Author Topic: Envisioning Amazing Martian Habitats  (Read 869882 times)

Offline nacnud

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Re: Envisioning Amazing Martian Habitats
« Reply #280 on: 11/01/2016 01:09 am »
What is the likelihood of a chunk of concrete flying off and hitting the dome fast enough to break the glass?

Look up what happened to Surveyor 3 when Apollo 12 landed 600 feet away. It was blasted by particles traveling at a minimum 70m/s.

I think landing on the other side of the hill from the domes is a sensible idea.
« Last Edit: 11/01/2016 01:10 am by nacnud »

Offline lamontagne

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Re: Envisioning Amazing Martian Habitats
« Reply #281 on: 11/01/2016 01:22 am »
What is the likelihood of a chunk of concrete flying off and hitting the dome fast enough to break the glass?

Look up what happened to Surveyor 3 when Apollo 12 landed 600 feet away. It was blasted by particles traveling at a minimum 70m/s.

I think landing on the other side of the hill from the domes is a sensible idea.
ok I'll find some new land

Offline Robotbeat

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Re: Envisioning Amazing Martian Habitats
« Reply #282 on: 11/01/2016 02:29 am »
What is the likelihood of a chunk of concrete flying off and hitting the dome fast enough to break the glass?

Look up what happened to Surveyor 3 when Apollo 12 landed 600 feet away. It was blasted by particles traveling at a minimum 70m/s.

I think landing on the other side of the hill from the domes is a sensible idea.
I think the Martian atmosphere will stop that. But even on Earth, you wouldn't want to be just 600 feet from a landing spaceship of that size! More like several kilometers.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

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Offline Lumina

Re: Envisioning Amazing Martian Habitats
« Reply #283 on: 11/01/2016 04:06 am »
How about a tunnel from the main dome to the landing/launch pads? You could keep the domes several kilometers away.

Good idea. At 0.38g the debris from a crash / explosion could fly a long way, damaging domes and scouring roads. With the labour constraint and the perpetual need for physical growth on Mars, it will be important to avoid the "broken window fallacy" over there. Here on Earth, we count selling cigarettes and the treatment of the ensuing cancers as economic growth. We're big enough to hide all this mess here, but the physical economy of Mars will not be forgiving of our mistakes.

Offline Lumina

Re: Envisioning Amazing Martian Habitats
« Reply #284 on: 11/01/2016 04:22 am »
How about a tunnel from the main dome to the landing/launch pads? You could keep the domes several kilometers away.
As a transportation infrastructure, I expect a surface road and rovers is less expensive than a tunnel.  The pad won't be used all that much after all, so low traffic.  The pads might be further away, but then they wouldn't fit into the illustration any more.  A little artistic licence there, perhaps. At least I'm not landing Petawatt class spaceships in the middle of cities with km tall towers ;-)

One thing to bear in mind is that Mars will either be an energy-rich and tunneling-intensive place, or else it won't be very much of an inhabited place at all. So if the tunneling machines will be there in abundance and kept busy at all times, their constant use will lead to improvements in their technology.

Also, relative costs of road making vs tunneling here on Earth, where roads are 1000 times more common than tunnels, might be very different on Mars where the surface is a pretty hostile place that is expensive to work in/on.

The attractiveness of tunnels on Mars has a network effect to it, making tunnels on Mars far more valuable than tunnels on Earth. Every additional kilometer of tunnel is another kilometer of pressurized, earth-like environment added to the base. So Mars will be the planet of the tunnels (not the canals, after all)

Relative notions of value that we are familiar with here won't necessarily apply there. At a distance of 10 to 20 light minutes, the price/cost of a product or service on Mars will depend on the Martian economy which is going to have different priorities than the Earth's economy. Things that are expensive on Earth might be cheap on Mars and vice versa depending on the different relative scarcity of each thing on each planet.

To see that point, consider that if there is no Martian economy but instead we bring everything from Earth, then everything you already have emplaced on Mars is "low cost" relative to everything you don't have which would be astronomically expensive. That's why the Apollo 13 astronauts used socks, plastic bags, suit hoses, the cover from the flight manual and bungee cords to connect a square carbon dioxide scrubber to a round hole in their emergency: those items were the only economical items available to them. Everything else that wasn't already there had an astronomical delivery cost and was therefore eliminated from consideration.
« Last Edit: 11/01/2016 04:27 am by Lumina »

Offline guckyfan

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Re: Envisioning Amazing Martian Habitats
« Reply #285 on: 11/01/2016 07:12 am »
One thing to bear in mind is that Mars will either be an energy-rich and tunneling-intensive place, or else it won't be very much of an inhabited place at all.

If their energy supply is twice what is needed for fuel production, it will be energy-rich indeed.

They may be somewhat limited over night.

