16 ms·

Domes are overrated

225 points by Amorymeltzer 7y ago

packet_nerd 7y ago
I didn't see addressed in the article, what about the ground? What keeps air from leaking out through porous sand and rock?
- jmull 7y ago
  I would guess by coating the floors/ground with sealing coating (and walls and ceilings if you're underground). It might need to be nice and thick to withstand wear, but maybe not that thick depending on how tough the sealant is, how regular the surfaces and how well maintained.
angrygoat 7y ago
> In an open system, an effectively infinite supply of natural raw materials can be used, and wasted, as needed. The Mars city solves this problem by building on the surface of a planet that is made of all the raw materials it could need. It makes me sad to think that exploration and settlement of the solar system would take with it this kind of thinking, which is dangerously close to rendering the Earth uninhabitable. The Earth (and Mars...) are, in some sense, closed systems, in that exploitation of resources has a hard limit beyond which we're looking at biosphere collapse, or just plain resource exhaustion. Maybe we could use space exploration to come up with a different way, and then roll that back into how we live here on Earth.
- netcan 7y ago
  Idk... To me, terms like "exploitation of resources" tend to be overloaded with connotations to "think past" concretely. People have a big impact on our environment, and the definition of "environment" keeps ratcheting up with the scale of humanity... As the number of people, the scale of our impact, and our knowledge of this impact our definition of "our environment" expands. That's not likely to change. We're not going back to our environmental niches and we're not going to be a impact-neutral observer of "the natural environment" either. We're going to maintain our place between gods and beasts, so to speak. That doesn't mean we don't/won't evolve. There is definitely no sense and future in bluntly walking in to environmental hard-limits like climate change, biodiversity crisis or any other pressing catastrophe. But.. perfecting ourselves to the point where we've "moved beyond" resource use shaped by our wants and needs, exploitation... In any case, I think the environmental ethos of the future can be left to future people. It will inevitably be shaped our ours' mistakes, and their consequences.
- twodave 7y ago
  I think a lot of those concerns disappear once you leave Earth. What makes our planet precious is how uncommon it is. The universe is incredibly vast, yet we have not observed life on any planet but our own. So to me whatever the cost is to a planet like Mars of putting life on its surface, that cost is well worth it (the planet certainly doesn’t mind). The only ones who might be offended by this idea are us Terrans.
  - brain5ide 7y ago
    We haven't tried that much planets yet, tbh.
jefftk 7y ago
> It turns out that the main advantage of domes – no internal supports – becomes a major liability on Mars. While rigid geodesic domes on Earth are compressive structures, on Mars, a pressurized dome actually supports its own weight and then some. As a result, the structure is under tension and the dome is attempting to tear itself out of the ground. Since lifting force scales with area, while anchoring force scales with circumference, domes on Mars can’t be much wider than about 150 feet, and even then would require extensive foundation engineering.
- rimliu 7y ago
  Does it need to be more extensive than "make the very bottom ridge of the dome wider than the dome itself (some kind of "lip") and place it into the groove carved in the rock?
  - pbhjpbhj 7y ago
    I'd have thought you'd use pegs (pitons, or piles) as for tents on Earth?
  - FeepingCreature 7y ago
    Yes... Remember that there's 1 bar of atmosphere in there. 150 feet (45m) makes for a circle of 140m circumference but 1600m^2 area. Since 1 bar ~= 100_000Pa, each of that square meters has 100KN of upwards force on it, for a sum of 160MN distributed over 140m of circumference or ~1MN per meter. So assuming the mass of the dome is negligible, we're talking about the equivalent strength of holding on to a mass of about 100 metric tons (compared to Earth gravity) per meter of dome. Ie. the amount of support you need per meter is the amount that you would need on Earth to hold up 100 metric tons against gravity. That's about a Boeing 737. Per meter.
    - rimliu 7y ago
      Steel cable with a diameter of 1inch has a breaking strength of 47 tonnes. Give it a safety margin and assume it can hold 10 tonnes. So you need 10 cables per meter. So I assume in case the "lip" being just a sheet of steel it can be way thinner than 25mm. https://imgur.com/a/h92bLIp https://imgur.com/a/h92bLIp
knolax 7y ago
What happens when the tent loses pressure? Wouldn't you then need fallback supports with compressive strength? Although assuming the force exerted by pressure is at least twice that of gravity (so that pressure minus gravity is still greater than gravity by itself) the requirements for the fallback supports probably don't have to hold as much load.
- Cthulhu_ 7y ago
  The whole thing would collapse. However, given a big enough scale, it would take a long time even if there was what we would think is a big hole in it. But even then, they'd have to have a number of contingency plans; a supply of compressed air that can be manually released in case of a power outage for example.
davedx 7y ago
Casey is also quite active on Twitter, been following him for a while. Well worth a follow: https://twitter.com/CJHandmer https://twitter.com/CJHandmer
tempodox 7y ago
Buckminster Fuller would be so disappointed.
- i_feel_great 7y ago
  So would be Nader Khalili
- eternalban 7y ago
  And that makes Walther Bauersfeld doubly disappointed: https://en.wikipedia.org/wiki/Walther_Bauersfeld https://en.wikipedia.org/wiki/Walther_Bauersfeld
  - tempodox 7y ago
    For all practical purposes, the sky over Mars is its own planetarium. Until light pollution reaches Earth level, that is.
kwhitefoot 7y ago
So the solution is to tie the dome down at more points. Sounds like a distinction without (much) difference.
- abricot 7y ago
  I think the point is, if you need to tie it down anyway, why limit yourself to the dome shape.
  - Aeolun 7y ago
    I guess it’s still a dome, just a huge one!
- perilunar 7y ago
  Or you could just add weight e.g. pile some sand on the outside of the membrane — you don't actually need the tie down, just an equivalent force.
bimmer44 7y ago
I believe this post ignores the implications of increased surface level radiation (Mars does not have a protective magnetosphere). See the two articles I link below. A structure like this might make sense for a shorter mission - but considering the thought experiment asks what structure would be suitable for a long term Musk-style settlement I don't think thin ETFE would be enough. At least part of the radiation risk is temporary solar events, so perhaps you could use a slightly hardened version of ETFE as the author suggests but keep all human activity near regularly placed deep shelters to retreat to when radiation spikes are detected? https://www.esa.int/Science_Exploration/Human_and_Robotic_Exploration/The_radiation_showstopper_for_Mars_exploration https://www.esa.int/Science_Exploration/Human_and_Robotic_Ex... https://phys.org/news/2016-11-bad-mars.html https://phys.org/news/2016-11-bad-mars.html
- t3hz0r 7y ago
  I think the implication is that under this tented tensile structure you could build whatever radiation shielded (or not) structures you wanted, and this just contains the air.
  - paulryanrogers 7y ago
    Could the air become unsafe after exposure to radiation?
    - peteradio 7y ago
      Radioactive particles (dust) in air are problematic. The gas in air does not become radioactive (at least in a dangerous way) from exposure to radiation.
      - michaelt 7y ago
        If the surface of mars is exposed to radiation capable of making particles become radioactive, does that mean the surface is already radioactive? Or would this only happen to airborne dust particles, not to sand particles on the ground?
pizzaparty2 7y ago
I thought going underground was the way to go. I wasn't imagining a "pressurized tunnel" but rather a pressurized underground complex filled with tunnels and rooms (minecraft). But maybe pressurizing an underground complex with walls made out of ...Mars is more difficult than building something on the surface? Going underground seemed like it had limitless room for easy expansion. I like the authors suggestion and it does sound better than a dome but living underground seems safer to me.
- david_draco 7y ago
  Yes, it is curious that natural land features are not exploited more. You can put that city wherever you want on Mars. Cover a canyon (walls for free). Use lava tubes. Or search for any peculiar geological feature that is amendable. I don't get why the assumption is a completely flat, desert surface.
  - 9nGQluzmnq3M 7y ago
