Author Topic: Elon Musk: glass geodesic domes  (Read 98919 times)

Offline KelvinZero

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Elon Musk: glass geodesic domes
« on: 10/28/2016 04:16 am »
Question from /u/Ulysius

As a follow-up, considering the synodal reuse of the ITS spaceships, what form of permanent habitation do you foresee? Shipped modules or an (eventual) shift to in-situ resource utilization such as Martian rigolith/plastic-reinforced concrete structures?

Thank you for your time.



Answer from /u/ElonMuskOfficial

Initially, glass panes with carbon fiber frames to build geodesic domes on the surface, plus a lot of miner/tunneling droids. With the latter, you can build out a huge amount of pressurized space for industrial operations and leave the glass domes for green living space.
I thought this was worth it's own topic because it is about the only thing we have that is specifically SpaceX.
What do we know about this sort of construction?

Wouldn't cylinders be more convenient and adaptable? Cylinders have the advantage that you can make variable volumes by extending their length. You can cover area in a grid more efficiently. They don't need anchoring. You can align them north-south to get the best sun.

What sort of tools would be necessary for these domes? What sort of work? Is it people clambering around in spacesuits or one dedicated robot type?
« Last Edit: 10/31/2016 09:37 am by KelvinZero »

Offline RonM

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Re: Glass geodesic domes
« Reply #1 on: 10/28/2016 04:40 am »
On Earth, geodesic domes can have issues with leaking, but that might be do to the DIY construction. A well engineered system should be okay.

One great advantage of a geodesic dome based on a sphere is that all of the triangular sections are the same shape. That should make construction easier.

Like any other structure attached to the surface, it will be hard to hold it down against the internal air pressure.

Offline KelvinZero

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Re: Glass geodesic domes
« Reply #2 on: 10/28/2016 08:02 am »
One great advantage of a geodesic dome based on a sphere is that all of the triangular sections are the same shape. That should make construction easier.
I hadn't thought about it till now, but I believe they are not all the same shape. Im not sure how few shape variations you can end up with.

https://en.wikipedia.org/wiki/Geodesic_dome.

This page mentions 6 edge sizes, but I dont know how many variations of triangle shape that represents.
http://geo-dome.co.uk/4v_tool.asp

You could pretty much construct an arbitrary cylinder diameter and length from a single triangle size though.. but Im not sure about closing the ends. That sounds similar to the dome problem.

Offline guckyfan

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Re: Glass geodesic domes
« Reply #3 on: 10/28/2016 08:12 am »
You could pretty much construct an arbitrary cylinder diameter and length from a single triangle size though.. but Im not sure about closing the ends. That sounds similar to the dome problem.

You can use a fiber dome on top and maybe steel in the ground. No need to have the domes transparent.

Offline docmordrid

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Re: Glass geodesic domes
« Reply #4 on: 10/28/2016 12:10 pm »
Translucent may be enough if it's a polyethylene, a pretty fair radiation shield and let's a bit of soft light in. Extra points if it's borated for neutrons.
« Last Edit: 10/28/2016 12:11 pm by docmordrid »
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Offline AncientU

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Re: Glass geodesic domes
« Reply #5 on: 10/28/2016 12:57 pm »
You could pretty much construct an arbitrary cylinder diameter and length from a single triangle size though.. but Im not sure about closing the ends. That sounds similar to the dome problem.

You can use a fiber dome on top and maybe steel in the ground. No need to have the domes transparent.

No need?  Is that from an engineering perspective?

For humans living underground, transparent has a significant psychological advantage.  Seeing the sun, sky, landscape, and stars, planets, and Galaxy at night will be a unique contribution to mental health -- it certainly will be* for me.

* 8)
« Last Edit: 10/28/2016 12:58 pm by AncientU »
"If we shared everything [we are working on] people would think we are insane!"
-- SpaceX friend of mlindner

Online Robotbeat

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Re: Glass geodesic domes
« Reply #6 on: 10/28/2016 02:02 pm »
The whole point of a geodesic dome would be if you want it transparent, IMHO. Sphere minimizes surface area (i.e. Area of heavy glass windows) that need to be transported from Earth. Cylinders would be better for most other uses, and tunnels (if it really is as easy as people seem to think it is... I'm not convinced) would work, too.

There was a geodesic dome built in Antarctica that was brought in by transport planes and built locally. It lasted decades until it eventually had to be taken down due to loads from the ever-shifting Antarctic ice sheet (a problem you wouldn't have on Mars). The advantage is you can build enormous structures with just the material you can fit in a small volume for transport. Or, you could have a fairly small fabrication machine producing members locally.

And it's beautiful.

I think that is the main reason. I suspect that if this all works out, there will be a few domes built but then most buildings will be variations on cylinders or perhaps at a big enough scale you could just build a huge block building.

