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#26 2015-12-26 00:35:04

IanM
Moderator
From: Chicago
Registered: 2015-12-14
Posts: 275

Re: Mars City - Your vision?

I was thinking more of Logan's Run, but with city blocks in a square grid. I agree with Robert that the modules would be stationary and permanent until terraformation advances enough to allow their removal. I think it'd be a better idea for a city that expands over time as opposed to a fixed dome that might ultimately need to be replaced as expansion goes on.

That being said, my vision was a city with a grid system for its streets, much like Manhattan, Chicago, or most other North American cities. However, such a grid would result in squares or rectangles, and we said that the most efficient dome/module with respect to atmosphere is a hemisphere. Obviously, the two shapes don't align well. We could just put the dome within the city block, but that wastes valuable space at the edges. We could also have a dome that has a square/rectangular base but which becomes hemispherical, but that transformation, unless the dome is made piecemeally like a geodesic one, might manifest itself as a structural defect and vulnerability. Or we could have a novel grid system based on a geometry more friendly to circles, but circles don't tessellate in any geometry.


The Earth is the cradle of the mind, but one cannot live in a cradle forever. -Paraphrased from Tsiolkovsky

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#27 2015-12-26 01:31:40

RobertDyck
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From: Winnipeg, Canada
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Re: Mars City - Your vision?

Here is one video that NASA published on 22 Dec 2015
Mars Exploration Zones
It shows one possible vision of a Mars settlement. You'll notice the 6-wheel truck that they've been working on shows prominently in the video; several versions with different tops: pressurized rover, unmanned propellant transport. At 4:18 in the video shows a base made with cylindrical modules. It's a hodge-podge arrangement, no streets. And the modules use the same CBM hatches as ISS; I think a planet would use doors that you can walk through upright. It shows white suits in one module, and orange ACES suits in another. ACES suits were partial pressure suits used on Shuttle during ascent, they weren't intended for EVA. I don't think there's a use for them on Mars. And their "food production" is a pair of greenhouses that use artificial light; no windows. Why wouldn't you conserve power by using sunlight? But this is one vision for Mars.

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#28 2015-12-26 02:05:18

IanM
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From: Chicago
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Posts: 275

Re: Mars City - Your vision?

I think that NASA video is a good representation of an early Mars settlement, suit and greenhouse issues aside. For the greenhouse, some want hydroponics; I can go for that, but I'd also like to see some tilling of the regolith to aid in terraformation, but that's another conversation.

I think such a hodge-podge would work decently enough in the early days, but I feel roads will become inevitable, even if only as building/block separators, especially with a city of 80,000 as Musk wishes, as such an arrangement with that many people would feel cramped and hostel-like, with insufficient bonds between residents, though it is quite possible that the original setup would survive in the city center, either as a hotel or museum.

The power is similarly fine given the type of settlement; I'm leaning pro-nuclear by the time the city reaches 80,000, but who says we can't have both? The bigger issue would be distribution - assuming above-ground buildings and blocks with their mini-domes, power lines could be put through the domes, but that could be a structural defect and vulnerability. Rather, they could be brought through the connections of the domes - I originally thought of such connections at ground level, where the domes immediately touch, but an underground or overground tunnel system, similar to Minneapolis or as you've said Winnipeg, would work. The power lines could be brought through such connectors, but bringing such high-voltage lines near where the people are is not the best idea.

The truck would be useful for out of city or simply agricultural purposes. The Martian landscape is not the most forgiving when it comes to vehicles, and I doubt many people would be avid drivers unless out of necessity. Perhaps it can be specialized to be a tractor, steamroller, street sweeper, bulldozer, and what have you.


The Earth is the cradle of the mind, but one cannot live in a cradle forever. -Paraphrased from Tsiolkovsky

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#29 2015-12-26 18:38:57

louis
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From: UK
Registered: 2008-03-24
Posts: 4,709

Re: Mars City - Your vision?