    Expandability. If you need more space in any direction, all you need to do is put up a few (high-tech) tarps, instead of excavating rock. Cities on Earth are generally not being in canyons either, even though that would give you "walls for free" as well.
    - pbhjpbhj 7y ago
      Floods and earthquakes make canyons sub-optimal for settlements on Earth too.
    - TeMPOraL 7y ago
      Keeping air in and radiation out aren't concerns on Earth, so other factors prevail in deciding where to build a settlement.
    - mdorazio 7y ago
      On the other hand, cities on Earth are very often bounded by other natural features like rivers and mountains that naturally constrain easily-usable space. On Mars it would seem to me the solution to needing more space would be the same as on Earth - build another city.
ReptileMan 7y ago
The way I would do it is send a lot of self replicating terraforming robots. That requires relatively little cargo - the only components that cannot be manifactured on mars directly are smd and processors.
- dvh 7y ago
  Show me a self replicating robot working in Arizona desert first.
  - deleted 7y ago
    [deleted]
- jacobush 7y ago
  Not that I believe we are anywhere close, but processors could be made on the moon. Maybe not modern ones, but working ones. Also if space is not a problem, quite large ones too.
- simonh 7y ago
  I have a Nobel prize and a billion dollars of VC money right here in my back pocket. All you've got to do is demonstrate your design for a self replicating general purpose constructor robot. Actually anybody's demonstrable design will do, and I'll give you a sweet cut of the VC money.
  - jtolmar 7y ago
    As reductive as "just send self-replicating robots" is, it's still potentially easier than a self-sustaining human civilization like the article is talking about. Both require building the entire set of infrastructure to build industrial infrastructure and computers. The robot approach requires that every single factory and excavator is automated* - a huge feat. The human approach requires every piece of infrastructure the robot one does, plus the infrastructure to make pressurized domes, oxygen, food, heating, etc, etc, and also requires shipping large numbers of humans through the vacuum of space - also a huge feat. I don't think it's a given that either approach is easier. * At least, automated enough that it's not bottlenecked by humans operating robot arms at a 30 minute feedback delay.
throwawaymath 7y ago
This is cool. Reading about the engineering challenges of a dome reminds me of Brunelleschi's Dome. Does anyone else have good examples of popular scifi tropes which have formed an engineering zeitgeist, but which are realistically very suboptimal?
Aeolun 7y ago
But what if someone stabs your fabric!? We could never have teenagers on Mars. You would never be able to find all the holes.
- all2 7y ago
  Except at the edges, the fabric could fly at 100+ feet. I want try this here to see how feasible it is for co trolled environmental spaces.
  - Aeolun 7y ago
    Well, yes. But there’s still a ton of edges. My initial comment was flippant, but the problem was serious. If it breaks, how would you find out?
    - all2 7y ago
      Barometric drop. Sufficiently sensored membranes would allow you to triangulate holes.
    - sfink 7y ago
      Release a bunch of balloons into the air. They'd float to the leak. If you want to get fancy, coat them with a glue that bonds to the ceiling material, and they'd fix the leak too! At least temporarily. My first thought was that they'd clog the hole automatically even without glue, but I think the pressure differential would just squeeze them through.
sornaensis 7y ago
A bit off topic but: It takes billions of dollars and many years just to construct things like subway systems in developed countries. The only way I see a mars mission happening is launching remote controlled equipment over the course of decades to the red planet and building and preparing everything as much as possible before so much as the first human arrives. I don't see any other way it happens with how expensive and risk averse we are as a society these days. And even then, the likely scenario is sending and constructing return vehicles for a very short human mission. And that's all assuming we figure out how to get people from here to there in a space ship for so many weeks in the first place! Maybe I'm just more pessimistic than the average HN user when it comes to sci fi stuff like this, I don't know. I just can't see humans investing the money to get over all these hurdles for a colony that we don't even know could work out currently-- we can't even make self sustaining habitats here on earth!
- krisoft 7y ago
  > assuming we figure out how to get people from here to there in a space ship for so many weeks in the first place! Why do you think that's an unsolved problem? Genuine question. I thought that part is a straightforward engineering problem. (A very challenging one of course. I'm not saying it's not, just one where we have a lot of previous experience. I never thought that the fundamental possibility of it is in question.)
  - sornaensis 7y ago
    Well there are no solid designs on the table for doing it. Mostly because it's a chicken and egg problem of making plans to send people somewhere they can't come back from right now. But it's far from just an engineering problem; there is a huge human element to it: For instance, we don't have a lot of experience with large groups of people in space for that long. We're talking at least 7 months each direction if they're coming back, plus waiting for the return window and executing it. That's an insane experiment in low gravity isolation that by itself hasn't been tackled-- most astronauts are only in space for 7 months at a time on average for a trip, and they need varying amounts of recovery afterward. We're talking about twice that, for an entire crew, plus time spent on the ground on mars in a lower gravity field than here on earth. Then there's the fact that the crew will need to be large to be sufficiently redundant... and that runs into the problem of having many people in a small isolated space for such a long period of time. I think the largest crews we've had up there were around 10 people. A mars mission would need enough people to prevent everyone from dying if something went wrong on the way there, the wait for the window, and the launch for the return trip, and the return trip itself. I don't think we know how many people that would take currently. I don't think we can confidently say that it's even possible until we have more experiments studying those things alone. I'm not at all an expert these are just layman opinions and observations, so if I'm off base I'd like to know. But that's how I understand just the problem of going there.
SideburnsOfDoom 7y ago
How do you contain failures to the roof, or fix them? Given that a tear would result in catastrophic depressurisation.
- allannienhuis 7y ago
  ya, you'd need multiples of these anyway, just for the redundancy. That said, it's fairly straightforward to put up separate walls that seal different compartments. The rectangular shape makes expansion and inter-zone connections a lot easier. Many air mattresses use similar techniques, and most inflatable watercraft have that redundancy.
empath75 7y ago
Starship is cool but it ain’t magic. They haven’t changed the rocket equation. It’s still going to be extraordinarily expensive to ship stuff to mars.
- jiofih 7y ago
  You’re gonna have to provide a bit more context for that challenge, considering all the information already available about it. Which figure do you think is wrong?
  - empath75 7y ago
    The completely absurd suggestion that we’re going to be shipping millions of tons of cargo to mars in this century, let alone this decade.
- theothermkn 7y ago
  The actual fuel cost to put things into orbit is quite small, on the order of $30/lb of payload. I've done this analysis on HN before, but the gist is that LOX and kerosene are about the cost of milk, and roughly as dense on average, and you need about 20-30 lbs of propellant for each lb of payload. The rest of the cost comes from labor and amortizing the launch vehicle and infrastructure. The cost floor is <stick wet finger in breeze> probably around $100 (2019 dollars) or so per pound. Not great, but not "extraordinarily expensive." This is without going to gun-assisted schemes for durable raw materials and the like. (Incidentally, this seems insane to me. It seems like you want rockets for people and fragile goods, and guns for anything that can take a few hundred to a few thousand gees or more, like steel or aluminum or water (ice) or.... But, this is just a SWAG. There could be hiccups there preventing a gun-assist cost floor much lower than that for rockets.)
StuffedParrot 7y ago
The author should read the mars trilogy. Its omission here is glaring.
crazygringo 7y ago
