A Boring Mars Base

[Ekramer]

I am aware there is another thread on The Boring Company (TBC), but that has become mostly updates on current and future vehicular tunnel projects on Earth (which is all fine and good).  This is about how a standard 12’ TBC tunnel could be used as a Martian habitat, scalable to any desired volume.  I’ve been messing about with the idea for a while, so here goes…

The basic idea is of a spiral, one long tunnel that wraps around itself, getting larger each turn.  Short radial tunnels connect the rings of the spiral, allowing quick and easy movement around the tunnel system.  The central ring becomes the main corridor, with compartments in the inner and outer rings accessed via radial corridors on each end.
 
The picture below shows the general layout of one inner ring and two outer rings, with eight radial corridors.   Each ring has eight compartments with two units each.  Units have various facilities such as housing, fitness, healthcare, offices, laboratories, workshops, maybe even a farm.  I don’t know the minimum turning radius of a TBM, but what is shown is probably too tight.  Consider it a ‘condensed’ version for illustration only. 

 For size comparison:
- Mars base shown is 420’ across at its widest point (excluding ramps)
- Star Trek, The Next Generation (Enterprise NCC-1701-D) saucer is 1,460 feet x 1,210 feet
- The Pentagon is 1,400 feet from midpoint on one side to opposite vertex

[Ekramer]

Construction begins with a boring machine on the surface making a curving ramp down to the required depth.  It levels off and bores increasing radius semi-circles before ramping back up to the surface.  A smaller machine makes the 8’ radial corridors connecting the rings.

Prefabricated airlocks are installed at the bottom of each ramp, and another at the far end of the garage.  Surface equipment can be brought down into the garage to be worked on in a pressurised environment.  The ramps themselves remain unpressurised, so they do not need extra reinforcement near the surface.  The top of the ramps are protected from dust storms by simple tents.

Directly below the main tunnel, an 8’ Jefferies tube allows life support and other infrastructure to be maintained without interfering with the main habitat.   Each compartment is connected to the Jefferies tube by a 4’ wide shaft.  The Jefferies tubes have 4’ wide connecting tunnels.

Prefabricated surface modules connect to the base via shafts.  The modules are sized to be transported on Starship, and then easily moved to their final location on the surface.  These modules allow immediate access to outside views without the fuss of donning a spacesuit. 
Some modules are used to control surface activity and some for crew to relax and socialise while taking in spectacular Martian landscapes.  Railroad dome cars are similar in size. 

https://www.google.com/search?udm=2&q=train+dome+car+interior

[Ekramer]

Compartments in the base have a verity of uses.  It turns out a 12’ diameter tunnel is a versatile size for human habitation.  Headroom can be traded for floorspace.  A floor 9’ wide has 10’ headroom, while a 10’ wide floor has 9’ headroom, and 11’ wide will be 8’ high.  Services are routed under the floor to the Jefferies tube below.  Fixtures and furnishings are flat packed for shipment and assembled by robots. 

Interiors with similar size constraints include trains, river boats, RV coaches, and private jets.  A Boing 737 has a 12’ diameter fuselage, a canal boat is 12’ at its widest, railroad carriages are 10’ to 11’ wide.   Motorhomes are 8’ wide, with slide-outs that extend the width to 10’, 12’ or 14’ for certain sections.  Humans have long experience designing comfortable, even luxurious interiors in similar size volumes as a TBC tunnel. 

https://skystyle-design.com/projects/concept-genesis
https://www.google.com/search?udm=2&q=widebeam+interior
https://www.google.com/search?udm=2&q=sleeper+carriage+interior https://www.google.com/search?udm=2&q=RV+coach+interior

Shown below are cabins for crew, officers, and commander.  Compartments will probably be longer than the 50-foot shown, so this is ‘worse case’.  I have ignored ring curvature due to my limited drawing skills, but tunnel curvature is shown.  Other facilities can likewise be designed in the space allotted.

[Ekramer]

A larger base is shown below.  Still smaller than the Pentagon or the Enterprise, but offering 2.5 miles of pressurised tunnel.  The base has a central corridor with two inner and two outer rings, plus straight sections linking the curved sections.  The central corridor would take about ten minutes to walk around. 

Is this a better shape than a spiral?  Would a third inner and/or outer ring make the central corridor too busy?  Would it be better to have one bigger base or two side by side?  For example, a mirror image of this one linked by the radial corridors at the top.  Airlocks could protect each base from catastrophic failure of the other.  There are many possibilities.