That's a great video NASA have produced there. A shame the reality doesn't match their promo.  They've had nearly 50 years to get us to Mars and have failed miserably.

However, it does show the sorts of things that would be technically feasible in the early stages of settlement.

That said, I feel that with the size of the habs and pressurised vehicles they are indulging in the usual NASA trait of over-solving.

For a settlement of say 20 people there is no need for such large imported vehicles or habs in my view.

NASA should be looking at less mass-costly solutions e.g. cut and cover for lightweight inflatable habs.

Pleased to see, however, they are running with PV power - my favoured route.  It's v. flexible.

I am not sure I agree with Ian M that a larger settlement needs to look to nuclear power (which I would assume means imported reactors). As the settlement grows I would recommend the colonists develop their own ISRU solutions to energy  e.g. solar reflectors and concentrators to power steam turbines (to generate electricity), district heating systems and smelters and to provide the power for manufacture of methane (as the storage power system). A more mature goal would of course be Mars-based construction of PV panels.


RobertDyck wrote:

Here is one video that NASA published on 22 Dec 2015
Mars Exploration Zones
It shows one possible vision of a Mars settlement. You'll notice the 6-wheel truck that they've been working on shows prominently in the video; several versions with different tops: pressurized rover, unmanned propellant transport. At 4:18 in the video shows a base made with cylindrical modules. It's a hodge-podge arrangement, no streets. And the modules use the same CBM hatches as ISS; I think a planet would use doors that you can walk through upright. It shows white suits in one module, and orange ACES suits in another. ACES suits were partial pressure suits used on Shuttle during ascent, they weren't intended for EVA. I don't think there's a use for them on Mars. And their "food production" is a pair of greenhouses that use artificial light; no windows. Why wouldn't you conserve power by using sunlight? But this is one vision for Mars.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#30 2015-12-26 21:59:18

SpaceNut
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Posts: 15,823

Re: Mars City - Your vision?

I can see that the module design was after a large dome is constructed, that said that we are just making a cookie cutter dwelling that is all the same for all to start within each newly made dome. Sure a nuclear reactor would be nice to have as a permanent source of power. Sure we will use a lot of differing power creating sources as that is the only way to build at a greater rate is to have excess power to do so with.

The first few domes will be oversided in area for what will support life within then as we have data from the biosphere to help with the right sizing of them for the number of people that it needs to support. Which means that we not only do the farming but minimal housing growth while mining the insitu resource to allow for the members under that dome to provide the roots for success.

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#31 2015-12-30 14:38:28

Tom Kalbfus
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Re: Mars City - Your vision?

Suppose we built this under a dome on Mars?
city_dome_by_tomkalbfus-d9m2k8i.png
It is an 8-mile radius map of New York City, the red circle would be the wall of the dome, everything outside of that is Martian landscape. Not all of New York City is under this dome, but most of Manhattan is. This is a 12.874752 km radius map for you folks on the metric system. Teterburo airport and LaGuardia are under this dome, therefore nonfunctional, but JFK Airport and Newark Airport are outside of this radius, thus we would convert them to spaceports. I think perhaps we could have a colony of this size by 2067, which would be on my 100th birthday, if I'm still alive. It would require a revolution in space travel if we are to build this by then, I think we are due for one sometime this century, if the difference between this and last is comparable to that between 1967 and 1867.

Last edited by Tom Kalbfus (2015-12-30 14:45:50)

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#32 2015-12-30 15:13:42

louis
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From: UK
Registered: 2008-03-24
Posts: 4,709

Re: Mars City - Your vision?

Sounds like that episode in the Simpsons where Springfield went under a dome! smile

Is such a dome feasible?  I doubt it - without supports that is. I am guessing in any case that at its highest point the dome - if it is to look like a dome - would be at least 3-4 kms tall at its highest point.

