Moon’s top layer has enough oxygen to sustain 8B people for 100k years
theconversation.com
theconversation.com
> You might be familiar with this if you know about electrolysis. On Earth this process is commonly used in manufacturing, such as to produce aluminium. An electrical current is passed through a liquid form of aluminium oxide (commonly called alumina) via electrodes, to separate the aluminium from the oxygen. In this case, the oxygen is produced as a byproduct.
This is currently not the industrial reality.
Aluminum is typically produced via the Hall–Héroult process which involves a carbon source and emits CO2. (Alternative processes which only emit oxygen are possible, but presumably those are more expensive.)
https://en.wikipedia.org/wiki/Hall%E2%80%93H%C3%A9roult_proc...
It won't cause lunar warming. But it will still be a problem and require significant energy and other resources.
It's likely that it will either be impossible or prohibitively expensive to keep CO2 levels at normal Earth standards.
See also: the ISS which operates with much higher atmospheric CO2 levels (up to 5000ppm) than would be considered healthy on earth (up to 1000ppm).
I work in a very small office shed, and if I leave the door and window closed tight it will quickly get over 2000 ppm (45-60 min). At that point I'm typically feeling more tired, and a bit foggy.
By keeping the window cracked I can keep the readings down in the 800-1100 range, and I feel much better.
In particular I find I am much less groggy in the mornings, and stepping outside doesn't feel like a breath of fresh air.
The changes I made are not options for most. I have an industrial rooftop HVAC unit for a space about 5x larger than my home. The fans run continually and there is no fresh air exchange per se but part of the return duct runs through the attic which is not air-tight, more of an open cavity. I change the air filter every 3 months and keep the returns clean by vacuuming regularly. I try not to close doors to encourage circulation, and my bedroom door had an vent to the hall above it -- not sound or light proof, but doesn't restrict airflow.
The key that I've found is airflow. A closed room and a bunch of fans won't help you, but circulating the air of your entire home will make a big difference. It's important that your home breathes. An airtight home is actually very unhealthy, though heating/cooling is more efficient.
Lastly, cooking is the worst offender for poor air quality. Having a stove-top exhaust hood that actually filters and vents outside is so important. Cooking without exhaust or fresh air can easily bring the kitchen and surrounding areas near 1000ppm in under an hour. I keep my exhaust vent on more often than not and it makes a big difference. Negative air pressure is good: air is pulled in from outside.
So just curious for my own designs, how certain are you about those ppm numbers you listed?
I'm thinking that the specific CO2 concentrations matter if one wants to relate the readings to various research on human mental performance.
Also, I am finding products that seem to require an Android or iOS device to work: no. They must be independent. If they had a webserver, nice idea, but all connections should be unrequired and switchable to off.
I would have assumed CO2 from the context, but since you mentioned cars I'm wondering if you mean CO, VOCs, and/or PM32.
Unless your car has the fans off and the windows rolled up for a really long time, I'd be surprised if CO2 was something you need to worry about. Maybe if you're sleeping in it with the windows rolled up?
CO in the house is definitely a concern. If you have a fireplace, woodstove, or furnace with a properly functioning chimney, you're unlikely to run into problems AFAIK. But people die every winter because they used a propane grill, or kerosene heater, or gas stove/oven in their house without proper ventilation. Or used a wood stove with ineffective / blocked chimney. So in colder climates having a functioning CO meter seems like a no-brainer.
In the house, similar awareness could be beneficial.
But I have not yet found a decent product. It is unacceptable that one is supposed to have a Google account or similar in order to read a ruler or configure a blender.
Sometimes I've had similar lines of questioning. Where it occurs to me that something might be a risk worth addressing, and so I'd better gather data until I'm confident everything is okay or that I'll have a way to notice when the risk becomes real.