Offline guckyfan

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Re: Envisioning Amazing Martian Habitats
« Reply #286 on: 11/01/2016 08:26 am »
One or two really big domes, well engineered, it is possible. One for a big stadium where a large crowd can gather and one as a kind of nature park with large trees and animals would be good to have and help make this feel like a home worth working for and living in.

Maybe Martians will not feel the need for a nature park like this but I think they will.

Such structures would come later in the development of the settlement, when most of the materials can be sourced locally. But 10 or 20m domes can be transported. At least a few of them.

Offline KelvinZero

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Re: Envisioning Amazing Martian Habitats
« Reply #287 on: 11/01/2016 08:41 am »
Hi guckyfan, I might have just deleted the msg you were replying to. Moved it to the correct thread:
..here..

Offline guckyfan

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Re: Envisioning Amazing Martian Habitats
« Reply #288 on: 11/01/2016 01:14 pm »
Hi guckyfan, I might have just deleted the msg you were replying to. Moved it to the correct thread:
..here..

OK, I think it happened while I posted. It caused me some temporary disorientation.  ;)


Offline lamontagne

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Re: Envisioning Amazing Martian Habitats
« Reply #289 on: 11/01/2016 03:12 pm »
I put a bit of structure inside the dome.

Mostly platforms wit a lot of greenery.  Could be sports areas instead.  Possibly a floor of high intensity agriculture, but that might better be done in closed rooms with controlled atmosphere and lighting.  Plants are happy in conditions that people sometimes find not all that pleasant...

Again, most of the living area is actually underground, these are just entry points to the city.

The exterior wall is a form of curtain wall, in a way.  It's self supporting, mostly, and pressure driven, except for the gravity loads that are transmitted by columns to the ground.

Offline gospacex

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Re: Envisioning Amazing Martian Habitats
« Reply #290 on: 11/01/2016 03:20 pm »
About a decade ago I worked with some ~40" glasses-free 3D 1080p plasma displays that shifted perspective 9 times as you walked around them.  They required(and displayed) 18 video inputs.  They worked pretty well, for any number of people from differing viewing geometries, simultaneously.

Every time I read about the importance of windows in the ITS and transparent elements of habs being psychologically important on this site, I think back to those.

A voice of sanity.
Millions of people spend weeks or even months on end with no outside view through windows. Tens, maybe hundreds of millions of people have rather crappy scene viewable from their home/office windows (such as a wall of the next building filling the entire view).
This is an invented problem.

Offline Robotbeat

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Re: Envisioning Amazing Martian Habitats
« Reply #291 on: 11/01/2016 03:33 pm »
So is the need to live on Mars. If displays or VR were sufficient, they could just stay home and save a whole lot of money, risk, and comfort.
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

Online JasonAW3

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Re: Envisioning Amazing Martian Habitats
« Reply #292 on: 11/01/2016 03:50 pm »
So is the need to live on Mars. If displays or VR were sufficient, they could just stay home and save a whole lot of money, risk, and comfort.

Some people prefer a challenge and money, risk and comfort aren't as important to them as the idea of going where no one else has ever gone.
My God!  It's full of universes!

Offline ch1le

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Re: Envisioning Amazing Martian Habitats
« Reply #293 on: 11/01/2016 04:07 pm »
LaMontage.

Can you give me the sketchup link? I might put my vizualisation skills to use and make some renderings. Finally a chance to contribute to this forum.
Best wishes,
M.

Offline KelvinZero

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Re: Envisioning Amazing Martian Habitats
« Reply #294 on: 11/01/2016 05:22 pm »
I put a bit of structure inside the dome.
Hi lamontagne,
I don't think flattened spheres are robust pressure containers. For example in the extreme, upper and lower sides approach flat and would be worse than cubes. I think you can elongate, but not flatten. Cigars and conical points are ok.. I think?

Why not just go the full sphere? I posted a picture of a hydrogen tank in the other thread but just noticed there is a picture of it in a NSF article right now:

https://www.nasaspaceflight.com/2016/10/ksc-groundwork-sls-block-1b-upgrades/

These were the links I posted in the other thread:
these gas tanks or this big liquid hydrogen tank

EDIT:
Ok I did a search on pressure tanks and did find lots of examples that look flattened at the ends. Can anyone explain that to me? (none of them where wider than they were tall though, and when I searched for high pressure tanks, more had spherical ends.)
« Last Edit: 11/01/2016 05:32 pm by KelvinZero »

Offline KelvinZero

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Re: Envisioning Amazing Martian Habitats
« Reply #295 on: 11/01/2016 05:55 pm »
I put a bit of structure inside the dome.
btw, elipsoid7 is my favorite. This is how I imagine it, with tiers, and a mall-like atrium in the center.

