67 votes
Accepted

Why not increase contact surface when reentering the atmosphere?

I've done a lot of work on this subject with researchers and engineers at JPL, NASA Langley, and NASA Ames. There are some interesting things that come out of high-fidelity CFM (Computational Fluid ...
Tom Spilker's user avatar
  • 18.3k
34 votes
Accepted

Why do the walls of a solid rocket booster not glow red hot?

Solid fuel does not burn unless it has been vaporized by heat from combustion. The boundary between solid and gaseous fuel is located at the point where the temperature equals the fuel vaporization ...
Woody's user avatar
  • 21.6k
32 votes

Why does the heatshield have to be on the outside?

To answer the title: Why does the heatshield have to be on the outside? Because most materials commonly used in spacecraft construction melt at the temperatures encountered during reentry. And most ...
Hobbes's user avatar
  • 128k
26 votes

Why do the walls of a solid rocket booster not glow red hot?

Simply - even a very thin layer of fuel is enough to isolate the heat. So only in the very last seconds will there be not enough fuel to isolate the heat flux. Then there is a liner between the fuel ...
tsg's user avatar
  • 1,003
20 votes
Accepted

How hot do rocket engine nozzles get?

Direct measurement is difficult; I've seen some optical methods used but can't put a hand on them at the moment. Here are some calculated inner and outer wall temperatures for the Space Shuttle Main ...
Organic Marble's user avatar
16 votes
Accepted

Why do some spacecraft have heat radiators? Why not repurpose the energy?

Yes, you would like to conserve the energy, but sadly that is not possible. The problem is: The energy you have is heat. The second law of thermodynamics states that entropy always increases, and ...
SE - stop firing the good guys's user avatar
16 votes

Why does the heatshield have to be on the outside?

To answer some other aspects: In the case of Starship, is the existing steel strong enough (to be non-ablative!), or would a different type of material be necessary? The melting point of most steel ...
ikrase's user avatar
  • 8,874
15 votes

Why is gold used in space technology to protect from heat radiation?

Astronaut spacesuits use gold (thin layer) Gold coating protects eyes from harmful sunlight Gold is also used by NASA in the construction of spacesuits. Because of its excellent ability to reflect ...
Евгений Новиков's user avatar
15 votes

What kind of heating would occur during a suborbital re-entry?

What kind of heating would occur during a suborbital re-entry Convective Heat Transfer is the dominant source of heat for any highspeed object moving through atmosphere. What kinds of peak ...
A McKelvy's user avatar
  • 2,482
12 votes
Accepted

Why is the Heat Shield of ESA's Solar Orbiter Black in colour?

Apparently, black was chosen despite its thermal properties. This 2005 paper was written at the end of the assessment phase where technical feasibility of the mission has been demonstrated. It shows ...
Hobbes's user avatar
  • 128k
11 votes
Accepted

Why doesn't Tesla's Roadster melt in space?

Not close enough to the Sun The Roadster's orbit has a perihelion (closest distance to the Sun) of 0.98 AU, that is to say only very slightly closer than Earth orbit. From Elon Musk's Twitter: At ...
MichaelK's user avatar
  • 1,819
11 votes

Parker Solar probe's heat survival - Heat vs Temperature

You are missing something basic here, which is that the Sun's corona is rather sparse. To take matters to an even greater extreme, consider the intergalactic medium. The temperature of the extremely ...
David Hammen's user avatar
  • 74.8k
10 votes

Dissipating large amounts of energy fast, in space

Don't convert it into heat in the first place, and then don't dissipate it fast. MSL used an electromagnetic brake to slow the descent of the rover from the skycrane. It dissipated the energy into a ...
Mark Adler's user avatar
  • 58.2k
10 votes

Why not increase contact surface when reentering the atmosphere?

There is a fixed amount of energy which has to be dissipated. You can, to some extent, choose how fast this is done -- more air resistance (either by getting into thicker air or having a bigger ...
Steve Linton's user avatar
  • 19.6k
10 votes

How do space blankets (thermal blankets) work?

