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old title Dome heating requirements
We will be on a very cold place when we live inside the 200m diameter by approximate 120m tall parabolic dome that we will build a small settlement within capable of provide for a permanent stay on mars once fully outfitted. The piled regolith gives 2 things with the activity in radiation protection but also insulation from the cold mars.
We have humidity, scrubbing of internal air, waste management, water creation, fuel and air to breath and so many more things.
AI generated content for the questions
Calculating the exact heating wattage for a dome on Mars requires detailed engineering specifications for the dome's construction materials and internal environment, but a rough estimate based on available data suggests the heating load would be tens to hundreds of megawatts (MW), primarily due to extreme heat loss.
The key factors that make heating a challenge on Mars are: Extreme temperature difference: The average temperature on Mars is around -63°C (-82°F), with nighttime temperatures plummeting to -73°C (-100°F) or lower. Maintaining a comfortable internal temperature (e.g., 20°C or 68°F) would require a temperature differential of over 80-90°C, leading to significant heat flow out of the dome.
Minimal atmospheric insulation: The Martian atmosphere is extremely thin, about 0.6% of Earth's atmospheric pressure, and composed mostly of carbon dioxide. This provides virtually no insulating "thermal blanket," allowing heat to dissipate rapidly into space.
High heat loss: The thin atmosphere combined with the low thermal conductivity of Martian soil (which acts as a good insulator for buried sections, but means heat loss to the air is a major concern for exposed surfaces) means that any exposed surface will lose heat very quickly through a combination of convection (minimal but present) and significant radiative transfer.
Estimated Heat Loss Calculation (Conceptual) Engineers on forums and in research have made preliminary calculations based on typical construction methods and Martian conditions: One such estimate for a 150m diameter, 75m tall dome (a similar scale to yours) with a 6cm thick glass shield (an R-value of ~0.06 m²K/W) suggests a heat flux of around 2,667 W/m² during a winter night.For your 200m diameter dome, the exposed surface area would be significant (the surface area of a 200m diameter hemisphere is \(\approx 62,800\,\text{m}^{2}\)).Multiplying the area by the heat flux gives a massive heat loss in the range of 100 MW or more.
This energy demand is enormous and highlights the need for: Exceptional insulation materials (far better than a single layer of glass).Potentially burying large portions of the habitat to use the regolith as insulation.Integration of life support systems, computing, and other activities as internal heat sources to recover as much thermal energy as possible.Robust, high-efficiency power sources on Mars to meet this demand
The wattage required to heat a Mars dome depends heavily on internal temperature requirements, the specific thermal properties of the regolith, and the Mars environment. Using standard engineering formulas and typical Mars regolith properties, the estimated heating wattage for a 200m diameter, 120m tall dome with a 10m regolith barrier is likely to be in the range of several hundred kilowatts (kW) to over a megawatt (MW) to counteract heat loss.
This calculation involves several key factors:
Heat Loss Formula: The basic principle for conductive heat loss is given by Fourier's law: \(Q=(\frac{k}{t})*A*(T_{inside}-T_{outside})\).\(Q\) is the rate of heat transfer (Watts).\(k\) is the thermal conductivity of the material.\(t\) is the thickness of the insulation.\(A\) is the surface area.\(T_{inside}\) and \(T_{outside}\) are the internal and external temperatures.Key Parameters:Dome Surface Area: A dome of this size has a significant surface area exposed to the Martian environment.Thermal Conductivity (\(k\)): Martian regolith is a poor thermal conductor, with an average conductivity around 0.039 W m⁻¹ K⁻¹ in the shallow subsurface. This low conductivity is a major advantage for insulation.
Temperature Difference: Mars' surface temperatures vary widely, from around -153°C to 20°C (-225°F to 70°F). The required internal temperature for human habitation would likely be around 20°C (68°F). The external temperature would vary seasonally and daily, requiring the heating system to handle a large temperature differential, especially during Martian night and winter.
