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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
48 votes
Accepted

Are heat shields just as necessary on launch as re-entry?

No, heat shields are not as necessary on launch, at least not the same type as used in re-entry, which is what most people think of when the term "heat shield" is used in space. A re-entry heat-shield ...
GdD's user avatar
  • 20.3k
41 votes

Why was the Friendship 7 Mercury heat shield detachable?

To reduce the force of the impact on landing the heat shield was designed to separate and be held on by a skirt that acted as an airbag. From the NASA list of Mercury illustrations: Figure 46: ...
1337joe's user avatar
  • 7,206
39 votes

Why do you need a heat shield on Mars entry if the atmosphere is so thin?

There is an atmosphere on Mars. An atmosphere ~1% as thick as Earth's sounds like it ought to 'basically not count as an atmosphere' but 1% earth's atmosphere is still quite a lot of gas! The pressure ...
Ingolifs's user avatar
  • 6,458
37 votes

Are heat shields just as necessary on launch as re-entry?

Heat shields are only good for braking, not for acceleration. Remember that the key to being in orbit isn't to be high up but to go sideways really fast. Launching a spacecraft means accelerating it ...
TooTea's user avatar
  • 1,765
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
30 votes

Why will the BFS reenter broadside rather than engine first?

F9 can enter engine first because it isn't returning from orbital speeds. While fast, it's a fraction of the speeds something returning from orbit (or further) comes in at. So the engines are out as ...
Saiboogu's user avatar
  • 6,417
30 votes

Could sheets of stacked graphene be used as part of a heat shield, since its melting point is 3000k to 5000 K

For a non ablative heat shield you need a material with a very high melting point and a very low thermal conductivity. It should not burn in hot air. Unfortunately graphene seems to have a high ...
Uwe's user avatar
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29 votes
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Testing of rocket heat shield on Earth

Ground testing of heatshield components and materials can and has been done in arcjet facilities. (image source) An arcjet typically combines a super- or hyper- sonic wind tunnel with a large ...
Organic Marble's user avatar
22 votes
Accepted

Why aren't RCS openings an issue for spacecraft heat shields?

The columbium jet nozzles themselves can take the heat, but "penetrations" of the spacecraft heat shield are a definite potential failure point, including penetrations for the Reaction Control System (...
Organic Marble's user avatar
17 votes

Would a dimpled heat shield reduce heat transfer during reentry?

The dimpled sphere may produce lower drag (though as Uwe points out I’m not sure if that is true in hypersonic flight). However, this does not mean that it will be better at surviving reentry. Higher ...
Quentin Clarkson's user avatar
17 votes

Why do you need a heat shield on Mars entry if the atmosphere is so thin?

An atmosphere does not need to be very thick to heat up a reentry vehicle significantly. And it should be noted that reentry vehicles entering the Earth's atmosphere get heated up at a pretty high ...
ikrase's user avatar
  • 8,883
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
  • 8,883
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
14 votes
Accepted

Who was the first to successfully implement on practice ablative heat shield?

As there's no answer for a long time, I've done some research with help of the links provided by others in the comments to the questions. And the "first" goes to ... Soviet Union. In short: US got a ...
Sergiy Lenzion's user avatar
14 votes

Why are the bottoms of spaceplanes black?

I'm afraid that in this case, at least, the conventional wisdom is correct. For the space shuttle at least: A black version with good high-temperature emittance is used on the lower surface of the ...
Organic Marble's user avatar
13 votes

Merging Shuttle and External Tank to reduce reentry heating

It would make reentry heating much less stressful, but would make landing the 7-times-larger-volume vehicle a royal pain, and would greatly increase the surface area that needs to be insulated. And to ...
CuteKItty_pleaseStopBArking's user avatar
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
12 votes
Accepted

Heat shield on Venus

The problems with temperature insulation for a situation like Venus, where you are surrounded by very high temperatures on all sides: Insulation is heavy. Insulation slows down the gradual spread ...
ikrase's user avatar
  • 8,883
12 votes
Accepted

Why did Columbia disintegrate lower into the atmosphere, not during its peak heat phase?

The story of the destruction of the orbiter during entry is told in extreme detail in Section 4 of Appendix D.7 of the Columbia Accident Investigation Board report Volume 2.1 The very short version of ...
Organic Marble's user avatar
11 votes

Why do you need a heat shield on Mars entry if the atmosphere is so thin?

Already a lot of good answers, so just one additional aspect to the explanation: When orbiting Mars, the vehicle has a lot of kinetic energy that has to be reduced to zero before landing. Coming from ...
Ralf Kleberhoff's user avatar
11 votes
Accepted

What is the heat shield refurbishment procedure for a crew Dragon capsule?

Disclaimers: This answer provides some more details about the engineering problem of trying to reuse an ablative heatshield. This discussion/analysis could arguably by better suited for the question ...
BrendanLuke15's user avatar
11 votes

Why are cone shaped heat shields used for Mars entry?

The following paragraph, in section IIIF of Prabhu and Saunders On Heatshield Shapes for Mars Entry Capsules, is the only direct comparison between 70-degree cones (Mars Viking heritage) and spherical ...
Erin Anne's user avatar
  • 12.1k
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 does the Parker Solar Probe's heat shield protect it from dust near the sun?

The heat shield (TPS) is not meant to protect the spacecraft from dust impacts. The statement is not quite accurate and (from a recent search) seems to have been removed from site. As an engineer on ...
That60sKid's user avatar
10 votes

Can a blimp dead drop on Mars or Earth this way?

NASA is working on an inflatable heat shield. Not quite a blimp, but a heat shield that's inflatable to a size much larger than the probe it's attached to. The extra area helps decelerate the ...
Hobbes's user avatar
  • 128k
10 votes

Has anyone explored using sound as a heat shield?

TL;DR: No, but sortof yes It's hard to prove a negative, but as PcMan's comment observes, this isn't worth pursuing since it falls apart on physical first principles. The first, and obvious, problem ...
geometrian's user avatar
  • 1,867
9 votes
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Archimedean braking for low density Venus lander + subsidiary question

Surprisingly the answer is yes there was studies done on that subject. A simple google search could yield this result: BUOYANT PLANETARY ENTRY https://apps.dtic.mil/dtic/tr/fulltext/u2/642361.pdf ...
Antzi's user avatar
  • 12.7k
9 votes
Accepted

Could a reentry powered monorail and flywheel make a kinetic engine for lift?

Take the super-optimistic 500 kJ/kg energy density of flywheel energy storage. In reality 10% of that would be a great result. $ E_k = {1 \over 2} mv^2$ so 0.5*1kg*(8km/s)^2 = 32MJ per kilogram of ...
SF.'s user avatar
  • 55.1k

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