{"id":1,"date":"2019-10-27T19:36:30","date_gmt":"2019-10-27T19:36:30","guid":{"rendered":"http:\/\/www.alanjacksonastronomy.com\/wordpress\/?p=1"},"modified":"2019-11-05T16:04:19","modified_gmt":"2019-11-05T23:04:19","slug":"a-better-life-underground","status":"publish","type":"post","link":"https:\/\/www.alanjacksonastronomy.com\/wordpress\/movies\/a-better-life-underground\/","title":{"rendered":"A Better Life, Underground"},"content":{"rendered":"\n

A while ago I was playing through Fallout 4 and happened to\nre-watch Deep Impact at around the same time, and it got me thinking about the\nfeasibility and logistics of constructing large-scale, long-term habitation for\npeople underground.  Some of you will\nrecognise the title as being the slogan used by the Vault-Tec Corporation of\nthe Fallout<\/em> series for the Vaults.<\/p>\n\n\n\n

The same general principles apply to both the Fallout<\/em> Vaults and the Ark complex from Deep Impact<\/em>, but they are somewhat different in scale, with the vaults of Fallout<\/em> intended to house around 1000 people each whereas the caverns constructed by the US government in Deep Impact<\/em> are intended to house 1 million people, albeit that this isn\u2019t necessarily a single massive complex.  As such I think it makes sense to start with the Vaults.<\/p>\n\n\n\n

Fallout<\/em> Vaults<\/h2>\n\n\n\n

Now, it is worth noting that in the lore of the Fallout\nuniverse the majority of the Vaults weren\u2019t actually intended to provide a\nshelter in which the inhabitants could wait out the nuclear holocaust, but were\nin fact designed around a series of bizarre and extremely unethical social\nexperiments.  These social experiments\nmostly seemed to consist of \u2018what happens if we create a society that is\nextremely unbalanced in some way or in which we have added something highly\ndetrimental or subtracted essential?\u2019 \nUnsurprisingly the near universal outcome of these experiments was that\nthe inhabitants went insane and killed each other (in either order).  I am going to intentionally ignore those and\nfocus on the smaller number of Vaults that were<\/em> actually intended as\nshelters from which their inhabitants could later emerge to re-settle the\nsurface.<\/p>\n\n\n\n

Imagining an isolated long-term habitat for around 1000 people is within reach of familiar things from the real world today, since we have submarines with complements of around 150 that can remain submerged for 6 months \u2013 limited only by their on-board food supplies.<\/p>\n\n\n\n

  • \"\"
    Flattened trees around site of Tunguska event. Leonid Kulik, 1927<\/figcaption><\/figure><\/li>
  • \"\"
    Artist’s impression of a large asteroid impact. NASA<\/figcaption><\/figure><\/li>
  • \"\"
    Mushroom cloud of the Castle Bravo weapon test. US Department of Energy<\/figcaption><\/figure><\/li><\/ul>\n\n\n\n

    Asteroid impacts and nuclear weapons, both guaranteed to ruin your day<\/p>\n\n\n\n

    What does a Vault need?<\/h3>\n\n\n\n

    Submarines are not completely closed systems, sea water is taken in regularly where it is then distilled to produce drinking water and electrolysed to produce oxygen.\u00a0 Scrubbers remove carbon dioxide from the atmosphere and wastewater is expelled into the ocean. A semi-closed system like that of a submarine is rather different from a completely closed system like Biosphere 2, and a lot simpler and easier to maintain, but I think it is a reasonable model for the Vaults.\u00a0 Filtration systems would of course be needed to remove any radioactive particles from inflowing water, but that is perfectly feasible and is actually how the in-game lore states that the water system of a Vault works.\u00a0 Indeed, this is central to the plot of the first Fallout<\/em> game.\u00a0 Unlike a submarine which is limited by being underwater a Vault could also have a similar system for air, having direct air intakes (with filtration) and outlets for maintaining a breathable atmosphere rather than the oxygen generators and carbon dioxide scrubbers a submarine works with.\u00a0 A Vault might well have a system like that of a submarine as a backup though since an air intake is more likely to be damaged by a missile strike than a water intake that could be drawing from an underground river.\u00a0 I couldn\u2019t find anything in the game lore, but I think it\u2019s reasonable to assume the atmospheric system works this way.<\/p>\n\n\n\n

