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#460
by
elmarko
on 15 Nov, 2006 16:10
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outward - 15/11/2006 1:24 PM
Hi Folks,
A while back someone on this forum was asking about whether the orbiter’s thermal protection system (TPS) was hot after landing. I think the answer was, no – not to the touch. But I’m curious about something…the quantity of thermal energy that becomes stored in the TPS must be substantial considering the loss of potential and kinetic energy the orbiter experiences. Now, although the outer surface of the TPS cools during the last parts of the descent, internally there must still be a considerable quantity of heat. How long does it take the internal volume of the TPS to cool to ‘room’ temperature? And is there any concern that the TPS heat will radiate inward and over- heat critical parts of the orbiter?
Thanks, (from a curious observer)
Phil
I believe it was me that asked about the TPS and that is a very good addendum to my question, so thanks (and thanks Jim!)
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#461
by
outward
on 15 Nov, 2006 17:10
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Jim - 15/11/2006 11:58 AM
outward - 15/11/2006 8:24 AM
Hi Folks,
A while back someone on this forum was asking about whether the orbiter’s thermal protection system (TPS) was hot after landing. I think the answer was, no – not to the touch. But I’m curious about something…the quantity of thermal energy that becomes stored in the TPS must be substantial considering the loss of potential and kinetic energy the orbiter experiences. Now, although the outer surface of the TPS cools during the last parts of the descent, internally there must still be a considerable quantity of heat. How long does it take the internal volume of the TPS to cool to ‘room’ temperature? And is there any concern that the TPS heat will radiate inward and over- heat critical parts of the orbiter?
Thanks, (from a curious observer)
Phil
That's why ground cooling and purge is hooked up to the orbiter at landing
Thanks for the response.....how does ground cooling work?...does it circulate cool air through various temp sensitive components?
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#462
by
Jim
on 15 Nov, 2006 17:21
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The purge system blows conditioned air through the same ducts that are used on the pad. The ducts purge the aft compartment, payload bay, midbody and fwd section. There is a separate AC system for the crew cabin.
The cooling system circulates freon through a heat exchanger that interaces with the orbiter heat rejection system (the same system that use the radiators on the payload bay doors) The orbiter system has cold plates on all the avionics and also remove heat from the crew cabin.
If the cooling and purge wasn't available at landing, the crew would power the orbiter and it would be ok. The thermal soak back isn't that bad
The purge and cooling systems are the large trailers that pull up to the aft of the orbiter right after landing.
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#463
by
spaceshuttle
on 16 Nov, 2006 17:30
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for some reason, my thread got deleted.
i'm gonna be on a physics field trip at disney in orlando around the time of the 117 launch, and i wanted to, does anyone know of the frequencies that i should tune to on my radio to hear launch coverage?
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#464
by
Jim
on 16 Nov, 2006 20:00
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None in orlando. on the spacecoast AM 1240 or 1350, if they have coverage, which might not be until less than an hour before launch
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#465
by
Andrewwski
on 19 Nov, 2006 22:22
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Aren't there also SW frequencies that carry voice communications?
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#466
by
Rocket Nut
on 19 Nov, 2006 23:42
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#467
by
Jim
on 20 Nov, 2006 00:43
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They use trunked systems now and it is hard to scan.
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#468
by
Rocket Nut
on 20 Nov, 2006 09:35
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Jim - 19/11/2006 8:26 PM
They use trunked systems now and it is hard to scan.
Or you can buy a scanner that receives trunked systems like the one I have. I got it at Radio Shack for less than $200. I received the Delta net this week without much problem. NASA PAO hijacked the frequency a few times, but most communications were direct from the control center.
The local HAM radio club also transmits a repeater in real time on VHF.
Cheers,
Larry
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#469
by
spaceshuttle
on 20 Nov, 2006 19:31
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#470
by
shuttlefan
on 27 Nov, 2006 00:05
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Overall, are night shuttle launches slightly more risky?
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#471
by
MKremer
on 30 Nov, 2006 06:01
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shuttlefan - 26/11/2006 6:48 PM
Overall, are night shuttle launches slightly more risky?
Post-Columbia and knowing the risks of ET foam loss/impacts, and knowing there's a much reduced chance of seeing any losses or 'hits' from those at night... yes, it is more "risky" in terms of real-time monitoring, but not in terms of the Mission itself.
Apart from that, a launch at night doesn't imply anymore risk than a daylight launch - any ET foam losses or potential TPS impacts are the same regardless.
The only difference is potential ground-to-orbit detection of any impacts in real time and where they might originate from the ET.
Frankly, once the SRBs ignite and the Shuttle launches there's not a whole lot anyone can do until it reaches orbit. Even then it's a matter of determining whether there's any TPS repairs that can be done or wait for a rescue Orbiter to reach the crew on the ISS.
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#472
by
C5C6
on 30 Nov, 2006 11:51
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what is the purpose of the throttle-up call if the onboard computers command the flight until ET separation?
and, where i can find a place where the "launch calls" (T-1h / T+10min) are explained???
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#473
by
Jim
on 30 Nov, 2006 12:13
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C5C6 - 30/11/2006 7:34 AM
what is the purpose of the throttle-up call if the onboard computers command the flight until ET separation?
and, where i can find a place where the "launch calls" (T-1h / T+10min) are explained???
The call is to make sure the computers are doing their jobs.
http://countdown.ksc.nasa.gov/shuttle/countdown/cdt/indexcdt.htmlYou will have to find the flight calls elsewhere. Most are abort boundary calls. One other is performance call
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#474
by
mkirk
on 01 Dec, 2006 21:13
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C5C6 - 30/11/2006 6:34 AM
what is the purpose of the throttle-up call if the onboard computers command the flight until ET separation?
The "Throttle Up" call really serves as a Comm Check and Status Report...the first comm check is the "roll program" call.
Think of "Throttle Up" as a point in time after liftoff rather than a command...the call tells the crew that from the perspective of the MCC (mission control center) all of the shuttle systems are performing nominally at this point in time.
Mark Kirkman
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#475
by
astrobrian
on 01 Dec, 2006 22:26
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To expand on the comm check portion, one of the last few missions, not sure which right off, I remember there was an instance where one of the audio channels was out after the throttle up call that was mentioned by the CDR.
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#476
by
Do Shuttles Dream
on 02 Dec, 2006 01:15
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So when you hear throttle up, it's already happened?
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#477
by
lsullivan411
on 02 Dec, 2006 01:50
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I think that was STS-121 and if I remember correctly it was something about UHF only, and it was expected and it would be cleared soon. Still get a little bit of a lump in the throat at "Go at throttle up"
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#478
by
psloss
on 02 Dec, 2006 02:00
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Do Shuttles Dream - 1/12/2006 8:58 PM
So when you hear throttle up, it's already happened?
Yup.
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#479
by
GLS
on 02 Dec, 2006 17:03
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Interesting question: At KSC there's the NTD (NASA Test Director). On the launches from VAFB, was it going to be a NTD or a "AFTD (Air Force Test Director)" or what???
