Author Topic: Envisioning Amazing Martian Habitats  (Read 869933 times)

Offline lamontagne

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Re: Envisioning Amazing Martian Habitats
« Reply #140 on: 10/20/2016 06:10 pm »
build a tunnel boring machine on Mars

I think on Earth these are limited to fairly shallow grades; can't really dig straight down. But with Mars (or Moon) gravity? I wonder how quickly you could get well below the surface?

And how sharply can they turn?
The're used for cars and trains, so very low angles. I expect they wouldn't turn.  They would dig into a wide trench, be dragged sideways, and then start again in the opposite direction, making a whole series of parallel tunnels.

As a specialised form of crusher, it would be interesting to analyse the energy required vs crushing basalt into powder, melting it into fibers and using these fibers in a tension structure.  the actual number of fractures required in large scale boring might be not that high compared to fine crushing.  Perhaps a mining engineer might chip in on this?



Offline lamontagne

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Re: Envisioning Amazing Martian Habitats
« Reply #141 on: 10/20/2016 06:27 pm »
I've found this interesting document on the closure rates of tunnels in ice sheets.
Closure if a function of pressure and ice creep, that seems fairly independent of temperature, but someone might want to do further research on this.  The images are for an horizontal ice sheet in Greenland, I believe, but the research covers many cases.  At first glance, deformation in Antarctica might be slower.

Anyway, these figures show heavy deformation in just a few years, so I would think twice about building in glaciers, even on Mars.  Ice is not all that stable, it would seem.


Offline zodiacchris

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Re: Envisioning Amazing Martian Habitats
« Reply #142 on: 10/20/2016 07:12 pm »
Thanks for posting this! Looking at the lower figure, deep tunnels only show a deformation of 20 cm in 10 years on earth, that is not all that bad. And terrestrial glacier tunnels are not pressurised, while the ones on Mars would be under pressure, which gives an opposing force to the creep, especially under lower gravity.
If braced with pycrete like a mine shaft, or your normal lined tunnel, deformation should not be much of a problem.

I have been in quite a few historical mines, and unless they are braced, collapse and rockfalls are fairly common there, too.

Offline CuddlyRocket

Re: Envisioning Amazing Martian Habitats
« Reply #143 on: 10/20/2016 08:48 pm »
build a tunnel boring machine on Mars

... how sharply can they turn?

The're used for cars and trains, so very low angles. I expect they wouldn't turn.  They would dig into a wide trench, be dragged sideways, and then start again in the opposite direction, making a whole series of parallel tunnels.

The art of digging a hole.

Quote
TBMs can make turns, but they're not exactly the hairpin variety. By carefully applying more pressure on one side of the cutting head, the machines can change course by about 0.125 in./ft. "A typical radius for a turn is between 300 and 400 ft," says Turner. "But we build special TBMs if jobs call for tighter turns. The tightest radius we ever dug was a 90 turn in 75 ft in a South African gold mine.

Set one off and have it dig in a spiral of increasing radius; then cut across the spiral for linking passageways etc.

Offline Chris_Pi

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Re: Envisioning Amazing Martian Habitats
« Reply #144 on: 10/20/2016 09:16 pm »
Set one off and have it dig in a spiral of increasing radius; then cut across the spiral for linking passageways etc.

That could be a very efficient use of a small number of boring machines - The one digging the spiral runs nonstop without needing to relocate to keep the tunnel system close together and the radial tunnels could be dug with pretty much whatever equipment is handy whenever one is needed.

A spoke-and-spiral plan allows for most of the work to be done on a very long continuous tunnel with the path(s) from one spot to another  being much shorter. Good for traffic through living/working space and the tailings conveyor for the big TBM never gets very long. If an unstable patch of rock is found just keep going and seal off that section later and abandon it.


Offline guckyfan

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Re: Envisioning Amazing Martian Habitats
« Reply #145 on: 10/20/2016 10:28 pm »
A spiral would be large. Maybe a good design later. I imagine they start at a cliff and go in there horizontally. Do whatever length is convenient and drill more parallel straight tunnels starting at the cliff again. If you get deep enough into solid bedrock you can make quite large caves. Big spaces will help feel not too enclosed.


Offline lamontagne

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Re: Envisioning Amazing Martian Habitats
« Reply #146 on: 10/21/2016 12:04 am »
Spiral city
from 200 to 500 m in radius, 20m dia tube.  About 8 km long.  At 500 m per month, less than 2 year to bore.

about 160 000 m2.

Offline R7

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Re: Envisioning Amazing Martian Habitats
« Reply #147 on: 10/21/2016 06:48 am »
As far as stairs are concerned, would it be possible with 8 foot ceiling heights to just jump from one floor to the next?

Matthew
Sure, for anyone who can comfortably do 3' vertical jumps on Earth...which is very elite club.
Median for average Joe aged 21-30 is 22.1" and 14.1" for regular Jill.
http://jumpshigher.com/average-vertical-jump
AD·ASTRA·ASTRORVM·GRATIA

Offline guckyfan

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Re: Envisioning Amazing Martian Habitats
« Reply #148 on: 10/21/2016 07:51 am »
Spiral city
from 200 to 500 m in radius, 20m dia tube.  About 8 km long.  At 500 m per month, less than 2 year to bore.

about 160 000 m2.