Other Factors: The presence of a CO₂ atmosphere (which increases conductivity slightly compared to a vacuum), internal air pressure, and potential ground ice or salt cementation can affect the effective thermal properties.
Estimated Wattage:
One conceptual design for a 250m diameter Mars habitat (Craterhab) lists a power input of 116 kW, though the exact shielding and internal conditions are not specified. The 10m thick regolith provides excellent insulation, but the sheer surface area of a 200m dome results in a substantial total heat loss that needs constant heating to counteract.A full engineering calculation with specific \(T_{inside}\) and minimum \(T_{outside}\) values is needed for a precise figure. The required wattage would represent a major power demand for the habitat
response after adding in waste heat from a 40 kilowatt reactor
The 40-kilowatt (kW) reactor produces a total thermal output (waste heat plus useful power) that can be harnessed. A 40 kWe (kilowatt-electric) reactor designed for Mars surface power would actually produce around 250 kW of thermal energy as waste heat, which is more than sufficient to heat the massive regolith barrier. The amount of wattage required for the regolith barrier depends entirely on the desired internal temperature of the habitat and the external Martian environmental conditions, but the available waste heat from the reactor is a substantial 250 kW.
Available Waste Heat A nuclear reactor generating 40 kWe (kilowatts of electricity) has a thermal efficiency of roughly 15-20%. Therefore, the total heat produced (\(Q_{total}\)) is significantly higher than the electrical output.
The waste heat (\(Q_{waste}\)) can be estimated as the difference between total thermal power and electrical power: Total Thermal Power: Approximately 250 kWth (kilowatts thermal).
Electrical Output: 40 kWe.Waste Heat Available: \(\approx \) 210 kW (250 kW - 40 kW). This 210 kW of heat can be passively transferred via heat pipes to the surrounding regolith. Heating Requirements & Thermal Properties The need for heating is to counteract heat loss to the extremely cold Martian environment.
Average Martian Temperature: The average surface temperature is around -63°C (210 K) but can plummet to -140°C at the poles.
Regolith Thermal Conductivity:
Martian regolith is a poor thermal conductor, with an average conductivity of approximately 0.039 W/(m·K). This low conductivity provides natural insulation. Given the immense size of the structure (200m diameter, 120m tall dome with a 10m thick barrier), the massive volume of regolith will have significant thermal mass and excellent insulating properties. The low thermal conductivity means that heat loss to the outside environment would be slow.Conclusion
The 210 kW of available waste heat from the 40 kWe nuclear reactor is ample to warm the regolith radiation barrier and likely the habitat itself, potentially even requiring a dedicated heat rejection system (radiator panels) to prevent overheating if not all the waste heat is needed for the habitat's thermal management. The primary engineering challenge would be efficiently distributing the heat throughout the large volume of the regolith barrier as needed for thermal control
I am sure Caliban can confirm this to be close to what we need and could do.
The greenhouse will add to this baseline requirement.
Massive Mars Greenhouse Effect Domes Would Heat Themselves
Talks to surface glass greenhouse structures and not really the dome we are planning.
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This post is reserved for an index to posts that may be contributed by NewMars members.
This new topic is a welcome addition to the body of knowledge that will be needed to guide development of a dome habitat on Mars.
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Bump new title making a broader possible content
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While this was started for the large dome of 200m being 120 m tall, that slowing was built over an open pit to gain regolith for brick its use is for all construction that mars requires for men to stay and thrive.
Not just for people Habitats but it also can be for a Mars Garage, Greenhouses, other Biomes ect....
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Part of this relates to the plumbing created from a starships hull
Seamless steel tubing generally offers superior strength-to-weight, as compared to rebar, so we should consider sending and using a machine to make tubing vs rebar to economize on material consumption required to build pressurized habitation volume. A tube is not stronger than a solid rod with the same external dimensions, but it is stiffer (more resistant to deformation under load) for the same mass, so tubes provide more material to satisfy a given strength and stiffness requirement than solid rods (rebar). So that ductility is not lost when cold soaked in the mildly cryogenic Martian night time temperatures, we will have to forego stronger grades of stainless in favor of austenitic stainless steels. Starships are already made from austenitic stainless steel alloys, so this is not a sourcing problem.
