International Space Station (ISS) managers are conducting a series of meetings to discuss problems relating to Node 3’s associated ammonia lines, which have suffered from rupturing during proof testing. Options available to managers range from reducing STS-130 to a shortened, single EVA, mission, to potentially postponing the flight via swapping the order of the 2010 shuttle manifest.
STS-130 under evaluation:
Endeavour has only just arrived at Pad 39A, and is enjoying a nominal flow towards her February 7 launch target. As reported on Thursday, all three orbiters are on track to easily achieve their schedule milestones, which would result in the completion of the opening three salvos of the 2010 manifest by May.
However, it appears outside factors may throw those plans into a level of disarray, as ISS hardware associated with Node 3 is suffering from issues during proof testing on the ground.
“It looks like we are just not catching a break. Today while proof testing one of the new flight unit ammonia lines there was another rupture,” noted a memo from ISS Flight Director (STS-130 Orbit 2 FD) Robert Dempsey late on Thursday night in a memo acquired by L2.
“A tiger team has been formed and dispatched to California to begin looking at options and schedule impacts.”
The ammonia lines are a vital element in the Active Thermal Control System (ATCS), providing cooling to Node 3 (Tranquillity Module) once installed during STS-130’s mission – which is dedicating two of its three EVAs to the associated “connection and activation” tasks.
The lines were set to be delivered to the Kennedy Space Center (KSC) from California at the end of the month, according to MOD Flight Readiness Review (FRR) documentation, which also noted issues with the qualification unit back on December 27, while one of the lines also leaked during testing in November.
The latest incident is understood to be at least the third failure, thus the concern.
At present, the issue is threatening to heavily modify STS-130 into a short – single EVA – mission, or may even result in the postponement of the mission until later in the year when a resolution/modification is available.
“Due to the history options could be a full redesign, a tweak, a new vendor – which would mean a slip to the nominal mission timeline. As you might expect, (ISS Program Manager Mike) Suffredini wants us to assess the impact to performing a modified mission where we just install the Node 3 and hook up the LTA (Launch To Activation) cables.
“We will also consider swapping the order of the missions.”
Strategy meetings will take place throughout Friday with the ultimate aim to have options on the table by next Tuesday.
“We are trying to target some sort of story by Tuesday’s SSPCB (Space Station Program Control Board) meeting,” added Mr Dempsey. “Since this is an impact to other flights we will need to sync up with them as well but let’s get our bearings first.”
With the STS-130 mission due to launch in less than a month, refining to what is called a Minimum Duration Flight (MDF) with one EVA would require a large amount of rework. Also, STS-130 crew tasks dedicated to the Station – such as work associated with the troublesome Urine Processing Assembly (UPA) Distillation Assembly (DA) – may be impacted during a shorter stay.
“What would be the impact to the mission if we essentially perform the Minimum Duration Flight in terms of analysis needed to be redone or turned on. I think in most cases this is stopping or cutting work but if it is major new work (e.g., trajectory rework) then it will be a challenge,” Mr Dempsey noted as questions to the associated teams.
“If we went beyond a MDF what could we accomplish in the docked time frame and how long would it take. For example, we could still do the DA work – but does it buy us anything staying docked for that? With no training time left, is there enough to fill a second EVA?”
Another concern for this refinement of the mission would be the ability to keep Node 3 – and Cupola – alive in a scenario that would see it installed, but without the completion of tasks associated with hooking up the module to the ammonia lines.
A “Survival Mode” is available – or at least has been evaluated – with an associated presentation attached to the memo. More will be noted on this should managers decide on this option.
“What are the longer term impacts to leaving Node 3 in this keep alive condition – stowage, thermal, cupola thermal in this config, etc. Do we put the PMA3 (Pressurized Mating Adaptor) corner shields back on the module? When/where could the remaining activities be performed,” questioned Mr Dempsey.
If the above questions result in negative answers, managers are likely to evaluate if the best scenario would be to simply delay STS-130 until later in the year, at which time a potential redesign of the ammonia lines in question may be available.
Such an option would require the rollback of the STS-130 stack, and housed in the Vehicle Assembly Building (VAB), while STS-131 continues processing tasks and replaces Endeavour on Pad 39A.
However, it is only an assumption at this stage that STS-131 would replace STS-130. Discovery’s flight is a heavy logistics mission and has been planned to take place after Node 3 is up and running, due to the number of new science racks in the Multi-Purpose Logistics Module (MPLM) Raffaello.
If such a swap cannot be achieved, the Shuttle Program – through no fault of its own – would have undertake a large-scale realignment of its schedule.
“Shuttle team – what are the impacts to changing the mission, what are the impacts to swapping flights?” Asked Mr Dempsey. “There are a lot more questions but this is just a starter.”
Assuming the swap would be with Discovery, it is not yet known if STS-131 can be accelerated from its March 18 launch date – and if it can, it would only be by a matter of days. However, under this scenario, real impacts would be felt downstream, as Endeavour’s STS-130 delay would result in a large delay to what is currently planned to be her final launch with STS-134.
Endeavour’s July 29 date to deliver the Alpha Magnetic Spectrometer (AMS) to the ISS would certainly slip, should managers opt to swap missions on the near term schedule – also impacting STS-133 and the potential STS-135 missions.
While the ammonia line problem is no fault of the Shuttle Program, such issues do show the validity in approving the proposed manifest stretch into 2011.
Outside factors, such as non-Shuttle related hardware, poor weather and launch date constraints relating to other visiting vehicles at the ISS were always a risk of impacting the schedule, even though the orbiters themselves are capable of easily achieving a five flight per year manifest.
More will follow over the coming days as the meetings work on a forward plan.
L2 members: Documentation – from which the above article has quoted snippets – is available in full in the related L2 sections, now over 4000 gbs in size