After nearly thirty years of Space Shuttle operations – with only eight flights remaining on the Space Shuttle Program manifest – NASA’s Program Requirements Control Board (PRCB) has officially baselined the STS-133 mission into the Flight Definition and Requirements Document (FDRD) – a mission that, at this time, is expected to be the final flight of the Space Shuttle.
Right now, STS-133 – along with STS-134 – is currently baselined to launch No Earlier Than July 29, 2010 on orbiter Endeavour. However, the Space Shuttle Program (SSP) and the International Space Station Program (ISSP) have, for some months now, been discussing the various options available to them as the SSP comes to an end.
As a result, the two programs have tentatively agreed to swap the order of the final two manifested missions – flying STS-134 on Endeavour in July 2010 and slipping STS-133 into mid-September on Discovery.
This process of swapping the flight order will be accomplished via a Change Request (CR) to the PRCB. The CR, which is expected to be submitted sometime this month, will enable mission planners and flight engineers to adequately prepare for each mission without excessive overlap in mission planning and flight production protection.
In all, the CR has to be approved by October 5, 2009 in order to avoid flight production confliction and ensure that the two missions can meet their respective launch dates.
However, the CR is expected to be approved long before October 5 as both the SSP and ISSP are determined to maximizing up-mass potential on the final Shuttle mission to the International Space Station (ISS).
As such, NASA is considering STS-133 as the final flight of the Space Shuttle. As a result, STS-133 will be the 134th and final flight of the Shuttle and the 39th and last voyage of Discovery.
The mission, if launched in mid-September 2010, will use External Tank 138, Solid Rocket Booster set BI-145, and Reusable Solid Rocket Motor set 113.
Carrying an ISS flight designation of ULF-5 (Utilization and Logistic Flight 5), STS-133 will carry several Department of Defense (DoD) payloads of opportunity. All of these payloads — MAUI, SEITI, SIMPLEX, and RAMBO-2 — have flown on numerous Shuttle mission before and will only be performed if time permits.
Nevertheless, unlike previous Shuttle missions, SSP managers have formed a special Tiger Team for this mission.
The team has been instructed to “think outside the box” in terms of improving performance on STS-133/ULF-5 under the assumption that “this will be the last flight of the orbiter used for STS-133,” notes the FDRD document — available for download on L2.
In fact, the tiger team held its first meeting on June 5th, identifying the following ISSP goals for STS-133: “Maximize Cargo Upmass (pressurized & unpressurized), Pre-position spares that can be flown on ELC-4, fly Logistics Module (Pressurized Logistics Module or Multi-Purpose Logistics Module) at maximum weight attainable, maintain a viable middeck capability of ~800 lbs, transfer 25 lbs of Oxygen to ISS, fly a full middeck for return trip to Earth, plan for one EVA (deferrable in real time if required), and perform an ISS Flyaround” after undocking.
Similarly, the Flight Operations and Integration office has summarized the current SSP goals for STS-133. This list consists of the following: last flight of OV-105 or OV-103 (target date to choose orbiter is Oct. 5), take advantage of last flight status to think ‘out of the box’ to maximize ability to meet ISSP’s goals for the mission, no compromises on crew or orbiter safety, and only minimal to no re-certification efforts allowed.”
Furthermore, the Tiger Team’s brainstorming efforts has yielded inputs on three categories of Trade Space Performance Enhancement.
The first category relates to performance enhancement strategies that should be pursued. These include reducing the STS-133 crew to five people, reducing mission duration to less than 12 days, removing fifth Cryo Tank Set and eliminating ballast, removing 6th GN2 Tank, and deleting ELC-4 LTA cable and associated hardware from the mission’s baselined payload.
The second category, which includes suggestions that “make sense but need more analysis/shelf life considerations,” includes such performance enhancements as reducing rendezvous altitude of Station and Shuttle, removing Aft Radiator Panels from Discovery, and performing a multistage Deorbit Burn at the end of the mission.
Finally, the third category (options that “are not thought to be good candidates for pursuit because of cost, schedule, risk, low return for magnitude of effort/distraction”) include throttling the Space Shuttle Main Engine’s from 104.5 percent to 106 percent during ascent and removing SRB parachutes and cameras.
These options were briefed by the Tiger Team to the Joint Mission Integration Control Board and the SSP Control Board with the knowledge that the Category-1 recommendations are being incorporated into a second CR for STS-133.
Furthermore, the FDRD notes that “CR-2 updates will be familiar to most, but not all reviewers, due to the support that has been provided to the Tiger Team. Therefore an expedited review is being requested for CR-2 in order to facilitate including updates in integration work.”
