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Consider a planet similar to Mustafar (of the Star Wars franchise). Ambient temperatures and pressures are nearly 400 Celsius and 80 ATM. A surviving crew of normal humans is running out of resources and is forced to land here.

I am asking this question because no one else has posted one yet. A similar question has been offered about a Venus base here which unfortunately does not concern itself with the species in the colony - they could be aliens. That question also does not help answer the question of resources - it specifically is asking about how advanced this species must be and what technologies they would need.

Because I am dealing only with human physiology, and current technology, this is a new question. I really wish to get a human answer, and avoid alien species and fictional technologies.

They can perform a controlled descent, adapting to pressure changes as they slowly (over days or months?) either glide or float down, but do not have limitless energy resources onboard. They have to somehow adapt to use the nearly limitless geothermal energy of this new home. They will have to scrub or electrolyze their own oxygen from a sulphur, Nitrogen, and CO2, atmosphere and develop a long-term climate control solution. They will have to at first renew but eventually create some sort of agriculture, in some sort of contained enclosures.

Some points:

  • Minerals are abundant, similar to Earth's crust. They must be mined or extracted.
  • Water will have to be recycled and eventually produced from elements in the atmosphere.
  • Silica (sand) is available to make high-temperature silicone for various applications.
  • Unluke Mustafa, there is a thick atmosphere creating very high surface pressures. The mass is roughly earth-like.
  • There are mountain ranges however there are also plains and desserts for settlements. No known oceans or lakes exist (except those of lava). If pools or lakes form, they certainly are not aqueous water.
  • There is no indigenous life.
  • There are no plans to "terraform" the planet. These are essentially Robinson Crusoe survivors needing to adapt to a new world and survive.
  • There is no perceptible sunlight on the surface except a dimly glowing sky during "daytime"
  • There is no satellite, so no tidal force.
  • There are areas available with little to no tectonic activity, and safely distant from volcanoes, but hot just the same. There are no tectonic or volcanic obstacles to habitability if the simply select a good site.
  • Combustion engines won't work in the atmosphere, so powered vehicles or aircraft would need to carry all their own propellants and are thus very impractical. Steam power is considered to be the most practical engine.
  • Solar radiation is shielded by a magnetosphere. There are no radiation obstacles to habitability.

A good answer identifies in two lists the elements absolutely essential to making the transition from their nearly self-sustaining spaceship with a dwindling energy source to a thriving surface-borne community in an artificial biosphere having only raw mineral resources but limitless energy. The first list is things that absolutely must have been onboard their ship in order to survive and make the transition. The second list is elements, compounds, or conditions which must absolutely exist on the hot planet in order to create their new habitat using the vast geothermal energy available.

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    $\begingroup$ Actually, a sun also applies tidal forces to its planets orbiting it. $\endgroup$ – Mr. Anderson Aug 13 at 17:57
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    $\begingroup$ You might want to consider a settlement entirely based in large airships. The planet still represents a source of mass/matter, but the crushing pressures are impractical to land. High in the atmosphere, the pressure is good, the sunlight abundant, the temps more manageable, and access to space much better. They might be able to utilize the above/below temps for aerothermal power, and use probes/robots to retrieve resources from the surface. Besides, I love the image of a floating city in the sky. $\endgroup$ – DWKraus Aug 13 at 22:33
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    $\begingroup$ How do you figure on unlimited power? The heat is a downer, not a source of energy. No solar power. If you settle anywhere that's stable, there's less geothermal, and the atmosphere is so hot the difference isn't very good. Resources wont' be any better than from any planet, but way harder to extract because of the conditions. Most of the work needs to be done by robots and mechanized factories (very robust ones, at that). Living in the toxic clouds would be hard enough. I suppose if they have to land, it is what it is. $\endgroup$ – DWKraus Aug 14 at 0:15
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    $\begingroup$ Where do your settlers get the (cool) coolant to start with? You don't get energy just from heat, you get energy from temperature differential, as @DWKraus said, the heat itself won't help you much! You have MORE limited power sources than on Earth's surface. $\endgroup$ – BIOStheZerg Aug 14 at 15:03
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    $\begingroup$ @Vogon Poet: Sorry, but that only works until they run out of coolant $\endgroup$ – jamesqf Aug 15 at 5:29
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The Challenges

Pressure

80 atmospheres is equal to 8.12 MPa of surface pressure. Many structural materials can tolerate this pressure (at 15 C), with a thickness based on how much stronger the material is. Tin walls (9 MPa yield strength) would need to be 1 meter (3.2 feet) thick in all places.

