The refractory material used to protect a space vehicle during re-entry need to have a low thermal conductivity, not support combustion, not be capable of melting (charring and sublimation are fine but melting isn't) and hopefully have a high heat of vaporization. Believe it or not, one of the best ways to protect spacecraft during re-entry is to use silicone foam (the same stuff they use on the Space Shuttle cryogenic tank).
Leading edge surfaces usually use carbon infused carbon fiber...though it supports combustion, the dense packing of the graphitic layers makes combustion very slow, and thus it mainly just ablates away.
Surfaces that don't have to take the high pressure of leading edges are usually protected by either silica foam (space shuttle tiles) or silicone rubber (Soyuz module). Other stuff that has been used in the past has been asbestos, fiberglass reinforced phenolic resin, and fiberglass reinforced melamine resin.
BTW the heat is dissipated by ablation...there is no where else for the energy to go. Basically, re-entry causes controlled burning away of your sacrificial ablative surfaces.
2007-04-02 06:35:36
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answer #1
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answered by Anonymous
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Important properties of materials : Re-entry
The two factors which must be met are great resistance to extremely high heat, and little if any expansion due to
heating. No melting or deformation due to heat and pressure.
Certain ceramic composites meet those criteria.
2007-04-02 06:49:18
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answer #2
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answered by zahbudar 6
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maximum persons are tired of the comparable excuse that it truly is an attempt to strengthen site visitors situations & such an excuse has now became lame. Its lower back the comparable subject of the ERP - did no longer think of the ERP helped very lots nevertheless. there are various approaches to regulate site visitors in Sentosa. perhaps for a initiate widening the roads would be sturdy as I notice that the roads are purely one lane on the two factor & the extensive buses that runs on those roads makes it look as though they are racing on an F1 direction. Its a count of time in the previous deadly injuries take place on Sentosa & i ask your self how the fee hike can help in such subject while there's a heavy site visitors congestion, ambulance can't get in & each physique is purely jamming their horns at one yet another. Oh... how approximately an air carry it is neither interior your budget nor environmentally friendly? maximum will a minimum of agree that for the period of spite of everything efforts have been exhausted, to regulate site visitors, imposing a value hike does no longer look too some distance fetched. concern here is there is often an absence in attempting to ensure the priority & the instant subject that is composed of recommendations is "assemble money" & the concept that money will remedy each little thing is in easily fact a vicious cycle. i will't help yet think of that alot people in Singapore purely spend money to ensure concerns like fines for this & that. This purely reinforces the belief of pay & u would be unfastened & the lesson learnt on the top of the day is... one must be wealthy - no longer very efficient in coaching the conventional public isn't it? I consider between the consumers whom suggested "milking a money cow" i think of it truly is an extremely apt description and that i completely agree. besides, on the lighter notice of issues, automobiles enter into Sentosa & get parked in a niche & the motor vehicle does not savour in any way, so truly it makes me ask your self... LOL besides, by using fact the fee hike has been set, no longer something will replace it! Does inviting solutions (or greater so "anger") from the conventional public help to alter this fact? ask your self... how much less site visitors one will see in Sentosa.
2016-11-25 21:11:49
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answer #3
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answered by ? 4
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It needs to be aerodynamic and it needs to have a surface material that can dissipate heat.
2007-04-02 06:26:31
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answer #4
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answered by Gene 7
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