Very interesting read. Just curious though -- I'd always assumed domes were just a fun sci-fi illustration/trope because they look cool -- not that they were necessarily taken seriously by engineers. Is the author just responding to that sci-fi concept (same thing as, spaceships don't make a whoosh sound in space), or are there more serious Mars plans that have genuinely proposed domes? I feel like the author isn't quite clear who he's responding to. Still interesting either way.
Avshalom 7y ago
Bubbles! you get the advantage of just having to ship an inflatable skin and then you just dig out a hole some fraction of sphere, put the bubble in and then fill the dirt back inside the bubble, now it's pressure supported and anchored.
amelius 7y ago
> It’s a pitiless frozen vacuum. The Earth’s south pole in the middle of winter is closer to a beach in Hawaii than the nicest place on Mars on the nicest day of the year. Wow, on the surface pictures made by the rover, it looks like a hot desert. I understand that the lack of water causes this drastic difference in appearance, but never would have imagined the difference to be so big.
- Sharlin 7y ago
  It’s the near-vacuum, plus the radiation environment, mostly. Temperatures on Mars can rise above freezing in the tropics, on a particularly warm summer day, but the average temperature on the planet is several tens of degrees C on the negative side. The author’s point is, I believe, that even in the southern polar night a human being can survive, for a while, with stone age technology. Whereas if the atmosphere around you isn’t breathable there’s not much you can do without (literally) space age gear.
viburnum 7y ago
Why did the author go to all the trouble to write this when within their own argument it’s obvious that it’s impossible for humans to survive and flourish without Earth?
deleted 7y ago
[deleted]
awinter-py 7y ago
air bed mars here I come
foxhop 7y ago
You smell humidified latex and vinyl. You see a canopy flowing as-far-as-your-eye-can-see over a vast red desert oasis. The oasis sprawls out to form lakes, ponds, and streams and slowly terraforms the landscape. An autmosphere grows using natural systems like trees, shrubs, vines, and prairy.
Someone 7y ago
OK. Let’s assume the technology works out, and that this is realistic: > the Mars city will need teams of specialists > On Mars, SpaceX hopes to get by with “only” a million people and a lot of manufacturing automation > What is the per capita area requirement on Mars? In a future post I’ll estimate this more rigorously but I believe it’s on the order of 10,000 sqft How do you bootstrap to get there? > If a Mars base is doubling its population every launch window, then the 5000->10000 person increment So, let’s say you are such a specialist. What would entice you to sign up for one of the first flights? Given the disadvantages (a return flight will be years out, if ever in your lifetime, and those in the first 10 or so flights will have to trust that 200-ish further flights will follow) I doubt ‘fame’ and ‘adventure’ will cut it (possibly for some people, but try finding 25,000 or so for those first flights, with the restriction on getting a good mix of expertises and a good psychological mix) I can think of: - coercion by your government - Earth being wasted enough to make Mars look enticing. - lots of unmanned flights, to ensure that the first flights going there have an escape vehicle, if needed.
- tomrod 7y ago
  Assuming my family is grown (and thus my direct life responsibilities fully attended), I'd sign up. Recall the older generation that cleaned up at Fukushima.[0] These are folks that knew their activities would be uncomfortable, may cause their death, but ultimately was absolutely vital to the benefit of all mankind. This view on life is not constrained to a single culture or background. Self-sacrifice in such a way is often considered the highest pinnacle of morality -- even under the auspices of selfish genes since the act does not directly benefit descendants. Planting trees in your later years that the fruit may be enjoyed generations after. You may ask if I have any special skills. I do, but suppose I don't. In such a place you will need grunts. And I'd be happy to join in to build humanity's insurance policy to be a bit broader. [0] http://www.cnn.com/2011/WORLD/asiapcf/05/31/japan.nuclear.suicide/index.html http://www.cnn.com/2011/WORLD/asiapcf/05/31/japan.nuclear.su...
  - fastball 7y ago
    Pretty sure they'd want people in the prime of their life, not people with grown children.
baybal2 7y ago
Have the man studied engineering? I don't feel so. Too much drama for a trivial issue. Point one, if a dome is in tension, you have not put enough weight. Point two, tents are more manufacturable and robust for as long as cost is concerned. Point three, massive human space colonisation will only happen long, long after we will get manufacturing automation, automated resource extraction, automated farming, and power production to "sci-fi" levels and above. We are not even 1% done on that, and that's the biggest point. Without getting to at least 1% on that scale, the talk about even ~100 people research outposts in space are pointless. Adding to that, once humanity will reach that level, the entire idea of going to space for something we don't get on earth will look silly. Once we get robots to the point where one can get a skyscraper constructed with a single mouse click, it will likely wouldn't matter much more if that skyscraper will also have to be airtight and have life support installed.
hinkley 7y ago
The common conceit I see in these designs is trying to use a single pressure vessel instead of nested ones. Humans only need a couple PSI to avoid physical damage to skin and eyes, and if you just leave most of the nitrogen out if the air you can drop the pressure significantly, still breathe, and not set things on fire (flammability is tied to oxygen partial pressure). But even then, a single fault in the system leaks all your air out and everyone dies. Space habitats so far look more like submarines. It’s a bunch of tubes with bulkheads. But they don’t scale, and some of the biggest ones so far are in fact inflatables. If you nested inflatable structures, the forces on them are due to the pressures between the layers. You could run an outer chamber that requires a respirator, an inner one for living space, and a third for medical. An alarm system in each layer could begin capturing atmosphere in the event of a breach, with emergency venting for over pressure. You would only risk half of your air to a single failure. The Eden project uses hexagons panels that resemble a blister on bubble wrap. No accuse angles there. And why can’t you cable a dome down the same as this design? The idea of a dome is volume. If you aren’t going to build upward in the dome, why bother? Building upward avoids interfacing with the envelope. If you could work out how to construct a dome over the top of an existing dome, you wouldn’t even have to move. Just deconstruct the inner dome and begin expanding outward.
- jiofih 7y ago
  This is all covered in the last third of the essay, including nested structures, depressurization and the proposed structure has much, much higher volume than a dome.
  - hinkley 7y ago
    Does he though? Felt like a throwaway sentence to me. Also, his idea about hanging buildings from the wires is bunk. If you hang your buildings from the tensile structure that is buoyed by air and you have a rupture, now your buildings are going to collapse. Likely onto other buildings. Since his design has no compressive strength at all there is no way to address that issue. [edit] what makes it more bunk is that in order to have tall structures, the entire habitat has to be the same height as the structure, instead of placing them near apex of a hemispherical structure. So he's just doubled the volume versus a sphere. Also if you make a bubble structure that tall you have to handle the pressure on the walls. I don't see where he mentions walls at all except when talking about how dome walls suck. Not as much as trying to pressurize a rectangular pressure vessel! The only place his solution shines is in 'doming' a valley or a canyon, where a dome has a host of other problems he hasn't even covered. I can't remember if the bubbles on the Eden domes contribute strength to the structure, but I expect you could design them to do so. Then the structure begins to more resemble a bouncy castle (like the ISS inflatable hab unit).
amluto 7y ago
I would suggest a refinement. The author proposes that the vertical cables be anchored in the ground with driven piles. This ought to work, but it’s ignoring a detail: the Martian surface is presumably permeable enough to air that the bottom of the structure would need to be lined. If the bottom were strong enough (e.g. the same material as the top), then the cables could be anchored to the bottom material. No piles needed. The resulting structure would look very much like an air mattress sitting on the ground, and air mattresses don’t need to be staked down.
- samatman 7y ago