However, you can pressurize the interiors of your structures.

Using a trimix blend of air humans can tolerate diving depths of up to 318 meters. The pressure at that depth is 53 atmospheres. Pressurizing the inside of habitable areas takes 5.4 MPa of stress off the enclosure.

Tin walls, then, would only need to be 0.3 meters / 1 foot thick. Steel walls (250 MPa) need only be 1 cm / 0.5 inches thick.

However, the strength of most materials fades as temperature increases.

enter image description here

Steel has a property that it gets stronger with rising temperature before it begins to weaken. At 400 C, steel's strength is approximately 100% of its cool (21 C) strength.

These walls would need to be coated in some material that prevents the air chemistry from etching away the steel chemically. This covering would need to be strong enough to handle occasional falling debris, scratches, and the outside temperature.

Temperature

enter image description here

Typical humans can't live in much hotter than 21 C weather. Insulation is essential to reduce the heating from the environment into the shelters. And active cooling will need to always be running to pump out the heat that does get in, as well as the shelters own waste heat.

Aerogel would likely be the candidate for wall insulation. Aerogel is, conceptually, a freeze-dried foam that your doomed crew might be able to manufacture in large volume while on approach.

At 400 C Aerogel has a thermal conductivity of 20 ${mW} \over {m * K}$. This is multiplied by the exposed area. $\Delta{Q} = c d \Delta{T} \rightarrow (20) d (380) = $. In this case, 7,600 mW = 7.6 W per meter of insulation thickness and per meter-squared of contact area between the hot and cold.

A typical modern air unit (no future science) can move 18,000 BTU per hour out. You'd need to design a special air unit that handles the very hot "hot" reservoir. However, assuming such designs are available to your crew and they perform at 18,000 ${BTU}\over{hr}$, that's 5,275 Watts of active cooling.

With 1 meter (3.2 ft) thick walls of Aerogel insulation, each cooling unit would only be able to service 694 square meters of shelter walls. For a typical 3 meter tall / 1 story structure, that'd be a square building 57 m (189 ft) wide, per air cooling unit. And you'd probably want a spare in case of breakdowns.

Unfortunately, Aerogel can only handle 2 MPa of pressure before breaking down. Steel walls may need to have lower-pressure cores so that the insulation can be put inside.

Thriving

Merriam-Webster defines thriving : to grow vigorously, to floursh.

I think it would be impossible to call a settlement thriving if its residence are trapped inside shelters. They need some way of getting out.

enter image description here

With the interior pressurized up to 53 atmospheres, the suit might not need to be as thick and strong. If an environmentally-sealed model can be designed that's just a few millimeters thick, it could allow a full range of motion.

However, the cooling challenges from before are re-raised. A human has a body surface area of 1.5 to 2 meters. A 1 cm thick insulation will let an operator work for about 91 minutes before heating becomes severe (+20 C). 6 cm of insulation would allow 9 hour of work outside, before needing to come in for cool air (and food + water).

Settlers might be tethered to close proximity to vehicles that can mount thicker insulation and heavier cooling units. But, they can still get outside.

Food : I'm not sure anyone has researched how plants behave in high pressures. The trimix that works fine for humans may be toxic for some breeds of plant life.

Chemistry

Industrial chemistry for manufacturing and infrastructure. Earth's chemistry is based on carbon chemistry -- particularly chemistry that happens near or at 1 atmosphere and 21 C.

You'll need to re-invent every chemical process. The dirt will be beyond sterile, it may be toxic to Earth-brought microbes. There will be a significant amount of try-fail in discovering chemistry. Until they can produce their needs, the settlement is in a slow decline.

A lot of computing power may allow simulation of conditions in faster-than-realtime. This reduces the amount of time spent figuring things out. Additionally, a lot of spare materials are essential for setting up small batch experiments, which might all fail, then tearing it all down and trying again.

