Question General Spaceflight Q&A

Urwumpe

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Tiles are replaced when they are damaged - discoloration is not damage. It is also not wear. The gray color is rather normal for the tiles after the first use, the really black tiles are fresh replacements.
 

orbitingpluto

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So they only look worn? That is reassuring, but how many flights did it take to get that "startles a shuttle n00b when he sees it" look on those tiles:lol:?

Also, you said the tiles are replaced when they are damaged. Did the shuttle fleet(in real life;)) ever need to have all the tiles replaced due to the wear of many reentries, or do the tiles stay with the shuttle throughout it's life?
 

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I've noticed in some photos of the orbiter sitting on the pad, there are some sort of "brackets" attacked to the outside of the payload bay doors. These items are always gone prior to launch. What are they for? I am guessing they have something to do with the RSS.
 

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How many different types of thermal protection tiles do the shuttles have?
I know that there are different ones rated for different temperatures but how many and what temparatures?

Darre
 

garyw

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I've noticed in some photos of the orbiter sitting on the pad, there are some sort of "brackets" attacked to the outside of the payload bay doors. These items are always gone prior to launch. What are they for? I am guessing they have something to do with the RSS.

Yellow brackets? Those brackets are to allow the payload bay doors to open. On the ground they cannot be opened as they do in space because the mechanism isn't designed for Earth Gravity so they use a brackets system to support the doors and help open them. They have nothing to do with the RSS.

---------- Post added at 23:19 ---------- Previous post was at 23:16 ----------

Tiles are replaced when they are damaged - discoloration is not damage. It is also not wear. The gray color is rather normal for the tiles after the first use, the really black tiles are fresh replacements.

If I understand correctly, the grey "smear" effect is actually a water repellent coating that gets smeared into the tiles during flight. it's quite normal.

So they only look worn? That is reassuring, but how many flights did it take to get that "startles a shuttle n00b when he sees it" look on those tiles:lol:?

One or two entries to cook the water repellent in.

Also, you said the tiles are replaced when they are damaged. Did the shuttle fleet(in real life;)) ever need to have all the tiles replaced due to the wear of many reentries, or do the tiles stay with the shuttle throughout it's life?

Tiles don't wear due to entry. They get damaged due to debris or processing problems and get replaced. I suspect that more than one tile on Discovery is the orginal.
 

DaveS

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Yellow brackets? Those brackets are to allow the payload bay doors to open. On the ground they cannot be opened as they do in space because the mechanism isn't designed for Earth Gravity so they use a brackets system to support the doors and help open them. They have nothing to do with the RSS.
Correct. The brackets are called vertical torque tubes and prevents the doors from warping when the orbiter is vertical. This is to prevent the doors from warping out shape and prevent the centerline latches from engaging.

The system that garyw is talking about only exists in the OPFs and is called the "zero-g counterweight system" and is like garyw wrote to remove the 1G loads on the doors. The "zero-g counterweight system" brackets are removed while in the OPF prior to rollover to make way for the vertical torque tubes which are installed shortly after arriving at the pad.

The vertical torque tubes are stored attached to the PCR main doors when not used by an orbiter.
 

IronRain

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This is not really a question about the shuttle itself but about the platform where the shuttle rests on. The crawler takes the platform to the launchpad and then place it on a couple of pillars. My question: Does the platform only rest on the pillars or is it also bolted in place or something?
 

Urwumpe

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This is not really a question about the shuttle itself but about the platform where the shuttle rests on. The crawler takes the platform to the launchpad and then place it on a couple of pillars. My question: Does the platform only rest on the pillars or is it also bolted in place or something?

The pillars lock into their counterparts on the MLP, but they are not bolted in place, the MLP is heavy enough to deal with the forces of the engines.

KSC-390C-5675.22.jpg
 

tblaxland

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The pillars lock into their counterparts on the MLP, but they are not bolted in place, the MLP is heavy enough to deal with the forces of the engines.
I'm sure I remember an issue with MLP hold-down bolt misalignment at one of the rollouts a couple of years back. This site is a little dated but:
http://www.apollosaturn.com/TM/mlptech.htm
1.1.4.1 Mobile Launcher to Mount Mechanisms The Mobile Launcher is supported on six Mount Mechanisms at the Mobile Launcher Erection Position, in the Vehicle Assembly Building and at the Launch Pad. The Mount Mechanisms are located around the perimeter of the Mobile Launcher and are designed to allow for slight mis alignment in positioning the Mobile Launcher and for expansion and/or contraction due to temperature. A nine (9) inch (maximum) diameter tapered centering pin attached to the Mobile Launcher is used to assure proper alignment. Hold-down capability is provided by twelve (12) bolts attaching the Mobile Launcher to each Mount Mechanism. The Mount Mechanisms are covered in Manual TM-486-MD.
 

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OK, didn't know about the bolts, I only remembered the centering pin.
They do not use the bolts any more starting with STS-1. Now the MLPs only rest on the mounts.
 

DanM

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How many missions launch on their scheduled date? Never once have I heard of one launching on time.
 

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I heard from an ISS manager that the on-time launch rate is about 51%.
 

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How many missions launch on their scheduled date? Never once have I heard of one launching on time.

They all launch on time. If they didn't they wouldn't be able to dock with the ISS as the plane change would be too great.

If you are asking about how many missions suffer a scrub on launch date then StarVoyager is about right.

Oddly enough, everyone seems hung up on the issues with STS-133 and they have forgotten that STS-125, launched on the first attempt.

133 will launch when everything is right which is as it should be.
 
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DaveS

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Transcript:
CDR Altman: Houston, Atlantis in the roll, with the FCS channel.
CapCom: Bypass across the board Scooter, no action.

That just means that Houston saw Aerosurface Servo-amplifier 1 (ASA 1) drop offline and that he crew didn't need to take any actions. I'm not quite sure of this but I believe "bypass across the board" means that ASA 1 was being bypassed completely as it had hard-failed.
 

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How difficult is it to find some item that hasn't been documented in the IMS?

Is it scary to conduct combustion experiments in micro-g and what precautions are in place during such experiments?
 

tblaxland

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Is it scary to conduct combustion experiments in micro-g and what precautions are in place during such experiments?
Watch some being performed (Garrett Reisman IIRC). He doesn't seem too concerned. No doubt the glovebox he is using provides additional comfort.
 

Izack

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It would be pointless to start a new thread for this:

Satellites_For_Sale_-_GPN-2000-001036.jpg


In this well-known image, I noticed that the Orbiter's elevons are raised. What is the reason for this?
 
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