STS-133: Three Flight Days and two EVAs added to Discovery’s mission

by Chris Gebhardt

As NASA managers continue to work through evaluations on the remaining three Space Shuttle missions – STS-133/ULF-5, STS-134/ULF-6, and STS-335 (Launch On Need for STS-134) – a reconfiguration of the launch manifest has begun via the June 10th PRCB (Program Requirements Control Board) decision to official increase the mission duration and content of the final planned flight of veteran orbiter Discovery.

Presented Mission Changes:

Meeting on Thursday, the all-powerful PRCB officially approved a Change Request recommendation to increase the mission duration of the STS-133/ULF-5 mission from 8+1+2 days to 11+1+2 days.

This mission duration increase follows an additional Change Request to add two previously unscheduled EVAs into the STS-133 docked timeline. Click here for previous baseline.

“The 5/18 SSPCB (Space Shuttle Program Control Board) requested the addition of 2 EVAs to STS-133 in order to perform unassigned EVA tasks before Shuttle retirement,” notes the June 10th PRCB document obtained by and available for download on L2

This addition of two EVAs (spacewalks) to the mission necessitated an increase in mission duration as an eight day flight did not provide the necessary crew time during the docked portion of the mission to perform two EVAs.

According to the PRCB document, “Performing these tasks during a Shuttle docked mission enables the crew to be trained more effectively and maximizes the EVA efficiency.”

Under the new mission timeline, Discovery’s crew will perform the standard post-insertion activities during FD-1 (Flight Day 1), including PMM (Permanent Multi-purpose Module) Leonardo pressurization and electrical checks via a ROEU (Remotely Operated Electrical Umbilical).

FD-2 will be spent performing the standard OBSS (Orbiter Boom Sensor System) inspections of Discovery’s WLE (Wing Leading Edge) RCC (Reinforced Carbon-Carbon) panels and RCC nose cap. The crew will also inspect Discovery’s OMS pods, T0 umbilicals, and upper flight surfaces as well as prepare Discovery and her various equipment/hardware interfaces for docking with the International Space Station.

The following day, Commander Steve Lindsey will guide Discovery through a 360-degree “backflip” maneuver along the Radial vector of the ISS – a maneuver called the R-bar Pitch Maneuver, or RPM.

Following docking on FD-3, ELC-4 will be unberthed from Discovery’s payload bay and berthed to its permanent location on the S3 truss’ lower outboard attachment point.

Then, on FD-4 the OBSS will be removed from Discovery’s payload to allow positive clearances for the removal later that day of the PMM Leonardo from Discovery. PMM Leonardo will then be installed to its permanent location on the ISS that same day as EVA-1 preparations occur inside the ISS.

The first EVA of the flight will then take place on FD-5. Activities for the first EVA of the flight will be split between numerous tasks for each of the two EV crewmembers.

For EV1, EVA-1 will begin with setup operations of the SSRMS (Space Station Remote Manipulator System). EV1 will then retrieve the LWAPA (Light Weight Adaptor Plate Assembly) from the ISS and install the LWAPA into Discovery’s Payload Bay.

EV1 will then move on to install the CLPA 1 onto the SPDM (Special Purpose Dexterous Manipulator); following this activity, EV1 will then remove EP1 from the SPDM before installing a cover over the SPDM CLPA 2.

EV1 will then cleanup the SSRMS before moving to help EV2 will the final part of work on the S1 FHRC P-clamps.

The final activity on EVA-1 for EV1 will “message in bottle.”

For EV2, EVA-1 will begin with the removal of Multi-Layer Insulation (MLI) blankets from ELC-4 ExPCA. This will be followed by part I of work on the S1 FHRC P-clamps.

After that, EV2 will move down to Discovery’s Payload Bay to assist EV1 with LWAPA installation. Then, EV2 will move on to perform work on the P3 CETA cart light before working on a bootie on the P1 PBVM.

Then, EV2 will relocate the APFR retrieve/tool Stanchion before beginning part II of the S1 FHRC P-clamp operation.

EV2 – time pending – will then perform a “get ahead” task before the final “message in bottle” task.

Also on tap for FD-5 are middeck transfers to/from ISS and “payload operations.”