The List

Needs to Be On The Ship:

  • Technology to manufacture large volumes of insulation
  • Hard suits for every worker in the labor pool, plus plenty of spares
  • Metal coatings protecting structures from the atmosphere that remain durable in that temperature and pressure
  • Sufficient computing capacity for a good guess at how to produce basic industrial chemicals in these conditions
  • Sufficiently good data on the chemistry of the planet for a good guess at conditions
  • Data on high-pressure hydroponic agriculture, and seed/plant stock that will tolerate the new conditions
  • Manufacturing to pre-build prior to landing.
  • High pressure pumps to bring the structures up to 53 atmospheres
  • Sufficient spares to keep the colony growing + maintained while industry is being set-up
  • Sufficient food to keep the colony alive while hydroponics is being set-up

On the planet:

  • Shallow mineral deposits (not much effort required to get materials until the settlement is on its feet)
  • High diversity of mineral deposits (many very different things: Sulfur, Iron, etc.) close enough to reach, and in high enough quantities to justify extraction.
  • Big difference between geothermal heating reservoir and surface.
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  • $\begingroup$ Wow! Exactly what this needs to get moving, thanks!!! Two points: would not likely need a pressure pump when ambient pressure is 80 ATM. They just need an air-tight but not pressure-tight barrier. Could be done with a pipe which filters and cools the outside air. Also, the ambient air outside and inside may provide sufficient delta T for a steam generator primary source, so digging may not be needed. Agree? $\endgroup$ – Vogon Poet Aug 14 at 20:03
  • $\begingroup$ You'll need to pressurize and depressurize the mix that people are breathing independently of the local air (which is probably toxic). You'll also need to be able to create lower pressure areas (like the gap in which insulation lives). You might be able to do something creative with outside air. As for using indoor air temperature to generate power : you'll want to be spending power to keep the heat out. I think any electricity generating operations are going to be from some "hot" reservoir outside to a "cold" reservoir, also outside. $\endgroup$ – James McLellan Aug 14 at 20:19
  • $\begingroup$ It would seem based on these facts that the first order of business would be to manufacture or have a 6kW air conditioning unit (per 700 m^2) in a 1cm thick enclosure, constructed either by environmental suit or by remote controlled robots. Once the enclosure + cooling system is constructed and operating, they can take up residence and work on expanding. The enclosure should probably be covering a mine entrance, although the ground may or may not also be extremely hot and impossible to cool $\endgroup$ – Vogon Poet Aug 14 at 20:57
  • $\begingroup$ A passable aerogel seems incredibly easy to produce if they have readily available quartz or sand and an acid (like sulphuric acid). supercritical conditions are not necessary apparently $\endgroup$ – Vogon Poet Aug 14 at 21:33
  • $\begingroup$ I’m about ready to accept this answer but I don’t understand a couple issues you suggest. The density of air inside needs to increase, so ultimately they must draw atmospheric air in. The ambient pressure is already far greater, there should be no need to pump air from high to low pressure. I believe it just needs to be scrubbed and vented in through a controlled inlet valve. The second point is the heat reservoir, which I believe could come from the atmosphere. Granted, in low density gas form it has much less enthalpy than soil, but it should be usable. Could you explain? $\endgroup$ – Vogon Poet Aug 15 at 20:52
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I don't think this would be possible with any reasonably sized craft at any reasonably advanced technological level.

Even if you could somehow handwave terraformation (a HUGE project expected to take at least decades, possibly millennia), a "normal" spacecraft won't have the tools/materials/knowledge/anything necessary for colonisation, neither for in-situ production of anything besides what they would make in-flight. They might quite easily die rather quickly ("running out of resources") on a more pleasant planet, like Mars, or even in slightly hostile places on the Earth! Upon sensing this kind of planet, they would probably just keep drifting through space hoping for someone to pick up their distress signal.

I'm presuming you want to pressurise the inside of the ship to something similar to the outside 80 atm. to protect it from being broken by the difference. I think it would be possible to survive it with low enough oxygen level (https://cdn.mos.cms.futurecdn.net/Gu9APTXv293FqfjwbW2zWf-650-80.jpg). However, there are two issues. First, even if you pre-pressurise in orbit to at least half of the target pressure, the difference is going to be WAY more than what any human ship would be designed to withstand. Normally your difference would be +1 (=earth-like to space-like), and your ship might be designed to take some more, but you're asking for at least +40 (in orbit before descending) or at least -40 (landed). Secondly, you're "running out of resources", how are you going to spend months increasing the pressure gradually? You could think about gliding through the dense atmosphere, slowly losing height, but your crew probably can't afford that either, because they're running out of resources.

