4 ms·

Lunar night being about 14 days might make that a bit more difficult for any permanent settlement. Storing 14+ days worth of <everything> is going to mean mass

Lunar night being about 14 days might make that a bit more difficult for any permanent settlement. Storing 14+ days worth of <everything> is going to mean massive amounts of storage.

mlyle 4y ago
Yup. Nuclear seems likely to be part of the solution.
schiffern 4y ago
>Storing 14+ days... is... massive ...which is why you want to be extra careful in how mass-efficient you are storing it. A tank of liquid oxygen masses only a few percent of its contents, and its contents store more chemical energy per mass than a lithium battery. Later on, insulated tanks are vastly easier to produce from lunar materials vs batteries. These are all nice leverage multipliers. MEA amine solution is made of 80% lunar-abundant elements, and stores 22% its mass in CO2.[0] Importing the amine, tanks, and extra equipment requires under 3 kg/person for energy storage, vs 34 kWh[1] of batteries. Nuclear is a popular notion, but the real-world economics don't seem to favor it. Effectiveness beats elegance,[2] apparently. [0] https://en.wikipedia.org/wiki/Amine_gas_treating https://en.wikipedia.org/wiki/Amine_gas_treating [1] https://www.nasa.gov/sites/default/files/files/Gellett_SolidStateAirPurification.pdf https://www.nasa.gov/sites/default/files/files/Gellett_Solid... [2] https://spacecraft.ssl.umd.edu/akins_laws.html https://spacecraft.ssl.umd.edu/akins_laws.html
- mlyle 4y ago
  > A tank of liquid oxygen masses only a few percent of its contents, and its contents store more chemical energy per mass than a lithium battery. Making liquid oxygen (as opposed to gaseous oxygen) is not a terribly efficient process.
  - schiffern 4y ago
    Naturally, there's a trade between LOX and pressurized oxygen gas. Reused propellant tanks of one Starship at 6 bar would hold ~14 metric tons of oxygen, enabling a continuous lunar population of over 1,000 people. The energy for compression or liquefaction isn't necessarily a show-stopper, it just works into the total energy efficiency of the storage system. Compression is nice because practical isothermal compressors are now being demonstrated.[0] Both liquefaction and compression require cooling. I do think it probably makes sense to do the thermal storage trick in reverse also, storing up a bank of "cold" at night to be used during the day. The thermal radiator panels still provide (derated) cooling in the day, but the thermal storage pool time-shifts the natural oversupply of cooling power at night. [0] https://newatlas.com/good-thinking/carnot-centrifugal-air-compressor/ https://newatlas.com/good-thinking/carnot-centrifugal-air-co...
tomrod 4y ago
Is setting up shop at the poles feasible?

Lunar night being about 14 days might make that a bit more difficult for any permanent settlement. Storing 14+ days worth of <everything> is going to mean massive amounts of storage.

mlyle 4y ago

Yup. Nuclear seems likely to be part of the solution.

schiffern 4y ago

>Storing 14+ days... is... massive ...which is why you want to be extra careful in how mass-efficient you are storing it. A tank of liquid oxygen masses only a few percent of its contents, and its contents store more chemical energy per mass than a lithium battery. Later on, insulated tanks are vastly easier to produce from lunar materials vs batteries. These are all nice leverage multipliers. MEA amine solution is made of 80% lunar-abundant elements, and stores 22% its mass in CO2.[0] Importing the amine, tanks, and extra equipment requires under 3 kg/person for energy storage, vs 34 kWh[1] of batteries. Nuclear is a popular notion, but the real-world economics don't seem to favor it. Effectiveness beats elegance,[2] apparently. [0] https://en.wikipedia.org/wiki/Amine_gas_treating https://en.wikipedia.org/wiki/Amine_gas_treating [1] https://www.nasa.gov/sites/default/files/files/Gellett_SolidStateAirPurification.pdf https://www.nasa.gov/sites/default/files/files/Gellett_Solid... [2] https://spacecraft.ssl.umd.edu/akins_laws.html https://spacecraft.ssl.umd.edu/akins_laws.html

mlyle 4y ago
> A tank of liquid oxygen masses only a few percent of its contents, and its contents store more chemical energy per mass than a lithium battery. Making liquid oxygen (as opposed to gaseous oxygen) is not a terribly efficient process.
- schiffern 4y ago
  Naturally, there's a trade between LOX and pressurized oxygen gas. Reused propellant tanks of one Starship at 6 bar would hold ~14 metric tons of oxygen, enabling a continuous lunar population of over 1,000 people. The energy for compression or liquefaction isn't necessarily a show-stopper, it just works into the total energy efficiency of the storage system. Compression is nice because practical isothermal compressors are now being demonstrated.[0] Both liquefaction and compression require cooling. I do think it probably makes sense to do the thermal storage trick in reverse also, storing up a bank of "cold" at night to be used during the day. The thermal radiator panels still provide (derated) cooling in the day, but the thermal storage pool time-shifts the natural oversupply of cooling power at night. [0] https://newatlas.com/good-thinking/carnot-centrifugal-air-compressor/ https://newatlas.com/good-thinking/carnot-centrifugal-air-co...

tomrod 4y ago

Is setting up shop at the poles feasible?