Minmus Taster Posted February 22 Share Posted February 22 Mainly curious about the atmospheric pressure, could a human survive in the denser atmosphere assuming they had a suit that would keep them warm? Or would they be crushed? Also curious about the the temperature, water collection, and different options for habitats. Quote Link to comment Share on other sites More sharing options...
farmerben Posted February 22 Share Posted February 22 Wikipedia says the surface pressure is 1.45 atm. That's about the pressure under 2 meters of water on earth. Not even enough to painfully pressure your ears. I'm curious if you could withstand crushing inside the gas giants. Quote Link to comment Share on other sites More sharing options...
cubinator Posted February 22 Share Posted February 22 The air pressure is no problem, people withstand way more when going underwater in submarines or diving. The temperature is cryogenic (like liquid nitrogen range) so you need to keep yourself insulated and avoid skin contact with the air, as it will start freezing your flesh solid on contact. Since the air is more dense than on Earth, it'll also be more effective at transferring heat out of you. You also need your own breathable air supply, of course, and make sure your airways are sealed against the atmosphere, because the methane is quite poisonous. Water is probably what most of the ground is made of, so if you dig some up and warm it up you can probably do whatever you need with it. If you're keeping your habitat comfortably warm, then you should make sure the part of it that's sitting on or right above the ground is not conducting any of that heat. The first problem would be that it would not be efficient. The second would be that it would start melting the ground...and your habitat would start to sink. If you've got so much hot air inside your habitat, though, you might consider one that allows itself to lift into the sky as a balloon. Quote Link to comment Share on other sites More sharing options...
Piscator Posted February 22 Share Posted February 22 Methane is actually non-toxic, but I would keep an eye on the hydrogen cyanide, carbon monoxide and other trace components of the atmosphere. Also, some of the tholins on the surface are probably not exactly healthy. Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted February 23 Share Posted February 23 (edited) They need pattens on the muddy Titan, to protect the spacesuit boots. Spoiler Also from freezing. P.S. It's also snowing there, so they need an umbrella. Once upon a time on Titan. Spoiler Edited February 23 by kerbiloid Quote Link to comment Share on other sites More sharing options...
Nuke Posted February 23 Share Posted February 23 how thick are your long underwear? Quote Link to comment Share on other sites More sharing options...
AckSed Posted February 23 Share Posted February 23 22 hours ago, farmerben said: I'm curious if you could withstand crushing inside the gas giants. Neptune is surprisingly not an instant death - if you're inside a sufficiently strong aerostat/submarine. And you avoid the fastest storms in the Solar System. Radiation is sorta benign this far out from the sun. The gravity at the 'surface' is 1.14 g, and the temperature at 1 bar is a brisk -201 deg. C. Go deeper and the temperature rises. Bob about in the relative calm of the North Pole and about *waggles hand* 30 bar pressure, and you'll almost be warm enough to not freeze. Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted February 23 Share Posted February 23 58 minutes ago, Nuke said: how thick are your long underwear? They cover spacesuits with blankets on the picture. 49 minutes ago, AckSed said: Neptune is surprisingly not an instant death - if you're inside a sufficiently strong aerostat/submarine. And you avoid the fastest storms in the Solar System. Radiation is sorta benign this far out from the sun. The gravity at the 'surface' is 1.14 g, and the temperature at 1 bar is a brisk -201 deg. C. Go deeper and the temperature rises. Bob about in the relative calm of the North Pole and about *waggles hand* 30 bar pressure, and you'll almost be warm enough to not freeze. Sounds like a nerd's paradise. Quote Link to comment Share on other sites More sharing options...
magnemoe Posted February 23 Share Posted February 23 23 hours ago, cubinator said: The air pressure is no problem, people withstand way more when going underwater in submarines or diving. The temperature is cryogenic (like liquid nitrogen range) so you need to keep yourself insulated and avoid skin contact with the air, as it will start freezing your flesh solid on contact. Since the air is more dense than on Earth, it'll also be more effective at transferring heat out of you. You also need your own breathable air supply, of course, and make sure your airways are sealed against the atmosphere, because the methane is quite poisonous. Water is probably what most of the ground is made of, so if you dig some up and warm it up you can probably do whatever you need with it. If you're keeping your habitat comfortably warm, then you should make sure the part of it that's sitting on or right above the ground is not conducting any of that heat. The first problem would be that it would not be efficient. The second would be that it would start melting the ground...and your habitat would start to sink. If you've got so much hot air inside your habitat, though, you might consider one that allows itself to lift into the sky as a balloon. How cold is the atmosphere compared to 4 degree water, as I understand saturation divers working out of diving bells as an 5 minute air supply if they have to disconnect the umbilical, more would be pointless as they would be so cold at this time, this is 30 year old data and more modern systems might be better but the tank would have to be large as the pressure is high and you are never far from your diving bell. Quote Link to comment Share on other sites More sharing options...