You could have more wide spaces in the top half, because that inward curving wall is hard to stand up close to. It is actually a bother for normal structures. At least it can give you a wide open sense of space. It is the lower half that is easy to stand next to, so you can divide that up into floors with the wall forming expansive windows. I imagine that area a bit like living in an airport: mall-like, but with wide window-walls looking out.

Offline KelvinZero

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Re: Envisioning Amazing Martian Habitats
« Reply #296 on: 11/01/2016 06:06 pm »
This was a bit off topic in the other thread, but I also like the idea of a cellular approach to surface dwellings, if you go that way: https://en.wikipedia.org/wiki/Honeycomb_(geometry)#Space-filling_polyhedra

This would
*allow your bases to grow organically,
*allow construction with uniform components
*allow redundant levels of safety from decompression
*allow repairs and additions without inconveniencing other cells.

You could create interesting varied internal volumes by removing some adjacent faces.
Outer faces could be outward curving, or flat if reenforced with internal cabling. Inner walls could be flat and reinforced with cables for both directions, or curved and designed to be sufficiently strong whether relying on tensile or compression strength.

Longer term I imagine living underground, but these surface areas could be your vertical farms and your parks.
« Last Edit: 11/01/2016 06:12 pm by KelvinZero »

Offline lamontagne

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Re: Envisioning Amazing Martian Habitats
« Reply #297 on: 11/01/2016 07:36 pm »
I put a bit of structure inside the dome.
Hi lamontagne,
I don't think flattened spheres are robust pressure containers. For example in the extreme, upper and lower sides approach flat and would be worse than cubes. I think you can elongate, but not flatten. Cigars and conical points are ok.. I think?

Why not just go the full sphere? I posted a picture of a hydrogen tank in the other thread but just noticed there is a picture of it in a NSF article right now:

https://www.nasaspaceflight.com/2016/10/ksc-groundwork-sls-block-1b-upgrades/

These were the links I posted in the other thread:
these gas tanks or this big liquid hydrogen tank

EDIT:
Ok I did a search on pressure tanks and did find lots of examples that look flattened at the ends. Can anyone explain that to me? (none of them where wider than they were tall though, and when I searched for high pressure tanks, more had spherical ends.)
You can look at the Wikipedia page "Pressure vessels".  There is a nice, short overwrap pressure vessel.  Or you can look at the propane pressure tank on your barbecue, if you have one. It's pretty stuby.
The vessel will keep its shape because there are no compression forces, all forces push equally towards the exterior and the walls are under pure tension. But yes, an ellipsoid is less mass efficient that sphere.  The strain in about double that of a sphere, or almost equal to that of a cylinder.  So this allows manufacturers to use the same thickness throughout.


Offline LMT

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Re: Envisioning Amazing Martian Habitats
« Reply #298 on: 11/01/2016 10:48 pm »
Dome Heat

I put a bit of structure inside the dome.

Mostly platforms wit a lot of greenery.  Could be sports areas instead.  Possibly a floor of high intensity agriculture, but that might better be done in closed rooms with controlled atmosphere and lighting.  Plants are happy in conditions that people sometimes find not all that pleasant...

Again, most of the living area is actually underground, these are just entry points to the city.

The exterior wall is a form of curtain wall, in a way.  It's self supporting, mostly, and pressure driven, except for the gravity loads that are transmitted by columns to the ground.

Nice-looking structure.  btw, on winter nights your heat flux will be quite high.  For example, if panes are simple 6 cm glass, the flux would be ~100 MW.  Might give that some thought.

Offline KelvinZero

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Re: Envisioning Amazing Martian Habitats
« Reply #299 on: 11/01/2016 11:02 pm »
You can look at the Wikipedia page "Pressure vessels".  There is a nice, short overwrap pressure vessel.  Or you can look at the propane pressure tank on your barbecue, if you have one. It's pretty stuby.
The vessel will keep its shape because there are no compression forces, all forces push equally towards the exterior and the walls are under pure tension. But yes, an ellipsoid is less mass efficient that sphere.  The strain in about double that of a sphere, or almost equal to that of a cylinder.  So this allows manufacturers to use the same thickness throughout.
Ok: it linked to this: https://en.wikipedia.org/wiki/Head_(vessel)
"Vessel dished ends are mostly used in storage or pressure vessels in industry. These ends, which in upright vessels are the bottom and the top, use less space than a hemisphere (which is the ideal form for pressure containments) while requiring only a slightly thicker wall."

..so it is suboptimal, but apparently only a bit. Im surprised. Does this rely on any 'unbendiness' of the walls? Would these maintain their shape if infinitly strong in tensile strength but fully flexible?.. I think I can see that is true now by imagining constant length chords across the dome. Tensile strength requirements go up, approaching infinity as they approach flatness, but it is not about bendiness (I really should look up the technical term for that :) )

 

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