    Provided that the intakes and filtration systems aren\u2019t\ndamaged, and that the nuclear reactor powering the Vault continues to function,\nthe Vault should then have an effectively unlimited water and air.  Reactors on submarines can go for over 25\nyears without being re-fuelled and it would certainly be possible to design a\nreactor to be able to last for longer than that, it would just need to be\nlarger and produce more excess power initially. \nThe one remaining problem we need to resolve then is food (strictly also\nwaste management, but a lot of that will go into making fertiliser).<\/p>\n\n\n\n

    Growing food underground<\/h3>\n\n\n\n

    The Vaults remained closed for a considerable amount of time.  In the lore of the game Vault 8 re-opened in\n2091, 14 years after the war, while Vault 76 opened in 2102, 25 years after the\nwar.  At the most extreme Vault 101 was\nintended to be a fully closed society, never re-emerging, and did remain\neffectively sealed until 2241, well over a century after the war.  Even for a 10-year period I think it would be\nfar more effective for the Vaults to grow their own food rather than try to\nrely on stored goods.<\/p>\n\n\n\n

    Being underground the Vault clearly can\u2019t rely on natural\nlight, so I looked into hydroponics and vertical farming.  Rather nicely my old home, Canada, has some\ngood examples to look at, there are quite a few remote communities in northern\nCanada (and also Alaska) where it is essentially impossible to grow food\noutside in the normal way, and where it is also difficult to ship fresh food in\nbecause of the remoteness.  As a result\nthere have been some enterprising initiatives using hydroponics systems in\ninsulated shipping containers.  The\ninformation I found suggested these containerised farms can achieve pretty\nimpressive yields, producing something like 100 kg (220 lbs) of lettuce each\nweek inside a standard shipping container (12.2×2.44×2.59 m).  From what I can find yields for potatoes,\ntomatoes and carrots (amongst others) are pretty similar to lettuce in the\nfield, but potatoes and tomatoes certainly require more vertical space than a\nlettuce, so I\u2019ll make the assumption that on average the crop yield for a\ndiversified containerised farm is about 50 kg\/week of produce.<\/p>\n\n\n\n

    I\u2019m going to presume that the Vault dwellers are vegetarian\nfor efficiency purposes, but we could probably have some chickens if we want.  So then how many people would the 50 kg\/week\nfrom our container farm feed?  Taking my\nown food consumption as a rough guide I\u2019d estimate I eat about 1 kg\/day,\nhowever I am not a vegetarian and a purely vegetarian diet has a lower calorie\ncontent per kilogram.  I\u2019ve also been\ntold that I don\u2019t eat very much.  As such\nI\u2019ll assume that our Vault dwellers eat more like 1.5-2 kg\/day.  The 50 kg\/week from our farm works out to\nabout 7 kg\/day, so 1 container farm should be able to support about 4\npeople.  To support 1000 people then we\nwould need about 250 containers.  One\nwould also need some extra space for logistics, getting new trays of plants\nready, cutting up plants being harvested, etc, so let\u2019s assume that would\nincrease the space requirement by 10% to 275 containers.  Laid out as a single layer of containers that\nwould cover an area of around 8200 square metres or 88000 square feet (also\n0.82 hectares or 2 acres for those more used to farming areas).<\/p>\n\n\n\n

