NASA works contingency with ET update

by Chris Bergin

Two more External Tanks have been added to the manifest that makes up the opening salvo of the final 17 Shuttle missions – revealed in a document that gives details for the next five flights.

ET-124 and ET-117 are both now officially in the processing flow, a flow that has timelines that support a continued use of the STS-300 rescue mission past the next two flights.

The resulting information was collated from information presented to the Shuttle PRCB meeting, which is available in full document form on L2. To join L2, click the advert —>

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While that contingency is expected to be dropped after two ‘clean’ flights with STS-121 and STS-115, ET’s 123 and 124 have been listed as required for the CSCS (Contingency Shuttle Crew Support) attached to mission three and four of the new manifest, namely STS-116 and STS-117.

Such support missions make the delivery dates for these tanks more constricted, which is noted by their current processing being tagged ‘red risk’ with their associated missions. This is also expected to ease after finalisations of the current modifications being made through wind tunnel testing.

ET-119, which will role out of the VAB (Vehicle Assembly Building) with Shuttle Discovery as STS-121 on Friday, is flying ‘as is’ – despite protests from sectors of the tank community – while the remaining tanks may see a level of modification past those seen on ET-119, specifically areas such as the ice/frost ramps. ET-94 and ET-120 are currently being used as test articles at the Michoud Assembly Facility (MAF) in New Orleans.

Order Now - Countdown CreationsHowever, those aforementioned ‘red’ processing dates remain, and currently affect STS-115’s August 28 NET (No Earlier Than) launch date.

‘STS-115 Launch 28 Aug: 84 days for KSC to process ET-118 (red risk): 55 days for KSC to process Rescue ET-123 (red risk): 62 days is minimal amount required by KSC in emergency processing conditions:

‘Lighted Launch Window 8/29 thru 9/13: Slip here will require 13S Soyuz to be moved. ISS plans to do this if required (If ULF1.1 launches in window). Soyuz will have to land in the dark,’ noted a document dated May from the Flight Operations & Integration Office at JSC.

‘STS-301 launch date = 11/11 (75 days after STS-115) (red risk). 72 days 02 is critical resource. 22P Progress 28 Jun Launch has 28 kg of 02 manifested (not full). Does not include consumables from 23P (18 October Launch). Does include 02 used via exercise.’

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The knock-on affect is seen with the next three flights, however these flights will also be eased by the expected stand-down of the ‘STS-300’ requirement – a scenario which would see such a requirement remain past the STS-121 and STS-115 likely being serious enough to warrant another grounding of the fleet.

‘STS-116 Launch 14 Dec: 88 days for KSC to process ET-123 (red risk). 110 day OPF means the Vehicle will be ready 2/9 for a CSCS rescue of STS-116. 57 day crew rescue. XX days critical resource (should be 90 days 02 “Guess”).

‘2/9 Rescue Flight: 31 days for KSC to process Rescue ET-124 (red risk). Slip rescue flight to 3/18 (90 days). ISS assess if this is feasible. KSC assess processing ET-124 in 68 days.

‘STS-117 Launch 22 Feb: 44 days for KSC to process ET-124 (red risk). Slip STS-117 Launch.

‘STS-118 Launch 11 Jun: 70 days for KSC to process ET-117 (red risk). STS-117 slip may impact STS-118 Launch due to KSC VAB High bay door mod.’

The tanks will be mentioned once again at tomorrow’s PRCB meeting, where Shuttle managers will be presented with rationale surrounding the LOX ECO (Engine Cut Off) sensor timers in relation to various MECO (Main Engine Cut Off) scenarios. This is believed to be a safety measure in case of issues with the troublesome sensors during the ride uphill.


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