  The bottom will have to be lined anyway, because the Martian soil contains a high fraction of toxic perchlorates. This is also bad news for trying to establish any sort of agriculture.
choeger 7y ago
Question: if we build such a structure and make really high, like 200m or more, would the denser atmosphere provide significant protection against the more nasty solar radiation?
rini17 7y ago
Won't any plastic surface on Mars collect dust and thus become opaque over time? This was too a problem on a mars rover solar panel, can't remember which one.
jwilliams 7y ago
As an aside - in the Kim Stanley Robinson Red/Green/Blue Mars series, the tents are supported, rather than solely relying on pressure. This includes the use of aerogels (or "airgels") for the struts.
jacobwilliamroy 7y ago
I find the popular colonialist view of space travel problematic, because if it comes to fruition, then that means that earthlings couldn't figure out how to take care of themselves. I don't see our salvation in the destructive exploitation of other worlds.
- nickparker 7y ago
  Orbital manufacturing will pay enormous technological dividends and help take care of Earth. If you step out of the parochial world where we happen to live on this planet, the fact that every one of our manufacturing processes is built around an ambient acceleration of 10 m/s^2 is weird and limiting. Beyond the freedom from gravity, orbital manufacturing provides for absolutely perfect vibration isolation (see LISA mission for an example). Made in Space Fiber / FOMS is just the tip of the iceberg. Semiconductor fabs are going up there sooner or later.
  - jacobwilliamroy 7y ago
    Are the energy savings really enough to justify sending stuff up and bringing it back down?
    - nickparker 7y ago
      It's not about energy, it's about processes that literally don't work on Earth. See Made in Space fiber[0] for an early example - they're producing best-in-class optical fibers which can't be made on Earth because convection introduces crystalline impurities. Their value per kg is attractive enough to make this a profitable business with today's launch costs. As launch costs drop and people explore this space we're going to discover a _lot_ of such problems. Solutions / mixtures essentially don't separate in micro-g so you can grow much better crystals, smelt very high entropy alloys, do all sorts of awesome tissue engineering, etc. The vibration isolation thing is also a huge force multiplier for all this. Ultra-precision manufacturing is a game of complete and total process control. Right now we spend absurd sums on isolation systems to block vibrations from the truck driving by half a mile away. In orbit you just make sure anything with moving parts is on a separate free body from your isolated component and they fly in formation. The LISA mission is doing this to position ultra-perfect reference objects and detect gravitational waves with baselines measured in thousands of kilometers. [0]: https://madeinspace.us/capabilities-and-technology/fiber-optics/ https://madeinspace.us/capabilities-and-technology/fiber-opt...
credit_guy 7y ago
Some people wonder why we should go to Mars. There's not much to profit by going there. In terms of mining, not much is useful there, plus asteroids are easier to mine. The benefit is that a colony on Mars would be an engine of innovation. People keep pointing out that NASA has produced hundreds of useful innovations (like space blankets). Imagine how many innovations would a colony of 500 people come up with when stranded there for months and years. It's not that we send them there with only sticks and stone tools, they'll have the most advanced technology we can fit them with, but they'll still find themselves in thousands of situations where their tools will be puny compared to their problems. Some in this thread mention boring machines. Well, just after a boring machine cuts a few meters of tunnel, someone lines that tunnel with some concrete elements. Where's the concrete coming from on Mars? Oh, I guess they can make it locally. Great, where are the components coming from? I guess you can mine them locally, but you'd need to bore some tunnels for that. A bit of a chicken and egg. What if the concrete does not set exactly like on Earth, because, you know, there's not enough humidity in their air (and there's not enough air either). These guys will face millions of problems. And they'll have no choice but solve them. It's going to be awesome.
- 3fe9a03ccd14ca5 7y ago
  Couldn’t this exact same argument be made for building a colony a mile under the ocean? except, of course, that we could easily rescue those people.
- nickparker 7y ago
  Citation needed that asteroids are easier to mine. They win on arbitrarily long timelines, but they start to look a lot worse if you want ROI in under 10 years. It takes a ton of energy to reach and return from most asteroids in a sensible period of time. With unlimited time you can use various slow tricks to park them in accessible orbits, but this is a gold rush not a 100 year infrastructure project. O'Neill had it right IMO, Lunar and Martian mass drivers firing up to Lagrange points are going to win. In the early days those bodies win because you can iterate on your mining tech way, way, way faster and keep up with the falling cost curve. In the later days economies of scale win the day.
- 7y ago
Causality1 7y ago
You could use nuclear weapons to dig a bunch of upside-down domes into the ground and seal the tops. It would only take a couple of years for radioactivity to reduce to the point they could be inhabited without protective clothing.
huntertwo 7y ago
I don’t understand the dedication of resources to solving problems on Mars when we have plenty of unsolved problems that affect people that are alive today and suffering. Maybe they don’t have the allure of private profit but I think it would be much more valuable to figure out how to grow and distribute food in food insecure places than to figure out how to grow and distribute food on Mars in addition to figuring out how to get there in the first place.
- bpodgursky 7y ago
  India's space program is a huge point of pride for their country (and rightfully so). They have problems to solve. It doesn't mean that it's wrong to spend a (relatively) tiny amount of money to give people something to aspire to, and to take pride in accomplishing together. We can do two things at once. You're only focus on the space program because it's technically similar to food insecurity. But you're ignoring the 50% of the economy which is focused on -- let's be honest -- irrelevant shit. Incredible sums of money (and time and effort) go towards entertainment (hollywood), fashion, jewelry, vacations, and other luxuries. If you want to divert more resources towards solving world hunger, take it from Hollywood. You don't need to strip bare a source of inspiration that unites people and moves humanity forward.
  - huntertwo 7y ago
    It’s valid to spend money on entertainment as an individual and all economies in the world have significant portions of the productivity of their population going towards “irrelevant shit”. India spending money on a space program seems like an insignificant amount of money to me compared to their total population and is likely not enough money to solve their food problems. We agree on this part. I spend money on vapid shit every day and so do millions of other people. They’re not bad. But, total resources for a Mars colonization effort seems like an order of magnitude more expensive than a simple space program for the benefit of an order of magnitude fewer people. In addition, the capital that is contributing to these efforts (ie Bezos and Musk money) is much more concentrated and can be mobilized in a much more precise manner. I don’t see Mars colonization as a source of inspiration outside of these SV types, and that’s not a significant enough population for me to find this justifiable.
pontifier 7y ago
This is very similar to an idea I've had about terrestrial weather protection. I wanted to use square ETFE pillows filled with hydrogen and tethered down to make a flat roof over an area. Flamability is a concern, so testing is required. I think it will be fine if I fully surround each hydrogen filled pillow with nitrogen filled ones.
bovermyer 7y ago
Remind me again, why is terraforming bad?
- krapp 7y ago
  Assume it was feasible to create a breathable atmosphere on Mars - that you could just melt the polar ice like in Total Recall, and boom, instant blue skies. Ignore the radiation Mars has been bathed in over the aeons, the toxicity of the soil, the low light levels which might make photosynthesis (and, thus, an ecosystem) impossible, and the lack of a magnetic field to shield the planet from solar winds[0]. How would you keep the necessary amount of atmosphere on the planet given its small size and gravity relative to Earth? [0]https://en.wikipedia.org/wiki/Terraforming_of_Mars#Challenges_and_limitations https://en.wikipedia.org/wiki/Terraforming_of_Mars#Challenge...
  - bovermyer 7y ago
    So, it's not that it's bad, it's that it's a hard problem.

