What could a self-sustaining lunar colony slowly lose that would ultimately prove fatal?

Question

I've got a lunar colony that was set up to be self-sustaining before a collapse of life on Earth. The colony has survived on its own for several thousand years through a period of technological regression. But now they've recovered to roughly their original technology levels, and realize that they've been slowly losing something which will soon threaten their ongoing survival. What could a colony on the lunar surface slowly lose that would ultimately prove fatal?

Some notes on their technology:

• The colony is a shielded crater about 12km across.
• They have advanced, but not magical, 3D printing technology.
• They have large solar collectors for power, but no fusion.

Some thinking so far:

• The obvious answer is oxygen, but lunar regolith is 40% oxygen so that's easy to replace.
• My understanding is that lighter elements are more likely to escape even tightly-sealed systems via atomic diffusion or simpler processes like opening and closing airlocks. So a slow loss of hydrogen (rare in lunar regolith) seems likely, especially if there's a mechanism via which it would become unbonded from water.
• Humans need a lot of trace elements to survive (zinc, magnesium, iodine, etc). Is there some process via which a key one of these would be slowly lost, no matter how carefully things are recycled? (i.e. soil is tilled to recover, air is scrubbed, etc.)
• I know certain substances exposed to space for long periods of time will degrade or chemically alter (space weathering), possibly in ways that wouldn't be easy to reverse. For instance, the flags planted on the moon are supposedly bleached of color because of ~50 years exposure to UV rays. What substances are most susceptible to this kind of degradation? I have a notion that some of these processes might cause, say, atoms to bind together into molecules that can't easily be separated back into constituent elements, but haven't found good sources with more detail. But if so, the parts of the colony exposed to vacuum/space (solar wind/flares, cosmic rays, micrometeor bombardment etc.) might be a weak point.

Answer 1

EDIT April 26, 2020 While searching through my answers for research related to another question I came across this answer. The irony that I wrote this one year ahead of the Coronavirus pandemic, which somewhat mirrored the description provided here, is unbelievable. I'd be puffing up my chest and shouting, "Why, oh why, did the world not listen to me!" but for a simple reality: who could have possibly guessed this would happen in our lifetime? well, aaronius... you couldn't have asked for better truth-is-stranger-than-fiction than the reality of today.

Immunity to Disease

Your lunar citizens live in a perfect environment! They have all the food they need, they have recycling that, frankly, removes most bacteria from their lives. Atmosphere is constantly recycled, which includes scrubbing. Water, too, is recycled, scrubbed and clean for use.

In fact, the colony has been disease-free for, well... forever.

And that is a massive risk. Disease has this nasty habit of hanging around. Stuck in some quiet, little corner of life or living until somebody moves the proverbial old stack of books in the attic out of the way and boom! you're sick.

And then everybody's sick

It isn't like everybody needs to start dying. Oh, they could. Diseases like polio, measles, etc., really aren't gone. We've simply enhanced human immunity through vaccination such that they can't get a foothold on the population anymore. If one of them peeked into the clean and controlled world of your lunar colony, it could wipe out the colony overnight.

But it really doesn't need to be that dramatic. Maybe it's just a newly mutated form of the flu. And suddenly people are having trouble getting out of bed, which means they're not maintaining and operating the closed, controlled environment. Repairs and adjustments aren't being made. And things begin to slip.

The funny thing is that doctors would be trying to fix the problem. At first it would be, "oh, this is an historical curiosity! When's the last time this happened? Here's two aspirin, you'll be all right!" Until one of them notices the problem. "Uh, Frank? You might want to take a look at this...." And then the medical community realizes the ugly truth, "uh, how are we going to stop this?"

Right up until Louise, who has an absolute genius for maintaining the ventilation systems, can't make it to work.

And then a fuse buried deep in the ventilation system blows....

And with his last breath, Louise's apprentice, who'd been buried in technical manuals and user guides for a week, says... "I think I fou...."

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Edit: The premise of this answer is that there are people today who believe we wash our hands too much. In other words, we have created an environment today that is so sanitary that we are already losing our natural immunity to many bacteria. An hermetic environment like a lunar colony would have this problem in spades because the bacteria in used resources (you should be thinking, "ewww... sewer...") requires sanitizing — and every resource is "used" (you should be thinking, "ewww... recycled bread...").

It could be said that a lunar colony (or any other hermetic colony) should actually introduce bacteria to ensure the healthy strength of the colonists (you should be thinking, "ewww... you're making people sick!"), which could actually be a rather cool aspect of a story.

