Optimal size for domes and other structures

[farmerben]

What is the optimal size for domes and similar structures on Mars or on the Moon?  How would you approach the problem?  What are the constraining limits?

1.  Wind loading or other structural parameters on Mars, not applicable on the Moon.

2.  Manufacturing limited.  Being easier to manufacture a small sheet of glass than a large one, and so on for other components.  Pyramids would actually be much simpler and stronger to build than domes using aluminum and glass.

3.  Transport limited.  Components have to fit inside a fairing for interplanetary travel so that sets the size constraint.

4.  Human scale.  If you can fit everything you need into 100m2 then why build bigger?  Even for agriculture on Earth it's usually better to build several small greenhouses rather than one huge one.  

5.  Constrained only by imagination and budget.  Flying and jumping sports might become the most popular activities on the Moon.  So a humungous aerodrome is desirable for purely entertainment purposes.

[darthgently]

4 hours ago, farmerben said:

What is the optimal size for domes and similar structures on Mars or on the Moon?  How would you approach the problem?  What are the constraining limits?

1.  Wind loading or other structural parameters on Mars, not applicable on the Moon.

2.  Manufacturing limited.  Being easier to manufacture a small sheet of glass than a large one, and so on for other components.  Pyramids would actually be much simpler and stronger to build than domes using aluminum and glass.

3.  Transport limited.  Components have to fit inside a fairing for interplanetary travel so that sets the size constraint.

4.  Human scale.  If you can fit everything you need into 100m2 then why build bigger?  Even for agriculture on Earth it's usually better to build several small greenhouses rather than one huge one.  

5.  Constrained only by imagination and budget.  Flying and jumping sports might become the most popular activities on the Moon.  So a humungous aerodrome is desirable for purely entertainment purposes.

1, 3, 4, 5, Yes.

I question 2.  The center of larger flat panes would be weaker than smaller flat panes of glass of similar thickness so the more panes in the dome the better, within reason (the fewer joins between panes the better also).  I think the optimum would be about the number of panes in  a hemidodecahedron at least (6 panes).  If you mean a very small room sized pyramid then I could see that.

Edited 1 hour ago by darthgently

[AckSed]

With regards to size, the psychological advantage of a wide-open space cannot be overstated.

Here's a company that makes 10-metre in diameter dome tents, 5metres high, with 80 square metre floor space: https://www.domecompany.com.au/dome-sizes/the-10-metre-dome/

Spoiler

As you can see, it's pretty big, yet it can be loaded on a pickup truck and assembled by hand. A 100m2 dome will be bigger still (11.3 metres in diameter), but you're right - it's probably good enough to give that sensation of space, air and light that people need if they're living in regolith-protected burrows.

Part of me also says that geodesic domes may be the most efficient structure, but the whole craze of dome-building in the 70s and 80s made the drawbacks when using them for living space apparent: your appliances and furnishings have to be custom-made, there's 'dead' space where the walls meet the floor and the acoustics are great for a concert hall, poor for privacy: https://earthtodome.com/2017/01/19/geodesic-dome-homes-the-good-the-bad-the-awesome/

However, there should absolutely be a park or botanical garden that isn't a dome. Think something like the Crystal Palace.

----

I can see one advantage for building domes and structures on Mars that Luna doesn't have: the atmosphere.

We know that Mars has elemental sulphur and enough iron for reinforcing steel rods. That says to me you could use sulphur concrete, and the atmosphere and much milder temperature range means that the binding agent - sulphur - won't sublimate off.

If you wanted to make normal cement (or edge-cases like magnesium cement or zinc oxychloride cement) there's the materials for that, too, and they will be able to absorb carbon dioxide as they crystallise. Probably a waste of water, but you could do it.

There is also plentiful carbon dioxide and some water; with chlorates also being a waste product when cleaning Martian regolith for use in greenhouse soil, that says to me 'PVC and polyethylene plastics for a vapour barrier and maybe even greenhouse windows'.

That's not to say Luna doesn't have its advantages. You're right about the Human Flying Dome. The Menace From Earth got it right the first time by making an attraction that everyone wants to experience, even the natives. It'd also be a good way to harvest water and carbon dioxide from visitor's breath. Tourists will go. "You mean it's free?" "Well, you've already paid for the ticket and brought water, food, your, er, waste and carbon, so yes."

The visitors will then experience the extra-splashy 0.1 G pool (don't ask where the water came from), the human Wall of Death, the human loop-de-loop track and the jungle gym. Though you'd have to have spotters who could tell when people overextend themselves, as they may feel light, but they are still overcoming inertia and working up a sweat - bad for the rich and unfit.