It would be nice and simple. Tunnel boring machines that size don't have the ability to do such narrow turns I believe but maybe they can design them.

Offline lamontagne

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Re: Envisioning Amazing Martian Habitats
« Reply #149 on: 10/21/2016 11:58 am »
Spiral city
from 200 to 500 m in radius, 20m dia tube.  About 8 km long.  At 500 m per month, less than 2 year to bore.

about 160 000 m2.

It would be nice and simple. Tunnel boring machines that size don't have the ability to do such narrow turns I believe but maybe they can design them.
I agree it is too tight.  I confused diameter and radius :-)  400m radius is the number I should have used.   The bore is probably a little large as well, at 20m.  In a text referenced in earlier posts they mention turns with a 90m radius were made, but its probably not a good idea.
Just imagine a slightly wider spiral.

One interesting characteristic of this idea is that we should be able to cost this fairly easily.  It's the cost of bringing a 400  (?)tonne machine to Mars, plus the cost for a large (2 MW?) solar array to power the tunnel boring machine and power the conditioning system.  A maintenance crew, and the value of the power used for 2 years of operation.  Could serve as a bench mark compared to other solutions

I wonder how large a bubble you can get from 400 tonnes of reinforced plastic, and what might be the mass of a regolith crusher that produced enough material to cover it, produce a stable compression structure to offset the internal pressure and what would be the energy used?

From an urban standpoint, it's a very controlled environment, somewhat akin to an utility model.  Looks like a 1950 theoretical architectural exercise.  Would they sell or rent m3 ?  From an investment standpoint, you should be able to rent out space very early in the project, by closing off completed sections.

Again, I wonder how this would compare to a more organic growth of individual domes/habitats, etc..


Offline lamontagne

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Re: Envisioning Amazing Martian Habitats
« Reply #150 on: 10/21/2016 12:05 pm »
The Hard Rock miner's handbook is joined.

This is really used in the industry, and contains all kinds of helpful rules of thumb and design metrics for conceptual designs such as the ones we are looking at here.

Enjoy, quantify and document  ;-)
« Last Edit: 10/21/2016 12:05 pm by lamontagne »

Offline Lumina

Re: Envisioning Amazing Martian Habitats
« Reply #151 on: 10/21/2016 03:01 pm »
Well since we're talking about tunnel boring machines again, it's time to go back to my favorite topic!!! :)

https://forum.nasaspaceflight.com/index.php?topic=34667.msg1362562#msg1362562

Very nice post. The mental model is absolutely the right one, in my opinion. Transporting one large machine that will produce tens of thousands of cubic meters of long-lived, reliable, robustly pressurized, radiation-protected habitat enclosures is definitely the way to go in terms of habitat architectures. The energy cost is not a problem, because only energy-rich overall architectures can lead to expanding permanent Martian settlements (anything less would have a too-high risk of dying out). So the problem is reduced to an engineering and logistical challenge of maintaining the TBM in working order, a complex but feasible undertaking for which we already have decades of transferable experience.

Offline lamontagne

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Re: Envisioning Amazing Martian Habitats
« Reply #152 on: 10/21/2016 03:43 pm »
Cross section of a 15m diameter tunnel showing a possible arrangement.
There would need to be staircases every few length as well.

The illustrated tunnel is a 20m long section.
Floor area  of this arrangement is 27m/m (excluding circulation and linear park).  For a 10 km tunnel, this would mean 270 000 m2 of living area.  So 27m2 per person for 10 000 might be possible, and perhaps not too crowded.

Large public buildings such as schools, stadiums, meeting halls might need a different solution though.

Hardly claustrophobic, IMHO.

Offline envy887

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Re: Envisioning Amazing Martian Habitats
« Reply #153 on: 10/21/2016 05:38 pm »
I like the large tunnel idea. It might be easier to implement initially by building large corrugated steel tubes in shallow trenches on the surface, then partially burying them for radiation protection. I'd add some Lexan skylights/windows/portholes for natural light.

I prefer steel for this concept because:
1) High strength to weight ratio
2) Easy to prefabricate, ship, and weld together panels on site
3) Can eventually be manufactured in very large quantities on Mars using byproducts of propellant manufacture and local iron oxide.
4) High density can fully load out the volume-constrained ITS design and ship via slow transfer.

A single 300t ITS cargo delivery would deliver 1100 prefabricated panels (2x6m and 275 kg each) to weld together a 300m length of 15m diameter tube, plus domed ends for some 60,000 m3 of pressurized interior space. 3mm thick corrugated panels could take more than 1 full atmosphere in tension at 15m and would be strong enough to support a fairly thick regolith covering even if depressurized. Interior panels could be welded directly to the skin and to each other to create additional structure with a wall-and-deck system.

Offline CuddlyRocket

Re: Envisioning Amazing Martian Habitats
« Reply #154 on: 10/21/2016 05:58 pm »
Spiral city

I'd have another radial tunnel at 90 degrees to the first. Possibly others at intermediate angles; they don't all have to come right to the centre.