If you ever saw John Travolta in The Boy in the Plastic Bubble, based on the life of David Vetter, you'll understand the problem. In fact, go read about how David Vetter died. That's the problem.

Answer 2

Materials exposed to vacuum for extended periods often become brittle and/or literally lose mass over time.

Outgassing, cold-welding, decomposition of alloys back to their constituent materials, coronal arcing due to ionization from exposure to ionizing radiation, acceleration of outgassing and decomposition again due to ionizing radiation exposure are all concerns both for metallic elements, barriers and bearings, and outgassing particularly for all plastic, polymer or latex components (seals etc) induce changes in surface interface chemistry and surface finish, and over sufficient time these would impact significant portions of the volume of a material.

Further, scratches and dings in vacuum-exposed surfaces can lead to rapidly-propagating fissures and cracks, due to thermal expansion / contraction.

Bearings will cold-weld, and even failing that, lubricants which survive well in vacuum-whetted conditions are both rare and exotic, and many of the ones which are found to work cannot take direct insolation as they will themselves offgas and change composition. Think airlocks, manipulator arms or waldoes, locking / docking clamps, wheels, rovers, et al.

All these issues can of course be dealt with individually, but en masse it means that absent new metallic components along all vacuum-exposed surfaces, they will be in serious trouble. I don't know if your thousands of years is even feasible... NASA has been studying these material science issues since the 1960's, as you can imagine, and they've a lot to say about it.

Two other issues are sublimation of solid materials as temperature climbs during insolation, and corrosion, which can be very strange and unexpected when surfaces are impacted by ATOX (see ESA paper below) - all of which support my basic contention:

Material thermal stress / embrittlement / volume & mass loss / corrosion on all vacuum exposed surface materials are the single greatest threat / risk to a longstanding Moon colony, and absent re-supply / repair would constitute a rapidly self-reinforcing series of chain-reactions leading to catastrophic enclosure failures.

1961 JPL Paper on Vacuum Exposed Materials
1969 NASA Paper on Vacuum Exposed Materials
European Space Agency Paper on Corrosion in Vacuum at LEO

Hope that helps some.

Answer 3

A non-obvious loss area would be Genetic diversity. After several thousand years of carefully controlled plant growth, and several thousand years of inbreeding, unless care was taken to maintain genetic diversity in plants and animals (including humans), a single mutated bacteria could take out a key component of the self sustaining ecosystem.

Answer 4

Volatiles like hydrogen, carbon, nitrogen, and noble gases. These elements are necessary for life and useful for industrial processes, while being difficult to replenish. Hydrogen, carbon, and even nitrogen can be used as rocket propellant which will consume these elements without any chance of recycling. They are also liable to loss through slow leakage. It is difficult to replenish these elements because they exist at parts per million concentrations in lunar regolith. This means many tons of regolith must be processed to obtain small quantities. However, we do know that permanently shadowed craters at the lunar poles at least contain water ice. It's quite possible they can contain other volatiles too. These volatiles are probably much easier to extract than the volatiles adsorped into lunar regolith. But it's quite possible that with 1000 years of continued exploitation that these deposits could run dry. It's been estimated that the Moon's north pole could have 600 million metric tons of water ice. While this seems like a lot of water, consider that we produced about 380 million metric tons of plastic in 2018. It's quite possible that with heavy extraction, these deposits could be depleted much faster than 1000 years.

Answer 5

The will to live

Survival on a lunar colony is a lot harder than here on planet earth. You are tired at the end-of-day, and the time to have and raise kids is just a little more than you can take. Population decreases until there is just not enough left for the colony to be viable/

Answer 6

Computer chips.

Computer chips are an interesting case. You can pack millions of high-end microchips into a single 1-ton storage container.

Conceivably you could store enough to provide spares and replacements for thousands of years of maintenance in a fairly small space.

Yet to actually produce more takes a huge industrial base. Chip fabs are vast collections of some of the most advanced technology on the planet with a single Fab costing north of $10 billion to build, employing many thousands of people and requiring extremes of purity of materials all requiring a vast external industrial base to produce all the rare materials, chemicals and solvent with high enough quality to be suitable.

Batteries

The problem with solar collectors on the moon... is that night on the moon lasts 2 weeks.

Sure, you get 2 weeks of solid sunlight but then you need to keep everything running for the next 2 weeks and for that you need to store enough power to run everything for 2 weeks without recharge.

