Cooling system for Venus/Eve spacecraft

[kiwiak]

So, we want to have spaceship that wont melt after 1 hour like venera probes.

How shoudl cooling work? I was thinking of some mod for spacecraft overheating on Eve, but i need some reference.

[magnemoe]

An air condition or refrigerator work by making the inside cold and the outside radiator far hotter than the environment so you get rid of heat. This would work on Eve who is just boiling hot so you need to reduce the inside temperature to say 30 degree and the cooling radiator to say 200 degree.

make sure the rest of the ship including cooling system can survive 100-150 degree and you are good.

On Venus this will be far harder radiators has to be 800 degree or something to get rid of heat. Rest of the ship including cooling system and reactor would not be able to operate at Venus temperature so you need to cool it increasing the cooling demand with an magnitude.

[78stonewobble]

Couldn't we, theoretically, just design some electronics that can work at venusian temperatures and higher?

[kiwiak]

An air condition or refrigerator work by making the inside cold and the outside radiator far hotter than the environment so you get rid of heat. This would work on Eve who is just boiling hot so you need to reduce the inside temperature to say 30 degree and the cooling radiator to say 200 degree.

make sure the rest of the ship including cooling system can survive 100-150 degree and you are good.

On Venus this will be far harder radiators has to be 800 degree or something to get rid of heat. Rest of the ship including cooling system and reactor would not be able to operate at Venus temperature so you need to cool it increasing the cooling demand with an magnitude.

WOudl some system that slowly dumps coolant, getting rid of heat this way make sense?

[Ralathon]

WOudl some system that slowly dumps coolant, getting rid of heat this way make sense?

Yea it would, that's how humans keep cool in environments that are 36+C.

Problem lies in mass. The best coolant for this is water, it has insane heat capacity and a massive evaporation enthalpy. Only ones more efficient in kJ/kg of evaporation enthalpy are metals like aluminium or iron and their high boiling point makes them rather unpractical. Water dumps about 2.3MJ of heat per kg. Say our spacecraft is a sphere (to minimize surface area) of a 1m radius and isolated with 10cm of glass wool.

This gives our spacecraft a surface area of about 12.5m^2. Glass wool has a heat transfer coefficient of about 0.04W/(m*deltaT). Our internal temperature is about 100C, outside is about 500C and our insulation is 10 cm. This gives us a heat influx of 2000W. So our system gains 2kJ per second. So a kg of water would keep this spacecraft alive for about 1100 seconds, or about 20 minutes.

20 minutes of life per kg of coolant is a pretty bad deal. Especially when you consider that spacecraft aren't that good at autonomous operation. They can't recognize what rocks are interesting to us. So even if we gave it a big tank with a few hundred liters of water it would only survive for a few days, barely enough to investigate a few nearby rocks. And that coolant is costly to put into space. The tyranny of the rocket equation ensures that you need a much larger rocket, even if your payload is only slightly heavier.

All in all, Venus is just a terrible, terrible place. We should just put up a sign that says "Here be dragons! Abandon hope all ye who lands!" and stay away from it.

[jwenting]

Doesn't matter anyway if it melts in 10 minutes because in 10 minutes it'll be so heavily corroded in the sulphuric acid atmosphere of Venus that it's dead anyway.

Why do people still think Venus is a nice, cozy place, if maybe a tad hot?

It's not, it's just about the nastiest spot in the solar system. You're sitting in boiling sulphuric acid that's pressing down on you at higher pressures than the inside of a pressure cooker.

Best plan might be to lower something on a very long superconducting cable from a craft either in very low orbit or flying very high up in the Venusian atmosphere, just over the clouds.

And try to keep something like that stable...

[xenomorph555]

Giant heat sheild, Icarus 2 style

[Brotoro]

The sulfuric acid in Venus' atmosphere is way up in the cloud layer, not down at the surface.

Besides…we have materials that can withstand concentrated sulfuric acid just fine.

[lajoswinkler]

We had an identical discussion last week, guys. Use the search option.

[Camacha]

We had an identical discussion last week, guys. Use the search option.

Or you could be a nice guy and link to the discussion