The only way I can see is a huge ship with closed sustainable ecosystem and population (=able to exist in space indefinitely) and with large arsenal of tools that are usable or adjustable for mining and construction. Imagine that the ship COULD, if they decided so, stay in the orbit for as long as they want, but they ran out of unobtainium that would allow them FTL travel out of the solar system. After a few years of orbiting they decide that nobody's coming to save them and that there's not much to lose, and do the landing. Such "colonisers" could simply sit in the ship (provided it can cool itself down, which might be a challenge), and slowly (over years or decades) expand out - first they might start mining some nearby minerals, then maybe build a few "insulated" buildings connected to the ship via sealed paths, and hopefully after a long time (generations) they might be able to either build a large dome over the ship and the city that's appeared around it, or to start terraforming the planet.

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In short, why do they even bother to land? From what you said, the planet is Venus 2.0. With 70 ATM that means you got around 70 bars of pressure on the surface, which is slightly less then the 93 bars of Venus. Sorry, but there is no way to just land on Venus and survive. Even "just" 70 ATM is way too much. That's around the pressure of a 900-meter deep ocean. Most submarines can't go that deep. And even a spaceship designed for this sort of stress wont be around for too long.

All of this ignores the fact that the surface-atmosphere layer isn't fun, either. If it isn't for the acid rain, then the flying debris of volcanos or just lightning will get out.

So what would happen?

Well, they would land and be trapped in their ship. I highly doubt they could even open the doors. Imagine trying to open a car door underwater, but the water has 70 times the force. Have fun! The ship would heat up, overwhelming the cooling system in a matter of maybe days and then everyone would die.

Sorry for the English, I am German.

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    $\begingroup$ Hi Erik, thank you for the answer. The plot is well established: A crew is forced to survive on a new home with unlimited energy but almost no natural resources - not even breathable air. They must convert from their comfortable self-sustaining environment to this new home with whatever they brought, lots or raw materials, and their ingenuity. I am not looking for any plot devices. $\endgroup$ – Vogon Poet Aug 13 at 17:40
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    $\begingroup$ You know its serious business when i get called by my first name xD See what i try to tell you is that they cant survive in a realistic world. You question is equal to asking "How can i survive in a Sub 900 meter under the ocean with no option of going up ?" Like, you cant. Its game over. Only in your case, the Planet is trying its very best to get into the Ship by heating it up. Change the scenario to not be Venus. Mars works just as well. Hell even the Moon is better. $\endgroup$ – Erik Hall Aug 13 at 17:43
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    $\begingroup$ Oh god i am getting dabbed on D: But yeah i do. Mine is about an AI but you know, same same. Fuck i hate this where you press enter and bam there goes your comment. So to get back, i still think you should praise it nicer. YOu are asking strangers for help they get nothing for. So you know, thats just my POV but i feel that would be good to do $\endgroup$ – Erik Hall Aug 13 at 17:53
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    $\begingroup$ @ErikHall Vogon is right though, This forum is for people who need help building a functional world. Asking for ways to make a particular situation work is 100% on topic. It's not plot. It is science. $\endgroup$ – IT Alex Aug 14 at 15:26
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    $\begingroup$ Ok ill give you a full list of why not. docs.google.com/document/d/… There is my answer. In short, just stop trying to make it work. It cant work how you imagine it. $\endgroup$ – Erik Hall Aug 16 at 11:52
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You cant land. No I mean its physically impossible to.

I dont know the exact proportions of the various gases you listed, but assuming co2 is the most common, at that temperature and pressure it's about 63kg per m^3. If your ships weight divided by its volume is greater than 63, itll float in the atmosphere, somewhere in the pressure gradient depending on the exact ratio.

A big 40ft steel shipping container (empty weight 4200kg), will rise like a hot air balloon on this planet. (Shippong container density is 53kg/m^3). The ship wont make it all the way to the bottom unless its constantly thrusting down. When the engine turns off, it will rise, my guess probably about 10km above the surface.

