Amid AMS-02 Uncertainty, NASA Continues Planning Efforts for STS-134
Despite new concerns about the readiness of the AMS-02 (Alpha Magnetic Spectrometer -02) payload to meet the currently targeted July 29, 2010 launch of the STS-134 mission, Space Shuttle Program mangers and flight planners are continuing their efforts to prepare all necessary components for flight on the 133rd Space Shuttle mission. No launch date decision – based on the payload – will take place until next month.
AMS-02 Potential Delays:
As reported by NASASpaceflight.com, an unknown issue related to AMS’ testing is threatening a delay to STS-134’s slot in the manifest, to the point it may slip behind STS-133, or even as far as 2011 in a worst case scenario. However, memos on Monday noted that no decision will be made on the schedule until after additional testing results and the launch of STS-131 in April.
“STS-131 is on track for 4/5. Pad turn around supports 5/14 for STS-132. If AMS slips past STS-133, talked about moving STS-132 to June or July but docking ports will all be taken up for July so that would leave June,” Monday’s DA managerial notes (available on L2) confirmed.
“STS-132 rolls to VAB on 4/13, would rather keep orbiter in OPF (Orbiter Processing Facility) if going to delay,” the notes continued. “Want to get STS-131 off the Pad before discussions plus AMS testing is in April. Keep pressing with dates we have, will have decision mid-April.”
STS-134 Mission Planning Updates:
The mission, currently scheduled to be the penultimate flight of the Space Shuttle Program and the 25th and final flight of orbiter Endeavour, is already well into processing activities at the Kennedy Space Center.
Nonetheless, the brunt of processing operations are set the begin in earnest next month following the launch of the STS-131 off of MLP-3, the MLP on which the STS-134 stack will be erected.
Under the current processing schedule, MLP-3 (Mobile Launch Platform 3) will be moved into VAB High Bay 3 in early/mid April ahead of SRB stacking operations — which are currently baselined to occur in a 20+10 days contingency timeframe beginning in mid- to late-April.
Following completion of SRB stacking and closeout operations, SRB/ET mate operations would pick up on May 27 – 16-days after the Tank’s arrival at the Kennedy Space Center.
Orbiter Endeavour would then rollover from her OPF on June 17 after 108-days of OPF processing for mating with her External Tank.
Following a week of mating, integration, and vehicle checkouts, Endeavour and the STS-134 stack would then be moved to Launch Pad 39A on June 24 for 30+5 contingency days worth of pad processing for a July 29th launch.
According to the 93 page Launch Site Flow Review (LSFR) document – available for download on L2 – the current baselined (as of January 19, 2010) Ascent Performance Margin for Endeavour and STS-134 is 577lbs.
Additionally, Endeavour’s total weight (with payload and onboard propellant) meets all emergency abort and landing constraints expect for one, the Contingency Return case which would occur after the deployment of ELC-3 to the ISS but before deployment of AMS-02 and any middeck transfers.
For this case, Endeavour’s weight (with a Forward Center of Gravity case) would be 233,473lbs — 473lbs over the 233,000lbs contingency return weight limit.
The LSFR document further notes that, in the event of a RTLS (Return to Launch Site) abort, a 185-second ARCS (Aft Reaction Control System) and 25-second FRCS (Forward Reaction Control System) propellant dump would be required to meet RTLS landing CG and weight requirements.
Similarly, a 120-second ARCS and 65-second FRCS dump would be required for a TAL (Trans-oceanic Abort Landing) abort to meet landing CG and weight requirements.
In all, Endeavour will carry nine primary payloads during the 12+1+2 day mission.
These payloads include the AMS-02, the ExPRESS Logistics Carrier 3 (with numerous payloads attached), and a new MISSE (Materials on International Space Station) experiment in Endeavour’s payload bay.
Riding up on Endeavour’s middeck will be a new GLACIER (General Laboratory Active Cryogenic on ISS Experiment Refrigeration) and CGBA (Commercial General Bioprocessing Apparatus) payload.
Additionally, Endeavour will carry the now-standard MAUI (Analysis of Upper Atmosphere Injections), RAMBO-2 (RAM Burn Observations-2), SEITE (Shuttle Exhaust Ion Turbulence Experiment), and SIMPLEX (Shuttle Ionspheric Modification with Pulsed Local Exhaust) Payloads of Opportunity which, as the name suggests, will only be performed is conditions and mission timelines allow.
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).
For Endeavour’s 25th and final scheduled flight, the orbiter will utilize LP03 (Left Pod 03) and RP04 (Right Pod 04) for her two Orbital Maneuvering System (OMS) pods, External Tank 137 (which is currently expected to arrive at the Kennedy Space Center on May 11), SRB BI set 144 and RSRM-112 (Reusable Solid Rocket Motor stack 112), and Operational Increment software OI-34.
