Questions tagged [heat]

Questions about issues related to heat and temperature, and situations where heat (too much or too little) is the primary issue. Examples include heat management in spacecraft and heat used for power generation using the flow of thermal energy from a source to a sink.

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What are the Specific heat ratios of fluorine, Isopropyl Alcohol and Uranium?

I needed to calculate thrust and velocities of a rocket engine and its exhaust and in order to do that, I needed the values of Specific heat ratio(k) of Fluorine and k of Uranium and Isopropyl Alcohol....
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4 votes
2 answers
115 views

JWST detector heat load

A lot of information has been published about shielding the JWST from solar radiation and the need to maintain the detectors at a low temperature, but little has been said about the other sources of ...
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3 votes
1 answer
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Long lived solar powered rovers without radioisotope heater units (like Zhurong), for use beyond Mars

The Yutu rovers use RHUs to stay warm and survive the two week long lunar nights, every other rover uses nuclear material as well (except Sojourner), but the Zhurong rover uses a novel storage-heating ...
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7 votes
1 answer
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How hot do the nose cones of fairings actually get on ascent?

I've been reading into aerodynamic heating of rockets, and it's seemingly a rather complicated topic. It's relatively easy to calculate the stagnation temperature at a given mach number, and that is ...
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4 votes
2 answers
209 views

Why aluminum is added in Multi Layer Insulation?

Aluminum is a highly conductive material. Instead of insulating the system from heat, it conducts. Multi-Layer Insulation aims to protect spacecraft from extreme heat by acting as a thermal barrier. ...
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3 votes
1 answer
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Conversion of heat into electricity in rocket nozzles

Can we use advanced thermoelectric materials to reduce the temperature of nozzles by converting heat energy to electric energy and reducing the strain on the nozzle material and the coolant while ...
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4 votes
3 answers
221 views

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

Basically, after some heat exchanger, a fluid is pumped to a radiator and then releases its heat to the void of space. But I'm having a hard time seeing how that is done fast enough. The fluid should ...
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5 votes
1 answer
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Why does ISS uses liquid ammonia in the Active Thermal Control System?

I saw this today and it made me very curious. See page 8 here: https://www.nasa.gov/pdf/167129main_Systems.pdf Ammonia has a boiling point of -30 C. The ammonia is liquid in these loops, so if ever ...
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14 votes
2 answers
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Ablative heat shield and conservation of energy, how much does ablated matter in fact "carry away" versus re-radiate the absorbed heat?

I saw Most heat shields ablate, that is they sacrifice material to carry heat away... in a comment under this answer and started writing: I think that shields ablate to produce a layer of complex ...
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6 votes
1 answer
251 views

What kind of insulation is used in the Ingenuity helicopter?

A press release from NASA today states “This is the first time that Ingenuity has been on its own on the surface of Mars,” said MiMi Aung, Ingenuity project manager at NASA’s Jet Propulsion ...
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3 votes
2 answers
355 views

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

If you lift a swing at a children's playground and release it will swing back and forth for a while, losing some altitude in each swing, mostly (?) due to drag. Eventually it has lost all energy and ...
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Do black holes emit enough heat to heat a planet? [closed]

Under what circumstances can a blackhole emit enough heat to allow life on an orbiting planet?
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6 votes
1 answer
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Starship surface heating on Mars landing

Mars atmosphere is much thiner than Earth's And then how much will Starship heat on a Mars landing comparing to a landing on Earth?
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1 vote
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How do you balance speed and exposure time when trying to reduce heating? [duplicate]

I'm trying to understand how you choose your acceleration/deceleration and trajectory during launch and reentry to minimize aerodynamic heating.* Ignoring efficiency in terms of delta-v (best leave ...
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15 votes
2 answers
3k views

How hot do rocket engine nozzles get?

What temperatures are encountered by the nozzles of rocket engines like those in SpaceX's Merlin series? Radiative or regenerative cooling, atmosphere or vacuum. There's plenty of info about exhaust ...
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3 votes
2 answers
326 views

How to determine heat transfer for survival on Venus?

I'm trying to determine how long a probe could survive on Venus' surface. Assuming its just a sphere of titanium with room temperature air inside, what would be the best method for determining the ...
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2 votes
1 answer
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In what conditions are the electronics of New Horizons housed?