However, I could imagine an area that size being enclosed with discrete pressurised areas of perhaps a sq. km. You'd enter air locks to pass from one discrete area to the next. Might be a kind of assembly of domes or a combination of domes, cubes and skyscraper pressurised areas.


Tom Kalbfus wrote:

Suppose we built this under a dome on Mars?
http://img00.deviantart.net/f72d/i/2015 … 9m2k8i.png
It is an 8-mile radius map of New York City, the red circle would be the wall of the dome, everything outside of that is Martian landscape. Not all of New York City is under this dome, but most of Manhattan is. This is a 12.874752 km radius map for you folks on the metric system. Teterburo airport and LaGuardia are under this dome, therefore nonfunctional, but JFK Airport and Newark Airport are outside of this radius, thus we would convert them to spaceports. I think perhaps we could have a colony of this size by 2067, which would be on my 100th birthday, if I'm still alive. It would require a revolution in space travel if we are to build this by then, I think we are due for one sometime this century, if the difference between this and last is comparable to that between 1967 and 1867.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#33 2015-12-30 16:17:34

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 3,565
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Re: Mars City - Your vision?

The materials from which to make a giant dome (transparent or opaque) do not yet exist.  Same problem as with the space elevator.  Both are great ideas,  but both also require the exotic materials unobtainium,  manurium,  and unbelievium. 

The problem with pressure domes and real materials is two-fold:  (1) the blowout loads from internal pressure,  which are worse than the gravity loads unpressurized,   become quickly unhandleable beyond a very trivial size (much smaller than a football stadium),  and (2) the other enormous load for which we have no techniques or materials is how to secure the dome to the ground (internal pressure wants to blast it upward).  That second is a lot harder to handle than the foundation to support gravity loads when unpressurized.   

I would remind everyone that gravity loads of a dome cannot be ignored:  the thing inherently will be unpressurized while under construction!  So you have to handle both gravity loads and pressure loads,  and not at the same time. 

I would also remind everyone of a very inconvenient fact of life:  the square-cube law.  Mass (and weight) varies as dimension cubed because material density does not scale at all.  Part strength varies only as dimension squared,  because fundamental material strength does not scale at all.  That's why dome size is limited to things far,  far smaller than any of the concepts debated above. 

And,  I would remind everyone that a remarkable lab result for material strength,  such as the tensile strength of an individual carbon nanotube,  is absolutely NOT the same thing as the strength of a real engineering material fabricated from such stuff. 

No one has made anything significant yet from nanotubes;  there isn't even a viable concept for how to attempt such a feat.  Spinning them into thread to be braided into ropes won't work,  because friction is inherently too weak to hold them together at anything like nanotube strength.  It would be no stronger spun and braided than any other similar size string or rope or steel cable.  Something new that we haven't yet conceived is required to make real engineering materials out of incredible lab stuff like nanotubes. 

I'd go with individual pressurized buildings connected by pressurized tunnels,  and maybe do large areas of aquaculture underneath an ice-covered lake.  The buildings are limited in size by square-cube law,  the ice-covered lake thing is not (although the warmth and photosynthesis light will require power proportional to lake area). 

GW

Last edited by GW Johnson (2015-12-30 16:18:20)


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#34 2015-12-30 20:08:55

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 15,823

Re: Mars City - Your vision?

Build it in the simular manner as the Copula on the ISS as it has both capabilities just change the scale for the framing to support the structure. Make it in the manner of a geodesic dome.

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#35 2015-12-30 23:07:59

Void
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Registered: 2011-12-29
Posts: 3,011

Re: Mars City - Your vision?

Have you even considered the Martian ice caps and Nuclear power?

Granted, the startup will be hard core.

I would not even consider it for the first settlement.  No, for that, the equator.  But for the Thorium Buffs, how about an ice cap city?