225 points by Amorymeltzer 7y ago

I didn't see addressed in the article, what about the ground? What keeps air from leaking out through porous sand and rock?

jmull 7y ago
I would guess by coating the floors/ground with sealing coating (and walls and ceilings if you're underground). It might need to be nice and thick to withstand wear, but maybe not that thick depending on how tough the sealant is, how regular the surfaces and how well maintained.

angrygoat 7y ago

> In an open system, an effectively infinite supply of natural raw materials can be used, and wasted, as needed. The Mars city solves this problem by building on the surface of a planet that is made of all the raw materials it could need. It makes me sad to think that exploration and settlement of the solar system would take with it this kind of thinking, which is dangerously close to rendering the Earth uninhabitable. The Earth (and Mars...) are, in some sense, closed systems, in that exploitation of resources has a hard limit beyond which we're looking at biosphere collapse, or just plain resource exhaustion. Maybe we could use space exploration to come up with a different way, and then roll that back into how we live here on Earth.

netcan 7y ago
Idk... To me, terms like "exploitation of resources" tend to be overloaded with connotations to "think past" concretely. People have a big impact on our environment, and the definition of "environment" keeps ratcheting up with the scale of humanity... As the number of people, the scale of our impact, and our knowledge of this impact our definition of "our environment" expands. That's not likely to change. We're not going back to our environmental niches and we're not going to be a impact-neutral observer of "the natural environment" either. We're going to maintain our place between gods and beasts, so to speak. That doesn't mean we don't/won't evolve. There is definitely no sense and future in bluntly walking in to environmental hard-limits like climate change, biodiversity crisis or any other pressing catastrophe. But.. perfecting ourselves to the point where we've "moved beyond" resource use shaped by our wants and needs, exploitation... In any case, I think the environmental ethos of the future can be left to future people. It will inevitably be shaped our ours' mistakes, and their consequences.
twodave 7y ago
I think a lot of those concerns disappear once you leave Earth. What makes our planet precious is how uncommon it is. The universe is incredibly vast, yet we have not observed life on any planet but our own. So to me whatever the cost is to a planet like Mars of putting life on its surface, that cost is well worth it (the planet certainly doesn’t mind). The only ones who might be offended by this idea are us Terrans.
- brain5ide 7y ago
  We haven't tried that much planets yet, tbh.

jefftk 7y ago

> It turns out that the main advantage of domes – no internal supports – becomes a major liability on Mars. While rigid geodesic domes on Earth are compressive structures, on Mars, a pressurized dome actually supports its own weight and then some. As a result, the structure is under tension and the dome is attempting to tear itself out of the ground. Since lifting force scales with area, while anchoring force scales with circumference, domes on Mars can’t be much wider than about 150 feet, and even then would require extensive foundation engineering.

rimliu 7y ago
Does it need to be more extensive than "make the very bottom ridge of the dome wider than the dome itself (some kind of "lip") and place it into the groove carved in the rock?
- pbhjpbhj 7y ago
  I'd have thought you'd use pegs (pitons, or piles) as for tents on Earth?
- FeepingCreature 7y ago
  Yes... Remember that there's 1 bar of atmosphere in there. 150 feet (45m) makes for a circle of 140m circumference but 1600m^2 area. Since 1 bar ~= 100_000Pa, each of that square meters has 100KN of upwards force on it, for a sum of 160MN distributed over 140m of circumference or ~1MN per meter. So assuming the mass of the dome is negligible, we're talking about the equivalent strength of holding on to a mass of about 100 metric tons (compared to Earth gravity) per meter of dome. Ie. the amount of support you need per meter is the amount that you would need on Earth to hold up 100 metric tons against gravity. That's about a Boeing 737. Per meter.
  - rimliu 7y ago
    Steel cable with a diameter of 1inch has a breaking strength of 47 tonnes. Give it a safety margin and assume it can hold 10 tonnes. So you need 10 cables per meter. So I assume in case the "lip" being just a sheet of steel it can be way thinner than 25mm. https://imgur.com/a/h92bLIp https://imgur.com/a/h92bLIp

knolax 7y ago

What happens when the tent loses pressure? Wouldn't you then need fallback supports with compressive strength? Although assuming the force exerted by pressure is at least twice that of gravity (so that pressure minus gravity is still greater than gravity by itself) the requirements for the fallback supports probably don't have to hold as much load.

Cthulhu_ 7y ago
The whole thing would collapse. However, given a big enough scale, it would take a long time even if there was what we would think is a big hole in it. But even then, they'd have to have a number of contingency plans; a supply of compressed air that can be manually released in case of a power outage for example.

davedx 7y ago

Casey is also quite active on Twitter, been following him for a while. Well worth a follow: https://twitter.com/CJHandmer https://twitter.com/CJHandmer

tempodox 7y ago

Buckminster Fuller would be so disappointed.

i_feel_great 7y ago
So would be Nader Khalili
eternalban 7y ago
And that makes Walther Bauersfeld doubly disappointed: https://en.wikipedia.org/wiki/Walther_Bauersfeld https://en.wikipedia.org/wiki/Walther_Bauersfeld
- tempodox 7y ago
  For all practical purposes, the sky over Mars is its own planetarium. Until light pollution reaches Earth level, that is.

kwhitefoot 7y ago

So the solution is to tie the dome down at more points. Sounds like a distinction without (much) difference.

abricot 7y ago
I think the point is, if you need to tie it down anyway, why limit yourself to the dome shape.
- Aeolun 7y ago
  I guess it’s still a dome, just a huge one!
perilunar 7y ago
Or you could just add weight e.g. pile some sand on the outside of the membrane — you don't actually need the tie down, just an equivalent force.

bimmer44 7y ago

I believe this post ignores the implications of increased surface level radiation (Mars does not have a protective magnetosphere). See the two articles I link below. A structure like this might make sense for a shorter mission - but considering the thought experiment asks what structure would be suitable for a long term Musk-style settlement I don't think thin ETFE would be enough. At least part of the radiation risk is temporary solar events, so perhaps you could use a slightly hardened version of ETFE as the author suggests but keep all human activity near regularly placed deep shelters to retreat to when radiation spikes are detected? https://www.esa.int/Science_Exploration/Human_and_Robotic_Exploration/The_radiation_showstopper_for_Mars_exploration https://www.esa.int/Science_Exploration/Human_and_Robotic_Ex... https://phys.org/news/2016-11-bad-mars.html https://phys.org/news/2016-11-bad-mars.html

t3hz0r 7y ago
I think the implication is that under this tented tensile structure you could build whatever radiation shielded (or not) structures you wanted, and this just contains the air.
- paulryanrogers 7y ago
  Could the air become unsafe after exposure to radiation?
  - peteradio 7y ago
    Radioactive particles (dust) in air are problematic. The gas in air does not become radioactive (at least in a dangerous way) from exposure to radiation.
    - michaelt 7y ago
      If the surface of mars is exposed to radiation capable of making particles become radioactive, does that mean the surface is already radioactive? Or would this only happen to airborne dust particles, not to sand particles on the ground?

pizzaparty2 7y ago

I thought going underground was the way to go. I wasn't imagining a "pressurized tunnel" but rather a pressurized underground complex filled with tunnels and rooms (minecraft). But maybe pressurizing an underground complex with walls made out of ...Mars is more difficult than building something on the surface? Going underground seemed like it had limitless room for easy expansion. I like the authors suggestion and it does sound better than a dome but living underground seems safer to me.

david_draco 7y ago
Yes, it is curious that natural land features are not exploited more. You can put that city wherever you want on Mars. Cover a canyon (walls for free). Use lava tubes. Or search for any peculiar geological feature that is amendable. I don't get why the assumption is a completely flat, desert surface.
- 9nGQluzmnq3M 7y ago
  Expandability. If you need more space in any direction, all you need to do is put up a few (high-tech) tarps, instead of excavating rock. Cities on Earth are generally not being in canyons either, even though that would give you "walls for free" as well.
  - pbhjpbhj 7y ago
    Floods and earthquakes make canyons sub-optimal for settlements on Earth too.
  - TeMPOraL 7y ago
    Keeping air in and radiation out aren't concerns on Earth, so other factors prevail in deciding where to build a settlement.
  - mdorazio 7y ago
    On the other hand, cities on Earth are very often bounded by other natural features like rivers and mountains that naturally constrain easily-usable space. On Mars it would seem to me the solution to needing more space would be the same as on Earth - build another city.

