Author Topic: LIVE: STS-120 Flight Day 8 - EVA-3 and P5/P6 Events (Read 120683 times)

NASAJim · « **Reply #640 on:** 10/30/2007 08:04 pm »

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edimus - 30/10/2007 3:56 PM
In answer to the question quoted, when the OBSS is stowed on station there is a plan to either provide power to the sensor package or have EVA remove the sensor package.

Even without the sensors installed, the OBSS boom needs to have keep-alive power so that the internal electrical boxes (mostly containing data and power relays) don't freeze. When they stow OBSS on ISS they will have a power umbilical that attaches to the SRMS interface on the boom to provide that power.

DaveS · « **Reply #641 on:** 10/30/2007 08:06 pm »

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edimus - 30/10/2007 9:56 PM
Please explain how this would dangerous, reckless or irresponsible.

It isn't a stable work-platform. And these blankets are eletrically charged. They would have to build some kind of stitching tool in order to repair this tear which would mean that hey would be awefully close to the blanket. Plus, they would have to work with tools insulated with Kapton.

jimmiemac · « **Reply #642 on:** 10/30/2007 08:07 pm »

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B: None of the EV crewmembers either in the 120 or Incr16 crews have any SAW training whatsoever.

On 116 and 117 Fuglesang, Curbeam, Reilly and Olivas had received extensive SAW training preflight.

Not so for the 120 or Incr16 crews.

This would not appear to be correct. From the NASA web site:

http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts120/sts120_interview_parazynski.html

Interview with Scot Scott Parazynski

Is there any concern with redeploying those solar arrays? They had a little trouble getting them back in. But they did successfully get them back in with a little help from some EVA astronauts. Any concerns about unfolding them again?

Well, as the lead spacewalker on the flight it’s my job to worry, I suppose, and so there are a number of contingencies that we could find ourselves in, in terms of deploying those solar array wings. Our advantage is that in the deployment we can apply more tensioning force as the wings deploy. So it’s less likely that the solar array panels will bind up as they unfurl from the blanket boxes. But there certainly is potential and we trained, quite extensively, not only in the water – where we practice a lot of our spacewalking activities – but we have a 1g simulator here in Houston, at the Johnson Space Center, where we can actually get hands on with real solar array hardware.

ace007 · « **Reply #643 on:** 10/30/2007 08:09 pm »

Whats the period of time that the OBSS sensors can survive without power? We have seen the Astronauts put covers over other sensative gear during times they have to go without power for a bit. If they only need the OBSS boom for a few hours would this kill it?

DaveS · « **Reply #644 on:** 10/30/2007 08:10 pm »

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ace007 - 30/10/2007 10:09 PM

Whats the period of time that the OBSS sensors can survive without power? We have seen the Astronauts put covers over other sensative gear during times they have to go without power for a bit. If they only need the OBSS boom for a few hours would this kill it?

¨
The OBSS is already insulated with many layers of thermal blankets. Yet it does freeze easily.

ApolloLee · « **Reply #645 on:** 10/30/2007 08:14 pm »

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DaveS - 30/10/2007 1:49 PM

B: None of the EV crewmembers either in the 120 or Incr16 crews have any SAW training whatsoever.

On 116 and 117 Fuglesang, Curbeam, Reilly and Olivas had received extensive SAW training preflight.

Not so for the 120 or Incr16 crews.

Why is that the case. I would think that problems with the arrays would be anticipated as a possibility considering they were working with them in this mission.

Edit: JimmieMac... thanks for the clarification.. I figured that...

Kel · « **Reply #646 on:** 10/30/2007 08:14 pm »

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DaveS - 30/10/2007 4:06 PM

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edimus - 30/10/2007 9:56 PM
Please explain how this would dangerous, reckless or irresponsible.
It isn't a stable work-platform. And these blankets are eletrically charged. They would have to build some kind of stitching tool in order to repair this tear which would mean that hey would be awefully close to the blanket. Plus, they would have to work with tools insulated with Kapton.

Do they actually need to repair the tear in order for the array to supply adequate power? It seems like the priority is to get the array extended - a little tear shouldn't affect power generation of the array as long as the cables are intact?

DaveS · « **Reply #647 on:** 10/30/2007 08:15 pm »

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ace007 - 30/10/2007 10:09 PM

Whats the period of time that the OBSS sensors can survive without power? We have seen the Astronauts put covers over other sensative gear during times they have to go without power for a bit. If they only need the OBSS boom for a few hours would this kill it?

I believe the maximum time without power is 3-4 hours. That doesn't give you alot time to work with. Maybe 2 hours if everything goes real smoothly.

DaveS · « **Reply #648 on:** 10/30/2007 08:17 pm »

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Kel - 30/10/2007 10:14 PM
Do they actually need to repair the tear in order for the array to supply adequate power? It seems like the priority is to get the array extended - a little tear shouldn't affect power generation of the array as long as the cables are intact?

´
It's isn't the power wires they're worried about. It's the possibility that this is a sign that the problem runs deeper than it looks like and it might escalate if you continue the deploy and damage the blanket further.