If you could build under the ice, you would have all the water you might want.  And with nuclear power, no fears of being cold.  And the Martian atmosphere would be there 24/7 a source of CO2 and N2 for your purposes.  Perhaps you could construct little hypersaline lakes around it, and tunnels in it and tunnels in the regolith under it.  And perhaps domes like this. 

http://en.yibada.com/articles/70598/201 … ontest.htm

But the long winters would be a nightmare.  Better have nuclear powered apple tree forests in tunnels underground or everyone goes crazy.

the-first-place-award-of-25-000-went-to-team-space-exploration-architecture-and-clouds-architecture-office-of-new-york-new-york-for-their-design-mars-ice-house.jpg?w=685

You have got to admit that those two polar ice caps are the biggest chunks of water on the planet (We think), and if you are Nuclear, whose afraid of the big bad wolf anyway smile

Last edited by Void (2015-12-30 23:10:21)


I like people who criticize angels dancing on a pinhead.  I also like it when angels dance on my pinhead.

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#36 2015-12-31 11:29:14

Tom Kalbfus
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Registered: 2006-08-16
Posts: 4,401

Re: Mars City - Your vision?

GW Johnson wrote:

The materials from which to make a giant dome (transparent or opaque) do not yet exist.  Same problem as with the space elevator.  Both are great ideas,  but both also require the exotic materials unobtainium,  manurium,  and unbelievium.

 
Interesting that you say that, because I think you would need something like a space elevator to transport 8.49 million people to Mars to populate this city under a dome. I project that this city might exist by the year 2067 AD, about 100 years from 1967, the year of my birth, interestingly in 1967 the Apollo Program was well under way, air travel was common place by jet engines, something the people of 1867 couldn't even imagine, we are in the same jet age today as we were in 1967, and I think that era is getting a little long in the tooth, the next age is the real space age, where space travel is as common as air travel is today or back in 1967 if you prefer, so we are 48 years in 1967's future, to get to 2067 we need to go forward 52 more years. I think a lot of people assume that 2067 will look a lot like today unlike the differences between 1967 and 1867.
3967a3c8fced24405e7c8174e995569a.jpg
This is what New York City looked like in 1867.
907862383_6d4a80a067_z.jpg
This is New York City in 1967.
slide-nyc.jpg
This is New York City today.
We've been stuck in the same technological era since I was born, with little things like computers changing a lot, but everything else staying about the same. I think we are due some technological breakthroughs by 2067, things have been developing slowly for the last 50 years. People in 1967 thought then they were at the dawn of the space age and that a moon base and manned trips to Mars were just around the corner. Just because things have slowed down over the last 50 years doesn't mean they will stay slow, the previous 50 years from 1917 to 1967 weren't slow at all, we witnessed the development of mass air travel in that time, so will the years 2017 to 2067 be more line the first half of the 20th century or the second?

GW Johnson wrote:

The problem with pressure domes and real materials is two-fold:  (1) the blowout loads from internal pressure,  which are worse than the gravity loads unpressurized,   become quickly unhandleable beyond a very trivial size (much smaller than a football stadium),  and (2) the other enormous load for which we have no techniques or materials is how to secure the dome to the ground (internal pressure wants to blast it upward).  That second is a lot harder to handle than the foundation to support gravity loads when unpressurized.   

I would remind everyone that gravity loads of a dome cannot be ignored:  the thing inherently will be unpressurized while under construction!  So you have to handle both gravity loads and pressure loads,  and not at the same time.

 
Seems to me you could pressurize the loads a little to inflate the dome, and then strengthen the dome and increase pressure inside and then strengthen it more, until we arrive at Earth seal level pressure at the base.

GW Johnson wrote:

I would also remind everyone of a very inconvenient fact of life:  the square-cube law.  Mass (and weight) varies as dimension cubed because material density does not scale at all.  Part strength varies only as dimension squared,  because fundamental material strength does not scale at all.  That's why dome size is limited to things far,  far smaller than any of the concepts debated above.

 
If you have a space elevator that hangs down from geosynchronious orbit around Earth, you have already solved the strength problem for the dome, we have materials that are that strong called carbon nanotubes, we just need to mass produce enough of it to make a space elevator, and we have 52 years to figure out how.