Every(?) time I've gone down that route, I later concluded that the concern really wasn't that big a deal, and that I'd just be hyper-focused on it because of anxiety or A.D.D. I.e., in the overall scheme of things, the true risks that deserve priority are pretty evident: good sleep and body weight, exercise, not smoking, keeping my finances in order, etc. I have a tendency to forget those primary issues when I start focusing on something that could, potentially, under some circumstances become a problem.
When I go down those rabbit trails, I end up reading a lot of articles, buying some unnecessary stuff from Amazon, planning for a project that realistically I'd never complete, and just worrying a lot.
If there's any takeaway from all this (for me, at least), it's "don't sweat the (probably) small stuff".
I think we shouldn't use orbital space station where space and energy is very constrained as model for lunar base (where space and energy will be quite easy to get by comparatively).
Average person breaths out ~1kg of CO2 per day or ~400 per year [1]. Corn field absorbs ~4000 kg of CO2 yearly per 1000 m2 [2]. The same 1000 m2 field will produce ~4000 ears or 320 000 kcal yearly [3][4]
Assuming 2000 kcal for average person (so 730 000 kcal yearly) - we need 2000 m2 of corn fields to produce food for that person and just 100m2 to absorb CO2 from that person. Food will be a more important constraint in a self-sustaining base.
That means if we build lunar base in the lava tubes (that are often over 300 meters wide and go on for kilometers), we can keep them self-sustainable at density of 1 person per less than 10 meters of the lava tube.
[1] https://www.nrdc.org/onearth/waiting-exhale#:~:text=So%20bre....)
[2] https://www.canr.msu.edu/news/corn_fields_help_clean_up_and_...
[3] https://www.quora.com/How-many-ears-of-sweet-corn-are-in-an-...
[4] https://www.nutritionix.com/i/usda/corn-1-ear-medium-6-0.75-...
There is a lot of very dubious math in everything from ‘amount of water consumed’ and ‘amount of carbon absorbed’, etc. which if you dig into it really doesn’t add up. This feels like one of them?
To solve this you need initial biomass (or CO2) and then after the harvest you burn or otherwise decompose everything you didn't eat to close the cycle and get your CO2 (and some of the energy) back.
The easiest way to achieve that initial CO2 concentration would probably be to bring about ~3.5 tonnes of coal per person, burn it with oxygen mined from lunar soil generating energy for your initial base-building (24 MWh of heat about 40% of which you can convert to electric energy) and capturing the resulting 8 tonnes of CO2 for agriculture.
Of course you'd bring reasonably pure carbon, not the cheap dirty stuff we dig from the ground with heavy metals and sulphur in it. Also catalyst would be needed to avoid producing carbon monoxide.
Another concern is how much volume of air we need in these tubes to keep the atmosphere breathable and suitable for enough CO2 to supply plants.
Assume the tube is a cylinder 150m in radius and 10 meter in height (height is horizontal here ;) ). That's 700 000 m3 of air which should weight about 857 500 kg. At 410.28 ppmv CO2 in air we can calculate that 0.0623240117 % of the air mass should be CO2, which is ~535 kg in that 10-meter section of the tube. This is a long way off the 8 tonnes of CO2 needed to grow the plants, but they don't want all of that CO2 at once anyway - so we store the waste plant matter from harvest and burn it slowly over the year to keep CO2 concentration in air breathable.
We could also separate the atmospheres for plants and for people to optimize CO2 ppm for each, but that makes math more complicated :)
You need about 2000 m2 of corn to feed one person over 1 year and just 100 m2 of corn will capture the CO2 exhaled by that 1 person in 1 year. Assume we live in horizontal lava tubes 300m wide, let's say 10 meters of that tube per person to have some margin of error. That's <535 kg of CO2 in air in that section of the tube and ~8000 kg of CO2 captured in corn planted there the moment before harvest.
It's doable IMHO. At least napkin math checks out.
Get plants with a more favorable Edible Carbon::Total Carbon ratio.