As such you'd need huge energy storage systems. Batteries degrade over time and need to be replaced. If you can manufacture suitable batteries you still need to keep all the equipment for manufacturing the batteries working long term.

The nuclear material in an RTG

RTG's are incredibly simple and reliable sources of power, good for hundreds or thousands of years depending on the fuel with minimal maintenance needed.

Solar power is great during the 2 weeks of daylight on the moon but then you have the 2 weeks of long-night.

Perhaps batteries and other energy storage systems were considered non-optimal when building the base but the systems needed to survive the 2 weeks of cold and to keep the oxygen recycling are run off of a set of RTG's similar to the ones proposed by NASA.

Plutonium-238 has a half-life of 87.7 years which is a bit short... but Americium-241 can be used as a fuel and has a half-life of 432 years.

So a couple thousand years ago the facility was built with a set of Americium-241 RTG generators that could provide plentiful power throughout the long dark night on the moon... but every 432 years half the Americium decayed away.

Now the generators have about 1/20th the Americium they started with, getting worse with each long night and the facility can just barely keep everyone warm and oxygen flowing and building enough energy storage to provide for the whole colony throughout the night is no minor feat...

Answer 7

Light and thus Energy.

^{This probably will happen as a result of natural phenomena involving Earth's magnetic cycles.}

The current dust storms on the moon - referred to as "Moon Dust Fountains" that occur as a result of electrostatic levitation of tiny particles of regolith (as a consequence of being stripped of electrons by the solar wind), are due to get much much worse:

NASA scientists have suggested that Earth's magneto-tail might cause "dust storms" on the Moon by creating a potential difference between the day side and the night side.

• The Earth's magnetic field (protecting the atmosphere, preventing it being stripped by the solar wind), is diminishing:

^{Attribution: Wikipedia 2019, CCASA License}

Over the last two centuries the dipole strength has been decreasing at a rate of about 6.3% per century. At this rate of decrease, the field would be negligible in about 1600 years.

The direct consequence of this is that the strength of the wind of atmospheric gasses stripped from Earth (and thus projected at the moon during that phase of rotation) will greatly increase and create an even greater charge difference between the dark and light side of the moon (the side facing Earth). (To be fair, the charge will first diminish for several hundred years, then grow alarmingly)

This means that the abrasive dust (albeit ballistic dust that settles) will vastly increase periodically - every 1 Earth month - obscuring solar cells and vision, smothering everything on the surface. Everything will get scratched and worn away much faster - further - it will get carried away in more static-dust storms. There will be less solar energy to mend and replace worn items.

This phenomenon will reach a peak (if the secular variation continues on-trend) 1,600 years in our future. Enough of the Earth's atmosphere may remain to make the planet salvageable, but what about the moon colony?

Answer 8

Something we didn't know we needed, because we always had it.

The people who built this colony were not fools. They would know plants need boron and humans need sodium. There would be provisions to tap lunar water and generate building materials and oxygen from regolith. Carbon is precious and would be carefully conserved. There will not be holes in the recycling scheme.

Likewise genetic diversity. The builders know about inbreeding. They know that charged particles hitting the moon can cause mutations. There would be giant sperm and egg banks for diversity and molecular genetic remediations.

But what about something humans have always had and so never missed. Something that keeps humans going, but is slowly dying. And when it is gone, we will slowly die as well. I mean Gaia - the Earth.

Maybe the gestalt of all that is alive on Earth is tied to life in some way - something that has been there so long that there is no name for it. And Gaia is not going to go easy. After the humans escape the Earth there is still life; the deep things, the tenacious things. Roaches and mites, the bacteria, the fungi. And maybe this power is great enough to reach the moon - so the humans there and their dogs and corn are sustained even though they do not know that they are.

But if there is a tipping point, and when after thousands of years the last feeble weed finally dies, whatever this power is goes with it.

It would be a sad story.

Answer 9

Electronics

Electronics manufacture require a vast and complex industrial base. There is no way the Moon Base has what it takes.

They have a large store of spare parts, and things don't break all that often, but there is a limit.

Some things can be replaced in non-electronic ways. Solar panels is probably the hardest to replace.

It might be possible to 3D-print some electronics. These are going to be very bad compared to todays electronics. Think really old computers filling buildings and doing very little.

