NASA STS-116 FD-8 Execute Package
MSG 076A (14-0598A) – FD07 MMT SUMMARY
The main topic at the MMT was a status of the Team Four activities with respect to a dedicated P6 retract EVA or potential simple get ahead tasks for P6 retract activities during EVA 3. The ongoing ISS P6 loads analysis and vehicle anomalies were also discussed. The MMT complimented both the STS-116 crew and the MCC team’s outstanding performance during EVA 2.
Because analysis and EVA technique development are on-going, a final decision regarding an additional EVA for the P6 retract was not made at the FD 7 MMT. The teams continue to review the benefits of performing an additional EVA on STS-116 or delaying this EVA to the stage or subsequent shuttle mission. The factors for this decision are the ISS loads analysis required to clear docking on the FGB nadir docking port which will be used by Soyuz in April and a continued development of EVA tasks and associated risk assessments for improving the P6 Array problems. The ISS MMT discussed the loads analysis today and will make a final decision tomorrow on whether the loads are acceptable for a Soyuz nadir docking. If the loads are acceptable, then both the Shuttle and Station Programs will likely defer the P6 retract to a downstream shuttle mission. If not, your mission timeline will likely be modified to incorporate this EVA activity with details to follow for uplink prior to FD 9.
A summary of the Team 4 activities related to a P6 EVA provided the MMT insight into the techniques being considered. These include an in-flight constructed tool used for grommet realignment, blanket manipulation, and/or interface with the guide wires. The reach and access associated with the array hardware was discussed since this drives the need for the SSRMS to provide a translation path along both solar array blanket boxes. The hazards associated with this EVA near an active solar array are well understood and the team continues to work on risk mitigation including which tasks should be completed in day versus night passes.
An overview of how the P6 EVA will fit into the mission timeline as well as what activities will have to be deleted were provided to the MMT. Several timeline options were presented including adding these tasks to EVA 3 or a separate EVA on flight day 9 or flight day 10. The EVA 3 option was dismissed due to the inability to generate/verify operational products in time. Additionally for EVA 3 solar array tasks, the SSRMS must be at worksite 5 which is not compatible with the EVA 3 power channel 1/4 tasks which require the MT at worksite 3. The FD9 and FD10 options were discussed each with their respective pros/cons. The team recommends the FD10 option due to the time required to generate/verify/uplink the operational products, numerous SCSC violations, and sleep shift impacts associated with the back to back EVA option.
If a P6 EVA is required, the mission timeline trades include Late Inspection since one of the 12+2 days would be required for the EVA. The MMT provided direction that the Late Inspection activity will remain on the timeline and will discuss any tradeoffs at a subsequent MMT if required.
EVA 3 Get Ahead Task – The ISS MMT approved a simple get ahead task for EVA 3 which would involve an EVA crewmember inputting a load into the P6 array structure via the blanket box. The MCC will provide you with details and a plan later today.
P6 Loads Analysis – The ISS team continues to analyze the P6 array configuration and how FGB docking loads can affect this structure. The loads model was run with the P6 array at a 30, 60, and 95 percent deployed position and includes a 1.5 uncertainty factor to protect for model uncertainties. Preliminary analysis indicates that no load exceedance exist for the 60 and 95 percent deployed positions with an FGB nadir docking. The P6 array is currently at the 56 percent deployed position (17.5 bays). The 30 percent deploy position does indicate a slight loads exceedance and array billowing. The ISS MMT will decide tomorrow if the analysis is sufficient to wait for a subsequent Shuttle mission to execute an EVA to retract the array.
ISS Attitude Control – The reason that Shuttle had to take attitude control yesterday was excessive momentum in the ISS CMG Momentum Manager likely due to increased atmospheric density due to the recent increased solar activity. The stack lost 450 meters of altitude and has since regained 300 meters while on Shuttle vernier control.
ISS RPCM LA2B Trip – At GMT 349/07:41 RPCM LA2B-E RPC 5 tripped open which powers the lamps on the Lab C&W panel. You can still hear C&W tones as well as initiate C&W events by pushing the buttons on the panel. Lights are available via PCS or the Russian C&W panels. There is no plan to R&R this RPCM while docked.
ISS N2 Transfer – N2 transfer continues and at the end of FD 7 approximately 41 lbs have been transferred. This activity will conclude on FD9.
Solar Activity – The MMT discussed the geomagnetic event during EVA 2 and the predicted activity for the near term. Space weather conditions are currently at high levels due to a flare that was observed from Solar Region 930. These conditions are expected to remain at moderate/high levels for the immediate future. The Space Radiation Analysis Group will continue to closely monitor this region for changes and activity. EVA 3 is in a good location in terms of groundtrack, there are no plans to alter the EVA, and it will be managed within the existing flight rules.