ReptileMan 7y ago

The way I would do it is send a lot of self replicating terraforming robots. That requires relatively little cargo - the only components that cannot be manifactured on mars directly are smd and processors.

dvh 7y ago
Show me a self replicating robot working in Arizona desert first.
- deleted 7y ago
  [deleted]
jacobush 7y ago
Not that I believe we are anywhere close, but processors could be made on the moon. Maybe not modern ones, but working ones. Also if space is not a problem, quite large ones too.
simonh 7y ago
I have a Nobel prize and a billion dollars of VC money right here in my back pocket. All you've got to do is demonstrate your design for a self replicating general purpose constructor robot. Actually anybody's demonstrable design will do, and I'll give you a sweet cut of the VC money.
- jtolmar 7y ago
  As reductive as "just send self-replicating robots" is, it's still potentially easier than a self-sustaining human civilization like the article is talking about. Both require building the entire set of infrastructure to build industrial infrastructure and computers. The robot approach requires that every single factory and excavator is automated* - a huge feat. The human approach requires every piece of infrastructure the robot one does, plus the infrastructure to make pressurized domes, oxygen, food, heating, etc, etc, and also requires shipping large numbers of humans through the vacuum of space - also a huge feat. I don't think it's a given that either approach is easier. * At least, automated enough that it's not bottlenecked by humans operating robot arms at a 30 minute feedback delay.

throwawaymath 7y ago

This is cool. Reading about the engineering challenges of a dome reminds me of Brunelleschi's Dome. Does anyone else have good examples of popular scifi tropes which have formed an engineering zeitgeist, but which are realistically very suboptimal?

Aeolun 7y ago

But what if someone stabs your fabric!? We could never have teenagers on Mars. You would never be able to find all the holes.

all2 7y ago
Except at the edges, the fabric could fly at 100+ feet. I want try this here to see how feasible it is for co trolled environmental spaces.
- Aeolun 7y ago
  Well, yes. But there’s still a ton of edges. My initial comment was flippant, but the problem was serious. If it breaks, how would you find out?
  - all2 7y ago
    Barometric drop. Sufficiently sensored membranes would allow you to triangulate holes.
  - sfink 7y ago
    Release a bunch of balloons into the air. They'd float to the leak. If you want to get fancy, coat them with a glue that bonds to the ceiling material, and they'd fix the leak too! At least temporarily. My first thought was that they'd clog the hole automatically even without glue, but I think the pressure differential would just squeeze them through.

sornaensis 7y ago

A bit off topic but: It takes billions of dollars and many years just to construct things like subway systems in developed countries. The only way I see a mars mission happening is launching remote controlled equipment over the course of decades to the red planet and building and preparing everything as much as possible before so much as the first human arrives. I don't see any other way it happens with how expensive and risk averse we are as a society these days. And even then, the likely scenario is sending and constructing return vehicles for a very short human mission. And that's all assuming we figure out how to get people from here to there in a space ship for so many weeks in the first place! Maybe I'm just more pessimistic than the average HN user when it comes to sci fi stuff like this, I don't know. I just can't see humans investing the money to get over all these hurdles for a colony that we don't even know could work out currently-- we can't even make self sustaining habitats here on earth!

krisoft 7y ago
> assuming we figure out how to get people from here to there in a space ship for so many weeks in the first place! Why do you think that's an unsolved problem? Genuine question. I thought that part is a straightforward engineering problem. (A very challenging one of course. I'm not saying it's not, just one where we have a lot of previous experience. I never thought that the fundamental possibility of it is in question.)
- sornaensis 7y ago
  Well there are no solid designs on the table for doing it. Mostly because it's a chicken and egg problem of making plans to send people somewhere they can't come back from right now. But it's far from just an engineering problem; there is a huge human element to it: For instance, we don't have a lot of experience with large groups of people in space for that long. We're talking at least 7 months each direction if they're coming back, plus waiting for the return window and executing it. That's an insane experiment in low gravity isolation that by itself hasn't been tackled-- most astronauts are only in space for 7 months at a time on average for a trip, and they need varying amounts of recovery afterward. We're talking about twice that, for an entire crew, plus time spent on the ground on mars in a lower gravity field than here on earth. Then there's the fact that the crew will need to be large to be sufficiently redundant... and that runs into the problem of having many people in a small isolated space for such a long period of time. I think the largest crews we've had up there were around 10 people. A mars mission would need enough people to prevent everyone from dying if something went wrong on the way there, the wait for the window, and the launch for the return trip, and the return trip itself. I don't think we know how many people that would take currently. I don't think we can confidently say that it's even possible until we have more experiments studying those things alone. I'm not at all an expert these are just layman opinions and observations, so if I'm off base I'd like to know. But that's how I understand just the problem of going there.

SideburnsOfDoom 7y ago

How do you contain failures to the roof, or fix them? Given that a tear would result in catastrophic depressurisation.

allannienhuis 7y ago
ya, you'd need multiples of these anyway, just for the redundancy. That said, it's fairly straightforward to put up separate walls that seal different compartments. The rectangular shape makes expansion and inter-zone connections a lot easier. Many air mattresses use similar techniques, and most inflatable watercraft have that redundancy.

empath75 7y ago

Starship is cool but it ain’t magic. They haven’t changed the rocket equation. It’s still going to be extraordinarily expensive to ship stuff to mars.

jiofih 7y ago
You’re gonna have to provide a bit more context for that challenge, considering all the information already available about it. Which figure do you think is wrong?
- empath75 7y ago
  The completely absurd suggestion that we’re going to be shipping millions of tons of cargo to mars in this century, let alone this decade.
theothermkn 7y ago
The actual fuel cost to put things into orbit is quite small, on the order of $30/lb of payload. I've done this analysis on HN before, but the gist is that LOX and kerosene are about the cost of milk, and roughly as dense on average, and you need about 20-30 lbs of propellant for each lb of payload. The rest of the cost comes from labor and amortizing the launch vehicle and infrastructure. The cost floor is <stick wet finger in breeze> probably around $100 (2019 dollars) or so per pound. Not great, but not "extraordinarily expensive." This is without going to gun-assisted schemes for durable raw materials and the like. (Incidentally, this seems insane to me. It seems like you want rockets for people and fragile goods, and guns for anything that can take a few hundred to a few thousand gees or more, like steel or aluminum or water (ice) or.... But, this is just a SWAG. There could be hiccups there preventing a gun-assist cost floor much lower than that for rockets.)

