L-2 MMT passes Discovery to move into final launch preps

by Chris Gebhardt

With Discovery deep into S0007 (Launch Countdown) operations, the Mission Management Team (MMT) has passed STS-128 to proceed towards the business end of the count – with the aim to launch early Tuesday morning. Meanwhile, NASA managers conducted a systematic review of Discovery’s Cargo Integration Hardware (CIH) and CSCS (Contingency Shuttle Crew Support) calculations brought forth at the FRRs.

Engineering Review:

As part of the standard pad processing flow, engineers at Pad-39A filled Discovery’s RCS (Reaction Control System) and OMS (Orbital Maneuvering System) tanks with 29,642lbs of propellant earlier this month.

In all, the OMS tanks were filled with 22,760lbs of propellant with the Aft RCS and Forward RCS tanks loaded with 4,970lbs and 1,912lbs of propellant, respectively.

The FO&I (Flight Operations and Integration) presentation to the SSP FRR on August 10th and 11th notes that the Aft RCS tanks received a “FULL” load of propellant while the Forward RCS tanks received a “MINIMUM” load.

Furthermore, the presentation – available for download on L2 – reveals that Discovery’s ballast boxes will not be filled for this mission. Also, the presentation notes that Shuttle/ISS rendezvous altitude is slightly lower than previous missions.

“Rendezvous altitude is 188-nautical miles,” notes the presentation. Previous ISS missions of late have seen rendezvous altitudes of ~190-nautical miles.

In terms of the cargo support hardware installed on Discovery, “All Cargo Integration Hardware (CIH) for this flight is certified, conforms to engineering design documentation, and has been delivered to KSC and installed in the vehicle.”

neptecOf the CIH being flown on Discovery, two are classed as first flight CIHs. These are the Harness Assembly Ethernet between TriDAR and the Payload General Support Computer (PGSC) and the Harness Assembly Standard switch panel to TriDAR.

Moreover, “Engineering products (data, requirements, drawings) and integration analyses have been completed with one Exception: STS-128 Verification Loads Analysis (VLA) Open Work,” notes the FO&I presentation.

This open work pertains to the nominal return mass of MPLM Leonardo on Discovery. This return mass falls outside of the medium and light weight MPLM return cases that have been previously analyzed in the VLA.

“ISS Program is performing work to protect for a ‘super light weight’ MPLM return case. ISS Program data will be delivered to the Structures Working Group (SWG) that will determine which payloads/cargo elements are affected and will define appropriate uncertainty factors to be applied to VLA-2 loads,” notes the FRR presentation.

This data was given the SWG on August 17 with the understanding that all necessary analyses would be complete by August 21.

While there is only a “low technical risk” that a super light weight return case would result in negative margins for Discovery, more cargo would have to be added to the MPLM if the negative margins cannot be cleared by analysis.

a413As such, the final analyses was presented to the Mission Management Team on L-2 (Launch minus two days) for final overview and approval, a meeting that also cleared flight rationale for the Forward Power Control Assembly (FPCA3) and the ongoing evaluations into the Flow Control Valves (FCVs).

Click here for NASASpaceflight.com articles on the FCV issue since STS-126.

The next portion of the FO&I presentation pertained to the Middeck Engineering Status.

“Crew Compartment Requirements have been defined and accommodated, ascent Crew Compartment Configuration Drawings (CCCDs) have been completed and released, and return manifest requirements are being defined and the engineering release is in work,” notes the presentation.

Moreover, for the Middeck Engineering Status, the usual L-10 Day Bench Review content is only one 5-MLE bag and one locker.

For STS-128, however, the L-10 Day Bench Review consisted of four 5-MLE bags, five lockers, and window shade bags.

Furthermore, “At the time of the L-30 Day Bench Review, Ascent Performance Margin (APM) was low so many middeck locations were not fully utilized.”

As a result, all middeck lockers with available space were left unfilled. Since APM is available and will no longer limit the amount of ISS middeck hardware, these empty spaces have been filled to maximize the amount of upmass to the ISS.

The next issue noted was with the Orbiter/Payload Middeck Electromagnetic Interface (EMI).

“During the MDS Qualification EMI test, two non-compliances of the Electromagnetic Environment requirements for use in the Middeck were found.

An AC generated power lead was noted to have a noise emission at 110 kHz and turn-on transient exceeded the duration limit by 110 micro-seconds.

These non-compliances were reviewed and rationale developed for Discovery’s flight.

In all, every FO&I IFA prior to and including STS-127 has been reviewed and either closed or classed as a non-constraint for STS-128.

CSCS/LON Analysis:

As with all post-RTF (Return To Flight) missions, Discovery will have a Launch On Need (LON) rescue mission for her Flight Crew in the event that she becomes disabled on orbit.

Even though a LON scenario is deemed unlikely, orbiter Atlantis will be prepared for a launch No Earlier Than November 12 to rescue the STS-128 crew on the International Space Station.

As has been seen on previous ISS Shuttle missions, Discovery’s LON flight would be a “Fly the Next Flight” mission – the STS-129 mission on Atlantis.

“STS-129 LON “Fly the Next Flight” Vehicle/Stack: OV-104 (Atlantis), ET-133, RSRM-108. Payload Bay Configuration: ISS-ULF3 (ELC1, ELC2, SASA, MISSE 7A/7B). Crew Size: 4 STS-129 crew up/11 down,” notes the FO&I presentation.

Given the “Fly the Next Flight” LON scenario, the STS-128 crew could be rescued from the ISS in 79-days (based on an STS-128 launch date of August 25 and an STS-129 launch date of November 12).

This is within the ISS’ support capability. “ISS CSCS consumables support 88 days (food) and 93 days (CO2 removal) for total crew size of 13 with Discovery remaining docked to the Station for 21-days and all 13 crewmembers exercising regularly.

“Waste & Hygiene Compartment, Urine Processing Assembly, Water Processing Assembly, and Oxygen Generator System (OGS) are operational,” notes the presentation (with a latest issue with OGS resolved).

Finally, all of the CSCS/LON analyses do not take into account the potential supplies from the HTV-1 and Progress 35 vehicles as there is no guarantee that these supplies will reach the station in the 79-day CSCS timeframe outlined at the SSP FRR.

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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