Austenitic steels do not "dramatically strengthen" when exposed to thermal processes used to heat treat (harden / strengthen) steels with different grain structures, such as martensitic steels. This makes them much softer and weaker than hardenable steels at room temperature, but they also do not become excessively brittle when exposed to extreme cold. All steels become much stronger at very cold temperatures, to include austenitic steels, but unlike martensitic steels, for example, austenitic steels do not become so strong and hard as to behave more like a brittle ceramic than a ductile metal like low Carbon steel at room temperature.
In steels, strength and hardness are linked together, meaning you do not get one mechanical property change without the other. You can surface vs through harden the steel, though. The excessive hardness, not the significant increase in tensile strength associated with heat treatment or exposure to cryogenic temperatures, is the problem. The austenitic 304L stainless is nominally a 28ksi Yield Strength material at room temperature, but chill it down to Martian night time temperatures and it becomes more like 100-150ksi. This tensile strength improvement also makes the steel harder, but comes at the cost of ductility and toughness. A hardenable martensitic steel like 300M (typically used in aircraft landing gear) starts out at 200ksi+ Yield Strength at room temperature. Thermal soak 300M to Martian night time temperatures and tensile strength becomes something stupidly high, in the range of 300-500ksi. If improved tensile strength was the only mechanical property change, then nobody would ever use austenitic steels for cryogenic propellant tanks. The problem is that the dramatic increase in tensile strength is accompanied by an equally dramatic increase in hardness that makes 300M behave less like steel and more like a ceramic when subjected to an impact loading. Very hard materials do not easily deform and then spring back into shape. When a steel as hard as 300M already is at room temperature, is accidentally struck by a rock after being cooled to mildly cryogenic temperatures, it will likely fracture or shatter like a ceramic pot.
We see this same behavior exhibited by very hard armor steels and high yield ship building steels at Earth-normal temperatures. When the material is struck after exposure to arctic-like temperatures, it can fracture or shatter, especially near weld lines. Ice breakers use special grades of steel in their hulls that do not become quite as strong and hard when cold soaked. The modified steel grain structure won't be as strong and hard at room temperature as "normal" ship building steels a result, but increased strength and hardness at lower temperatures partially compensates. When that is not enough, thicker hull plating is used when colder service temperatures alone do not imbue the steel hull plating with insufficient tensile strength and hardness to meet the structural requirements for the ship's hull. Ordinarily, ice breakers use thicker hull plating by default to enable them to strike and break-up surface sea ice so that commercial ships fabricated from lower cost Carbon steels can then transit arctic waters without substantial hull reinforcement and using more expensive grades of slightly weaker specialty steels.
On Mars, we have no real choice but to accept cold soaking at night, which means we need austenitic steels for construction. However, we could thermally regulate the steel tubing structure's temperature by filling it with liquid CO2 and using it as part of the colony's habitat thermal regulation radiator system. This is just an example, since the strengthening and hardening of any steel alloy is not a straight line as service temperature decreases. However, if keeping the LCO2 inside the structural tubing at a "balmy" -50F vs -100F, also managed to keep the 304L's yield strength in the 65-75ksi range, then it becomes a "more ideal" structural steel that retains greater ductility. 65ksi is about the same as annealed 4130 chrome-moly tubing used in aircraft construction, so obtaining the associated tensile strength and hardness "bump" over 304L's room temperature mechanical properties would make it very suitable for construction purposes. There's obviously a non-zero risk of a CO2 leak inside the habitat dome from using the structure this way, so other engineering considerations must be taken into account. Still, it's an interesting idea with the potential to reduce material consumption while creating a lighter but stronger structure using what is otherwise a "weak" structural steel. Perhaps it's only a suitable structural reinforcement and material economization concept for greenhouses used to grow food for the colony. This was a "work with what you got" vs "work with what you wished you had" idea, and maybe it won't work at all for any number of technical reasons.
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