They tend to be a combination of a highly reflective material, aluminized mylar usually, with a thin mesh in between the layers. The goal is to reflect as much light as possible (specifically those ...
PearsonArtPhoto's user avatar
  • 121k
10 votes
Accepted

Conversion of heat into electricity in rocket nozzles

This would not be useful in general. Thermoelectric converters don't convert heat into electrical power, they generate electrical power from the flow of heat across them. You still need to cool the ...
Christopher James Huff's user avatar
9 votes

Why does ISS uses liquid ammonia in the Active Thermal Control System?

Ammonia is used because it has excellent heat transfer properties (as you mention) and a low freezing point. Because of its toxicity, the ISS has internal coolant loops which use water as a heat ...
Organic Marble's user avatar
9 votes

Why does the heatshield have to be on the outside?

"perspiration of ablative material This appears in science-fiction and allows for the possibility of easy maintenance and multi-use, but these benefits are only realizable if some very big ...
DKNguyen's user avatar
  • 369
8 votes

How are spacecraft engineered to prevent overheating?

There are many ways to control the temperature of a satellite and the distribution of heat within a satellite. Often they are wrapped in multi layer insulation, which gives them their typical golden ...
Rikki-Tikki-Tavi's user avatar
8 votes
Accepted

Why aluminum is added in Multi Layer Insulation?

Gold is used to reflect solar radiation but what about aluminum? Some multilayer insulation (MLI) definitely has a gold-like color, but no gold is used in MLI. The gold-like color color is a result ...
David Hammen's user avatar
  • 74.8k
7 votes
Accepted

Does it get cold in a container in space?

All objects in a vacuum will have a decreasing temperature, unless new heat is supplied. The reason for that is energy lost to thermal radiation, which is electromagnetic radiation carrying energy ...
SE - stop firing the good guys's user avatar
7 votes

Why doesn't the Tesla Roadster's windscreen crack or break in space?

The Tesla Roadster is not experiencing 250°C temperatures. This answer to another question shows that in Earth orbit it will be just over 0°C, similar to you and me: What's the typical ...
Sir Adelaide's user avatar
7 votes

Would it be possible to avoid the heat-from-friction problem when re-entering the atmosphere by performing (vertical) "U-turns"?

It isn't possible to avoid heat from friction in re-entry, you have to deal with it in some way. What you are describing is called a skip-reentry, and it doesn't require wings. This technique was used ...
GdD's user avatar
  • 20.3k
7 votes
Accepted

How does a radiator work fast enough on a space craft?

You asked for corrections, and indeed I see three immediately. They involve: a material's emissivity; its specific heat; and the concept of back radiation. The full-up expression of the Stefan-...
Tom Spilker's user avatar
  • 18.3k
7 votes
Accepted

Could a Stirling engine be used to produce more electricity in space?

The first boring problem is that most space based solar implementations are weight limited, and it is hard to conceptualize an array of heat engines that are lighter weight than just a slightly larger ...
GremlinWranger's user avatar
6 votes

Why doesn't Tesla's Roadster melt in space?

The roadster will radiate the additional heat away. Radiation is proportional to the fourth power of the temperature, so a slight increase in temperature massively increases the amount of outgoing ...
rghome's user avatar
  • 295
6 votes
Accepted

How are spacecraft engineered to prevent overheating?

The key points in thermal design for satellites, which envelopes "to prevent overheating" are: Have a design that specifically has a heat loss path, this by definition has to be a high ...
Puffin's user avatar
  • 9,524
6 votes

How does a thermal control system of a spacecraft basicaly work?

In the general case of "spacecraft" meaning any satellite, manned or otherwise, or upper stage the hierarchy for thermal control looks like this: Passive systems materials chosen for their radiative ...
Puffin's user avatar
  • 9,524
6 votes

Dissipating large amounts of energy fast, in space

In a vacuum, there are only two ways to get rid of the heat, radiators and sublimators. You can not simply get the energy in the heat back to useful forms like electricity, due to the laws of ...
SE - stop firing the good guys's user avatar
6 votes

How much delta-v is lost to heat of exhaust?

Partial answer to a very cool question! While the pun was not intended, I'll take credit for it anyway. (see also this answer) One of the functions of the nozzle† is indeed to "remove" as much of ...
uhoh's user avatar
  • 149k

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