A plant that can be harvested continuously would also be beneficial.
The ideal plant may be something simple like grass. We can't eat it, so would need another intermediate step. Possibly Cows or Sheep. These would be grown for milk and not meat.
Also, smelting aluminium takes a lot of power. The Tiwai Point Aluminium Smelter [1] uses 13% of New Zealand's electricity to separate the aluminium and oxygen.
[1] https://en.wikipedia.org/wiki/Tiwai_Point_Aluminium_Smelter
Circumference of the moon: 10,921km
Longest power transmission line: 2,543km (Belo Monte-Rio de Janeiro transmission line, Brazil)
So it sounds quite feasible actually
But even more so near the poles, where there's no need to build transmission lines around the entire circumference to access constant sunlight. Prime real estate for moonbases!
What if the moon was just a mining and energy "moon" how amusing would that be.
Without atmosphere, you just point the panel to the sun and you'll get 100% power again regardless of how low the Sun is over the horizon.
Because ... microasteroids and co.
The missing atmosphere that gives you more light also do not protect you against countless small projectiles.
But when space is not a problem: I would just use solar foil. Not as efficient per square meter, but can cover much more area with a given volume and weight freight restraint.
They'll hit you all the same regardless of your movements. A very simple mechanical system that does a full rotation every 28 days would suffice.
If you don't need to import the solar foil from Earth, it becomes a much better alternative. Low maintenance means nobody needs to visit the surface to fix stuff.
Contrast that the asteroid materials/free space situation where the solar collector is made from a polymer film coated with thin films of metals and/or semiconductors to either reflect and concentrate or convert energy.
The title of that article suggests that oxygen is limiting but really you need 4 parts N2, Helium, SF6, or some other inert for one part of O2 if you don’t want everything to burn up. Those large airspaces in the O’Neill colonies are unrealistic for that reason.
H2O is limiting in terrestrial ecosystems and that is true in the rest of the universe. Part of the resolution of the Fermi ‘paradox’ is that most of the life in the universe is outside the frost line where a significant part of most bodies is water. Liquid water is generic in outer solar system bodies and probably some interstellar bodies where it takes tremendous luck for dry inner solar system bodies to have a thin sheen on the surface like we do.
I can picture a ‘Galileo’ on a slightly less cooked Io or more cooked Europa getting hassled by the church about the significance of oxygen in the Earth’s atmosphere. ‘Don’t you know life would be impossible without high levels of radiation?’
Consider a relatively modest 1km square patch of such a massive array. At the equator this patch will consist of panels laid out flat horizontally relative to the 'ground', with a 10m patch spaced every 10m (no gap). At 80 degrees latitude this patch will consist of panels angled up at 80 degrees in longitudinal strips. Let's say each panel is a square 10m x 10m. If the next strip towards the equator is placed 10m away from the foot of the strip 'behind' it, almost all of the strip behind will be obscured in it's shadow. In fact the strips would need to be spaced about every 60m instead of every 10m. That's 1/7th the density. Instead of 1 sq km of panel area you'd only have 0.14 sq km of panels.
It’s true that there are still short periods of darkness even at the poles, but they’re not months long like on Earth.
Further, you could still access 24 hour sunlight by building a transmission grid with multiple solar panels, but the length of the transmission lines required would be much shorter near the poles.
Of course this means seriously low temperatures as in below negative 150 range. https://svs.gsfc.nasa.gov/Gallery/moonpole.html
You get similarly extreme cold temperatures (-180C or so) anywhere on the moon during darkness, even at the equator.
There are some advantages to those temperatures being so consistent, but a compromise location is probably the better alternative.
D-He3 is the lowest temperature aneutronic fusion reaction. Not all fast neutron hardening problems go away because a small cross section of reactions will be D-D even at the higher temperature (and potentially short bursts of higher fast neutron flux if temperature control is inadequate and low). However, most of the energy comes out as fast charged particles, which is open to direct conversion. Ditching the steam cycle is a big deal in terms of plant size and weight.