Cross section of a 15m diameter tunnel showing a possible arrangement.
There would need to be staircases every few length as well.

Seems a lot of wasted volume. Why do you need three walkways?

Offline lamontagne

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Re: Envisioning Amazing Martian Habitats
« Reply #155 on: 10/21/2016 07:04 pm »
I'd have thought sealed glassified would have been rather fragile.  why not just bare rock?  Inject grouts into any cracks.
Is there such a thing as a nuclear tunnel boring machine?  All I find is area 51 conspiracy garbage on the subject.  And a weird patent.  Can't we just break the rock, please?


Offline lamontagne

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Re: Envisioning Amazing Martian Habitats
« Reply #156 on: 10/21/2016 07:07 pm »
I like the large tunnel idea. It might be easier to implement initially by building large corrugated steel tubes in shallow trenches on the surface, then partially burying them for radiation protection. I'd add some Lexan skylights/windows/portholes for natural light.

I prefer steel for this concept because:
1) High strength to weight ratio
2) Easy to prefabricate, ship, and weld together panels on site
3) Can eventually be manufactured in very large quantities on Mars using byproducts of propellant manufacture and local iron oxide.
4) High density can fully load out the volume-constrained ITS design and ship via slow transfer.

A single 300t ITS cargo delivery would deliver 1100 prefabricated panels (2x6m and 275 kg each) to weld together a 300m length of 15m diameter tube, plus domed ends for some 60,000 m3 of pressurized interior space. 3mm thick corrugated panels could take more than 1 full atmosphere in tension at 15m and would be strong enough to support a fairly thick regolith covering even if depressurized. Interior panels could be welded directly to the skin and to each other to create additional structure with a wall-and-deck system.

The tunnel shown is 10 km long.  With your figures, that is 33 x 300 tonnes trips for the ITS.  I think it makes more sense to bring a 300-600 tonne machine (2 trips) to dig the tunnel.  As far as the power required goes, it will be needed anyway after construction for the habitat, so it is not an extra cost.

Tunnels win on this one, IMHO  ;-)

Offline lamontagne

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Re: Envisioning Amazing Martian Habitats
« Reply #157 on: 10/21/2016 07:13 pm »
Spiral city

I'd have another radial tunnel at 90 degrees to the first. Possibly others at intermediate angles; they don't all have to come right to the centre.

Cross section of a 15m diameter tunnel showing a possible arrangement.
There would need to be staircases every few length as well.

Seems a lot of wasted volume. Why do you need three walkways?
You need walkways because you need corridors anyway, and might as well have them out in the 'open'.  You can't move from room to room at this scale of habitat.

Think of the extra volume as buffer space.  Adds inertia to the system.   And it answers some of the worries about confinement that always get raised.  And it's cheap space, because the tunnel boring machine makes a 5m radius bore or 7.5 m radius bore at about the same rate.

You need to keep the bores at least 10m from one another on Earth, for structural reasons.  You can't bring them all to the middle, too fragile.  So yes, just a few all the way through.  The laterals are much tougher to build anyway.  I'm not certain you could actually cross tunnels as I have illustrated.  much easier in 3D space than real space ;-)



« Last Edit: 10/21/2016 07:20 pm by lamontagne »

Offline iengineerit

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Re: Envisioning Amazing Martian Habitats
« Reply #158 on: 10/21/2016 07:20 pm »
First post here, and would like some feedback (gently).

If you give me a heat source and some water, I'm pretty sure I can cultivate life anywhere.  It might be a Dyson sphere, but energy is our challenge on Mars, right?  Your renewable energy sources are solar and wind (especially on the poles?), so to colonize you'd seed with nuclear and develop the others. 

I'll build an ice dome first.  It would be "printed" using water ice and a radial arm, and would embed a continuous fiber with each layer of accretion.  If you pressurize the inside, the tendency will be for the ice to "creep" past the fiber thread that surrounds the perimeter of the dome, but that's okay.  I might not need the fiber at all, since it only has to last a few months.

Why?  That's my growing season.  I make the walls (3D printed, remember) to be like Fresnel lenses, focusing the sunlight toward the center of the dome.  At the poles, I have a relatively CONSTANT rate of radiation for some time.  You need X amount of watts per square meter?  I make a dome X size (60m?), focus the light toward the center, and have a tiny (10m?), thin bubble of plastic to diffuse it, retain some heat (internal greenhouse, within my dome.  No wind in there), and enjoy 24/7 sunlight while my crops grow.  Need less light?  Then add pigment (like red dirt??) to your water as your dome is being formed.

I'd colonize the poles first.  And if someone would spot me about $40mil, I'd build what I'm discussing in Antarctica.  Six months on, six months off. 

Okay, fire away.

Offline nacnud

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Re: Envisioning Amazing Martian Habitats
« Reply #159 on: 10/21/2016 07:24 pm »
You've pretty much described the hab in the second post in the thread :). Only big difference is ice needs pressure or it will sublimate so you need a pressure barrier that encloses the ice. Plus the equator gets more sun so perhaps best to start there ish...

 

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