Answer 10

Phosphorus

Always a good candidate when you need an elemental bottleneck to life, phosphorus is needed in minimal quantities, but by pretty much all known life. A closed ecosystem will recycle it pretty well, as long as there is no population growth, so the lunar colony could have been fine with small reserves to compensate the inevitable losses that probably still slowly occur. But now, even without population growth (due to it being a closed environment) they realize the reserves are pretty much gone.

Now, there is phosphorus on the Moon. Probably not much on any given square kilometer, but the Moon is big. And that's where things can get interesting: we may very well be running out of it on Earth, in as little as half a century, according to some - population growth means more fertilizer needed, because of the bigger human (and support) biomass. As of now, we are mining the stuff en masse, and looking for new deposits as the old ones run out. With population growth slowing down and mining techniques getting more sophisticated, maybe we'll be fine. Or maybe not.

If there is not enough phosphorus on Earth, then we'll have to get it where it is. And the nearest source is the Moon: as diffuse as it is, it may at some point become economical to process lunar regolith in bulk for it and varied other elements. Forget the Helium-3 baloney, this is why we could have lunar harvesters.

The problem for the lunar colony is that all nearby sources of phosphorus have long been mined, both for its own reserves and for Earth. So they will have to find new sources.

A short term solution may be to, ah, decrease the colony's biomass in order to recycle its phosphorus. Hey, now we know what Soylent Green is made of...

Answer 11

It's not about what gets out, but what gets in. To survive that long, mankind will make many many trips out into the Lunar landscape to gather and process lunar regolith so that they can replace lost air and water supplies. However, regolith is extremely hazardous to human life. It's highly abrasive, nearly impossible to filter, and it builds up in the lungs causing Silicosis. Each time a lunar rover goes out to get more of the stuff, a little bit more of this fine dust comes in on the vehicle's chassis. Slowly it's concentrations build up in the air of the colony increasing the cases of respiratory ailments and early death until eventually, it kills so fast that no one can survive long enough to procreate.

Answer 12

Genetic Diversity

With the relatively small breeding population, over tens or hundreds of generations minor genetic defects could be interbred into major genetic defects. It's up to the author to determine what kinds of defects are being introduced. Based on those choices, the colony may be in danger of dying out from a single bad virus or defect induced infertility that forces birthrates too low to sustain the colony.

Answer 13

There are many things and I would like to list and explain everyone of them (as far as my knowledge goes)

1. Bone density loss.

In space astronauts have been found to lose bone density despite intense workout sessions.

Your people on lunar colony have been inside a dome for 1000s of years where gravity is 1/6th of what their bones have evolved for. Hence the bone density loss will soon make their bones too brittle and render their bodies useless.

2. Genetic diversity loss.

The reason humans have survived is genetic diversity. In the dome you built the people will obviously inbreed for 1000 of years.

Assuming average age of 60 years and age at which people make offsprings to be around 33 there will be around 30 generations from inbreeding.

Effectively finishing their genetic diversity which means a single bacteria is enough to wipe out your colony.

3. Trace metals loss (Zn, Mg,etc)

No matter how good you are recycling you always lose some of things (to be recycled) in the process. Trace metals are useful in our day to day uses and survival.

Their loss can't be compensated until your colony finds a vast reserve of these metals on moon.

4. Hydrogen and nobel gases loss.

The abundance of these gases on earth makes us too ignorant of their use.

Nobel gases are extensively used in medical fields like Radon for treatment of cancer, and arc welding uses helium,etc.

Hydrogen is maybe the cleanest source of energy after solar energy systems you have installed in the colony.

In case of any future expedition they will need hydrogen in bulk, the loss of hydrogen means they are confined to the colony forever. (Unless they use solar sails which is pretty much impossible as they have same technology as we have today).

All points I could think of.

Edit- I would like to thank everybody in comment who has corrected me. :)

Answer 14

Information.

All this time they still used the original networked computer system. The centralized datacenter had massive redundancy, but not quite infinite self-repair. During the technological regression, the redundancies failed one by one. Even at recovery, no one wanted to learn the complex system, and there was no case for building another.

I had been up forever, with not one user-facing glitch.

One fine day, that last backup failed. The system went down, permanently.

They still have computers, and are quick to crudely network them back together. But they lost their archive of information. A lot of files were recovered from the laptops, and a lot of information still existed in peoples heads, but the bulk of it was lost.

Most crucially, the manuals for the life support systems. They cannot maintain them for long without them, even at the same tech level, any more than a smart engineer could maintain the International Space Station without any reference material at all.

