Forward Plan: STS-126 rolling to Pad 39A in a few weeks – STS-125 back to VAB

by Chris Bergin

While the status of STS-125’s Hubble Servicing Mission remains fluid, managers at the Kennedy Space Center (KSC) are creating plans to move Endeavour and her stack to Pad 39A in around two weeks time.

This plan would result in Endeavour launching as STS-126 for the final mission of the year, around November 14.

Hubble Fallout – STS-126 Gaining Focus:

Endeavour’s role as the STS-400 LON (Launch On Need) shuttle means she will need to be rolled off Pad 39B, for rare trip midway down the crawlerway, before being placed on Pad 39A for her primary STS-126 mission.

This will be pre-empted by STS-125/Atlantis being rolled back to the Vehicle Assembly Building (VAB) for the interim period.

There Atlantis would remain until the status of Hubble becomes clearer, with the potential to launch in STS-119’s February launch window. This would result in Discovery taking up the STS-400 – which may be re-named – role on Pad 39B, ahead of her eventual move to Pad 39A for an April mission to the International Space Station (ISS).

Another option is based around a worst case scenario with Hubble’s health, which would move STS-125 to April, launching after STS-119 in February, with Endeavour taking up the STS-400 role after post flight processing from STS-126.

The problem with Hubble relates to what is currently believed to be a hard fail of the Control Unit/Science Data Formatter (CU/SDF), part of the Science Instrument Command and Data Handling system “Side A”. Efforts are continuing to switch operations to the redundant “Side B”.

On the ground, a replacement unit is bring prepared, though it will take at least a month just to check the device and add the replacement to the STS-125 flight plan.

“There is a ground unit that can possibly be used, as it was developed for flight, but they have to have 30-45 days to check it out and have to revise the EVAs,” added notes on numerous memos on the forward plan.

At the Kennedy Space Center (KSC), Hypergolic loading of the Reaction Control Systems (RCS) was halted while pad processing with Endeavour waited for instructions from shuttle managers.

“S0024, Hyper Propellant Load: The remaining hyper load operations are on hold until the impact of HST on orbit problems are determined,” noted processing information this week, before a clearer “current approach” was forthcoming late on Tuesday.

This plan is based on rolling back Atlantis to the VAB in less than two weeks time, before rolling Endeavour off Pad 39B, to the fork in the crawlerway, then forward to Pad 39A for what will be a November 14 – or there about – launch date.

“Due to the Hubble mission problems we will delay collecting the Delta CoFRs (Certification of Flight Readiness) for STS-126,” noted another memo. “If STS-125 is rolled back to the VAB then STS-126 will stick to mostly the same timeline we are on now to launch on November 14th instead of November 16th.

“We are presently planning to pick up again with S0024 operation on Thursday morning to load hypers to the STS-126 load instead of previously planned STS-400 load and then plan to roll to Pad A in about two weeks.”

Endeavour can be rolled from pad to pad with a full load of hypergolics without issue. The only requirement to offload would be if she was demated and rolled back into her Orbiter Processing Facility (OPF).

One key driver to launching Endeavour as early as possible for STS-126 relates to the crew – known as “Crew Loading”. However, this is now being aided by an improved timeline, as all relevant centers do their bit to help Endeavour’s launch window, which is restricted by a launch beta angle cut out on November 25.

Another issue relates to an effort to add up to an additional 1,750 lbs of payload inside Endeavour’s “Leonardo” Multi-Purpose Logistics Module (MPLM), with analysis into the best case scenario being hit by a week-long delay due to the shut down of JSC during Hurricane Ike.

The analysis of several options to increase what is already the heaviest logistics flight to the International Space Station (ISS) centered around the results of the Verification Loads Assessment (VLA), which initially raised concerns.

However, the process is now coming to a conclusion, via NASA SE&I (NASA Systems Engineering and Integration) and the MPLM’s contractor, Alenia Space of Italy, on what now appears to be more conservative 600lb increase to the MPLM’s cargo – added to the end cone of the module.

“On STS-126, the model for the MPLM and cargo was delivered to SE&I last week. Alenia brought forward their analysis that showed the 600 lbs. case. The Structures Working Group is happy with that. This is for the end cone mass on the MPLM,” noted the latest Shuttle Stand-up/Integration report this week.

“It turns out that the mass stowed in the bags is 590 lbs., 420 lbs. of which is actual stowage to go in logistics. Got Coupled Loads Analysis (CLA) results. CLA is where the Cargo Mission Contract (CMC) folks run a pseudo-VLA and pass results back to our folks to put uncertainty factors on.

“We got the results back from the over/out-of-tolerance rack case for the MPLM (3 or 4 racks out of tolerance). Are currently working up uncertainty factors for those racks, but it looks like it will be pretty good. Also, their return case is very light, below our VLA tolerances, so they are also doing a CLA for that.

“We should see where that is this week. We will apply uncertainty factors on our VLA Cycle 2 case results based on these results, and hopefully clear that case too. Think the critical path now is SE&I/Orbiter guys.”

Endeavour’s logistics run to the ISS involves key delivery of items required to support the expansion to a six man crew on the Station next year.

Discovery STS-119/STS-129:

While Atlantis awaits her rollback confirmation, work has been proceeding at a good pace inside OPF-3 with Discovery, as she readies for her primary mission of STS-119 – and now the potential of “STS-400” requirements.

A key milestone was reached in processing over the past week, with the installation of her three Space Shuttle Main Engines (SSMEs), and continued progress with the boundary layer transition modification – which will gain valuable data on Thermal Protection System (TPS) performance during re-entry.

“Completed engine installation on Friday. picking up with engine securing and get into leak check,” added the Stand-up. “On the boundary layer transition mod, have completed all the wiring. Will start bonding the tile this week. This activity is going well.”

“Orbiter docking system pyro system checkout was completed Monday and is good. Nose landing gear thermal barrier rework was removed Monday and new thermal barrier were ordered because the ones delivered did not meet requirements,” added processing information.

“Post SSME installation engine securing is in work through Wednesday. Radiator functional testing is scheduled for Tuesday and Wednesday.”

One of Discovery’s future flights – STS-129, currently set to launch in October, 2009, though likely to slip – also received official confirmation of the crew assignments to the mission.

As revealed by a month ago, the crew will consist of Marine Col. Charlie Hobaugh as commander, joined by Navy Capt. Barry Wilmore as pilot. The Mission Specialists are Robert Satcher, Navy Capt. Michael Foreman, Marine Lt. Col. Randy Bresnik and Leland Melvin.

L2 members: All documentation – from which the above article has quoted snippets – is available in full in the related L2 sections, updated live.

Related Articles