The day night cycle is almost a month long which means you need extreme energy storage, but daytime temperatures go from colder than the arctic winter to past the boiling point of water. The poles don’t get as hot, but they also get months long night due to the moons axial tilt.
But no matter how you slice it, that two weeks of darkness is a problem. You're going to need nuclear power up there. Fortunately, most of the objections to it on Earth don't apply up there. Space is already a radioactive hell scape in general, there's nothing alive to kill, there's no (currently-known) mechanisms for waste to propagate anywhere you didn't originally put it, etc. etc. We know we can build fission reactors small enough to put out reasonable amounts of power and fit into a payload of a rocket, since we have vessels powered by them already.
https://en.wikipedia.org/wiki/Solar_thermal_energy#High-temp...
Don't they already handle these extremes in satellite solar panels?
That is a very good question, because larger panels would mean more mass and cost more.
So careful balancing of the factors? or a different panel formula?
The notion of temperature is quite weird on the Moon. There's no air over there, and temperature does not make sense in a vacuum. Or rather, there's some type of temperature, but it does not affect the solar panels, simply because the solar panels of countless satellites work just fine.
One could say that the 110C refers to the temperature of the regolith. But that's only if the regolith is directly exposed to the sun, which obviously will not be the case for the regolith underneath the solar panels. And even if it were the case, you can make the supports of the solar panels to be thermally insulating, and again, since there's no air, there won't be any way for the heat to travel from the regolith to the panels.
That said, there are options simply being further from the equator directly translates to lower daytime temperatures, but that also means lower subsurface temperatures. Really the point isn’t it’s impossible to use solar on the moon, just significantly more difficult than on a satellite.
Does anyone know how this compares to earth? And what amount of energy is needed to practically make some human usable oxygen?
tl;dr the earth has plenty of oxygen, it's not really a problem. Other gases are though.
Far less actually. From Wikipedia:
> The total mass of Earth's hydrosphere is about 1.4 × 10^18 tonnes, which is about 0.023% of Earth's total mass
The Earth doesn't need this because it has a breathable atmosphere, but you can just look at the oceans and ballpark figure that to about 8/10ths of their mass (the oceans, not the planet).
Mars would be a better comparison to the moon.
> Does anyone know how this compares to earth?
I'm not sure the moon needs those type of scars.
Maybe they'll find a way to use an N99 filter dome over their operations.
The progress of man seems so naturally tuned towards destructive outcomes. We bounce from one fucked up scenario to another, each one an attempt to put a band-aid on a gaping wound left by our failure to consider how our technological progress seems to leave us with ever more urgent issues to address to insure our own survival and that of our descendants. Maybe we're the virus that is learning how to defeat the planet's immune system and ultimately kill it.
https://www.space.com/34372-new-moon-craters-appearing-faste...
(Not to mention, OP was talking about large obscuring dust clouds. Not pockmarks.)
I think OP doesn't realise how big the moon is. Those asteroid impacts kick up massive plumes of smoke, but we don't really notice it because the Moon is pretty freakin big.
I'm actually a geophysicist. I do have a pretty good idea not only of how large the moon is, but of where it is in relation to earth, it's age, common rock types found there, origin theories, its effect on earth, its cultural usage down through time, etc.
In my own work I have used knowledge of tidal effects to help me correct seismic data to optimize subsurface resolution so that companies could determine whether there was a resource there that could be economically exploited.
I appreciate you taking the time to read my original post and to comment. This is exactly the sort of discussion I figured it would generate.
What value do we place on things that we have all enjoyed and marveled at? Which one or which group of us gets to speak for all of us?
I for one am glad that sentiment no longer prevails.