Answer 15

Prior answers have focused on the genetic diversity of humans. We have more bacteria in our guts than cells in our bodies. There are many bacteria on our skin. Part of our immunity and well being is due to the interaction of our bodies with those bacteria. Hunter-gatherer societies have far more diversity of bacteria. Losing genetic diversity in those bacteria will cause strange problems.

Answer 16

Their minds.

We've spent tens of thousands of years evolving to expect the sun to rise once every 24 hours, providing electromagnetic radiation filtered through our nitrogen/oxygen atmosphere, to hear the birds chirping in the morning, to smell the wind, climb the trees, and wade in the sea.

There are so many thousands of little things that we don't notice at all on Earth, simply because they're so fundamental, and seem so irrelevant. Once we've measured all the needs our bodies have, and provided that to the lunar colony, we might consider ourselves done, and not realise we missed something important.

Until the murders start.

Answer 17

Social unity and pacifity (not sure if the latter is a real world)

Basically, such a small colony relies heavily on any conflict being within society, and between two groups that are willing to discuss it out or seek peaceful options only.

If you split into two societies, or have any other conflict (between more than a couple individuals) whhich escalates to violence on both sides, your colony is doomed if the conflict/split can't be resolved ASAP.

For example, a colony might start under martial law, and then only slowly transform away from it. This could leave some privileged and unprivileged groups (military descendants vs. civilian-descendants), which so far managed to talk out their differences, but not some worker teen found some anarchists scripture in the archives and motivates other people to escalate the conflict. Maybe after some unifying figurehead dies, or just over time.

Answer 18

Genetic Integrity

Earth has the magnetosphere to keep harmful solar radiation out but the moon doesn't. This means the luna colony needs radiation protection but even with such protection, everyone if going to receive increased doses of radiation than on Earth. Every time someone goes outside, they'll receive more radiation.

All this radiation will eventually lead to genetic degradation which can accumulate in the colonists offspring leading to increased genetic diseases.

Bone Density

The reduced gravity leads to calcium loss and weaker bones and finally osteoporosis. It's would be hard to stop people from breaking bones regularly.

Answer 19

The bane of self-replication: Imperfect copying

How is this facility being maintained? By the factories 3D printing new components. Okay, so far so good. How are the factories being maintained? The factories 3D print new factory components. In particular, how are the 3D printers maintained? Replacement printers are themselves 3D printed.

The specifications on these things will not be 100% the same. This means that the capabilities of the factory will drift over time, as the collection of machinery is constantly cycled through new "generations". Effectively, you have a population that mutates over time. The 10th generation of "descendants" from the original manufactories were probably basically the same. The 1000th generation, imperfect copying repeated over and over and over, is a hunk of junk in comparison.

This wasn't a big problem before, when the people running the show knew what they were doing. They would inspect the new equipment and run it through a body of tests. If it deviates too much, the new unit is scrapped. If a bad unit somehow gets through the body of tests, they'd remove it soon after installation.

But once the collapse happened, they stopped really understanding this. They got lax. Let's suppose that much of the maintenance documentation and expertise was lost in the Great Whatever. The survivors wouldn't be able to tell that subtle problems were creeping up on them. They said 'eh, this seems to be working fine' and the level of quality gradually degraded over time. Such a long time it tooks thousands of years for anyone to notice.

When they look, they find that (for instance) the expected shelf lives of a new (say) door jamb or air filter has decayed to such a large degree that components that used to last for 10 years now have to be replaced twice a month. It just got worse so slowly nobody ever caught on.

After they notice things have gotten so bad the facility is nearly constantly in danger of catastrophic decompression (and the like) it then takes them awhile to figure out what the problem really is.

Answer 20

According to NASA, the Earth has a Schumann resonance frequency of about 7.8Hz. The humans and animals living on Earth are kind-of calibrated to this. The Moon has a different frequency, which may have either long-long term or not-that-long term serious effects, e.g. in physiology or mood.

Here are three examples:

1. The brain alpha waves are in the range of 8-12Hz. In case of "alpha blocking" occures then the subject is facing anxiety, high stress, insomnia.
2. Theta waves are between 4 to 8Hz. If you don't have enough there is again anxiety, poor emotional awareness, stress.
3. The last one is pure speculation, but your blood has magnetic properties as well, and you are currently immersed in an electromagnetic field with the above mentioned frequency. Again, I am not bio-physicits, but it is hard to believe that missing this environment on long term (10-20-30+ years) does not have any effect.