StuffedParrot 7y ago

The author should read the mars trilogy. Its omission here is glaring.

crazygringo 7y ago

Very interesting read. Just curious though -- I'd always assumed domes were just a fun sci-fi illustration/trope because they look cool -- not that they were necessarily taken seriously by engineers. Is the author just responding to that sci-fi concept (same thing as, spaceships don't make a whoosh sound in space), or are there more serious Mars plans that have genuinely proposed domes? I feel like the author isn't quite clear who he's responding to. Still interesting either way.

Avshalom 7y ago

Bubbles! you get the advantage of just having to ship an inflatable skin and then you just dig out a hole some fraction of sphere, put the bubble in and then fill the dirt back inside the bubble, now it's pressure supported and anchored.

amelius 7y ago

> It’s a pitiless frozen vacuum. The Earth’s south pole in the middle of winter is closer to a beach in Hawaii than the nicest place on Mars on the nicest day of the year. Wow, on the surface pictures made by the rover, it looks like a hot desert. I understand that the lack of water causes this drastic difference in appearance, but never would have imagined the difference to be so big.

Sharlin 7y ago
It’s the near-vacuum, plus the radiation environment, mostly. Temperatures on Mars can rise above freezing in the tropics, on a particularly warm summer day, but the average temperature on the planet is several tens of degrees C on the negative side. The author’s point is, I believe, that even in the southern polar night a human being can survive, for a while, with stone age technology. Whereas if the atmosphere around you isn’t breathable there’s not much you can do without (literally) space age gear.

viburnum 7y ago

Why did the author go to all the trouble to write this when within their own argument it’s obvious that it’s impossible for humans to survive and flourish without Earth?

deleted 7y ago

[deleted]

awinter-py 7y ago

air bed mars here I come

foxhop 7y ago

You smell humidified latex and vinyl. You see a canopy flowing as-far-as-your-eye-can-see over a vast red desert oasis. The oasis sprawls out to form lakes, ponds, and streams and slowly terraforms the landscape. An autmosphere grows using natural systems like trees, shrubs, vines, and prairy.

Someone 7y ago

OK. Let’s assume the technology works out, and that this is realistic: > the Mars city will need teams of specialists > On Mars, SpaceX hopes to get by with “only” a million people and a lot of manufacturing automation > What is the per capita area requirement on Mars? In a future post I’ll estimate this more rigorously but I believe it’s on the order of 10,000 sqft How do you bootstrap to get there? > If a Mars base is doubling its population every launch window, then the 5000->10000 person increment So, let’s say you are such a specialist. What would entice you to sign up for one of the first flights? Given the disadvantages (a return flight will be years out, if ever in your lifetime, and those in the first 10 or so flights will have to trust that 200-ish further flights will follow) I doubt ‘fame’ and ‘adventure’ will cut it (possibly for some people, but try finding 25,000 or so for those first flights, with the restriction on getting a good mix of expertises and a good psychological mix) I can think of: - coercion by your government - Earth being wasted enough to make Mars look enticing. - lots of unmanned flights, to ensure that the first flights going there have an escape vehicle, if needed.

tomrod 7y ago
Assuming my family is grown (and thus my direct life responsibilities fully attended), I'd sign up. Recall the older generation that cleaned up at Fukushima.[0] These are folks that knew their activities would be uncomfortable, may cause their death, but ultimately was absolutely vital to the benefit of all mankind. This view on life is not constrained to a single culture or background. Self-sacrifice in such a way is often considered the highest pinnacle of morality -- even under the auspices of selfish genes since the act does not directly benefit descendants. Planting trees in your later years that the fruit may be enjoyed generations after. You may ask if I have any special skills. I do, but suppose I don't. In such a place you will need grunts. And I'd be happy to join in to build humanity's insurance policy to be a bit broader. [0] http://www.cnn.com/2011/WORLD/asiapcf/05/31/japan.nuclear.suicide/index.html http://www.cnn.com/2011/WORLD/asiapcf/05/31/japan.nuclear.su...
- fastball 7y ago
  Pretty sure they'd want people in the prime of their life, not people with grown children.

baybal2 7y ago

Have the man studied engineering? I don't feel so. Too much drama for a trivial issue. Point one, if a dome is in tension, you have not put enough weight. Point two, tents are more manufacturable and robust for as long as cost is concerned. Point three, massive human space colonisation will only happen long, long after we will get manufacturing automation, automated resource extraction, automated farming, and power production to "sci-fi" levels and above. We are not even 1% done on that, and that's the biggest point. Without getting to at least 1% on that scale, the talk about even ~100 people research outposts in space are pointless. Adding to that, once humanity will reach that level, the entire idea of going to space for something we don't get on earth will look silly. Once we get robots to the point where one can get a skyscraper constructed with a single mouse click, it will likely wouldn't matter much more if that skyscraper will also have to be airtight and have life support installed.

hinkley 7y ago

The common conceit I see in these designs is trying to use a single pressure vessel instead of nested ones. Humans only need a couple PSI to avoid physical damage to skin and eyes, and if you just leave most of the nitrogen out if the air you can drop the pressure significantly, still breathe, and not set things on fire (flammability is tied to oxygen partial pressure). But even then, a single fault in the system leaks all your air out and everyone dies. Space habitats so far look more like submarines. It’s a bunch of tubes with bulkheads. But they don’t scale, and some of the biggest ones so far are in fact inflatables. If you nested inflatable structures, the forces on them are due to the pressures between the layers. You could run an outer chamber that requires a respirator, an inner one for living space, and a third for medical. An alarm system in each layer could begin capturing atmosphere in the event of a breach, with emergency venting for over pressure. You would only risk half of your air to a single failure. The Eden project uses hexagons panels that resemble a blister on bubble wrap. No accuse angles there. And why can’t you cable a dome down the same as this design? The idea of a dome is volume. If you aren’t going to build upward in the dome, why bother? Building upward avoids interfacing with the envelope. If you could work out how to construct a dome over the top of an existing dome, you wouldn’t even have to move. Just deconstruct the inner dome and begin expanding outward.

jiofih 7y ago
This is all covered in the last third of the essay, including nested structures, depressurization and the proposed structure has much, much higher volume than a dome.
- hinkley 7y ago
  Does he though? Felt like a throwaway sentence to me. Also, his idea about hanging buildings from the wires is bunk. If you hang your buildings from the tensile structure that is buoyed by air and you have a rupture, now your buildings are going to collapse. Likely onto other buildings. Since his design has no compressive strength at all there is no way to address that issue. [edit] what makes it more bunk is that in order to have tall structures, the entire habitat has to be the same height as the structure, instead of placing them near apex of a hemispherical structure. So he's just doubled the volume versus a sphere. Also if you make a bubble structure that tall you have to handle the pressure on the walls. I don't see where he mentions walls at all except when talking about how dome walls suck. Not as much as trying to pressurize a rectangular pressure vessel! The only place his solution shines is in 'doming' a valley or a canyon, where a dome has a host of other problems he hasn't even covered. I can't remember if the bubbles on the Eden domes contribute strength to the structure, but I expect you could design them to do so. Then the structure begins to more resemble a bouncy castle (like the ISS inflatable hab unit).

amluto 7y ago

I would suggest a refinement. The author proposes that the vertical cables be anchored in the ground with driven piles. This ought to work, but it’s ignoring a detail: the Martian surface is presumably permeable enough to air that the bottom of the structure would need to be lined. If the bottom were strong enough (e.g. the same material as the top), then the cables could be anchored to the bottom material. No piles needed. The resulting structure would look very much like an air mattress sitting on the ground, and air mattresses don’t need to be staked down.

