavour.
Designed to collect detailed data during rendezvous, proximity ops, and (un)docking, Endeavour’s crew will document, via photographs, all STORRM targets for photogrammetry objectives following Shuttle/ISS hatch opening and prior to Shuttle/ISS hatch closure.
However, in terms of nominal Shuttle/ISS undockings, Flyarounds, and separations, this is where the similarity for STS-134 will end.
Endeavour’s Sep burns 2 and 3 (including all the mandatory STORRM burns) have been redesigned to facilitate a mini re-rendezvous with the ISS to “accomplish the STORRM re-rendezvous objectives” before completing the flyout of Endeavour to a point “in front” of the ISS in terms of the vehicles’ orbital trajectories and relative positions.
Conversely, the ISS also carries four (4) new operations that will be performed during the docked portion of the mission – one of which is simply the delivery and installation of the ELC-3 pallet with numerous ORUs (Orbital Replacement Units). More articles will follow on this DTO.
The second new ISS item references the 134/ULF6’s premiere payload: the Alpha Magnetic Spectrometer (AMS).
Installed to the PAS-2 on Flight Day 4, the AMS will be supported by a “FCR” team in the Payload Operations Control Center (POCC). This team will act at the “primary interface with ACO and MSFC (Marshall Space Flight Center) POD.”
Additional support personnel will be located at JSC from launch through Launch +3months, at which point the support team will transfer to a remote POCC.
The next new ISS op to gain mention at the STS-134 MOD FRR was the 2B PVTCS fill operation on EVAs 1 and 2.
As noted by the MOD presentation from the Flight Director, “2B PVTCS has a slow ammonia leak that will eventually result in loss of 2B cooling. Tasks on EVA 1 and EVA 2 configure cooling systems (ETCS/EETCS/PVTCS) to fill the 2B PVTCS using ammonia from the Loop B ATA.”
To accomplish this, EVA-1 will be spent configuring jumpers and venting nitrogen from the system. EVA-2 will then be performed to configure the valves and Quick Disconnects to “execute the PVTCS fill, [vent] ammonia from jumpers after the fill, and [stow] jumpers.”
The 2B PVTCS will remain operational during the fill process.
Instead, “New pre-breathe protocol will be used for the first time on EVA 3.”
The In-Suit Light Exercise (ISLE) EVA Pre-Breathe Protocol will be used to new pre-EVA conditioning for space crews. While currently planned of execution prior to EVA-3, the MOD FRR presentation notes that the procedure will be evaluated “post EVA 3 to determine whether ISLE will be used on EVA 4.”
The procedure does not require overnight campout in the Quest Airlock or CEVIS exercise. It is anticipated that this procedure will help conserve oxygen usage aboard the ISS.
For the actual procedure, the two spacewalkers will perform a 60-minute mask pre-breathe with the airlock depressed to 10.2 psi. They will then don their spacesuits (EMUs) and perform standard EMU purge before the airlock is repressurized to ISS ambient levels.
Following this, the EVA crew will spend 100 minutes performing in-suit pre-breathe, 50 minutes of which will consist of light in-suit exercise with 50 minutes of resting (nominal) in-suit pre-breathe.
The crew has been trained in the Neutral Buoyancy Lab (NBL) to limit their exertion and minimize cycling on the suits.
(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: Larry Sullivan MaxQ Entertainment/NASASpaceflight.com, plus from L2 Presentations).