GW Johnson wrote:

And,  I would remind everyone that a remarkable lab result for material strength,  such as the tensile strength of an individual carbon nanotube,  is absolutely NOT the same thing as the strength of a real engineering material fabricated from such stuff.

 
That's why we have 52 years to work on it, why to people consider it reasonable to assume no technological progress in 52 years. Technology has been slow over the last 50 years, rapid over the 50 years before that, I'd say it was due to speed up, if not, then artificial brains can figure out things that human brains cannot.

GW Johnson wrote:

No one has made anything significant yet from nanotubes;  there isn't even a viable concept for how to attempt such a feat.  Spinning them into thread to be braided into ropes won't work,  because friction is inherently too weak to hold them together at anything like nanotube strength.  It would be no stronger spun and braided than any other similar size string or rope or steel cable.  Something new that we haven't yet conceived is required to make real engineering materials out of incredible lab stuff like nanotubes.

 
And scientists and engineers will have brain fart for the next 52 years and not figure it out over that time. I guess the scientists in the early 20th century were much smarter than the ones today, who can only stare at nanotubes and not figure out how to make things work!

GW Johnson wrote:

I'd go with individual pressurized buildings connected by pressurized tunnels,  and maybe do large areas of aquaculture underneath an ice-covered lake.  The buildings are limited in size by square-cube law,  the ice-covered lake thing is not (although the warmth and photosynthesis light will require power proportional to lake area). 

GW

I guess you like tunnels and corridors. The problem with individual pressurized buildings is you can't go outside, my proposal would bring the "outside" under one roof., it is about the size of an O'Neil colony.
ac75-1883f-450x353.jpg
like this one.

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#37 2015-12-31 11:34:22

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 3,565
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Re: Mars City - Your vision?

The ISS cupola structure is only about a meter wide.  If you keep the same transparency panel size,  then it is your metal framing that must be quite large as you scale up your geodesic dome size.  Those metal framing members are subject to the square-cube scaling law.  No way around that,  and steel is only so strong.

That being said,  about the largest dome structures humanity has ever built are the roofs on domed sports stadiums.  Those are subject to gravity and wind loads,  but not internal pressure loads.  Even ignoring the internal pressure problem,  that's just about the largest size of domed structure we can attempt at this time in history.  If one assumes our first cut pressure domes are about half a stadium dome in size,  and opaque because we are using metals,  that's about 50 or 60 meters across. 

And no stadium dome has ever been transparent!  The glasses and plastics are nowhere near as strong and simultaneously as ductile as the metals.  (Which is why I said what I said about unobtainium,  manurium,  and unbelievium.) 

That's not to say we won't invent solutions to these limitations,  but we haven't yet.  And I might add,  some problems persist for long intervals.  Magnetic fusion confinement has been tried without real success for 65 years now.  Maybe they'll find the answer with the latest attempt,  but I'd advise not holding your breath. 

GW

Last edited by GW Johnson (2015-12-31 11:38:26)


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#38 2015-12-31 12:52:29

Tom Kalbfus
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Re: Mars City - Your vision?

There are plenty of craters on Mars with a radius of 8 miles or greater. One might choose to have a flat dome over a crater, sandwich a layer of water between two sheets of transparent material, cross beams of slanted sheets of metal can reflect light through while adding strength and weight. We might just use the formular weight = airpressure. See the following diagram: (not to scale)
crater_dome_by_tomkalbfus-d9m712a.png
Lets start with a crater:
martiancraterplaxco.jpg
Now we put a city on its bottom.
mars_crater_city_by_tomkalbfus-d9m75hd.png
Since the impact shattered the bedrock, it should be rather easy to landscape however we want, we can even carve out the topography of New York City if we want, and Just add water to fill the river basins, and we have "New New York City"

Last edited by Tom Kalbfus (2015-12-31 13:22:31)

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#39 2015-12-31 17:53:09

louis
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From: UK
Registered: 2008-03-24
Posts: 4,709

Re: Mars City - Your vision?