In one of answers to the question What are the long term effects of Space Weathering on man-made materials? there is a link to Wikipedia article about Kapton. In this article mentioned that NASA's ...
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6 votes
2 answers
257 views

How deep into the corona could the Parker Solar Probe go without being damaged?

An answer to the question Has any object launched from Earth gone into the Sun? says The probe will repeatedly touch the outer corona until mission end in 2025, with the closest approach being 3.83 ...
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9 votes
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How do space blankets (thermal blankets) work?

On earth, blankets serve to primarily buffer temperature changes / heat transfer that would occur via convection (e.g. a blanket traps air near you so that after your body warms it, it doesn't just ...
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1 vote
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What are the methods of heat transfer on a tubular heat pipe and how is its thermal circuit?

I would like to know how many heat transfer methods are on a tubular heat pipe and the configuration of its thermal circuit.
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2 votes
1 answer
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How much heat is reabsorbed by a high-speed object?

I have been playing around with an app to demonstrate high speed objects entering earth's atmosphere. I am using the drag equation to approximate how much kinetic energy gets converted into heat at ...
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2 votes
1 answer
164 views

Which theory does this reentry heating rate equation come from?

The paper by Wang et al. at Scitech 2018 uses the following constraint on the rocket heating rate (equation (3) in the paper): $$k_Q \sqrt{\rho} V^{3.15} \le \dot{Q}_{max}$$ (screen shot) I am ...
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-5 votes
1 answer
149 views

How to heat up the inside of a metal ball in space

Ok, they say third times the charm. Say you had a metal ball around 30 feet in diameter. At a distance of 143 million miles from the sun and you were trying to heat the air up inside the ball using ...
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5 votes
0 answers
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Understanding the basics of spacecraft thermal control systems

I have a broad understanding that in spacecraft cooling systems where a circulating liquid is used, a first coolant usually runs through the spacecraft and collects heat and then passes through a heat ...
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5 votes
0 answers
169 views

Design considerations for a space suit going to Mars?

Essentially, I am trying to design a heat exchanger for a space suit traveling to mars. From my understanding, I assumed that the energy generated from the space suit relates to the astronaut as well ...
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2 votes
1 answer
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How do Stirling radioisotope generators maintain a temperature differential in a vacuum?

I was reading the wikipedia page on RTGs and happened to stumble upon the section about efficiency. There were three methods that seemed to rely on direct conversion of thermal energy into electrical ...
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7 votes
1 answer
679 views

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

Solar Orbiter (SolO) is a planned Sun-observing satellite, under development by the European Space Agency (ESA). Due to its proximity to the Sun, it receives about 13 times more solar energy than we ...
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2 votes
0 answers
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Minimal heating a realistic reentry vehicle could achieve?

In this question, I asked whether it would be possible to make a reentry vehicle that could slow down from orbit and glide to the ground entirely passively. The answers and comments point out several ...
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0 answers
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At the same temperature, what's the relation of speed of heat loss between Earth and Mars?

Mars has a thinner athmosphere than Earth. Let's say you have a similar shelter of the same volume and made of the same materials in Mars at -70 Celsius, and in Earth in some place in the Antarctica ...
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3 votes
1 answer
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Why don't the hottest temperatures of a re-entering spacecraft occur near the "bottom"?

The paintings of the Apollo command module and space shuttle below portray the heating effects of re-entry. The whitest parts of the spacecraft get the hottest, with cooler parts in red and darker ...
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5 votes
1 answer
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Maximum speed based on atmospheric altitude given maximum temp?

I saw the question Could escape velocity be achieved in the atmosphere? and thought it probably could've been asked better. I'm sure there's an equation to calculate the average heat generated by an ...
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24 votes
2 answers
4k views

Why not increase contact surface when reentering the atmosphere?

If a craft were to increase the surface area where contact is made with air during reentry, I imagine the heat quantity per area unit would decrease, making the use of (heavy) heat shields less of a ...
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3 votes
1 answer
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Launch pads flame deflectors

I was interested in knowing if all launch pads possess a flame deflector. I'm inclined to say yes, as the structure seems vital for a safe launch. Wanted to make sure, though, if there could be a case ...
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2 votes
1 answer
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Heat balance of the ISS: breakdown?