I've had lots of time to marvel at technology in my nearly 40 year oil and gas career. A lot of the work that I did when I started in the exploration end of that industry has now been used, even decades later, to drive exploitation in areas that I came to know and appreciate for their raw beauty and isolation. The rock cycle teaches us geoscientists (I'm a geophysicist) that time changes everything and not even the rocks are forever.
In the grand scheme of things looking down through time it appears that a case could be made for humans being only the latest one of a series of afflictions that earth has endured in the past. No doubt earth is resilient enough to survive and establish a new equilibrium should we manage to deplete enough resources here that we can no longer survive as a species, and like rats escaping a flood, hop on any interstellar flotsam available in a bid to save ourselves from our own technologically-induced suicide.
With that in mind, maybe on that journey all of our specks will find useful combinations of interstellar particulates and elements and will become the building blocks of new life somewhere else.
While the whole fiery ending here on earth may be a low spot for us collectively, you have to remember that every local minima is by definition the point after which things start looking up as the next cycle begins.
You've been here ten years, so I would think you're familiar with HN guidelines [1], but please remember:
> Please don't sneer, including at the rest of the community.
> Please respond to the strongest plausible interpretation of what someone says, not a weaker one that's easier to criticize.
Consider directing your volunteer HN moderation at that absurdity.
I actually considered this with the understanding that any dust clouds would be localized and persistent due to the lower gravity on the moon. The finest fraction of moon dust will remain suspended longer than here on earth and the absence of wind will localize the effects. This suspended dust will over time, blur our view from earth of the areas being actively exploited for minerals, oxygen, etc.
I don't see the practicality of conducting mining operations under a dome to localize and control dust so the machinery being employed will be outside any containment and when you do this on a massive scale to potentially support interplanetary travel you will raise a cloud of dust that will take a long time to settle.
I am opposed to this. Since we are two different people with different life's experiences, you don't have to be.
Thanks for adding to the discussion.
First, you have to take into account size. The smallest feature on the moon that can be seen with the naked eye is ~ 300km in diameter. IF aesthetics are your main concerns, plumes smaller than this should be no problem.
2nd, I don't agree that dust will remain suspended longer. Dust on earth is suspended in the atmosphere, which the moon lacks. On the moon, dust follows a parabolic trajectory, like a thrown rock on earth.
Last, lunar dust is the same color as the lunar surface. like a white cloud on a white background, it would be extremely difficult to differentiate.
I personally think a dust cloud on the moon would be cool, but this is beside the point.
Thanks for contributing to this discussion.
If you are not interested in engaging further on the technical question of if dust would be visible, or the relative value of aesthetics vs utility, I guess there isn't anything to discuss at all.
Suspension requires an atmosphere! All dust particles on Earth experience a 9.8 m/s² acceleration towards the surface of the Earth, but other forces from the moving gases in Earth's atmosphere around them can easily overcome that for a small particle.
All dust particles on the Moon will experience a 1.62 m/s² acceleration towards the surface of the Moon — which is lower — but there are no gases to stop them. They are on a ballistic trajectory from wherever they they were launched. They will impact the surface of the Moon in fairly short order, unless you launch the dust at orbital or escape velocity (upwards of 2 km/s in both cases).
A larger scale operation that might provide oxygen or fuel for boosters traveling away from earth might need to operate full-time for extended periods so that mining operations will be creating a cloud of dust constantly and though it may settle slowly, it will probably be detectable.
Since many of the moon mining plans involve using it as a base for operations away from earth it seems unlikely that these operations would be one and done. I think that once you prove that you can satisfy that need for fuel or air to breathe in your operations and processing that it will only ramp up with time as new uses will be discovered.
I could be wrong. It would not be the first time nor is it likely to be the last.
Longer version: https://youtu.be/JrBdYmStZJ4
That’s less then I would have guessed (cities can have tens of thousands of people/km²), but still way over the current world average (excluding water areas) of about 15/km².
They are literally scraping top layer and smelting it for aluminium with oxygen as a side product.
https://scholar.google.com/scholar?q=mining+moon+oxygen&hl=d...