I think that's an interesting approach Tom.  And the concept can be proved with much smaller craters can't it?  You could gradually scaled up.

Just a thought - is there some sort of gel material that needs to be loaded at the joins to create a seal?  Perhaps there is some sort of organic material that would do the job?

Tom Kalbfus wrote:

There are plenty of craters on Mars with a radius of 8 miles or greater. One might choose to have a flat dome over a crater, sandwich a layer of water between two sheets of transparent material, cross beams of slanted sheets of metal can reflect light through while adding strength and weight. We might just use the formular weight = airpressure. See the following diagram: (not to scale)
http://orig13.deviantart.net/3489/f/201 … 9m712a.png
Lets start with a crater:
http://www.marsartgallery.com/images/ma … plaxco.jpg
Now we put a city on its bottom.
http://img00.deviantart.net/f28c/i/2015 … 9m75hd.png
Since the impact shattered the bedrock, it should be rather easy to landscape however we want, we can even carve out the topography of New York City if we want, and Just add water to fill the river basins, and we have "New New York City"


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#40 2015-12-31 19:28:21

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 15,823

Re: Mars City - Your vision?

The counter pressure via water while nice means another layer over the water to keep it fro subliming away.....I would recomend that we do a lower internal pressure to reduce the loading on the dome...maybe some where around 5Psi.....

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#41 2015-12-31 19:50:21

louis
Member
From: UK
Registered: 2008-03-24
Posts: 4,709

Re: Mars City - Your vision?

SpaceNut wrote:

The counter pressure via water while nice means another layer over the water to keep it fro subliming away.....I would recomend that we do a lower internal pressure to reduce the loading on the dome...maybe some where around 5Psi.....

I saw something a while back about floating plastic balls being used to prevent - or greatly reduce -  evaporation in reservoirs on Earth. Same for sublimation on Mars?

Happy New Year to all Forum Folk! smile


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#42 2016-01-01 11:34:59

Void
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Registered: 2011-12-29
Posts: 3,011

Re: Mars City - Your vision?

Happy New Year Louis!

I have been posting about putting plastic bags on the surface of a body of water.  In my case I would fill them with a fluid/solid, but a gas pocket on top could also be included.

As I see it these would be balloons around ice pans, for instance in one case.  Encapsulating them.  If you calculated the thermal inertia for the ice, the mass of the pieces and the thermal conductivity could go a long way towards making sure that the temperature of the surface ice was low, and therefore the vapor pressure would be low.  The encapsulation by plastic would easily suppress the remaining efforts of the cold ice to evaporate.

So, imagine a surface of such flat, plastic encapsulated ice pans.  Without further efforts, the "Joins" between ice pans would be exposed to atmosphere, and would also be locations where mechanical forces might damage the plastic balloon envelopes.  Those joins could have ice or extreme brine between them.  Still that is a bit less stable than what I want.  We might consider putting a felt around the perimeter of the ice pans, something to absorb and cope with mechanical displacements, rubbing.  With that things might be better.

I would not stop with that.  I would put a "Tenting" above that.  Here, if we have a "Web" (The plastic sheeting) that we can join from many small pieces to large pieces, we can consider one big dome.  It would not make that much sense, but you could.  The pressure inside of the dome would not be very much greater than the outside ambient pressure.  It might even be the same.

To justify doing this we would ask what the value of the "Epidermis" tent is?  Well, although the "Balloon Pans" would greatly suppress evaporation, there would still be some.  So this "Epidermis" Tent would allow the vapors to collect there for re-collection into water.

Also this "Epidermis" would be rather easy to replace, as it ages.  From reading RobertDyck's materials, I can see that using plastic envelopes will require the payment of a cost, as they will age rapidly in the Martian environment.