LSFR Baseline Modification for Endeavour:
As with all Space Shuttle missions, Endeavour will undergo a series of evaluations and modifications before her STS-134 mission.
For this flight, technicians in OPF-2 (Orbiter Processing Facility bay 2) will undertake one final modification to NASA’s youngest orbiter, as well as three (possibly four) Mission Kit modifications.
For the only Orbiter modification, a “dedicated power feed to the Fuel Cell H2 (hydrogen) flowmeter [that is] separate from the Cell Performance Monitor (CPM)” will be installed to ensure the protection of power to the CPM during flight.
This modification adjusts MPCAs 1 and 3 (Mid Power Cell Assemblies 1 and 3) to “utilize spare MPCA pin locations and 1-amp fuses to provide a dedicated power feed to the Fuel Cell H2 flowmeter separate from the CPM to protect against power loss of the CPM,” notes the STS-134 LSFR presentation.
The existing design feeds power to the Fuel Cell H2 flowmeter and CPM from the same 1-amp fused circuit.
“Separation of H2 flowmeter and CPM power feed would eliminate impact to CPM.”
A loss of power to a CPM during a countdown would result in an automatic launch scrub; likewise, a loss of power to a CPM during flight would “[result] in crew impact for alternate data collection to verify Fuel Cell health.”
Technicians have been tracking this problem through all three orbiters via inconsistent flowmeter behavior.
The worst of these behaviors came during the STS-124 flight of orbiter Discovery when a blown out fuse caused a loss of power to a CPM.
A temporary fix was devised in the form of flying the #1 and #3 H2 flowmeters in a powered down pattern after de-pinning them — a modification that was flown twice, once each of Discovery (STS-128) and Endeavour (STS-127).
LSFR STS-134 Mission Kits Modification Baseline Overview:
In all, three Mission Kit modifications are planned, with the possibility of one additional mission kit modification pending.
The first modification relates to a change in the IBA boom configuration.
For STS-134, the IBA (Inspection Boom Assembly) would be modified to “reflect new boom and sensor pack 1 installation changes as well as Orbiter return without Boom,” notes the LSFR presentation.
Since the OBSS (Orbiter Boom Sensor System) will be transferred to the ISS at the end for Endeavour’s docked mission, the IBA will be modified during this flight to an EIBA (Enhanced Inspection Boom Assembly) that is “more compatible” with the SSRMS (Space Station Remote Manipulator System).
The EIBA will have a modified grapple fixture interface and numerous, minor hardware modifications to better support long-term on-orbit stay.
For part of this modification, two crewmembers during one of the three STS-134 EVAs (spacewalks) will replace the standard Shuttle EFGF (Electrical Flight Grapple Fixture) from the grapple end of the OBSS with a standard ISS PDGF (Power Data Grapple Fixture).
The second baselined Mission Kit mod is for the STORRM (Sensor Test for the Orion RelNav Risk Mitigation).
This DTO is designed to “test the Vision Navigation Sensor (VNS) and Docking Camera planned for Orion” and will be tested during Endeavour’s docking and undocking to/from the ISS.
The modification here provides for a revision to the “order blanket installation and MECSLSI (Mission Equipment Cargo Support Launch Site Installation) plan.”
Finally, the last baselined Mission Kit modification relates to the Payload Cable Harness.
“Payload Cable Harness modification for ROEU (Remotely Operated Electrical Umbilical) and AMS-02 updates MECSLSI to include two longer ELC-3 ROEU Power/Control cables to allow the ELC Sill Latch cables to be mated further forward on the starboard sill,” notes the LSFR presentation.
In this manner, STS-134 is a unique flight in that all 12 Payload Retention starboard sill location connections are required for the mission. Also, this is the first flight in which 2 ROEUs are required on the same side of the payload bay since both ELC-3 and AMS-02 require 2 starboard latch connection locations.
Each ROEU power/control requires “6 cables for 3 Sill connector locations and ELC3 ROEU power/control cable lengths are short for 2 available starboard sill connector locations.”
In short, this modification will lengthen the ELC-3 ROEU power/control cables and will “mate the ELC-3 Sill Latch cables further fwd to allow for the ELC ROEU Pwr/Control cable connections on the starboard sill.”
Finally, the yet-to-be-baselined modification pertains to the IBA.
“Port LWTSA (Light Weight Tool Stowage Assembly) Cushion modification” will modify the port LWTSA to accommodated the return of the OBSS’s EFGF — which will be removed as part of the EIBA (Enhanced Inspection Boom Assembly) modification.
Fit checks were planned for January 2010.
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