STS-121/ULF1.1 FD 03 Execute Package
MSG 011A (13-0609A) – FD03 MISSION SUMMARY
Page 1 of 2
Page 1 of 2, MSG 011A (13-0609A)
Good morning, Discovery!
Great day yesterday, finishing flight day 2 early, that’s amazing. As for today, just a rendezvous. However, you will be losing a crewmember at the end of the day, but then again, you’re gaining a Station.
L5L is still warm and we plan on using it for the rendezvous. We will call you to reselect it sometime before NC4 – when PROP sees it at its warmest.
The WLES System continues to work well and all the ascent summary files have been received on the ground. We expect the starboard wing units to get too cold to operate over the next day or so due to the -YSI attitude we’ve been flying, but are expecting those units to warm up again after we undock. Port wing temperatures look good for the docked mission, but we expect them to get too cold to operate after undocking. Thanks for all your work in this area.
FD2 MMT Crew Summary
The MMT met to review the mission progress and there were only a few items of significant discussion. These include the management of the L5L jet for rendezvous, the FES PRI B shutdown on FD 1, and a review of the preliminary ascent video and Wing Leading Edge sensor system data.
L5L: The MMT concurred with the plan to continue to thermally condition L5L and maximize the probability of all 6 VRCS jets being available for rendezvous. Based on the real-time data and thermal analysis predictions, the temperatures are expected to be warm enough to have L5L available for rendezvous/docking and the post docking maneuver to attitude. However, if all 6 vernier jets are not available, the MMT concluded that ALT DAP should be used for the RPM since it’s a certified configuration and published procedures are already in place. The MMT understood that the risk of using ALT DAP is that the attitude excursions may result in some of the RPM photos being of insufficient quality, possibly requiring some focused inspections. Based on Draper simulation data, VRCS (5 or 6 jets) results in roll excursions of about 5-7 degrees when between 145 and 215 degree pitch (Orbiter bottom side imaging window), whereas ALT DAP results in roll excursions of about 20-25 degrees. The primary concern is that 5 of 6 vernier jets are not a certified ISS loads configuration and there is also the possibility of jet shelf pulsing, ISS loads resonance, or other off nominal DAP performance with 5 jets during the RPM.
FES PRI- B: As you know oscillations in evap out temps were observed on FES PRI B (high load and topper) in the post-insertion timeframe. Full up FES PRI A worked well during ascent and in post insertion prior to selecting FES PRI B. The topping and hi load FES were flushed on FD1 and no indications of ice were noted. During the core flush procedure, the secondary high load also exhibited oscillations and took longer to stabilize than normal. There is no definitive cause of these oscillations although the likely candidates are the FES PRI B controller and/or temperature sensors in the midpoint block which is located between the high-load and topper. The SECONDARY high load oscillations have been observed before on other missions. Neither FES PRI B nor the SECONDARY FES are being declared failed at this time and further troubleshooting will be planned for post undocking. It is quite possible that the plan will be to use FES PRI A for deorbit/prep entry. This plan will continue to evolve over the next few days and is being worked by the Entry Flight Director and EECOM.
Wing Leading Edge Sensors – All the WLEIDS data has been downlinked and the preliminary assessment is that the system detected 6 probable impacts during ascent (tripped the .87 Grms sensor limit). Three of these were on the port wing and three were on the starboard wing. This is very similar to the number of probable impacts that were observed on STS-114 and there may be some correlation between the two missions.
Imagery – The teams continue to review the ascent imagery data (ET LOX feedline camera, ground cameras, WAVE aircraft video, and debris radar). The preliminary characterization is the debris environment was substantially less than that observed for STS-114. These reports show two events that may have impacted the Orbiter. The first event was at approximately 19 seconds (Figure 1) and the other was at ~285-294 seconds. Both of these are outside the critical debris region of concern that spans from 35 seconds to 140 seconds. Exact size and velocity estimates are still being refined.
The 19 second event that was observed to be a single piece of debris traveling between ET and Orbiter fuselage which could indicate an impact although the image quality is poor . For the 285-294 second event (Figure 2), multiple (~5-12) pieces of ET debris were observed and one piece possibly impacted the Orbiter. The debris originated from aft of bipod on -Y side of LO2 feedline, traveled toward the Orbiter fuselage, changed direction abruptly, and then fell aft breaking into several pieces after possible contact with Orbiter. Early prediction are a 33 feet/sec average velocity with a maximum velocity of 67 feet/sec. The ascent camera views have not detected any visible signs of TPS damage as a result of these events.
The LDRI FD2 imagery shows a protruding gap filler (Figure 3) on the port side near outer edge of wing. It is located in an area where GAP fillers were not replaced with a tile thickness of 2.6 inches. Initial measurements estimate the protruding GAP filler to be about 1/2 inch. The aeroheating community is analyzing this to determine if any future action is required to remove. Additionally, all of the Tyvek covers on the FRCS thrusters were reported to have come off within about 8 seconds MET, which meets the velocity requirements for all of these covers. Finally, the imagery experts reviewed the ET handheld photography and confirmed the MCC assessment of ice being the unusual item reported by Mike Fossum. Ice was also observed in the STS-114 handheld photography and this has been observed on other missions as well.
Of course we’ll have a better assessment of the TPS (wing leading edge RCC and tile) after tomorrow’s FD 3 MMT when the FD2 inspection data will be reviewed.
