STS-124 slips to May 31 on back of opening ET fallout

by Chris Bergin

NASA has started a week-long process of refining their launch date targets, caused by delays to scheduled delivery dates for several External Tanks. STS-124 has already slipped to NET (No Earlier Than) May 31.

ET-128 – STS-124’s tank – is now inside the Vehicle Assembly Building (VAB), but has not made it to KSC in time to support the previous May 25 launch date, while STS-119 is now certain to slip into 2009. All slips will not affect the ability to complete the full manifest through to 2010.

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Manifest and STS-124 Latest:

May 31, the new NET (No Earlier Than) launch date target for Discovery, was caused by the lack of contingency days in the flow, following the late shipping of ET-128, and its extended trip from New Orleans due to high winds in the Florida region.

‘(Will be made) official next week. Slipped from 5/25 due to ET delivery delay,’ noted one memo updating the status of the opening meetings that concentrated on STS-124.

Given the delay to ET-128’s arrival, the exact dates for the VAB flow remain fluid.

‘Pegasus arrived at the turn basin yesterday at 11:04 EDT. The tank was transported to the VAB with lift into high bay 4E planned for this morning,’ noted Thursday processing information.

‘SRB/RSRM: BI-134 / RSRM-102: Booster Closeouts are complete, less ordnance installation, which is scheduled for April 1. Final ordnance installation will occur after ET Mate.

‘On vehicle in OPF, are down to nine TPS (Thermal Protection System) cavities. Plan to close PLBDs (Payload Bay Doors) on Friday for rollout. Then will start series of structural leak checks requiring jack transfers, landing gear and ET door closures (three or four days required).

‘Will configure vehicle for rollout scheduled at end of April.’

The delay to STS-124 was expected, although managers appeared to be very protective about being too open with regards to the fluid status of the launch dates. This was exemplified in the latest Stand-up/Integration meeting, chaired by NASA Test Director Steve Cash.

‘There have been rumors circulating about tank delivery. We are on schedule to launch May 25, 2008, and a LON tank will be available,’ noted the minutes from the meeting, which is officially no longer the case.

However, Cash appears to note that – as expected – STS-119 will move out of 2008, due to the upcoming slips to STS-125 and STS-126 – believed to be heading to October and December respectively.

‘Fully expect to launch HST and ULF2 flight this calendar year,’ added the Stand-up. ‘Have the ability to absorb minor slips in the schedule. Are working on ET schedule very hard. Mr. Cash believes we will meet our schedule.’

Meeting the schedule – or to complete the manifest by 2010 – is more than likely, given planning documents show that 2008 only had to see three launches being completed in the calendar year, to ensure the manifest remained on track.

With two missions already under their belts, with four still achievable, and Atlantis no longer retiring in 2008 – decided months ago, yet still not officially announced as per budgetary requirements – 2010 is not under any strain.

The next key meeting will take place early next month, when the Michoud Assembly Facility (MAF) pass on their latest processing estimates for ET-127 (STS-125) and ET-129 (STS-126).

Both tanks are the first in recent years to be built ‘from scratch’ – as opposed to being existing tank builds that have been modified as per safety requirements.

Unspecified processing issues added to the workload on processing these tanks – officially classed only as processing stretch on the schedules – thus delaying their expected delivery dates.

ET-127’s first role will be to support STS-124 – as the LON (Launch On Need) tank that will fly with Endeavour, should an emergency arise on Discovery’s flight. Its regular flow will see it mated with Atlantis for the trip to Hubble. Currently this is due in late August/Early September, but is expected to slip to October.

The relation to STS-124 will be known via refined delivery dates, which will help assess the amount of CSCS (Contingency Shuttle Crew Support) time required in the time in-between STS-124 launches, and LON capability will be achieved.

“ET-127: This next tank out is in final horizontal assembly. On LO2 tank, are working harness routing, cable installation and cable tray dam installation,” noted the latest MAF processing information. “On intertank, are continuing with cable routing. On H2 tank, have ice/frost ramp, longeron, feedlines, bellows heater, and small components closeouts in process.”

ET-129’s opening role will be to sit with Endeavour on Pad 39B – the last shuttle to ever use the pad that is already undergoing Constellation (Ares I-X) modifications – at the same time STS-125 launches from Pad 39A. This is due to the lack of ISS Safe Haven on the Hubble flight, and a much-shortened timescale to rescue the STS-125 crew if required.

“ET-129: Stands are complete, longeron access is in work, and are working ice/frost ramp base trimout,” added the MAF report. “Also have series of activities in backshops: titanium yokes, vertical struts and LO2 feedline sections.”

Endeavour and ET-129 will then enjoy a quick tour around the coastal area of KSC, as the STS-126 stack is rolled back to the fork in the crawlerway, before then rolled to the vacated Pad 39A in preparation for the primary mission.

Further changes to the launch dates will be published when they are known.

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