Rising high in the atmosphere will give advantages like solar panels for power. You can build a thriving colony floating in cities on the clouds similar to how we'd colonise venus.

Itll be cooler and less dense up there too. Way more survivable.

Humans in weighted pressure suits with cooling systems could descend for mining, or we could send robots. However the atmosphere gives us some pretty nifty options. Co2 to oxygen via the moxie process, but more interestingly that atmosphere can be refined to give us a plastic ( https://phys.org/news/2019-02-scientists-plastics-sulfur.html ). That plastic could be used to form a floating city.

We'd need to bring resources for manufacturing and converting the atmosphere, and 3d printing from it, and enough food, water, and machines to recycle it. Anything else needed on a deep space mision wed need to start with. So meds, clothing, spare parts, computers, etc.

Long term the colony would need to exchange or mine water (or some mineral with hydrgen), as well as metals.

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Re-reading your question, I think I have an answer for you. You basically want a hot Mars.

Give up the super dense atmosphere, you can have atmosphere either somewhat "stronger" than Earth's, or somewhat weaker (maybe like Mars's, but not thinner, think of heat-shield braking), but not more than a few bar, just make its composition bad enough to be neither breathable even with superadvanced filters nor usable for combustion engines. Strong permanent cloud cover can stop most sunlight (definitely enough to make solar power unfeasible). You can tweak your atmosphere temperatures depending on the distance from their star, and day/night variations based on the atmosphere density, but it should be cooler than what you say above. Just drop the atm. pressure and temperature and all of your other points can easily stay!

When I say "hot Mars", I don't mean atmosphere, though. You want very hot core and lots of tectonic activity. That would give you your "unlimited source of power". If you want details on how the colony could proceed, just have a look at Zubrin's The Case for Mars and replace "nuclear" with "geothermal"!

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  • $\begingroup$ I didn't want to make it a part of the answer, but just like Erik Hall said above: I'm doing this for fun, so while I'm happy to share ideas, don't expect detailed lists... $\endgroup$ – BIOStheZerg Aug 14 at 15:23
  • $\begingroup$ I appreciate this but I am not trying to change the plot devices, my problem is that I have a good list but do not know everything that would be needed to bring or to be available on the planet for the plot to work. I am assuming that given the right equipment and resources, all the obstacles to survival in a place which only provides raw energy and raw materials can be overcome. Changing the planet make-up so it is less hostile fairly well destroys the entire story, nor does it help reach an answer. $\endgroup$ – Vogon Poet Aug 14 at 15:57
  • $\begingroup$ I see your point, but "Changing the planet make-up so it is less hostile" makes it possible for a modern human spaceship&crew to survive for any prolonged period of time. Think about it this way: if a modern human ship landed on our own Earth, even in a reasonable climate, they are not guaranteed to survive more than a few weeks without support from other humans. If the ship is large enough and they have a good way to get energy, your scenario is possible on gently hostile planet (such as Mars) with some "normal" suspension of disbelief. If it's Venus, they are dead before hitting the ground. $\endgroup$ – BIOStheZerg Aug 14 at 16:29
  • $\begingroup$ Thank you and this is my point: “ they are not guaranteed to survive more than a few weeks without support from other humans.” So this question is asking exactly that: what support is needed, given that they begin the journey being safe and self sufficient, but the clock is ticking on their resources. How much time do they have? By design, they have as much time as is needed to make the transition. As I included in the question, it’s ok if they take months or longer to reach the surface, but ultimately, they must do that. $\endgroup$ – Vogon Poet Aug 14 at 19:40
  • $\begingroup$ @ErikHall OK thank you very much for your effort in pointing out the challenges of getting down to a safe spot on a hot planet. You put a lot of thought into it, and I appreciate that. But I already thought of all those things. I'm sorry you got the idea that this was a "crash landing," but I clearly pointed out in the question that they can take as much time and prep as needed to reach the surface. They are not crashing, this is just the only planet they can reach. No cryo-sleep or FTL to reach another system. They're stuck, not crashing. See the difference? But your ideas are useful. $\endgroup$ – Vogon Poet Aug 17 at 1:06

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