Various small pre-fab domes are shown, and one large dome.  At Gardens By The Bay in Singapore there is a Cloud Forest dome (link below).  It is a spectacular piece of engineering and a beautiful botanical wonder.  The Mars base below shows a dome of the same size, all within a 5-minute walk of any part of the base.  I expect Martians will not behold such a sight for many decades, but one can dream.

Cloud Forest, Singapore: https://www.google.com/maps/place//@1.2840661,103.8654794,335m

[Ekramer]

The first base on Mars will be joined by others to form a campus.  Habitats can be connected directly to each other or to an inter-habitat tunnel.  There will be different sizes and shapes depending on function.  Eventually, an 18-foot diameter boring machine will be transported to Mars, allowing for upper and lower floors in the tunnel, with larger open spaces.  A 26’ tunnel allows for three floors, and a 35’ tunnel allows four floors.  The basic architecture allows for huge flexibility as technology advances and experience is gained in this new environment.

Over time large surface structures will be constructed, including huge domes containing resorts and theme parks.  However, construction projects of such magnitude and complexity will be a huge undertaking on Mars.  Building an empty pressurised dome must be followed by multiple major construction projects within the dome.  Like on earth, each structure within the dome will have unique engineering, construction and maintenance challenges.

Existing SpaceX graphics of their Mars city show a chaotic series of small structures, some connected by pressurised walkways and some isolated.  Moving around that city requires at least some outside activity, with all the hassle and danger that entails.  Constructing such a city requires heavy equipment and a dedicated team of skilled builders operating in low gravity and a near vacuum. 

The challenge of automating the tunnelling process here on Earth is smaller than the complexity needed for surface construction on Mars.  The ongoing maintenance of many small pressure vessels on the surface is staggering, especially over decades.  A surface base would become littered with abandoned modules needing repair or upgrades to be useful again.  Tunnels have a history of surviving centuries or millennia, even if abandoned to their fate.

[Ekramer]

A prototype underground base can be built on Earth in a matter of months to test interior layouts and systems.  In a few years, the first airtight prototype can test life support systems and long-term habitation with several dozen people. 

If the cost is reduced as planned, several earth-bound uses could be found.  Regions with extremes of hot or cold could be developed, or areas currently out-of-bounds for ecological reasons.  The self-sustaining technology needed on Mars would minimise local impact on Earth. 

A million square feet of accommodation can fit under Central Park in New York City.  The same under the great parks of other major cities around the world.  Even without a view, this is extremally valuable real estate.  Bunker-like security and space-grade life support is part of the deal.  Extreme weather events would go unnoticed in your city beneath the city.  You would no longer have to move to New Zealand to have a reasonable chance of surviving the apocalypse!  A dedicated loop to the airport (or offshore launch platform) would be a valuable convenience until then.

The citizens of war-torn regions may find building (or re-building) underground preferable to apartment blocks vulnerable to missile and drone attack.  Even chemical weapons would have little impact with double airlocks.  The peace and quiet of sleeping underground without fear of air raid sirens may become more attractive to more people in coming years.

There is a long history of putting critical manufacturing in facilities hardened from attack.  While a 12’ tunnel is not suitable for final assembly of large objects, the assembly lines of many components and products could be adapted without undue problems.

The Boring Company has so far focused on transport tunnels, but ultimately other uses may be more valuable.  For most city apartments, sunlight is limited and the “view” is of another building overlooking you.  Open a window and you get noise and pollution.  Major urban developments of the 21st century may mostly reserve surface areas for parks and recreation, with living quarters below. 

A Boring residential development in several major cities would normalise spiral living.  While not for everyone, it would become another lifestyle choice.  By the time Mars tickets are being sold, most of the target audience would have at least visited a spiral, and may already live in one.  Over the last century, living in tall buildings has become perfectly normal, though it has downsides.  Living in an underground spiral may soon become just as normal.

[Nomadd]

 There are reasons hot bunking isn't good for long term.

[Ekramer]

There are reasons hot bunking isn't good for long term.

I'm not thinking of shared bunks (if that is what you mean).  Each person would have dedicated space.  There will likely be the equivalent of First Class, Second Class, etc.  It may be that everyone has larger quarters with dedicated bathroom.

Further Edit
I grew up on the top of three bunks with less than a foot between my nose and the ceiling, with not enough floor space left to fully open the door.  Even the crew quarters seems palatial to me as our eight person family lived in a smaller space.  I guess it's what you're used to.

[KilroySmith]

Interesting ideas. 

One minor nit is that the living quarters you draw assume people don't need intimacy and sex. You're drawing a single-sex submarine. There are no provisions for couples quarters, unless every couple is given a train car to themselves.  It would be difficult to split the living quarters into smaller couples spaces, because of access to the radial tubes.