Edit: I had a brainwave: Lunar kung-fu. Re-enact The Matrix and old wuxia - in real life! Wall-running, diving through a window from 5 metres away, impossible rolls and flips, mid-air sword duels - you too can feel like a superhero!

Edited 1 hour ago by AckSed

[farmerben]

I know a roofer who shingled a geodesic dome "once".  Key word "once".

[magnemoe]

18 minutes ago, AckSed said:

With regards to size, the psychological advantage of a wide-open space cannot be overstated.

Here's a company that makes 10-metre in diameter dome tents, 5metres high, with 80 square metre floor space: https://www.domecompany.com.au/dome-sizes/the-10-metre-dome/

  Hide contents

As you can see, it's pretty big, yet it can be loaded on a pickup truck and assembled by hand. A 100m2 dome will be bigger still (11.3 metres in diameter), but you're right - it's probably good enough to give that sensation of space, air and light that people need if they're living in regolith-protected burrows.

Part of me also says that geodesic domes may be the most efficient structure, but the whole craze of dome-building in the 70s and 80s made the drawbacks when using them for living space apparent: your appliances and furnishings have to be custom-made, there's 'dead' space where the walls meet the floor and the acoustics are great for a concert hall, poor for privacy: https://earthtodome.com/2017/01/19/geodesic-dome-homes-the-good-the-bad-the-awesome/

However, there should absolutely be a park or botanical garden that isn't a dome. Think something like the Crystal Palace.

----

I can see one advantage for building domes and structures on Mars that Luna doesn't have: the atmosphere.

We know that Mars has elemental sulphur and enough iron for reinforcing steel rods. That says to me you could use sulphur concrete, and the atmosphere and much milder temperature range means that the binding agent - sulphur - won't sublimate off.

If you wanted to make normal cement (or edge-cases like magnesium cement or zinc oxychloride cement) there's the materials for that, too, and they will be able to absorb carbon dioxide as they crystallise. Probably a waste of water, but you could do it.

There is also plentiful carbon dioxide and some water; with chlorates also being a waste product when cleaning Martian regolith for use in greenhouse soil, that says to me 'PVC and polyethylene plastics for a vapour barrier and maybe even greenhouse windows'.

That's not to say Luna doesn't have its advantages. You're right about the Human Flying Dome. The Menace From Earth got it right the first time by making an attraction that everyone wants to experience, even the natives. It'd also be a good way to harvest water and carbon dioxide from visitor's breath. Tourists will go. "You mean it's free?" "Well, you've already paid for the ticket and brought water, food, your, er, waste and carbon, so yes."

The visitors will then experience the extra-splashy 0.1 G pool (don't ask where the water came from), the human Wall of Death, the human loop-de-loop track and the jungle gym. Though you'd have to have spotters who could tell when people overextend themselves, as they may feel light, but they are still overcoming inertia and working up a sweat - bad for the rich and unfit.

Edit: I had a brainwave: Lunar kung-fu. Re-enact The Matrix and old wuxia - in real life! Wall-running, diving through a window from 5 metres away, impossible rolls and flips, mid-air sword duels - you too can feel like a superhero!

Now you could make an huge park by merging multiple domes. Or build up walls who hold it up. This will work on Mars, 
On the moon you have radiation and micro meteoroids so you want something more protected as in underground or covered by rocks, water also works and is transparent but is heavy. 
Weirdly larger domes might be safer as an breach will be far away and its lots of air to get lost so it would had be be one serious breach to not give many minutes to evacuate. You would sleep underground anyway. 

And the fun factor like water running and an 1/10 g jungle gym would be major selling points but I guess you could build this cheaper in LEO. Now the moon is the genuine and classy thing while the cheap LEO parks are ripoffs. 

[darthgently]

23 minutes ago, magnemoe said:

Now you could make an huge park by merging multiple domes. Or build up walls who hold it up. This will work on Mars, 
On the moon you have radiation and micro meteoroids so you want something more protected as in underground or covered by rocks, water also works and is transparent but is heavy. 
Weirdly larger domes might be safer as an breach will be far away and its lots of air to get lost so it would had be be one serious breach to not give many minutes to evacuate. You would sleep underground anyway. 

And the fun factor like water running and an 1/10 g jungle gym would be major selling points but I guess you could build this cheaper in LEO. Now the moon is the genuine and classy thing while the cheap LEO parks are ripoffs. 

Here is water running over a toroidal geodesic.  How thick would the water layer need to be to provide shielding?  On the moon you’d need a double layer to contain the water

https://www.explore.com/1413186/fly-into-jewel-changi-airport-singapore-largest-indoor-waterfall/

47 minutes ago, farmerben said:

I know a roofer who shingled a geodesic dome "once".  Key word "once".

Yeah, shingling domes is not the way to go.  Just make the panes and joins water tight on earth