samatman 7y ago
The bottom will have to be lined anyway, because the Martian soil contains a high fraction of toxic perchlorates. This is also bad news for trying to establish any sort of agriculture.

choeger 7y ago

Question: if we build such a structure and make really high, like 200m or more, would the denser atmosphere provide significant protection against the more nasty solar radiation?

rini17 7y ago

Won't any plastic surface on Mars collect dust and thus become opaque over time? This was too a problem on a mars rover solar panel, can't remember which one.

jwilliams 7y ago

As an aside - in the Kim Stanley Robinson Red/Green/Blue Mars series, the tents are supported, rather than solely relying on pressure. This includes the use of aerogels (or "airgels") for the struts.

jacobwilliamroy 7y ago

I find the popular colonialist view of space travel problematic, because if it comes to fruition, then that means that earthlings couldn't figure out how to take care of themselves. I don't see our salvation in the destructive exploitation of other worlds.

nickparker 7y ago
Orbital manufacturing will pay enormous technological dividends and help take care of Earth. If you step out of the parochial world where we happen to live on this planet, the fact that every one of our manufacturing processes is built around an ambient acceleration of 10 m/s^2 is weird and limiting. Beyond the freedom from gravity, orbital manufacturing provides for absolutely perfect vibration isolation (see LISA mission for an example). Made in Space Fiber / FOMS is just the tip of the iceberg. Semiconductor fabs are going up there sooner or later.
- jacobwilliamroy 7y ago
  Are the energy savings really enough to justify sending stuff up and bringing it back down?
  - nickparker 7y ago
    It's not about energy, it's about processes that literally don't work on Earth. See Made in Space fiber[0] for an early example - they're producing best-in-class optical fibers which can't be made on Earth because convection introduces crystalline impurities. Their value per kg is attractive enough to make this a profitable business with today's launch costs. As launch costs drop and people explore this space we're going to discover a _lot_ of such problems. Solutions / mixtures essentially don't separate in micro-g so you can grow much better crystals, smelt very high entropy alloys, do all sorts of awesome tissue engineering, etc. The vibration isolation thing is also a huge force multiplier for all this. Ultra-precision manufacturing is a game of complete and total process control. Right now we spend absurd sums on isolation systems to block vibrations from the truck driving by half a mile away. In orbit you just make sure anything with moving parts is on a separate free body from your isolated component and they fly in formation. The LISA mission is doing this to position ultra-perfect reference objects and detect gravitational waves with baselines measured in thousands of kilometers. [0]: https://madeinspace.us/capabilities-and-technology/fiber-optics/ https://madeinspace.us/capabilities-and-technology/fiber-opt...

credit_guy 7y ago

Some people wonder why we should go to Mars. There's not much to profit by going there. In terms of mining, not much is useful there, plus asteroids are easier to mine. The benefit is that a colony on Mars would be an engine of innovation. People keep pointing out that NASA has produced hundreds of useful innovations (like space blankets). Imagine how many innovations would a colony of 500 people come up with when stranded there for months and years. It's not that we send them there with only sticks and stone tools, they'll have the most advanced technology we can fit them with, but they'll still find themselves in thousands of situations where their tools will be puny compared to their problems. Some in this thread mention boring machines. Well, just after a boring machine cuts a few meters of tunnel, someone lines that tunnel with some concrete elements. Where's the concrete coming from on Mars? Oh, I guess they can make it locally. Great, where are the components coming from? I guess you can mine them locally, but you'd need to bore some tunnels for that. A bit of a chicken and egg. What if the concrete does not set exactly like on Earth, because, you know, there's not enough humidity in their air (and there's not enough air either). These guys will face millions of problems. And they'll have no choice but solve them. It's going to be awesome.

3fe9a03ccd14ca5 7y ago
Couldn’t this exact same argument be made for building a colony a mile under the ocean? except, of course, that we could easily rescue those people.
nickparker 7y ago
Citation needed that asteroids are easier to mine. They win on arbitrarily long timelines, but they start to look a lot worse if you want ROI in under 10 years. It takes a ton of energy to reach and return from most asteroids in a sensible period of time. With unlimited time you can use various slow tricks to park them in accessible orbits, but this is a gold rush not a 100 year infrastructure project. O'Neill had it right IMO, Lunar and Martian mass drivers firing up to Lagrange points are going to win. In the early days those bodies win because you can iterate on your mining tech way, way, way faster and keep up with the falling cost curve. In the later days economies of scale win the day.
7y ago

Causality1 7y ago

You could use nuclear weapons to dig a bunch of upside-down domes into the ground and seal the tops. It would only take a couple of years for radioactivity to reduce to the point they could be inhabited without protective clothing.

huntertwo 7y ago

I don’t understand the dedication of resources to solving problems on Mars when we have plenty of unsolved problems that affect people that are alive today and suffering. Maybe they don’t have the allure of private profit but I think it would be much more valuable to figure out how to grow and distribute food in food insecure places than to figure out how to grow and distribute food on Mars in addition to figuring out how to get there in the first place.

bpodgursky 7y ago
India's space program is a huge point of pride for their country (and rightfully so). They have problems to solve. It doesn't mean that it's wrong to spend a (relatively) tiny amount of money to give people something to aspire to, and to take pride in accomplishing together. We can do two things at once. You're only focus on the space program because it's technically similar to food insecurity. But you're ignoring the 50% of the economy which is focused on -- let's be honest -- irrelevant shit. Incredible sums of money (and time and effort) go towards entertainment (hollywood), fashion, jewelry, vacations, and other luxuries. If you want to divert more resources towards solving world hunger, take it from Hollywood. You don't need to strip bare a source of inspiration that unites people and moves humanity forward.
- huntertwo 7y ago
  It’s valid to spend money on entertainment as an individual and all economies in the world have significant portions of the productivity of their population going towards “irrelevant shit”. India spending money on a space program seems like an insignificant amount of money to me compared to their total population and is likely not enough money to solve their food problems. We agree on this part. I spend money on vapid shit every day and so do millions of other people. They’re not bad. But, total resources for a Mars colonization effort seems like an order of magnitude more expensive than a simple space program for the benefit of an order of magnitude fewer people. In addition, the capital that is contributing to these efforts (ie Bezos and Musk money) is much more concentrated and can be mobilized in a much more precise manner. I don’t see Mars colonization as a source of inspiration outside of these SV types, and that’s not a significant enough population for me to find this justifiable.

pontifier 7y ago

This is very similar to an idea I've had about terrestrial weather protection. I wanted to use square ETFE pillows filled with hydrogen and tethered down to make a flat roof over an area. Flamability is a concern, so testing is required. I think it will be fine if I fully surround each hydrogen filled pillow with nitrogen filled ones.

bovermyer 7y ago

Remind me again, why is terraforming bad?

krapp 7y ago
Assume it was feasible to create a breathable atmosphere on Mars - that you could just melt the polar ice like in Total Recall, and boom, instant blue skies. Ignore the radiation Mars has been bathed in over the aeons, the toxicity of the soil, the low light levels which might make photosynthesis (and, thus, an ecosystem) impossible, and the lack of a magnetic field to shield the planet from solar winds[0]. How would you keep the necessary amount of atmosphere on the planet given its small size and gravity relative to Earth? [0]https://en.wikipedia.org/wiki/Terraforming_of_Mars#Challenges_and_limitations https://en.wikipedia.org/wiki/Terraforming_of_Mars#Challenge...
- bovermyer 7y ago
  So, it's not that it's bad, it's that it's a hard problem.