Author Topic: Expedition 24 thread (June 2 - September 24, 2010) - Includes ETCS Updates  (Read 181931 times)

Offline rdale

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Crew trained about a year ago for this already, since it's part of the Big 14. Not all crews do this training, but they did.

Offline rdale

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Ops & Engineering are now up for 24/7 support, looks more like a shuttle flight in the control center. We train for these sorts of issues, we've been fortunate to never have faced this significant of a problem in the past, but feel good to get this fixed and back to research.

Offline rdale

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Courtenay: We are still in the process making sure we can start R&R on Thursday. Showing live video from the NBL as they start working on details of the timeline tasks.

Offline rdale

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Based on how today's NBL goes, we'll be able to figure out if Thursday is a go or if we need another day. S1 pump module is on Bay 7. It weighs ~ 500lbs, replacement is on ESP-2 which is on the other side of the truss, and down below. So crew has a fair amount of translation to do.

Offline rdale

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Spare has a grapple fixture so can use the arm, or have the crew carry it. Baseline for generic Big 14 assumes that we don't have robotics because of external power loss. We're single-string, so testing to see if we can get enough redundancy on arm to use it as-is.

Online Chris Bergin

Live from the NBL:

Offline rdale

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We know we can use the arm if we needed to get the crew to safety, so it will be used, but we need to see if we have enough power margin to use it for the entire EVA or just as a safety issue.

Offline rdale

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First EVA is to prep removal of existing PM. Most challenging is the NH3 QD connections that they need to release, since the external loop uses ammonia all of the lines are pressurized. We've done this before on different parts of ETCS and they are trained in case they get NH3 on them. It's just a timeline challenge.

Online Chris Bergin

Location of the spare PM:

Offline psloss

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Crew trained about a year ago for this already, since it's part of the Big 14. Not all crews do this training, but they did.
The way I parsed that was that the crews do generic training on some of the Big 14 ORUs, but not all of them.  This crew did train for a pump module ORU R&R.

Offline rdale

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Power challenges also impact the EVA preparation (L2 has a 800 page checklist BTW)

Offline rdale

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Crew already has airlock & suit systems ready to go because of the previous planned EVA, but still timeline issues. Another NBL tomorrow if we're good for Thursday, but we can slide one more day. That will be final run prior to EVA1. We can run another NBL prior to EVA2 if needed.

Offline rdale

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Mark C: How do you consider this in terms of urgency related to manning.

Mike: It's independent of 6-person crew. With one loop down, already mentioned arm, DDCUs have some residual capability since they don't overheat at lower loads. If we lose loop B, we can't cool other components so it'd be a significant challenge.

Offline rdale

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Mark: Clarification on number of spares.

Mike: 2 operating, 4 spares. Others are on ESP2, ESP3, ELC1, ELC2.

Offline rdale

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Eric @ Chron: You are saying primary concern that second module fails so components would "fry" on the outside as opposed to the station overheating on the inside.

Mike: NH3 flows through some parts outside to cool, then through heat exchangers which take heat from the inside. (Plenty of info on that here and in L2 so I'm not going to retype how the station cools.)

Offline psloss

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Crew already has airlock & suit systems ready to go because of the previous planned EVA, but still timeline issues. Another NBL tomorrow if we're good for Thursday, but we can slide one more day. That will be final run prior to EVA1. We can run another NBL prior to EVA2 if needed.
Courtenay McMillan prefaced that with saying that there's a two-week preparation period "baseline" involved in EVA R&R for one of these critical ORUs.
« Last Edit: 08/02/2010 08:28 PM by psloss »

Offline rdale

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Eric: So the crew won't be burning up in there? (What happens if we lose Loop B)

Mike: Russian system can provide some life support, most systems won't do 6 crew. So first thing would be to use them for life support and 50kg prop per day for station keeping (that's not an issue.) Bigger challenge is powering up systems needed to do the EVA. We asked team to give us rundown if we do have the next failure before PM changeout.

Offline rdale

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Robert: Where is this failure rank in the history of ISS?

Mike: It's up there, being external adds an element of challenge. SARJ was a significant issue, but we always had plenty of power and that was early in the ISS life (it was a long-term worry more than short.) Other is the solar array tear during redeploy in 10A, because it took us a while to figure out if we could even do a fix.

We never planned for solar array tears since we didn't think that could happen. This is one we knew could happen, have trained for, and planned for, and put spares up for.

It is a significant failure, so it's one we need to get. So it's a big system issue that we need quickly. Sometimes they are unplanned which takes a while to solve, but that's not the issue. Having the EVA already planned is very significant due to the prep work most of which was already done.

Offline rdale

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What are potential snags during EVA?

Courtenay: We trained Big 14 task-based, so much of the choreography is not worked out to the level of detail that they can train during generic. So NBL is working out the details. Where we might snag is the NH3 QD plumbing, to disconnect the actual PM, venting the PM (although we have analyzed that well, just worried about actual execution for timing snags.) Most of the rest of the task is logistics. It's a big box to move around and hand off.

Offline rdale

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Can you use the Cupola RWS or back to Destiny?

Going back to Destiny, video in the Cupola can't be powered up. Plus it's on the other side of the space station, so really not an impact anyways.

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