STS-133 refined to a five crew, one EVA mission – will leave MPLM on ISS

by Chris Gebhardt

Shuttle managers have baselined STS-133 – by way of the Flight Definition Requirements Document (FDRD) mission update – into a 10+1+2 day mission, involving a crew of just five, a Flight Day 4 docking and just one EVA. The move was made to allow for additional mass to be carried by the Multi-Purpose Logistics Module (MPLM) – which will remain as a new addition on the International Space Station (ISS).

STS-133 Mission Evaluations:

As reported by this site in June, NASA has already officially baselined the STS-133 mission in the FDRD – a process that converts a mission from assignment planning, into the baseline schedule.

P2Right 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) are discussing the various options available to them, as the SSP draws closer to the end of its current – subject to extension – launch manifest.

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 (Program Requirements Control Board). The CR 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 maximize up-mass potential on the final Shuttle mission to the ISS.

Nevertheless, the order in which STS-133 will fly wasn’t the only special consideration NASA was giving to this mission. In fact, NASA baselined two different versions of STS-133 based on ISS Program and Shuttle program projected needs.

At the time of the baseline into the FDRD, it was unknown which flight option NASA would choose to fly for STS-133, the 12+1 day Multi-Purpose Logistics Module Option (Option 1) or the 10+0 day Permanent Logistics Module mission.

However, the latest Program Requirements Control Board (PRCB) meeting has confirmed that NASA has opted for option 2 – with a modified mission duration capability of 10+1+2 days.

“As you may have heard, the ISSP is interested in increasing upmass as much as possible on this mission, which could possibly be the last mission in the assembly sequence,” noted Tuesday’s MOD 8th Floor News memo on L2.

“One method for doing this would be to reduce the crew size to 5 to reduce the upmass associated with supporting a crew member on orbit. Additionally, the Program agreed to reduce the number of EVA’s to 1 and add an additional rendezvous day (which gives more time for the 5 person crew to accomplish the Shuttle Thermal Protection System inspection).

“Both Programs have now agreed to baseline the mission in this way with a duration of 10 + 1 + 2.”

Under the approved changes to the mission baseline via the updated FDRD presentation on L2, the STS-133 mission will have “the first set of performance enhancements recommended by the STS-133 Tiger Team” incorporated into the mission’s parameters.

As such, the STS-133 orbiter will have its 5th cryo tank set removed, as well as its 6th Gaseous Nitrogen tank, during turn-around processing in its Orbiter Processing Facility.

P3The Aft winch will also be removed from the orbiter and the LTA cables and now-unnecessary supporting hardware for the Express Logistics Carrier 4 (ELC-4) deleted from the cargo manifest. That is not, however, to say that ELC-4 has been deleted. It will still be an integral part of the STS-133 payload to the ISS.

Furthermore, the Multi-Purpose Logistics Module (MPLM) – either Raffaello, Leonardo, or Donatello – which will fly on STS-133 will be modified and re-designated as a Permanent Logistics Module (PLM) which will be left on the ISS after STS-133 departs.

STS-133 will also see a configuration change to its Solid Rocket Boosters (SRBs). In order to eliminate as much weight as possible to maximize cargo upmass on this mission, the STS-133 SRBs will have their water impact structures and foam, cosmetic paint, water impact foam, and Reusable Solid Rocket Motor Nozzle Severance System removed.

Moving to a five person crew – the minimum number of crew members necessary to adequately and safely perform all the necessary inspection and docking preparation activities in the early days of the mission – has been under discussion for some time, prior to the FDRD update.

P4As a result of all this upmass savings, the PLM will now be able to carry 3,002lbs more equipment than it would have under Option 1. Efforts to increase upmass availability in the MPLMs were first seen ahead of STS-126.

“Approved the change to the STS-133/ULF5 FRD. Mission will be rebaselined as 10+1 day mission with Flight Day 4 (FD4) rendezvous, Permanent Logistics Module (PLM) which will be left on ISS (not returned via orbiter), 1 EVA and 5-person crew,” added the 8th Floor News.

“EVA task must be stage deferrable and cannot require dual-arm ops in parallel with EVA (single arm ops in parallel with EVA is OK based on crew tasking).

“Going from 6-person to 5-person crew results in an 871 lbm ascent performance gain (including removal of ballast). Additional ascent performance improvements to increase ISS upmass will be reviewed at a later time via separate CR.

“(There is) forward work to identify candidate list of ascent performance improvements. Ascent Performance Tiger Team is scheduled to finalize the list of recommended improvements via an offline meeting on 8/7/09, followed by formal CR review process and PRCB (TBD date).”

The new preliminary mission timeline shows the STS-133 crew conducting the standard OBSS (Orbiter Boom Sensor System) inspections of their Orbiter’s Wing Leading Edge and Nose Cap RCC (Reinforced Carbon-Carbon panels) on Flight Day 2 (FD-2), FD-3 will involve preparations for their arrival at the ISS.

Docking to the ISS will take place on FD-4, with unberthing and transferring the ELC-4 and PLM to the ISS on FD-5. Activating the PLM on FD-6 will be followed by either the only EVA (Spacewalk) or a Focused Inspection of their vehicle’s heat shield on FD-7.

Performing the final middeck transfer to and from the Orbiter and closing the hatches between the ISS and Orbiter will take place on FD-8, with undocking and late-inspection on FD-9, landing preparations on FD-10, and landing at the Kennedy Space Center on FD-11.

However, given the now likely scenario of an extension of the Shuttle Program to 2012 – and the addition of three more Shuttle missions after STS-133 – based on the Augustine Commission’s report to President Obama and Congress, it is unknown if these changes to the STS-133 flight plan will still be incorporated if the Shuttle Program is extended.

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.

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