Instead, consider enlarging your Jeffries tubes to use the same 12' diameter TBC.  Quarters could then be placed anywhere in the main spiral, with access down to the Jeffries tube and from there to the rest of the complex.  Or, perhaps more reasonably, swap the positions of the Jeffries tube and main spiral to provide additional shielding to the occupants (they'll be deeper).  The Jeffries tube then becomes a main concourse, providing easy access UP to the surface components, and DOWN to the living quarters. 

If you're assuming sufficient in-situ cement production to line all the tunnels, then there's no reason for surface domes to be constructed on Earth and transported.  The bottom half is constructed of concrete (or simply concrete lined pockets) with glass, Lexan, or transparent aluminium either transported from earth in bulk, or created locally.  I'm not sure that long term any of those options (other than TA) are appropriate given the need for radiation shielding - perhaps long term building with a clear 1m thick ice layer between sheets of glass would work.  For the control domes, using the same technique as earth (horizontally viewing windows with a radiation-shielding (probably dirt) roof) would reduce radiation sufficiently for the purpose. 

[Ekramer]

Interesting ideas. 

One minor nit is that the living quarters you draw assume people don't need intimacy and sex. You're drawing a single-sex submarine. There are no provisions for couples quarters, unless every couple is given a train car to themselves.  It would be difficult to split the living quarters into smaller couples spaces, because of access to the radial tubes.

Instead, consider enlarging your Jeffries tubes to use the same 12' diameter TBC.  Quarters could then be placed anywhere in the main spiral, with access down to the Jeffries tube and from there to the rest of the complex.  Or, perhaps more reasonably, swap the positions of the Jeffries tube and main spiral to provide additional shielding to the occupants (they'll be deeper).  The Jeffries tube then becomes a main concourse, providing easy access UP to the surface components, and DOWN to the living quarters. 

If you're assuming sufficient in-situ cement production to line all the tunnels, then there's no reason for surface domes to be constructed on Earth and transported.  The bottom half is constructed of concrete (or simply concrete lined pockets) with glass, Lexan, or transparent aluminium either transported from earth in bulk, or created locally.  I'm not sure that long term any of those options (other than TA) are appropriate given the need for radiation shielding - perhaps long term building with a clear 1m thick ice layer between sheets of glass would work.  For the control domes, using the same technique as earth (horizontally viewing windows with a radiation-shielding (probably dirt) roof) would reduce radiation sufficiently for the purpose.

Thanks for the reply.  I kind of designed for worst case (i.e. how small can it be).  Even in this scenario the senior officer cabins have double sofa beds, and a day room could be added between the bed and bathroom.  The commander quarters take up the full width, so only one per unit.  Of course many cultures have solved communal living and sex, see "love hotels" in Japan.

I'm trying to make the base as efficient as possible, therefore one corridor with smaller Jefferies tubes below.  But of course the basic concept is very adaptable and I'm sure many varieties will be tried.

I agree that eventually manufacturing components and constructing surface structures on Mars will happen.  However, I think TBC is trying to automate the whole process (no humans in tunnel during building) for a reason.  It will be several years (decades?) before factories and supply chains are established on Mars.  In the meantime pre-fab on earth and minimal assembly on Mars will dominate.

Edits: Spelling, sorry

[BN]

Mars has massive lava tubes which can be used.

Up to 250m inner diameter.

[Ekramer]

Mars has massive lava tubes which can be used.

Up to 250m inner diameter.

Yes, but there are several problems that may mean a TBC tunnel is better.

- Lava tubes may not be in a preferred location
- Starships landing and launching nearby may disrupt the stability of a lava tube
- Large scale construction will still be needed to build individual pressure vessels inside the lava tube.
- Pressurising a whole lava tube is a challenge similar to building the Hoover dam.  Eventually yes, but not in first decades.

The fact that TBC is working toward building 12' tunnels in a fully automated way is (to me) a strong indication this is the preferred plan for pressurised volume on Mars.

[BN]

We just need to send some small rovers out to find one the right size, use sealant and install a door I don't think it invokes any large scale construction. Send two 8m doors for an air-locked lava tube.

If not, just dig a hole using shovels, built a pit-house with a vertical entrance hole like the natives in NA.

[Craigles]

Well it's a fun thought. But what about leaks?

Since elongated slender tubes have relatively more surface area for a given volume, you have to effectively seal a large surface for air leaks. I'm thinking that the surface area of long tube varies directly with the volume, whereas the surface area of a sphere is 4πr² . How would you seal a long tunnel? For example, would most of the volume be unpressurized, or pressurized with cheap Martian atmosphere? How would you deal with cracks from thermal expansion or from stress at the joints, and leaks from the permeability of in situ materials?

