Author Topic: ISS concern over S1 Radiator - may require replacement via shuttle mission  (Read 12028 times)

Offline refsmmat

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What about the two stowed radiators on P6?  Have they been decertified or are they too hard to get to?  I bet they simply wouldn't fit.  Darn it...  just 300 feet away.  To think there could be a whole extra shuttle mission, just because of a stray thruster cover.

Offline robertross

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What about the two stowed radiators on P6?  Have they been decertified or are they too hard to get to?  I bet they simply wouldn't fit.  Darn it...  just 300 feet away.  To think there could be a whole extra shuttle mission, just because of a stray thruster cover.

Those radiators are not compatible (fit, ect).


Offline Chandonn

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What about the two stowed radiators on P6?  Have they been decertified or are they too hard to get to?  I bet they simply wouldn't fit.  Darn it...  just 300 feet away.  To think there could be a whole extra shuttle mission, just because of a stray thruster cover.

The two stowed radiators on P6 are the smaller ones used for the photovoltaic arrays.  They are smaller than the regular radiators and were only used when the USOS was simply Unity, Destiny, Z1, and Quest.  There's a lot more equipment up there now, and I doubt the smaller radiators could handle that (plus, 2 larger radiators and 1 smaller one on the S1 segment would have to use a different amount of ammonia than it is curently designed for).
« Last Edit: 04/02/2009 01:15 pm by Chandonn »

Offline bigboy_99

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Not the whole rotating assembly, just one radiator. No need to replace the whole thing. The radiator is maybe 2 x 3 meters / 1,000 kg max and would fit nicely on an ICC or another cross bay structure. No need for an extra dedicated flight.

Analyst
I think you're actually talking about the radiator beam assembly on which the three radiator wing assemblies are mounted on. I was talking about the actual radiator wings. They're the ORUs, not the individual panels.

A radiator consists of 8 panels and is, as you say, an ORU in its own right.  Folded up they measure about 11ft x 9ft x 2.5ft and weigh about 2,475 lbs (3.35m x 2.75m x 0.76m, and 1120 kg).

I'm sure many have seen the attached photo, which gives some idea of scale of these radiators.

If that's the case, couldn't a whole new radiator be flown on a ULF such as STS-131 or 132? You got space, and people who have been in the area and know whats there and how to get it done.
Steve

Offline AndrewSTS

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Space isn't the issue, mass is. Depends on attach structure in the PLB etc. You'd want to send up a MLPM with the flight too. At least it isn't too heavy.

Offline vt_hokie

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So, do they have spares on the ground?  And if not, how long will it take to build one?

Offline kch

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So, do they have spares on the ground?  And if not, how long will it take to build one?

"We'll have that ready for you next Tuesday" ... ;)

Offline Peter NASA

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I believe Boeing have a spare that requires a bit of work. I see this as leaning towards a R&R.

Offline Analyst

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Knowing the root cause would be nice.

Analyst

Offline Ben the Space Brit

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Knowing the root cause would be nice.

The article says that a micrometeorite collision is the current favorite explanation.  I imagine it was something similar to the impact that buckled one of the HST's original solar arrays.
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Offline Chris Bergin

Knowing the root cause would be nice.

The article says that a micrometeorite collision is the current favorite explanation.  I imagine it was something similar to the impact that buckled one of the HST's original solar arrays.

Where does it say that?

I wrote in the article:

"Though the cause of the damage has not been confirmed, the survey was called after Russian spacewalkers reported one of the Service Module thruster covers had impacted the S1 radiator, after it was jettisoned during a spacewalk last year, making it the leading candidate - especially since all the other panels remain in good shape."

I'm guessing you read the reason they do survey's on the outside of the ISS (to check for MMOD) :)
« Last Edit: 04/02/2009 07:53 pm by Chris Bergin »
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Offline marshallsplace

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Knowing the root cause would be nice.

Analyst

Root cause (how the radiator covering separated - possible/probable impact and how it became unstuck..etc) may indeed help in the design of more robust cooling radiators for future space stations.  However, I think we will have to stick with the original design for the possible R&R  ;).

Offline iamlucky13

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Knowing the root cause would be nice.

Analyst

Root cause (how the radiator covering separated - possible/probable impact and how it became unstuck..etc) may indeed help in the design of more robust cooling radiators for future space stations.  However, I think we will have to stick with the original design for the possible R&R  ;).