So, the use of a sacrifice layer that can be changed out "Live", is perhaps a good idea if you are infatuated with getting photons through such a layer, into the waters of a lake on Mars.

I am not so sure that that is what we want to do.

I am not against a "Skylight" here and there, but I am now turning away from the concept of relying on direct photosynthesis in lakes, since I think there are many good alternatives, that will not butt heads with the Martian environment as much as a plastic covered lake will.

Having said that I am very much in favor of lakes as the core of a city in many situations on Mars.

I would rather however, for the most part cover them with economic durable materials over ice, and those materials probably have to be Opaque to light.  But a skylight here and there could be just fine.

I originally was interested in a close analog of Antarctic Lakes where photosynthesis would be promoted by light going through the ice.  I now am much more interested in Hypersaline Lakes.

I have been trotting this out over and over:
https://en.wikipedia.org/wiki/Lake_Vida

Lake Vida is one of the largest lakes in the McMurdo Dry Valley region and is a closed-basin endorheic lake. The permanent surface ice on the lake is the thickest non-glacial ice on earth, reaching a depth of at least 21 metres (69 ft). The ice at depth is saturated with brine that is seven times as saline as seawater.[1] The high salinity allows the brine to remain liquid at an average yearly water temperature of −13 °C (9 °F). The ice cap has sealed the saline brine from external air and water for thousands of years creating a time capsule for ancient DNA. This combination of lake features make Lake Vida a unique lacustrine ecosystem on Earth.[2]

The above sounds incredibly uninviting as it is raw, but as a big salt pond, a Hypersaline lake has properties which should allow humans to easily modify the situation to their favor.

Lets start with Thorium Reactors.  (It seems I only hear the sound of crickets when I say "Thorium Reactor!"  smile).

If you are in love with Thorium Reactors, you can just make them as heaters.  Heat up a very warm layer of water at the bottom of the lake, and you have already made the lake much more valued.  For a lake like that as long as you keep the lower warm layer sufficiently more salty than the upper cold layer, the water will not turn over on it's own, and you can do a long term energy storage at the same time with both thermal storage, and salt gradients.

But of course you know that I also want to use solar energy to power such a lake.  And I want to show that human comforts can be provided in a rational way, while obeying the physical laws of the environment of Mars, and not incurring massive maintenance costs.

So where lakes might be possible, you can have properties, of radiation protection, habitat connectivity, energy utilization/storage, and by many methods biological support chemistry.

Radiation protection is obvious.

Habitat connectivity would be available with "Big Piping".  That would be large sized pipes that connect in a network, and some are vertical and protrude from the ice and above it, while being rooted to solid rock foundations below.  Horizontal connectors would be use to connect these partially flooded skyscrapers with each other, and with other types of habitat including rock and ice tunnels outside the bounds of the lake.  For the Vertical towers protruding from the ice, I suggest that a berm of Earth encases them all the way up and above the ice, to protect them from mechanical movement of the ice.  (If ice is used).

These "SkyScrapers" protruding above the ice will make excellent receiver towers for heliostat redirected sunlight.  I can see three varieties:
-Raw sunlight including full U.V. delivered to a hydricity device.
-Selective reflected light (Without U.V. directed to aquatic greenhouses in the towers.  Spirulina being a proposed "Crop".  The lighting intensity as high as the crop will tolerate.  This will make the most efficient usage of windows, delivering the maximum amount of photons, to the crop, while greatly reducing the percentage of the received light that would be U.V.
-Lounges.  I should be quite reasonable to put lounge rooms in these towers where they can have greater protection.  These would be places where people could look out of viewing ports, read books, have meetings and gatherings.   The lounges would also have decorative plants to create the sense of a park.  Perhaps heliostats would be used to increase the solar flux into them.  Or perhaps they would rely to a greater extent on artificial lighting.

Connectivity would also be facilitate by the fact that in a hypersailine lake you could have "Ice Fishing" holes, and bring objects into and out of the lake through them.  I have discussed this elsewhere.