    Size of the Vault<\/h3>\n\n\n\n

    The last point on how much space the farms would take up\nbrings us on to the next topic, which is how much space our Vault needs.  Somewhat ironically considering the\nhyper-capitalist society in which Vault-Tec developed the Vaults operate a bit\nlike a commune.  There is a communal\ncafeteria where everyone eats together, so the housing is more like dormitories\nthan individual apartments and I\u2019m going to say that a typical unit for a 4-person\nfamily is about 40 square metres (2 bedrooms, a common room and a bathroom),\nwhich I\u2019ll increase to 50 to account for corridors.  For 1000 people then the residential wing\nwould be about 12,500 square metres, about 1.5 times as large as the\nfarming\/hydroponics wing.  I think there\nwould want to be a central space where all of the residents could be gathered\nin one place for events, like an old village hall, which could also double as\nthe dining area.  Allowing about 1.5\nsquare metres per person (which is a rough calculation I found for restaurants)\nthat would mean we would want the event space to be about 1500 square\nmetres.  There are then going to be\nkitchens, classrooms, workshops, an infirmary, storerooms, a gym, offices, etc.  How much space that would all take up I\u2019m\nreally not sure, but as a rough estimate I\u2019m going to guess about half as much\nspace as the living quarters, so about 6,000 square metres.<\/p>\n\n\n\n

    Since we are underground what we really care about more than\nfloor area is the volume.  Conveniently\nthe 2.59 m height of a standard shipping container is also a good ceiling\nheight for the living areas so I will just assume they are the same and then\nincrease the total to 3 m to account for ducts or wiring under the floor or\nabove the ceiling.  In total then the farming\nand residential areas come to about 85,000 cubic metres.<\/p>\n\n\n\n

    Finally, there is the support apparatus of the Vault, the\nnuclear reactor, the water and air filtration systems, sewage treatment, etc.  Looking at cross-sections of nuclear\nsubmarines the reactor compartment doesn\u2019t seem to take up that large a\nfraction of the hull space, likewise the water filtration and air\nscrubbers.  I left these until last since\nthey are more volumes rather than floor areas. \nBased on looking at submarines I am going to assume that we want another\n10,000 cubic metres to house these facilities. \nRounding up for convenience that brings our total to around 100,000\ncubic metres.<\/p>\n\n\n\n

    How does that 100,000 cubic metres compare with some other\nunderground structures?  The most obvious\ndirect comparison (and what I suspect the concept of the Vaults are based on)\nis the Cheyenne Mountain Complex in the US, which just like the Vaults was\nbuilt to withstand a nuclear attack. \nSize-wise the main tunnels of the Cheyenne Mountain Complex total about\n200,000 cubic metres along with additional space in support and access tunnels\nso overall it is probably about two and half times the size we estimated for a\nVault.  That suggests to me that the\n100,000 cubic metre estimate for a Vault is pretty good.  As a comparable facility Cheyenne Mountain\nalso conveniently provides us with an estimate for how much constructing a\nVault might cost.  In 2018 dollars\nCheyenne Mountain cost about $1 billion to build.  Since the Vault has a nuclear reactor rather\nthan diesel generators, which is more expensive, I think it\u2019s reasonable to\nguess that a Vault might cost about $1 billion too.  The lore for the first Fallout game does\ncontain a reference to Vault 13 costing $645 billion (overrunning from an\noriginal budget of $400 billion), but unless the US in the Fallout<\/em>\nuniverse has experienced at least one period of very high inflation that seems\nrather off.<\/p>\n\n\n\n