FD-6 will see the crew perform a Focused Inspection of Discovery’s TPS (Thermal Protection System) if required, PMM activation and ingress, middeck transfers, and a water dump.

FD-7 will see EV1 and EV2 go back outside the ISS for the second and final EVA of the mission.

For this EVA, EV1 and EV2 will spend the first 3-hours 45-minutes performing the same tasks.

The EVA will begin with the Removal and Replacement of the “Lab CP13 Light” followed by the installation of an S1 radiator grapple stow beam.

The final simultaneous task to be performed on the EVA will be work on the Starboard CETA Rail stub.

After that, EV1 will stow a TS stop and work on a S3 MT (Mobile Transporter) stop. Then, EV1 will work on a SSRMS Elbow CLA cover.

EV1 will then move on to install a S0 Bay 3 Bootie/Grounding Connector followed by 45-minutes of “get ahead” tasks.

Meanwhile, EV2 will work on the S3 CETA light, perform tool reconfigurations and perform 15-minutes of “get ahead” tasks.

Also on tap for FD-7 will be middeck transfers to/from the ISS.

FD-8 will then see Discovery’s crew perform a reboost maneuver for the ISS, transfer the GLACIER unit from Discovery to the ISS, and receive some much-deserved time off.

Post-EVA transfers, crew news conferences, and off duty time will then dominate FD-9.

On FD-10, Discovery will undock from the ISS for what is currently expected to be the final time. After performing a fly around maneuver of the ISS, Discovery’s crew will then perform the standard OBSS late-inspections of Discovery’s TPS.

FD-11 will be spent checking out Discovery’s Flight Control System, hot firing her Reaction Control System jets, and reconfiguring the Crew Module for reentry and landing.

Then, on FD-12, Discovery will return to Earth with a planned landing at the Kennedy Space Center.

However, increase of Discovery’s mission duration will translate to the need to carry more supplies and Fuel Cell consumables to orbit – resulting in a lower Ascent Performance Margin (APM).

With the new configuration, Discovery’s APM is projected to be +482 lbs – a decrease to the previous +877 lbs projection for an 8+1+2 day flight. This APM was determined based on a 5-minute launch window, the addition of 191 lbs of middeck supplies, 700 lbs of aft ballast for Center of Gravity considerations, and 2100 lbs of OMS assist fuel with no CoPV (Composite Overwrap Pressure Vessel) offload.

STS-133 Specific Articles:

The need to carry more Cryo for Discovery’s Fuel Cells will also drive the need to change the prop offload targets during the STS-133 countdown.

For an 8+1+2 day flight, 640 lbs of Oxygen was scheduled to be removed from Discovery’s Cryo tank sets. Now, for an 11+1+2 day mission, only 200 lbs of Oxygen are available for offload from Discovery’s PRSD system.

However, perhaps most important is the effect that the additional crew training for the EVAs will have on the mission’s launch date.

“Current 9/16 Targeted Launch Date (TLD) cannot be supported due to Crew Loading for the new mission duration and EVA requirements,” notes the PRCB presentation.

In fact, a launch slip of four and one half weeks will be required at the minimum to allow the crew loading/training schedule to remain “green.”

At this time, the earliest possible launch date for shuttle Discovery and the STS-133/ULF-5 mission is October 21, 2010 (through that is with no contingency days or crew training margin. This date, however, is not an official Change Request since there is no formal proposal for a launch date change for STS-133 at this time.

Nonetheless, since integrated orbit simulations are scheduled to begin the week of June 28th, a final decision on a TLD and mission content is required by July 1.

In all, all branches and departments have approved the presented changes to the STS-133/ULF-5 mission providing that a subsequent change to the mission’s Target Launch Date “supports the required training additions.”

Additionally, the Beta Angle Cutout calculations in early November will have to be reassessed for the new mission duration.

“MO organization needs to ‘tune’ the beta cutout date in November 2010 to the 133 planned duration,” notes the presentation.

The current Beta cutout begins on November 7 but is based on the STS-134 12-day mission plan.

Therefore: “Recommendation: Approve S072133D to increase the mission duration to 11+1+2 days and add two scheduled EVAs and approve the return of the LWAPA and process the update to the FDRD (Flight Definition Require Document).”

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