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#200
by
Zephon907
on 15 Jul, 2009 23:56
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Hey, thanks guys for the quick answers. I enjoy watching the launches and mission coverage on NASA TV, but there are a lot of things I don't have a clue about.
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#201
by
mdo
on 16 Jul, 2009 10:13
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#202
by
patmamu
on 16 Jul, 2009 14:28
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Out of curiosity, I was reading a report on L2 about the fuel cell and was wondering what type of redundancies the orbiter has for a Fuel Cell loss. Would it have any impact on mission and if so what would that be? Thanks in advance.
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#203
by
Jim
on 16 Jul, 2009 15:46
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Out of curiosity, I was reading a report on L2 about the fuel cell and was wondering what type of redundancies the orbiter has for a Fuel Cell loss. Would it have any impact on mission and if so what would that be? Thanks in advance.
There are 3 fuels cells and loss of one would be minimum duration mission, loss of two would be immediate return
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#204
by
The-Hammer
on 16 Jul, 2009 16:48
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Mike Moses with Candrea Thomas:
Water cycled through the fuel cell, then we can transfer for drinking water (which we do). If we don't drain the water, it'll build up, of course. Too much water would let the electrolyte compound into the fuel cell. It would end up drying out the fuel cell. Worst case would be the fuel cell getting way too hot, way too fast. We monitor the temps, the trend on the past few launch attempts have been that the temps are creeping up a bit. We can't monitor the KOH (electrolyte compound) on orbit, but we can on ground. When we run the SSPTS system, it takes off a lot of the load from the fuel cells. That means, we don't dry the fuel cells out enough, and the temps increase. If we can't, then we can't take as much power from the SSPTS, then we lose some mission durations. Preliminary calculations show a normal mission, not anything currently big enough to knock off mission duration. We'll ask JSC again today just to check.
Copied this from the Launch/FD1 thread because it is an excellent explanation of "Why (power-wise) can't the shuttle stay docked forever with the SSPTS on?"
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#205
by
ChrisGebhardt
on 16 Jul, 2009 19:53
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Why does the SRB on the left have a black ribbon around the top? Is it to indicate which SRB (left or right side) it is?
It is also referred to lovingly as the "wedding ring."
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#206
by
Hobbs
on 17 Jul, 2009 12:32
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OK this is one of those pessimistic "what ifs...", but what is the contingency if there is a significant loss of cabin pressure while on orbit but not docked to ISS, from looking at the reference manuals the ACES suits cant withstand pressures lower than 100K ft and only have 10 minutes of O2 so that doesn't seem like an option.
Would they just immediately deorbit and land/egress wherever they ended up? Any links to documents about this would be greatly appreciated
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#207
by
Jim
on 17 Jul, 2009 13:08
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Would they just immediately deorbit and land/egress wherever they ended up? Any links to documents about this would be greatly appreciated
No, Not enough time to prep for deorbit. Have to close payload bay doors, attach seats, etc. Your scenario is not survivable.
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#208
by
butters
on 17 Jul, 2009 13:49
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Copied this from the Launch/FD1 thread because it is an excellent explanation of "Why (power-wise) can't the shuttle stay docked forever with the SSPTS on?"
I can think of a bunch of potential reasons, but why can't the fuel cells be shut down while the orbiter is docked to the ISS?
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#209
by
Jim
on 17 Jul, 2009 13:52
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I can think of a bunch of potential reasons, but why can't the fuel cells be shut down while the orbiter is docked to the ISS?
1. restarting is hard and risky
2. LH2 is boiling off so why not use it to produce power
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#210
by
Maty
on 17 Jul, 2009 13:53
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Was doing some thinking today....
During the RPM, photographs are taken using 800mm and 400mm lens. Now they are some hefty super-tele lenses and, at least down here, would require some effort to maintain them stable to get a decent shot. Does anyone know how things go in zero-g? Without gravity it probably becomes a lot easier to handle the lenses, requiring little effort to move and therefore not requiring much input to stablise. Would the photographers just be in free drift near the window or is there a system in place to maintain the lenses steady?
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#211
by
billshap
on 17 Jul, 2009 16:11
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What exactly is the "big loop?" Is it merely joining together A/G1 and S/G1? Or is there something more complex involved?
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#212
by
mjcrsmith
on 17 Jul, 2009 17:13
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If I recall correctly the only thing behind the RCC panels is the airframe.
If this is the case, would filling in the back of the RCC's with tile material provided any measure of structural reinforcement and thermal redundancy?
Granted there would be a weight penalty.
Thanks,
Roger
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#213
by
elmarko
on 17 Jul, 2009 18:08
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What exactly is the "big loop?" Is it merely joining together A/G1 and S/G1? Or is there something more complex involved?
Yes, pretty much. If I remember correctly, The Big Loop will connect the ISS, Orbiter, MCC for the shuttle, and MCC for the ISS all on one loop.
Would appreciate any correction, though.
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#214
by
janmb
on 17 Jul, 2009 20:29
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Sorry if covered, but unable to find anything through searching...
Approximately during which time window of the total ascent is foam debris considered a potential threat to the vehicle?
(Asking about numbers here, not the principles determining this)
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#215
by
mark147
on 18 Jul, 2009 21:29
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Sorry if covered, but unable to find anything through searching...
Approximately during which time window of the total ascent is foam debris considered a potential threat to the vehicle?
This has been asked a few times recently. First 2 mins 15 secs.
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#216
by
kraisee
on 21 Jul, 2009 01:02
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Is there any documentation regarding the deployment of the Centaur or PAM assisted payloads from the Shuttle?
In particular I'm trying to find out what sort of range those payloads had to have from the Orbiter before the engines were ever ignited.
Ross.
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#217
by
Jim
on 21 Jul, 2009 01:10
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Is there any documentation regarding the deployment of the Centaur or PAM assisted payloads from the Shuttle?
In particular I'm trying to find out what sort of range those payloads had to have from the Orbiter before the engines were ever ignited.
Ross.
When there were 3 PAM spacecraft, they were deployed one per day.
IUS and Centaur were to be deployed 6-8 hours after launch.
The IUS and PAM's fired 40 minutes or so after deployment.
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#218
by
yinzer
on 21 Jul, 2009 01:28
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The IUS planners guide here says SRM arm happened after the IUS was at least 10 miles away from the orbiter.
I dug some more and found some documentation for STS-93. OMS-2 left Columbia in a 144.7x153.7 nmi orbit. After deploying Chandra, Columbia performed a separation maneuver using one OMS engine for 34.0 seconds, applying a delta-V of 30 ft/sec and ending up in a 153x163 nm orbit. IUS ignition took place one hour later. It should be fairly simple to calculate the distance between the IUS and Columbia given this information.
Further edited: a press release stated Columbia was about 30 miles from Chandra at the time of IUS ignition.
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#219
by
glen4cindy
on 22 Jul, 2009 01:49
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I did not know exactly what to search on to find an answer to this question, but, I have always be highly curious as to exactly how the shuttle is mated to the ET stack.
I see these V shaped rods attached to the ET and they come together at the bottom of the V and attach to the shuttle.
I suppose there is some sort of bolt and nut at the shuttle connection that explosively separates at ET separation.
So, just exactly how is this done? I know it has to be robust to handle the weight of the shuttle, the power of the thrust of the main engines during ascent and such. When ET SEP occurs, there appears to be no evidence whatsoever that there was ever an ET attached.
Thanks for any help with this question.