I tend to prefer inflatable domes. Enormous ones are already used on Earth for various uses.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline vapour_nudge

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Re: Glass geodesic domes
« Reply #7 on: 10/28/2016 02:12 pm »
What about problems of heat loss in the below freezing temperatures? (A good question for KelvinZero 😄)
« Last Edit: 10/28/2016 02:13 pm by vapour_nudge »

Offline docmordrid

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Re: Glass geodesic domes
« Reply #8 on: 10/28/2016 02:15 pm »
IR reflective coatings w/double layer panels? A vacuum layer between them should be trivial.
« Last Edit: 10/28/2016 02:16 pm by docmordrid »
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Online Robotbeat

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Re: Glass geodesic domes
« Reply #9 on: 10/28/2016 02:31 pm »
Yes. If you had a reflective shade that went over the dome at night and retracted in the day, the dome could be heated entirely via the Sun.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline RonM

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Re: Glass geodesic domes
« Reply #10 on: 10/28/2016 02:36 pm »
One great advantage of a geodesic dome based on a sphere is that all of the triangular sections are the same shape. That should make construction easier.
I hadn't thought about it till now, but I believe they are not all the same shape. Im not sure how few shape variations you can end up with.

https://en.wikipedia.org/wiki/Geodesic_dome.

This page mentions 6 edge sizes, but I dont know how many variations of triangle shape that represents.
http://geo-dome.co.uk/4v_tool.asp

You could pretty much construct an arbitrary cylinder diameter and length from a single triangle size though.. but Im not sure about closing the ends. That sounds similar to the dome problem.

The panels are the same shape if the dome is based on an icosahedron. Each panel is an equilateral triangle.

Other shapes are used to make better use of the available rectangular building supplies.

http://geo-dome.co.uk/wiki/article.asp?uname=29

Spend some time examining the pages you find.

Online Robotbeat

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Re: Glass geodesic domes
« Reply #11 on: 10/28/2016 02:50 pm »
Icosahedrons are the only ones that are based on identical equilateral triangles with identical vertices.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline nacnud

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Re: Glass geodesic domes
« Reply #12 on: 10/28/2016 03:23 pm »
A big dome with individual buildings inside gives the freedom to build, demolish and rebuild as seen fit. Another option could be to build individual buildings and roof over the streets. This would require less roofing materials. Have a few examples of both.

Offline Mongo62

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Re: Glass geodesic domes
« Reply #13 on: 10/28/2016 05:24 pm »
I just wanted to point out that the National Geographic episode shows diagrams of geodesic domes (among other items) on the surface of Mars in two scenes at timestamps 2:25-2:32 and 29:15-29:54.

Given their placement in the video, I suspect that these might be borrowed from SpaceX plans for the early Mars settlement.
« Last Edit: 10/28/2016 07:39 pm by Mongo62 »

Offline gosink

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Re: Glass geodesic domes
« Reply #14 on: 10/28/2016 07:41 pm »
Would heat loss be the problem - or would excess heat be the problem?  After all, Mars' atmosphere is nearly just a dusty vacuum.

I know they go through contortions when engineering the Mars rovers to make sure they don't get too cold at night, but would that remain the same for a building sized structure, presumably with all sorts of equipment running all night?

Online Robotbeat

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Re: Glass geodesic domes
« Reply #15 on: 10/28/2016 07:43 pm »
If the building was the size and activity of a large shopping mall, they'd be fine as long as they used good insulation (double pane, etc) on the panels.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline KelvinZero

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Re: Glass geodesic domes
« Reply #16 on: 10/28/2016 08:19 pm »
The panels are the same shape if the dome is based on an icosahedron. Each panel is an equilateral triangle.
Do you mean domes of only 20 faces? Once you tesselate and distort vertices to remain on a sphere obviously they must become something other than equilateral, simply because they were equilateral while perfectly planar.

To me the 20 face variation is not that interesting because the size you could transport would probably be even smaller than ITS volumes.

Offline RonM

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Re: Glass geodesic domes
« Reply #17 on: 10/28/2016 08:34 pm »
The panels are the same shape if the dome is based on an icosahedron. Each panel is an equilateral triangle.
Do you mean domes of only 20 faces? Once you tesselate and distort vertices to remain on a sphere obviously they must become something other than equilateral, simply because they were equilateral while perfectly planar.

To me the 20 face variation is not that interesting because the size you could transport would probably be even smaller than ITS volumes.

Oh, that's right. The cords do change when you distort the vertices. For practical domes with many panels, they can't be the same shape.

Offline LMT

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Re: Glass geodesic domes
« Reply #18 on: 10/28/2016 09:24 pm »
Eden Project

A big dome with individual buildings inside gives the freedom to build, demolish and rebuild as seen fit. Another option could be to build individual buildings and roof over the streets. This would require less roofing materials. Have a few examples of both.



It does open up the space, doesn't it?

Your Eden Project greenhouse example seemed especially apt, at least to us.  We used Eden Project specs as a basis for the notional 2,000,000 m3 Lake Matthew domes



One unsung virtue of Eden Project ETFE engineering, potentially very important on Mars: 

It's cryogenic.



An architectural overview of the Eden Project, with references.

Offline nacnud

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Re: Glass geodesic domes
« Reply #19 on: 10/28/2016 10:38 pm »
Eden project does seem the most apt, the roof is a dynamic structure giving so much more that just protection from weather. Your thread is long and I've yet to read it all but given that in-situ resource utilisation is going to be vital where can one easily find fluorine on Mars?

Hydrogen from water, carbon from CO2, fluorine from?

Genuine question, no criticism intended.