    Deep Impact<\/em> Caverns<\/h2>\n\n\n\n

    In principle we could just take the calculations for the\nVault and multiply it by 1000 to get the Ark caverns for Deep Impact, but there\nare some important differences.  Firstly,\nthe Ark caverns were only intended to house people for 2 years, not over 10\nyears.  For that time span it is probably\neasier to rely on stored food than worry about the logistics of setting up\nfarms, though there might be some farming to make up shortfalls in specific\nnutrients.  For that shorter time it\nwould also be more reasonable to ask people to put up with more confined living\nquarters.  Moreover, although it might\ntake two years for enough of the ash to rain out of the atmosphere for plants\nto begin photosynthesising properly again, that doesn\u2019t mean that the people in\nthe shelter need to stay inside for 2 years. \nThe people only need to stay inside long enough for the worst of the ash\nand debris falls to subside so that tents, buildings, etc don\u2019t get buried\nunder ash.  The same would also apply to\nthe Vaults, people would only need to stay underground while the bombs were actually\nfalling, and maybe a few days to a few weeks afterwards at most.  After that initial period they could erect\ntents and pre-fabricated structures on the surface.  Even if the people didn\u2019t really want to be\non the surface they could certainly put up greenhouses and run the farms up\nthere.  In the case of the Vaults though\nI decided to stick with the times in the Fallout<\/em> lore.<\/p>\n\n\n\n

    Overall then I think that the Ark caverns would only need to\nbe about the size of 500 Vaults (about 50 million cubic metres), maybe even\nless.  The film also, wisely, chose to\nuse the limestone caves of Missouri as the basis for the Ark complex, reducing\nthe amount of excavation required as some of the caves are already very large,\nthe Cathedral Room of the Marvel Cave for example is over 500,000 cubic metres\nby itself.  In terms of costs we might\nexpect the construction of the Ark caverns to cost around $500 billion, which\nis a lot, but spread over several years would only require perhaps a third of\nthe present US military budget of nearly $700 billion to be diverted.  That would probably be enough to fall under\nPresident Beck\u2019s description of \u2018too much to hide\u2019 but still wouldn\u2019t represent\na major financial issue to the US government.<\/p>\n\n\n\n

    Nonetheless there is a major issue that is different for the\nArk caverns than for the Vaults, and that is that an asteroid impact is orders\nof magnitude more devastating than a nuclear war.  Today the US and Russia both have around 1500\nnuclear warheads, but in the far more tense times prior to the war in Fallout\nthe number of warheads around could be much higher.  Assuming that all of the warheads get\nlaunched that could be a combined yield of 100,000 megatons or more.  By comparison the asteroid in the film is\nabout the same size as the one that wiped out the dinosaurs and that impact was\na 100 million megaton event.  The\nkilometre-high tsunamis described by the film are a bit of an exaggeration, but\nnonetheless this is still far more devastating than any nuclear war could ever\nbe.<\/p>\n\n\n\n

    Taking the impact of the larger Wolf fragment as being\nanalogous to the Chicxulub impact and locating the impact site in western\nCanada as stated in the film the Ark caverns in Missouri roughly 4000 km away\nwould be in the region that is likely to experience gale- to hurricane-force\nwinds, causing severe damage to trees and structures.  This could potentially be a problem for the\nair intakes of the caverns, as could the multiple metres debris that is likely\nto rain down.  Alongside the blast wave\nin the air there is also a blast wave in the ground, something comparable to a\nmagnitude 10 earthquake.  The magnitude scale\nfor earthquakes is logarithmic in wave amplitude and the seismic energy (which\nis equal to amplitude1.5<\/sup>) will drop off roughly as the square of\ndistance from the centre, so that would be similar to a magnitude 7.3\nearthquake with an epicentre 40 km away. \nThat is a major earthquake so the caverns would need to be constructed\nwith earthquake resistance in mind.  As\nwell as thinking about the internal structures of the caverns this would also mean\nlooking at and reinforcing natural faults in the rock.  This is probably going to make construction\nof the Ark caverns several times as expensive, starting to become a major\nfinancial outlay for the US government.<\/p>\n\n\n\n

    It is also worth noting that the final sacrifice of the crew of the Messiah<\/em> in the film to destroy the Wolf fragment wouldn\u2019t actually have helped, because the rain of fragments through the atmosphere would produce enormous flash heating at the surface as they burnt up, causing massive forest fires all over North America.  Shortly after witnessing that rather spectacular display of meteors Elijah Wood would thus probably have burnt to death, though that would have been a bit of a downer ending to the film.<\/p>\n\n\n\n

    References<\/h2>\n\n\n\n