As of now, the Tiger Team has been tasked with reporting their final assessments of all Category-2 recommendations to the SSP and ISSP no later than mid-July. Any accepted recommendations from that meeting will then be presented to the “STS-133 Flight Integrated Product Team for integration into the STS-133 mission.”
STS-133 – Option 1:
The first option for STS-133 will see Discovery launch with five Cryo Tank sets, six GN2 tanks, and a six person crew on a 12+1 day mission with one baselined EVA (Spacewalk).
Further, Discovery’s primary payload – in addition to the DoD payloads of opportunity – would be a Multi-Purpose Logistics Module (MPLM) and the Express Logistics Carrier 4 (ELC-4).
For the MPLM, four active longeron latches, one active keel latch with keel camera, and a Remotely Operated Electrical Umbilical (ROEU) that will provide 28V heater power and 124V of temperature and pressure checks will be used to install the module into Discovery’s Payload Bay.
Inside the MPLM will be two Utilization racks, three Resupply Stowage Platforms, and two Resupply Stowage Racks.
ELC-4 will have four active longeron latches for the deck assembly and two passive longeron latches and one passive keel latch for the Keel Assembly.
A ROEU will provide 28V heater power to the ELC and a Payload Power Switching Unit (PPSU) will provide additional electrical inhibit capability.
ELC-4 will also require “unique Flight Software for the PPSU’s internal heater on/off telemetry.”
Furthermore, the payload that will be attached to ELC-4 for launch (under option 1) will be the HPGT, a SARJ Race Ring, a spare Express Pallet Controller Assembly, and FRAM based SASA ORU-2, CTC-2, and four empty Passive FRAM sites.
Additionally, Discovery will carry a GLACIER freezer to the ISS and return a used GLACIER to Earth. Also, Discovery will deliver a Commercial Generic Bioprocessing Apparatus/National Lab Pathfinder (CGBA/NLP) to ISS.
In all, Discovery’s expected payload weight is ~35,461lbs with an additional 1,326lbs of ballast in the aft. The MPLM is expected to weigh 18,304lbs, ELC-4 9,516lbs, and the middeck payload 7,591lbs. That leaves an overall Ascent Performance Margin of ~800lbs.
Overall, the mission objectives for STS-133 are to “deliver utilization, logistics, and resupply, deliver and install ELC-4 to S3 Lower Inboard, deliver spare HPGT and transfer to ELC-2 for stowage, and install the Functional Cargo Block Power Data Grapple Fixture.”
The preliminary mission timeline for Option 1 shows Discovery docking with the ISS on FD-3 (Flight Day 3), EVA-1 (HPGT transfer and ELC LTA cable activities) occurring on FD-4 along with ELC-4 unberth and installation to ISS, MPLM unberth and installation to ISS on FD-5, Focused Inspection activities and middeck transfer operations on FD-6, rack transfers to and from the MPLM on FDs 7-10 with MPLM rebirth in Discovery’s Payload Bay on FD-10, Undocking and flyaround on FD-11, and landing on FD-13.
In a desire to maximize upmass to the ISS, Option 2 for STS-133 incorporates the Category-1 recommendations of the Tiger Team as presented in June to the SSP Control Board.
To this end, under Option-2, Discovery would launch ELC-4 and a Pressurized Logistics Module (modified MPLM for long-duration on-orbit stay) to the ISS.
Discovery would launch with only four Cryo tank sets and five GN2 tanks for a 10+0 day mission with only five crew members and one contingency/deferrable EVA.
For this option, Discovery’s total payload weight would be 38,193lbs – with the Pressurized Logistics Module weighing 21,502 lbs, ELC-4 weighing 9,680 lbs, and the middeck payload weighing 7,011 lbs.
This would give the mission an approximate Ascent Performance Margin of 839 lbs with only 126 lbs of ballast in the aft.
For this option, the ELC-4’s payload would be an Heat Rejection (Sub) System radiator, CTC-2, and two empty FRAMs only.
The Pressurized Logistics Module – which would remain on the station after Discovery’s departure – would carry two International Standard Payload Racks and a To Be Determined Cargo Rack Equivalent compliment only.
The mission’s objectives would be the delivery and installation of ELC-4 to S3 Lower Inboard, the delivery and installation of the Pressurized Logistics Module to a To Be Determined location, and the capability for one deferrable EVA if a Focused Inspection should be required.
Under this option, Discovery would dock on FD-4, berth the ELC-4 and Pressurized Logistics Module to the ISS on FD-5, activate and ingress the Pressurized Logistics Module as well as conduct middeck transfers on FD-6, perform the only EVA or Focused Inspection on FD-7, Undock on FD-9, and land on FD-11.
L2 members: Documentation – from which the above article has quoted snippets – is available in full in the related L2 sections, now over 4000 gbs in size.