NASA managers have made the decision to move the launch of STS-117 to a NET (No Earlier Than) launch date of April 22, after early damage evaluations on the External Tank and Atlantis’ left wing.
Following the hail storm damage to the vehicle, the decision to rollback to the Vehicle Assembly Building (VAB) – midnight Saturday night – has led to a repair timeline, with the late April target classed as the current best case scenario.
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What is currently known is that there are over 7000 divots or damage areas on ET-124, mainly located at the top end of the LOX tank. There is also at least one IFR (Ice Frost Ramp) that has been damaged.
The current plan is to rollback to the VAB for a full assessment of the damage to the tank, with the hope that the damage can be repaired in the VAB. However, there is a possibility that the tank will have to be sent back to the Michoud Assembly Facility (MAF) in New Orleans, if the damage is too serious for repair at KSC.
‘The decision has been made by the program to Roll Back to the VAB to assess and repair all damage. The Tank has sustained thousands of hits. At this time there is no definitive total number hits on the tank. Assessment was done by visible zones,’ noted one of several NASA memos that have been urgently flying around the agency today.
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Earlier, it was hoped that the March launch window could be saved, although that was based on the damage to the tank being classed as ‘minor’.
‘Minor ET repairs in VAB – Possibly make the end of the March 25th window. Major ET repairs in VAB – Might be able to make the April 23rd – May 24th window. R&R (Remove and Replace) ET with the 118 tank – STS-117 will launch in July and STS-118 will move to August 26th,’ added a pre-Lockheed Martin (MAF) assessment memo.
However, the possibility of keeping to the March timeline was removed following a lunch time meeting with ET engineers and managers, which noted an updated three pronged plan.
‘The March launch window is no longer an option. Currently KSC is looking at three options. The first is a 21 day VAB repair period without tank removal. This option allows the first launch attempt at the beginning of the April/May window (22 April),’ added a NASA memo at 1pm Houston time.
‘The second option has the tank demated and transferred to the VAB storage cell for repair. This options extends the VAB period but allows a first attempt at the end of the April/May window(20 May). The last option is a tank R&R. ET-117 is expected here mid April. This option has the first attempt 15 June.
‘With all of these options Engineering is accessing all time and cycle requirements and what additional work is required. No option will be given priority until extensive evaluation of all damages are compiled in the VAB. There is some concern about hail that could have pin balled between the orbiter and tank that has not been seen yet.
‘Presently engineering is discussing whether to continue fueling the OMS system or to Off load the oxidizer already tanked. Either way the loading or detanking will be completed Wednesday AM. Roll back preps and OMBUU demate Thursday. Friday and Saturday are P/L removal days and Sunday Rollback. We are expecting a fueling decision by the end of the day but that does not affect the overall plan.’
The other area of concern is Atlantis herself, as she managed to sustain 27 hits to her left wing. However, the damage was not classed – at first viewing – as hits on the RCC (Reinforced Carbon Carbon) panels that are located on the leading edge of the orbiter’s wings.
‘There were around 27 Orbiter tile damages located on the port side chine and wing tip area,’ added the 1pm NASA memo. ‘Many of the damages were depressed coating with no visible base substrate showing. The worst case (depth wise) .5” x.5” x.12 in depth. RCCs have no visible damage, but will be inspected in the VAB.’
Further articles will follow. Please refer to the live update pages on L2 (for NASA memos, emails and images) and on Atlantis’ section (open to all) to review the breaking of what proved to be exclusive news updates throughout the day.
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