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If you’re curious why it won’t melt: https://www.nasa.gov/feature/goddard/2018/traveling-to-the-sun-why-won-t-parker-solar-probe-melt https://www.nasa.gov/featu

If you’re curious why it won’t melt: https://www.nasa.gov/feature/goddard/2018/traveling-to-the-sun-why-won-t-parker-solar-probe-melt https://www.nasa.gov/feature/goddard/2018/traveling-to-the-s...

lordnacho 5y ago
Basically not much heat is transferred because there's not many particles to do the transfer, like a hot oven. What I didn't understand was the coolant. It's got to dump whatever heat it picks up somewhere? Just a big radiator?
- Denvercoder9 5y ago
  > It's got to dump whatever heat it picks up somewhere? Just a big radiator? Yes. The absence of any medium in space makes radiating the only way to get rid of heat.
- pcl 5y ago
  The article puts some numbers on it, as well: > That means that while Parker Solar Probe will be traveling through a space with temperatures of several million degrees, the surface of the heat shield that faces the Sun will only get heated to about 2,500 degrees Fahrenheit (about 1,400 degrees Celsius).
  - cableshaft 5y ago
    I'm a little curious how they were able to determine this before even sending a craft there and measuring it and have a high degree of confidence in its accuracy.
- HPsquared 5y ago
  The thing about space is, heat transfer is all radiative. The "dark" side of the probe, which is in its own shadow, faces the darkness of space (which is very cold indeed). Therefore you can put insulation on the side facing the sun, and a radiator on the dark side to remove any heat that gets through the insulation.
  - criddell 5y ago
    But space is a vacuum which is a pretty good thermal insulator. How are they dumping the heat?
    - DecoPerson 5y ago
      Pick a material for the surface of the radiator which has high emissivity. That is, when the material gets warm, it will convert the thermal energy to electromagnetic energy (light). Some of this light will escape, leading to a cooling effect. This is known as “incandescence” or “black body radiation”, and it’s why metals glow red hot when they’re heated to a certain temperature. (Though it’s not always red, it can be white, blue, or even UV. Animals are warm enough to glow in infrared, which is what thermal cameras detect).
    - haimez 5y ago
      The physical mechanism is radiative cooling: https://en.m.wikipedia.org/wiki/Radiative_cooling https://en.m.wikipedia.org/wiki/Radiative_cooling More details about the specific mechanism on the Parker Solar Probe’s cooling system: https://blogs.nasa.gov/parkersolarprobe/2018/09/14/parker-solar-probes-solar-array-cooling-system-fully-activated/ https://blogs.nasa.gov/parkersolarprobe/2018/09/14/parker-so...
    - moffkalast 5y ago
      IR radiation, in a nutshell.
Aachen 5y ago
Relevant part: the capturing cups are of metals with high melting points, plus > The corona through which Parker Solar Probe flies, for example, has an extremely high temperature but very low density. Think of the difference between putting your hand in a hot oven versus putting it in a pot of boiling water And for the rest of the craft there is a highly reflective heat shield.
- t8e56vd4ih 5y ago
  are you saying this protects you from Corona? why isn't this in the news?
  - ragebol 5y ago
    Putting your head in a hot oven continuously will probably prevent you from dying of the coronavirus indeed.
    - Cthulhu_ 5y ago
      As does flying to the sun, for that matter. Can't catch corona if you're ~150 million kilometers away from the nearest other person.
      - Aachen 5y ago
        The vacuum probably also helps. I'd also expect a few mm of vacuum might do the trick of avoiding contracting covid, though I'd not (as the Dutch say) put my hand in the flame for it. (Equivalent expression in English might be that I'd not wager a lot of money on it, i.e. that I'm not completely certain given the consequences if it's wrong.)
      - dr_dshiv 5y ago
        Corona is dangerous.
        dr_dshiv 5y ago
MengerSponge 5y ago
They're going at night, duh

lordnacho 5y ago

Basically not much heat is transferred because there's not many particles to do the transfer, like a hot oven. What I didn't understand was the coolant. It's got to dump whatever heat it picks up somewhere? Just a big radiator?

Denvercoder9 5y ago
> It's got to dump whatever heat it picks up somewhere? Just a big radiator? Yes. The absence of any medium in space makes radiating the only way to get rid of heat.
pcl 5y ago
The article puts some numbers on it, as well: > That means that while Parker Solar Probe will be traveling through a space with temperatures of several million degrees, the surface of the heat shield that faces the Sun will only get heated to about 2,500 degrees Fahrenheit (about 1,400 degrees Celsius).
- cableshaft 5y ago
  I'm a little curious how they were able to determine this before even sending a craft there and measuring it and have a high degree of confidence in its accuracy.
HPsquared 5y ago
The thing about space is, heat transfer is all radiative. The "dark" side of the probe, which is in its own shadow, faces the darkness of space (which is very cold indeed). Therefore you can put insulation on the side facing the sun, and a radiator on the dark side to remove any heat that gets through the insulation.
- criddell 5y ago
  But space is a vacuum which is a pretty good thermal insulator. How are they dumping the heat?
  - DecoPerson 5y ago
    Pick a material for the surface of the radiator which has high emissivity. That is, when the material gets warm, it will convert the thermal energy to electromagnetic energy (light). Some of this light will escape, leading to a cooling effect. This is known as “incandescence” or “black body radiation”, and it’s why metals glow red hot when they’re heated to a certain temperature. (Though it’s not always red, it can be white, blue, or even UV. Animals are warm enough to glow in infrared, which is what thermal cameras detect).
  - haimez 5y ago
    The physical mechanism is radiative cooling: https://en.m.wikipedia.org/wiki/Radiative_cooling https://en.m.wikipedia.org/wiki/Radiative_cooling More details about the specific mechanism on the Parker Solar Probe’s cooling system: https://blogs.nasa.gov/parkersolarprobe/2018/09/14/parker-solar-probes-solar-array-cooling-system-fully-activated/ https://blogs.nasa.gov/parkersolarprobe/2018/09/14/parker-so...
  - moffkalast 5y ago
    IR radiation, in a nutshell.

Aachen 5y ago

Relevant part: the capturing cups are of metals with high melting points, plus > The corona through which Parker Solar Probe flies, for example, has an extremely high temperature but very low density. Think of the difference between putting your hand in a hot oven versus putting it in a pot of boiling water And for the rest of the craft there is a highly reflective heat shield.

t8e56vd4ih 5y ago
are you saying this protects you from Corona? why isn't this in the news?
- ragebol 5y ago
  Putting your head in a hot oven continuously will probably prevent you from dying of the coronavirus indeed.
  - Cthulhu_ 5y ago
    As does flying to the sun, for that matter. Can't catch corona if you're ~150 million kilometers away from the nearest other person.
    - Aachen 5y ago
      The vacuum probably also helps. I'd also expect a few mm of vacuum might do the trick of avoiding contracting covid, though I'd not (as the Dutch say) put my hand in the flame for it. (Equivalent expression in English might be that I'd not wager a lot of money on it, i.e. that I'm not completely certain given the consequences if it's wrong.)
    - dr_dshiv 5y ago
      Corona is dangerous.
      - dr_dshiv 5y ago

MengerSponge 5y ago

They're going at night, duh