Is there available breakdown of the heat balance of the International Space Station? In particular: How much heat is produced? by direct warming by sun by warming of solar panels (heat for the ...
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3 votes
1 answer
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Selection criteria for coolant media on spaceships

What is the selection criteria for coolant media on spaceships? I have read that ammonia as well as water glycol have been used. These two have very diverse properties. So what makes both of them ...
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4 votes
1 answer
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Could a spacecraft produce lift using sublimating material?

Following this question, could a spacecraft approaching upper atmosphere from very low circular Earth orbit, produce lift to soar propulsively, bleeding speed at constant apoapsis, by sublimating ...
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6 votes
1 answer
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How much delta-v is lost to heat of exhaust?

It occurred to me that all of the kinetic energy not going exactly in the opposite direction of a spacecraft is wasted! Since heat is essentially kinetic "noise" in objects, I wondered how much more ...
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4 votes
0 answers
71 views

Has the monthly average skin temp of the ISS increased during its years in orbit?

Is there a source of monthly average sun-side maximum temperatures during its (ISS) years in orbit?
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7 votes
2 answers
3k views

Why is Adiabatic wall temperature taken as the driving temperature in rocket engines?

Going by the definition of convective heat transfer coefficient from Wikipedia (which I have started to doubt; reason follows): $h=\frac{q}{\Delta T}$, where the $\Delta T$ is taken as the difference ...
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2 votes
2 answers
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Orbital reentry glider with no heat shield

Let's assume a reentry craft designed to not use heat protection like Soyuz or the Space Shuttle, and budget is not an issue. The Concorde max surface temperature was 400 K, so let's use this as a max ...
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  • 729
2 votes
1 answer
255 views

What advances are there in heat-resistant materials for engines?

As one of the difficulties in engine design is to prevent it from melting, one can expect research to be conducted on what materials to use for thrust chamber and nozzle. Many engines seem to use ...
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6 votes
1 answer
365 views

Parker Solar probe's heat survival - Heat vs Temperature

This is not about about heat shields, materials, coolant, etc. I am not quite not getting the science that explains the Heat Vs Temperature, which is how the Parker probe is going to survive the ...
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2 votes
1 answer
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How are the Titan Transtage's tanks protected from its engine?

As a follow up to this answer which identifies the two pointed objects flanking the Titan Transtage's engine in an unusual configuration as its propellant tanks: How are these protected from the heat ...
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4 votes
1 answer
392 views

Generating power in zero-g

When generating electricity, energy is lost to friction in mechanical bearings (e.g. turbine or generator bearings) and as heat, through resistance in transmission wires. If you were generating ...
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9 votes
2 answers
2k views

SpaceX Falcon-9 fairing heating during launch?

In watching the SpaceX SES-12 launch last night, I noticed what looked like the fairing of the rocket glowing a bit a while after launch. This was most obvious in the SpaceX video SES-12 Mission ...
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1 vote
1 answer
338 views

Cooking in Space

Someone in the Worldbuilding SE asked How to Build a BBQ for the ISS. My first through was: Why not just stick it in a sealed container out in direct sunlight for a bit? It'll get plenty cooked ...
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4 votes
2 answers
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Why doesn't the Tesla Roadster's windscreen crack or break in space?

The car is on the sun side of space as seen by the lens flare. This means that the car will absorb high amounts of radiation, heating the car up to well over 250 degrees Celsius . A car windscreen ...
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8 votes
5 answers
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Why doesn't Tesla's Roadster melt in space?

Tesla's Roadster is somewhere above us taking sunlight directly part of the time, then very cold on the next half of the orbit. Or when it rolls, one side gets hot, the other is cold. Why don't the ...
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0 votes
1 answer
348 views

heat recovery thermodynamics in space

Let me try ask it this way. How efficient is current power generation thermodynamic cycles in space? Is it even used? My info is that most spacecraft use PV solar panels, is the heat turned to energy ...
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6 votes
2 answers
742 views

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

I'd like to know how a thermal control system of a spacecraft basically works. As the only possibility to get rid of the thermal heat is through radiation, I'd like to get a basic qualitative ...
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