Getting it on the ground so the engineers can take a close look at it will be the most useful thing that can be done as far as figuring out the root cause, as long as they can stow it without "damaging the damage" too much. That definitely means sticking with the original design, but at the same time, five other panels appear fine, and there is at least one known difference between that radiator and the other five: the contact with the jettisoned cover.

Now for my own thoughts: Since that radiator is apparently an ORU, it can obviously be isolated, although based on the fact that they don't appear to be discussing doing that pre-emptively despite the risk of failure without immediate notice, I'm supposing it would require more than flipping a switch to do so. I'd expect that if they decided that radiator needed it before a replacement was ready, they could drain it and disconnect and cap the ammonia lines and get by with 17% less cooling capacity.

Offline robertross

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Getting it on the ground so the engineers can take a close look at it will be the most useful thing that can be done as far as figuring out the root cause, as long as they can stow it without "damaging the damage" too much. That definitely means sticking with the original design, but at the same time, five other panels appear fine, and there is at least one known difference between that radiator and the other five: the contact with the jettisoned cover.

Now for my own thoughts: Since that radiator is apparently an ORU, it can obviously be isolated, although based on the fact that they don't appear to be discussing doing that pre-emptively despite the risk of failure without immediate notice, I'm supposing it would require more than flipping a switch to do so. I'd expect that if they decided that radiator needed it before a replacement was ready, they could drain it and disconnect and cap the ammonia lines and get by with 17% less cooling capacity.

I don't think they can safely operate in that config. They may need to reduce power generation/consumption to offset the reduced cooling capacity.

They would probably need not only a purge event to remove the bulk of the ammonia, but also a preservation medium (like nitrogen) to fill the void. If they seal off the radiator panel, the pressure equalization as they re-enter needs to be taken into account, otherwise the pipes could crush, or any residual ammonia could escape and cause a hazardous/toxic condition in the payload bay.

It might require a catch bottle with equalization/relief valves.

Offline Launch Fan

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When will they decide on the plan?

Offline Ben the Space Brit

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@ Launch Fan

Probably not for a while.  There needs to be a lot of work done to decide what has gone wrong and what needs to be done next.  I would expect the damaged radiator to be taken out of service and an inspection, either by EVA or using Canadarm 2's cameras to get enough data to decide on a next move.

My guess is that any repair would probably take six months to a year to get into the manifest.
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Offline MKremer

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My guess is that any repair would probably take six months to a year to get into the manifest.

If that turns out to be the case, hopefully it will remain operating normally that long.

One other thing to consider is a procedure to jettison the array (throw it overboard) if it can't be returned.

If it springs a leak in the panel there's no way they'd risk a return (contaminating the payload bay with ammonia residue and vapors). The same if the array can't be fully folded enough to engage and tighten the panel cinches and locks - otherwise they'd need to develop and carry along enough contingency hardware to lock a partially folded panel tightly in position for reentry.

A jettison that large would be fascinating to watch (remember the old Hubble solar wing?), but tricky to implement and get it moving away in a safe direction.

Offline Jorge

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My guess is that any repair would probably take six months to a year to get into the manifest.

If that turns out to be the case, hopefully it will remain operating normally that long.

One other thing to consider is a procedure to jettison the array (throw it overboard) if it can't be returned.

If it springs a leak in the panel there's no way they'd risk a return (contaminating the payload bay with ammonia residue and vapors). The same if the array can't be fully folded enough to engage and tighten the panel cinches and locks - otherwise they'd need to develop and carry along enough contingency hardware to lock a partially folded panel tightly in position for reentry.

A jettison that large would be fascinating to watch (remember the old Hubble solar wing?), but tricky to implement and get it moving away in a safe direction.


Having observed the development of contingency plans to jettison the P6 arrays had something going awry during the whole 116-120 relocation dance, I think those procedures could be adapted in a fairly straightforward fashion to radiator jettison. It'd still be a complex procedure, but it'd have the advantage of being mostly written already.
JRF

Offline Riley1066

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This is a job for STS-135, not STS-132 3 or 4

(and yes I know that there isn't an STS-135 envisioned, but IMHO this is a big enough job to warrant its own mission, without dropping the other manifest items)
Go at Throttle Up!

Offline rdale

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How many EVA's will this require?

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