STS-131: Discovery’s Logistics Flight Baselined by PRCB

by Chris Gebhardt

As NASA continues to plan for a potential extension to the Space Shuttle Program past the original retirement date of September 30, 2010 – as well as the addition of the STS-134 flight to bring the Alpha Magnetic Spectrometer to the Station – the Program Requirements Control Board (PRCB) has officially baselined the STS-131/ISS-19A mission, the first of two Contingency Logistics Flights (CLFs) that were originally classed as “optional” in the post-Return to Flight planning manifests.

The Mission and Crew:

Taking on the duty of flying the first CLF mission is veteran orbiter Discovery. If the current manifest holds, STS-131 will be the 38th and second-to-last mission for shuttle Discovery, with the STS-134 mission being Discovery’s – and the program’s – final flight.

To get to orbit, the mission will use External Tank ET-135 and Reusable Solid Rocket Motor set 110 as well as Orbiter flight software OI-34. The latest flight software, OI-33, was debuted with Endeavour during STS-126.

Currently targeting launch in March 2010, Commander Alan Poindexter, Pilot James Dutton and Mission Specialists Richard Mastracchio, Dorothy Metcalf-Lindenburger, Clayton Anderson, Stephanie Wilson, and Naoko Yamazaki from the Japanese Aerospace Exploration Agency (JAXA) will fly the 12+1+2 day mission.

The Flight Crew Operations Directorate has requested that the mission be extended to a 13+1+2 day mission in order to give the flight crew more time to perform all of the mission’s objectives.

This request has been initially rejected as there is enough time to accomplish all of the identified objectives in a 12+1+2 day mission.

As always, the exact duration of the mission is subject to change as the preceding shuttle flights unfold and the mission’s timeline is refined.

The Payload and EVAs:

The STS-131 mission will deliver supplies to the International Space Station (ISS) via the Multi-Purpose Logistics Module (MPLM) Raffaello and the Light-weight Multipurpose Experiment Support Structure Carrier (LMC).

Secured inside the MPLM will be “Zero-G stowage racks, an EXPRESS rack, a Muscle Atrophy Resistive Exercise (MARES) unit, a Window Orbital Research Facility (WORF), one Crew Quarters Rack, a Minus 80 deg Laboratory Freezer for ISS (MELFI), Resupply Stowage Racks (RSRs), as well as Resupply Stowage Platforms (RSPs),” notes the baseline presentation, available to download on L2.

Furthermore, the preliminary mission timeline indicates that Raffaello will be berthed to the ISS on FD-4 with 5 full days of logistics transfers before it is re-berthed in Discovery’s payload bay on FD-10.

For preliminary mission planning purposes, the PRCB has predicted that the MPLM will weigh 27,242lbs at liftoff and will contain 16 interior racks as well as 12 Aft Endcone Stowage spaces.

While the final layout of the interior of the MPLM has not yet been decided, technicians working with the MPLM have been instructed to protect for the possibility of late stowage while future “Integrated Stowage Platform options” are being worked.

Moreover, a new Ammonia Tank Assembly (ATA) will ride to orbit aboard the LMC. Also attached to the LMC will be the Passive flight Releasable Attachment Mechanism (PFRAM) which will remain berthed to the LMC for the duration of the mission.

During the flight’s docked phased, Discovery’s astronauts will perform three spacewalks or EVAs. These EVAs will see the Removal and Replacement (R&R) of the ATA as well as a Rate Gyro Assembly on the S0 truss, the retrieval of the European Space Agency’s SOLAR experiment (which has been attached to the Columbus module since its arrival at the ISS in February 2008), and the retrieval of the JAXA MPAC and Seed experiments.

EVA-1’s primary activity will involve removing the spent ATA from the S1 truss and temporarily stowing it on another part of the station’s structure.

This operation will be followed on EVA-2 by the installation of the new ATA to the S1 truss and the return of the spent ATA to the LMC in Discovery’s payload bay. Both of these EVAs are classed as “assembly critical” and thus will be a high priority for the Flight Crew once they reach the ISS.

The third and final scheduled EVA of the mission contains the three “highly desired” objectives of retrieving the SOLAR (on Columbus) and JAXA MPAC and Speed experiments (located on the Exposed Facility of the Japanese Experiment Module) as well as the R&R of the S0 truss Rate Gyro Assembly.

The baseline presentation notes that the R&R of the S0 truss Rate Gyro Assembly is currently under review for inclusion in the official mission timeline. Thus, this operation is not considered critical, or even necessary, for the following STS-132 mission or subsequent ISS vehicle dockings and undockings.

For the return trip to earth, the SOLAR experiment will be attached to the PFRAM on the LMC and the spent ATA will be attached to the LMC where the new ATA was fastened during launch.

Additionally, several Department of Defense related payloads of opportunity will be flown on Discovery.

These include SEITI, MAUI, SIMPLEX, and RAMBO-2 (Ram Burn Observation-2).

Several additional baselines for STS-131 will follow over the coming months – each expanding on the mission outlines – via the PRCB, which is expected to open baseline requirements for STS-132 sometime in the summer.

L2 members: All 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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