cubinator Posted February 23 Share Posted February 23 (edited) 2 hours ago, magnemoe said: How cold is the atmosphere compared to 4 degree water, as I understand saturation divers working out of diving bells as an 5 minute air supply if they have to disconnect the umbilical, more would be pointless as they would be so cold at this time, this is 30 year old data and more modern systems might be better but the tank would have to be large as the pressure is high and you are never far from your diving bell. I might do some math in a bit regarding the actual heat transfer (math below), but qualitatively in the meantime: Have you ever seen someone dunk a bouquet of flowers in liquid nitrogen for a few seconds, then take them out and shatter the flowers like glass? It's that cold. I've frozen wet ice cubes together in an industrial freezer at somewhat survivable temperatures in just a few seconds - I think on Titan you'd have a hard time even drawing in your first unprotected breath as your mouth and nose freeze shut. Disclaimer: I just googled around for some heat transfer coefficient values and eyeballed a fairly low fluid velocity arbitrarily The heat transfer rate is going to depend on the heat transfer coefficient and the temperature difference. For air, I'll say the heat transfer coefficient is 25 and the temperature difference is 21 degrees (assuming dealing with surface body temperature of 25 degrees). In that case the heat transfer rate is 525 W/m2. For Titan, I'll assume the heat transfer coefficient is 1.5 times that for air (not really sure of the exact value) and the temperature difference is 205 degrees. In this case the heat transfer rate is 7687.5 W/m2, almost 15 times more. For water, with a temperature difference of 21 degrees and a heat transfer coefficient of 5000, the heat transfer rate is 105000 W/m2. So water seems to be quite a bit better at wicking heat than Titan's air, but let's see how much of a threat it is anyway. Water (which you contain a lot of) has a specific heat capacity of 4.186 J/g*degree C. So if you have 1 mL of water in your mouth spread over an area of, say 10 cm2 or 0.001 m2, at a temperature of 310 K, the temperature would need to be lowered by 37 degrees to reach the freezing point and begin to form ice, corresponding to an energy of 154.88 Joules. At the heat transfer rate we calculated earlier for Titan's air, and taking into account the smaller area, if you drew in a breath at 2 m/s or so, the water in your mouth would reach 0 degrees Celsius at t=20.15 seconds. Ok, so that's not complete instant solidification, at least in your mouth. For comparison with my example from before, liquid nitrogen apparently has a heat transfer coefficient of 300 to 800, around the same as air. That means that indeed, imagining dunking stuff in liquid nitrogen is a decent analogy to what would happen to it on Titan. And while we've found out that swishing liquid nitrogen in your mouth *might* not *instantly* freeze some of your spit, I think we can be absolutely sure that for no amount of time would it be pleasant. Furthermore, your eyes are more exposed and likely a bit cooler than the inside of your mouth, so we can be sure that should your face be exposed to the atmosphere you would have significantly less than 20 seconds before your eyelids start to freeze. You might be blinded around the same moment you realize there's no oxygen in what you're breathing - a frightening scenario. Anyway, it seems that Titan is definitely very dangerous to expose your face in, but if you should accidentally expose some skin out of your jacket, say, with your glove loose around your wrist, you might have up to 20 seconds to get your glove back on before you start getting serious frostbite - and beyond that, there is no mercy. All of this assuming you don't touch a rock with your bare hands, wade in the shores of Kraken Mare, or encounter a gust of wind in your totally rad wingsuit, any of which would make things much, much worse. Edited February 23 by cubinator now with back-of-napkin math Quote Link to comment Share on other sites More sharing options...