And as long they're stuck in this off-nominal configuration, they can't let the SARJ auto-track the sun, so currently they're down both SARJs.

edimus · « **Reply #649 on:** 10/30/2007 08:18 pm »

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DaveS - 30/10/2007 5:15 PM

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ace007 - 30/10/2007 10:09 PM

Whats the period of time that the OBSS sensors can survive without power? We have seen the Astronauts put covers over other sensative gear during times they have to go without power for a bit. If they only need the OBSS boom for a few hours would this kill it?
I believe the maximum time without power is 3-4 hours. That doesn't give you alot time to work with. Maybe 2 hours if everything goes real smoothly.

The thermal clock used for OBSS is 90 minutes. Handoffs between SRMS and SSRMS are constrained by this.

DaveS · « **Reply #650 on:** 10/30/2007 08:20 pm »

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edimus - 30/10/2007 10:18 PM

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DaveS - 30/10/2007 5:15 PM

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ace007 - 30/10/2007 10:09 PM

Whats the period of time that the OBSS sensors can survive without power? We have seen the Astronauts put covers over other sensative gear during times they have to go without power for a bit. If they only need the OBSS boom for a few hours would this kill it?
I believe the maximum time without power is 3-4 hours. That doesn't give you alot time to work with. Maybe 2 hours if everything goes real smoothly.

The thermal clock used for OBSS is 90 minutes. Handoffs between SRMS and SSRMS are constrained by this.

OK, that's waay worse than I thought. That gives you what? 20 minutes to ingress the OBSS, set-up the tools, fix the problem, egress the OBSS and hand it back to the SRMS?

Best case all that would take the double if even that.

Kel · « **Reply #651 on:** 10/30/2007 08:31 pm »

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DaveS - 30/10/2007 4:17 PM

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Kel - 30/10/2007 10:14 PM
Do they actually need to repair the tear in order for the array to supply adequate power? It seems like the priority is to get the array extended - a little tear shouldn't affect power generation of the array as long as the cables are intact?
´
It's isn't the power wires they're worried about. It's the possibility that this is a sign that the problem runs deeper than it looks like and it might escalate if you continue the deploy and damage the blanket further.

And as long they're stuck in this off-nominal configuration, they can't let the SARJ auto-track the sun, so currently they're down both SARJs.

I know that they can't operate either SARJ in this config, which is why getting the P6 extended is a priority (but not at the expense of simply continuing to extend right now when they haven't had time to figure out what exactly is causing it to hang up). My quesion is - do they actually need to repair the small tear, or can they operate "as is" once it's fully deployed?

DaveS · « **Reply #652 on:** 10/30/2007 08:37 pm »

It can operate "as-is" but right now the the tear is in the way of a full extension which is required to operate the SARJ.

Lee Jay · « **Reply #653 on:** 10/30/2007 08:51 pm »

Mike described the two primary issues with the tear during the briefing. They are that it prevents full extension, as Dave just said, and that the tension loads have to be carried through the hinges. The hinge is where the tear is, so even if they could get the array fully deployed, they couldn't tension it.

Take a look at this image:

http://spaceflight1.nasa.gov/gallery/images/station/crew-14/html/iss014e10084.html

At least two possibilities exist - the hinge itself broke, or the hinge became detached from the Kapton substrate. The second is the one Mike mentioned at the briefing.

JimO · « **Reply #654 on:** 10/30/2007 08:56 pm »

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Kel - 30/10/2007 4:14 PM
Do they actually need to repair the tear in order for the array to supply adequate power? It seems like the priority is to get the array extended - a little tear shouldn't affect power generation of the array as long as the cables are intact?

The physical damage is the broken hinge between two of the slats. That was a load-bearing structural member that was critical to the fully-deployed tension placed along both edges of the entire wing -- something lke 75 lbs, Mike S said. Without that tension, ALL dynamic operations -- thrusters, dockings, wiggles -- have not been validated for lack of hazard to the array. It was suggested that a wire loop would have to be wrapped across the gap to take up the tension for full deployment.

Jason Davies · « **Reply #655 on:** 10/30/2007 09:02 pm »

Wow, Mr Jim Oberg! How amazingly awesome it is to have you on this great site! So, for those clueless like me, it's not a need to sew up that orange material, it's more to make sure the tension is ok through the wing...that structural integrity that was mentioned. Torn hole, can be lived with, unstable wing, not good?

Joffan · « **Reply #656 on:** 10/30/2007 09:05 pm »

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DaveS - 30/10/2007 3:20 PM

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edimus - 30/10/2007 10:18 PM

The thermal clock used for OBSS is 90 minutes. Handoffs between SRMS and SSRMS are constrained by this.
OK, that's waay worse than I thought. That gives you what? 20 minutes to ingress the OBSS, set-up the tools, fix the problem, egress the OBSS and hand it back to the SRMS?

Best case all that would take the double if even that.

Where's Bruce McCandless when you need him?

David AF · « **Reply #657 on:** 10/30/2007 09:14 pm »

Thanks for transcribing the briefing Chris. Catching up with this eventful day!

BigKiai · « **Reply #658 on:** 10/30/2007 09:17 pm »

Does it appear that the wire snagged on a grommet, causing the seam it is on to rip?

nathan.moeller · « **Reply #659 on:** 10/30/2007 09:24 pm »

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dotdk - 30/10/2007 3:33 PM

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eeergo - 29/10/2007 10:29 PM
Maybe using the OBSS? But probably it's not remotely certified to do anything like that, and less being the SSRMS the one which grapples it.
Not an obvious solution to this one.

But it is certified to go under the belly of the shuttle with a crewmember to pull out gap fillers?

They never used the OBSS for that. They used the SSRMS.