The Moon is the most valuable real estate between Venus and Mars.
For safety, I'd not build it aimed directly at Earth, but require some trajectory corrections not to miss the planet. Otherwise it's just a weapon.
Everything that is in space and big enough and can be roughly guided, can be a devastating weapon.
Which is why I love the idea of peaceful space exploration and am not so happy about the latest developements to arm the space again.
When it's guided, you may be able to see it coming, see the jets for changing trajectory, and it can evade an impactor designed to turn it into a lot of smaller pieces that will burn up in the atmosphere. If it's just a rock covered in F22 paint it'll be a lot harder to see before it hits.
https://en.wikipedia.org/wiki/Mass_driver
First time I heard about it was in:
https://en.wikipedia.org/wiki/The_High_Frontier:_Human_Colon...
There is also an amazing English translation, and a blog on how it was done: https://lparchive.org/Policenauts/Update%2042/
Unless you are talking about launching it at lunar escape velocity directly at earth orbit.
Since the oxygen is in the form of oxides that need splitting, there's no reason the CO^2 can't be recycled in the same way.
So a small amount of oxygen can be recycled indefinitely, if you have the energy to do so. Food is the same. Both require small amount of material to sustain humans, and recycle indefinitely via solar energy.
The difficulty comes from sourcing building/construction materials, i.e. metals via moon-mining.
There is also some water on the moon - and some hydrogen we could use to make water.
Now we just need to deal with the temperature ranging from -173,+127 and then we can build a nice moon base.
Cuz if it’s just pure oxygen I’m pretty sure that’s not safe.
Only for growing plants, we would have to bring some or extract it somehow?
I tried to look up if nitrogen exists on the Moon, seems like it basically does not. I didn't realize how rare carbon is there either. We'd need to bring a _lot_ of things it seems.
Life needs more than oxygen. Why do we keep positioning the Moon as some sort of life boat for when we muck up Earth past the point of survivability?
"Sillicates." (Emphasis on the "ates".)
Oxygen is an integral part of most rock-forming minerals.
'Nuff said.
perhaps my perspective has been skewed over time (or this concept was lost on my naivety at the time) but now it feels like interstellar colonization is more about an escape hatch for the inevitable end of civilization on earth. we'll destroy (intentionally or not) what we have here, set up shop somewhere else and start the process all over again?
The Apollo took 51hrs to get there, unmanned missions took 4-5 days
Half the books I've read about lunar colonies would probably disagree. :D
One of the results that is really hard to avoid is that if there is a large-scale space civilization around, using the entire solar system... planets aren't really militarily defensible. Without some sort of technology like shields or something that don't seem plausible, they're just sitting ducks. Following along from there, that tends to mean that the planet-bound are going to try to be very highly controlling of the space civilization for as long as possible. They'll be torn between the high levels of wealth the space civilization is sending back down, which will rapidly become completely necessary to sustain their life style, and the fact that every ship in space is a deadly weapon. If you can get to the asteroid belt in a reasonable period of time, you can accelerate from there at a rate that is going to be uninterceptable by the time it gets to Earth.
There's a reason why there's a lot of sci-fi about the space settlers fighting Earth for independence. It's not a terribly difficult analysis to see that as a highly likely outcome. I've only sketched it here.
(As another for-instance... it becomes highly advantageous for Earth to do everything in its power to make darned sure those space colonies can't survive independently, up to and including full intelligence penetration to kill any research attempt to come up with alternate sources for hydrocarbons or nitrogen or complex manufacturing. But the economics and politics inexorably push towards doing more stuff in space for those in space, because it's a lot cheaper than the shipping costs, and as the space-bound get more wealthy and more numerous, eventually they can start smuggling equipment and find places to extract these resources even so....)
[1] https://phys.org/news/2020-05-carbon-emissions-moon-theory-b...