PakledHostage Posted February 25 Share Posted February 25 On 2/23/2024 at 11:00 AM, cubinator said: Anyway, it seems that Titan is definitely very dangerous to expose your face in, but if you should accidentally expose some skin out of your jacket, say, with your glove loose around your wrist, you might have up to 20 seconds to get your glove back on before you start getting serious frostbite - and beyond that, there is no mercy. All of this assuming you don't touch a rock with your bare hands, wade in the shores of Kraken Mare, or encounter a gust of wind in your totally rad wingsuit, any of which would make things much, much worse. You seem to be in the right ballpark, heat transfer rates, wise. Growing up, the MET office used to quote wind chill values in W/m^2. Really dangerous wind chills would be on the order of 3500 W/m^2. (They did this because people generally misrepresent windchill "feels like" temperatures as actual temperatures, but they gave up trying to fight the good fight about 25-30 years ago and allowed stupidity to reign...) Anyhow, one important consideration about heat transfer in cold water vs. cold air is that cold water is above freezing so won't cause freezing injuries. Cold gasses obviously can. Removing your gloves, even for only a handful of seconds, at -40°C is dangerous, especially if the wind is blowing. Quote Link to comment Share on other sites More sharing options...
magnemoe Posted February 25 Share Posted February 25 3 hours ago, PakledHostage said: You seem to be in the right ballpark, heat transfer rates, wise. Growing up, the MET office used to quote wind chill values in W/m^2. Really dangerous wind chills would be on the order of 3500 W/m^2. (They did this because people generally misrepresent windchill "feels like" temperatures as actual temperatures, but they gave up trying to fight the good fight about 25-30 years ago and allowed stupidity to reign...) Anyhow, one important consideration about heat transfer in cold water vs. cold air is that cold water is above freezing so won't cause freezing injuries. Cold gasses obviously can. Removing your gloves, even for only a handful of seconds, at -40°C is dangerous, especially if the wind is blowing. You have an valid point, you also have cold water survival dry suits who let you survive for many hours in 4 degree water. Standard on helicopters flying to old rigs here in Norway. Also seen an simplified version on ferries in Northern Norway as an replacement to life vests. Primitive versions of this was used during WW 2. Quote Link to comment Share on other sites More sharing options...
NFUN Posted February 26 Share Posted February 26 6 hours ago, PakledHostage said: You seem to be in the right ballpark, heat transfer rates, wise. Growing up, the MET office used to quote wind chill values in W/m^2. Really dangerous wind chills would be on the order of 3500 W/m^2. (They did this because people generally misrepresent windchill "feels like" temperatures as actual temperatures, but they gave up trying to fight the good fight about 25-30 years ago and allowed stupidity to reign...) Anyhow, one important consideration about heat transfer in cold water vs. cold air is that cold water is above freezing so won't cause freezing injuries. Cold gasses obviously can. Removing your gloves, even for only a handful of seconds, at -40°C is dangerous, especially if the wind is blowing. what about at -40°F? Quote Link to comment Share on other sites More sharing options...
PakledHostage Posted February 26 Share Posted February 26 26 minutes ago, NFUN said: what about at -40°F? Same thing. You know that, or you wouldn't have asked. Quote Link to comment Share on other sites More sharing options...
cubinator Posted February 26 Share Posted February 26 (edited) 10 hours ago, PakledHostage said: You seem to be in the right ballpark, heat transfer rates, wise. Growing up, the MET office used to quote wind chill values in W/m^2. Really dangerous wind chills would be on the order of 3500 W/m^2. (They did this because people generally misrepresent windchill "feels like" temperatures as actual temperatures, but they gave up trying to fight the good fight about 25-30 years ago and allowed stupidity to reign...) Anyhow, one important consideration about heat transfer in cold water vs. cold air is that cold water is above freezing so won't cause freezing injuries. Cold gasses obviously can. Removing your gloves, even for only a handful of seconds, at -40°C is dangerous, especially if the wind is blowing. That is a very interesting point about cold water! Still pretty deadly though... Nice to know my math sounds reasonable! My intuition is to take everything I said as an absolute maximum. Any water on you that's spread thinner than whatever I assumed it was will freeze faster, and I didn't even get into heat transfer through skin. Man, I want to see windchill in W/m2 now, that makes way more sense from a physics perspective. Frostbite in x minutes is a useful metric where I'm from. Edited February 26 by cubinator Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted February 28 Share Posted February 28 Just watched the documentary trailer. No, thanks. Go to that Neptune yourself, if you want to... Spoiler Quote Link to comment Share on other sites More sharing options...
.thumb.png.572b74ce81b88d2dc11d0cc31275c803.png)
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.