On earth, water leaks are a big problem for concrete tunnels under the water table. Likewise, natural gas distribution companies have expensive gas leaks.

[DanClemmensen]

Well it's a fun thought. But what about leaks?

I think that most underground schemes will need sealants that are made on Mars in large volumes. Plastics can be made starting from methane, which can be made starting from CO₂. The appropriate polymer and the appropriate mix with rock dust are problems to solve.

[Ekramer]

We just need to send some small rovers out to find one the right size, use sealant and install a door I don't think it invokes any large scale construction. Send two 8m doors for an air-locked lava tube.

If not, just dig a hole using shovels, built a pit-house with a vertical entrance hole like the natives in NA.

You may get lucky and find a suitable one exactly where you want it.  However, you still have a big construction project to line the lava tube as Martian rock is toxic.  Any surface airlock would have to be anchored deep into surrounding rock to keep it from popping out like a cork.  And the other end would also have to be sealed.  A 20m diameter tube would need a 20m airtight seal at one end even if the surface opening is smaller.

I’m not sure if you jest about using shovels.  Conditions for pit houses have to be exact, weak enough to be shovelled but strong enough to not collapse.  On Earth those conditions are very rare.

[sdsds]

What motivates having all the spirals at the same depth?

[Ekramer]

Well it's a fun thought. But what about leaks?

Since elongated slender tubes have relatively more surface area for a given volume, you have to effectively seal a large surface for air leaks. I'm thinking that the surface area of long tube varies directly with the volume, whereas the surface area of a sphere is 4πr² . How would you seal a long tunnel? For example, would most of the volume be unpressurized, or pressurized with cheap Martian atmosphere? How would you deal with cracks from thermal expansion or from stress at the joints, and leaks from the permeability of in situ materials?

On earth, water leaks are a big problem for concrete tunnels under the water table. Likewise, natural gas distribution companies have expensive gas leaks.

It’s a good  question, and one that ANY pressurised volume on Mars must deal with.  It is true that a sphere is more efficient, but there is a reason that pressurised cylinders are common but spheres are not.  Sphere sections are difficult to fabricate, and the larger, the harder.  Final assembly needs special rigs outside for the bottom half and *inside* for the top half.  When done, the inside rig has to get out somehow. 

Doing this on Earth is hard enough, on Mars virtually impossible.  You can get the same volume much easier by making a smaller diameter cylinder.  Ironically, cylinders have more easily usable ‘human’ space than the same volume sphere.  Both engineering and human factors lead away from spheres for pressurised habitats.

So… manufacture thousands of cylinders on earth, transport to Mars, dig trenches, connect them all together, and cover with a few meters for radiation shielding.  While each cylinder can be very leak resistant, joints are a problem, especially over decades.  There’s no silver bullet, only trade-offs.

Alternatively, embark on a major construction project on the surface of Mars. Build a pressurised bunker-like structure requiring heavy equipment and precision construction, very difficult even on Earth.  I think all this is pushing SpaceX toward automated tunnelling deep enough that ground pressure is greater than internal pressure.

I expect the TBM will spray a sealant onto the bare tunnel walls, then press the prefabricated panels into the sealant.  Ground pressure will squeeze the tunnel panels tight.  There will always be some leaking, as we have found on the International Space Station.  SpaceX have slides explaining how they plan to get oxygen from the Martian atmosphere.

[Oersted]

Hi Ekramer, and thank you for all the work and thought you put into this concept.

I thought about something very similar a long while ago, I don't remember if I posted in the Amazing Habitats thread about it, but just to say that I agree with your idea. Long curved tunnels intersecting in various ways because that is just the way TBM's work.

If the ground is propitious for it, I think several layers of circular tunnels could even be a good idea.

A lot of people haven't realised that TBM's are absolutely the most efficient way of carving out pressurizable volume on Mars, using the bedrock itself as the building material. Luckily Elon saw it a long time ago, which is why he started the Boring Company. I think it was his friend Jurvetson who confirmed that in a documentary.

As I have said often, you shouldn't bring the building material to Mars, you should just carve out the building material that is already there.

This is what the first city on Mars is going to look like. Get used to it folks. Just like on Earth, we humans will start out living in caves. 

[Ekramer]

What motivates having all the spirals at the same depth?

Oh, great question.  You could dive down deeper and build more levels beneath each other.  I’m not convinced it is better than building another spiral next door.  I think deeper tunnelling gets more challenging, but it may be worth it in some cases.