…in what proximity would you have to be to the sun and how fast would you have to be spinning (like a rotisserie chicken) so that your light side didn’t burn and your dark side didn’t freeze; rotating just enough to keep a relatively stable temperature?
Absolutely absurd, I know but this question somehow popped into my head and won’t leave. 😆🐔🔥🧊
A wizard drops you on the moon. You immediately panic about not being able to breathe, plus your salivia is boiling and your blood is…well, it killed you pretty darn quickly.
Thankfully, the wizard noticed and set spells that puts a tiny bit of atmosphere right over your head, and , repairs the damage inflicted already. There is a chair and a go-board in front of you.
“Wait, that’s it?” you ask the wizard after he explains what the spells did. “Arent I going to burn, or freeze, or something?”
“Eventually, yeah,” says the wizard as he sits down. “But the human body’s great at homeostasis. Since your blood isn’t boiling it can circulate heat within you, you can burn calories to add heat as needed, and sweating is absurdly effective since the relative humidity of a vacuum is pretty much less than zero.”
“But, didn’t the Apollo capsule spin to manage heat, and aren’t there huge radiator fins on the ISS so they don’t slowly burn? I thought managing heat was hard?”
“It is. For an inanimate object. Especially one that isn’t filled with water or surrounded by a thermo exchange medium. You ever see a capsule bleed or a probe sweat?”
Even once you achieve the perfect rotation, the unfiltered UV would likely eventually give you cancer.
Seems like a good question for Randall Monroe, if he hasn’t already done something similar.
That or TheStraightDope!
The “how high to drop a steak for it to perfectly cook” and “does a submarine work as a spaceship” comes to mind, but afaik nothing similar to this one
You should post this in c/askScience
Outside of all the assumptions to make this work, the real issue is that the “dark side” doesn’t cool you like you’re thinking. Getting rid of heat in space is actually a hard problem to solve as a vacuum is a great insulator. Heat has to be radiated away, and that takes time and lots of surface area.
This is exactly what I am curious about. I’m fully aware of the mountain of assumptions needed to make this work lol. I guess its the “its ~-200°C out here but I’m not frozen” thing that makes my head spin a bit.
Interesting and does make sense. Where does this image of stuff freezing instantly as it “enters” space vacuum come from?
Moisture as any other fluid when exposed to vacuum of space expands and boils this transforms to vapour and that process absorbs energy which could cause the freezing.
Probably because many pop science articles will mention that the background radiation of the universe is at about 2-3 degrees above absolute zero. Plus things like the night side of mars being freezing, pluto being a frozen rock, comets being made of ice etc…
Depends on the entry I suppose. A liquid being sprayed out you’d imagine would do exactly that (assuming it’s not being heated by sunlight), but that’s probably because spraying means it’s a lot of tiny droplets, all with very little heat energy individually and lots of surface area to lose it. A big block of something like hot metal wouldn’t suddenly freeze, but cool as fast as its surfaces could radiate the internal heat.
This is going strictly as a thought experiment, the math or physics is probably different to some degree.
I think an additional effect is that, the drop in pressure causes any liquids exposed to it to vaporise, which is an exothermic process, and it’s a race to see whether it boils off entirely or the inner part freezes to solid from the drop in temperature through conduction. So the immediate surface of your body would either dry out or flash freeze but the inner part take a while to solidify.
Why there is any ice in space and it doesn’t just sublimate away over time I’m not sure.
What I had in mind was stuff like people getting shot into space in sci-fi, stuff like that. Theyre usually shown to freeze in the matter of seconds. So I guess thats unrealistic, though its a little sad because that means its a much more painful death by suffocation
Yes, that’s correct. Scenes like from Total Recall or Mission to Mars are totally wrong. It will be more like the opposite of drowning but about as bad. I’m trying to remember if The Expanse got it right in the several examples, they usually do pretty good hard science. It may have been a combination, since anyone seeing someone NOT freeze will say it looks fake.
As an earthling, you have evolved over the course of billions of years to deal with sunlight at a distance of one astronomical unit. That’s the distance of the earth’s orbit. That’s probably the most comfortable distance.
The Apollo moon missions used a so-called “barbecue” mode that rotated the capsules at three revolutions per hour. They did this during the 3-4 day coast phases to and from the moon. As far as I know this was able to mostly hold the interior temperatures in the “survivable” range.
earthling, you have evolved over the course of billions of years to deal with sunlight at a distance of one astronomical unit.
…plus a planet’s magnetic field, plus a few kilometers of atmosphere!
That’s a good starting point, but caveats:
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My bet is that most of our thermal circulation is via the movement of our blood. That’s probably not directly analogous to spacecraft.
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If one isn’t just talking thermal, we do burn at 1AU. Go lie in the sun without cover long enough – especially if you’re pale-skinned – long enough, and you’ll get burned. Without the atmosphere, we’d be hit by more UV light, too.
Agreed. With no suit or any other thermal management tech, it’s going to be hard to survive anywhere just on thermal grounds alone.
However, let’s say you want to mitigate problems with sunburn and climb to a higher solar orbit. I haven’t calculated anything. But my intuition says you’re no longer getting enough heat input, and you will end up freeze dried. (The dried part is a vacuum effect we were told to ignore.)
Without the atmosphere, UV is going to be among the least dangerous wavelengths for you to have to worry about.
looks puzzled
I don’t think that it mostly stops more-energetic stuff.
Hmm.
Are you thinking of the magnetosphere rather than the atmosphere? I didn’t mention that, but I guess that’d also be a factor.
The atmosphere stops a lot of the high energy stuff. It gets absorbed, and turned into a shower of lower energy particles.
I remember reading once about an astronaut seeing blue flashes in their eyes. When they realised, they got behind the water tank sharpish. It was high energy particles passing through their eyeballs.
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Probably significantly further away than the earth’s orbit, given that (1) you can die of heatstroke from exposure to the sun at earth’s surface, and that’s with miles of air still absorbing much of the radiation; and (2) in the vacuum of space, there would be no air or other substances to conduct away your body heat, so you’d have to rely solely on radiative heat to cool off.
So even though its minus hundreds of degrees, your skin wouldn’t freeze instantly on your dark side in this situation?
It’s not minus hundreds of degrees, it’s body temperature. Vacuum has no temperature, and it’s an insulator, not a conductor.
That makes perfect sense to me on paper. It still makes my head spin thinking about though lol
I think part of the unintuitiveness is caused by our knowledge that things quickly freeze in space.
Freezing is produced by a combination of temperature and pressure, but because the former fluctuates a lot more than the latter in our daily experience, the role of pressure isn’t part of our intuition. But in a vacuum, things freeze even at relatively high temperatures.
Yep, in space, getting rid of excess heat is a much harder problem than you’d think, because radiation is a lot less efficient compared to convection (distribution of heat through movement of fluid like air or water).
I have no idea where to even start with this one, but I love the question!