Now, energy utilization/storage:  Not only could you use Thorium Reactors;

You may use the powers of corrosion to generate heat.  Soils containing Olivine, Pyroxene, and Feldspar, will decay in the presence of water, or rather Oxidize.  This not only will generate Hydrogen, but it may even give off heat.  In order to use that heat, however, you need a very big collector.  Well a Hypersaline is a very big collector.
Soil delivered to the bottom will corrode, and give off Hydrogen and Nitrous Oxide, and also heat I believe.  That heat will be stored in the bottom layers of the lake.  The result in part may be useful clays.  The process takes a few years, so the soil could be change out periodically. And;

You may harvest the atmosphere of Mars, generating your condensed gases using a combination of Cryogenics, and Reverse Osmosis.
The Carbon Monoxide can be fed into the lake, or parts of it as food for Bacteria, which may also digest Hydrogen produced by the corrosion of soil.  You may also deliver the Oxygen for them to Breath.  Since there is twice as much as needed to Oxidize the Carbon Monoxide, you may provide some of the Oxygen to Humans.  Or you might increase the Oxidation of the lake for bacterial growth.  You don't want too much oxidation or you "Burn up" you bacteria.

Now you can grow your microshrimp.  They will require enough Oxygen, but may be tolerant of the temperature and salt levels in lower reaches of the lake.  So, you have chemosynthetically provide a vast food supply for your people, the Microshrimp.   Or if you don't like Microshrimp paste products, then consider growing other aquatic animals. They of course require greater sheltering, not being as tolerant of the conditions in the lake, particularly high salinity.


Now;
by many methods biological support chemistry.  Been there, done that.  But lets make it better and hope to link up with Spacenut and RobertDyck and their greenhouses.

No problem big piping connects to their greenhouses, and the lake provides utility resources to assist in them growing nice vegetables in them.

So, we have bulk production of Spirulina, Microshrimp, and optional production of Vegetables and Fish.

I will stop here, except to mention that "Big Piping" can provide some fail safe safety measures, much like sink traps.  Suppose one of your Skyscrapers depressurizes, your probable path of escape, if you are not trying to effect a repair, is down the pipe.  Barometric methods including sink traps, may provide survival and recovery methods in that situation.

Done.

-

Last edited by Void (2016-01-01 12:39:56)


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#43 2016-01-01 12:00:46

Tom Kalbfus
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Registered: 2006-08-16
Posts: 4,401

Re: Mars City - Your vision?

SpaceNut wrote:

The counter pressure via water while nice means another layer over the water to keep it fro subliming away.....I would recomend that we do a lower internal pressure to reduce the loading on the dome...maybe some where around 5Psi.....

More air pressure underneath simply requires placing more weight on top to hold it down, since the net direction of all that pressure under a flat zero curvature dome on top of a crater is up, then the direction of weight is downward toward Mars. Having water is just one option, you also could have a roof of glass, you could have a roof consisting of slanted steel mirrors between transparent layers of glass or plastic or you could have a transparent water layer. Steel has its advantage because its stronger and denser than water a water layer sandwiched between glass, you have a source of water for sprinklers. Deep craters are preferable if you want tall structures under the dome.

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#44 2016-01-01 12:42:26

Void
Member
Registered: 2011-12-29
Posts: 3,011

Re: Mars City - Your vision?

Tom, just a quick thing.  I have been told that normal glass is not strong in water.  It is much stronger in a vacuum.

I think the reason is that water lubricates the tiny cracks in the glass, and so makes it weaker.  Not entirely sure about that though.  What did you think of the post I just created before yours?


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#45 2016-01-01 13:52:11

Tom Kalbfus
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Registered: 2006-08-16
Posts: 4,401

Re: Mars City - Your vision?

Void wrote:

Tom, just a quick thing.  I have been told that normal glass is not strong in water.  It is much stronger in a vacuum.

I think the reason is that water lubricates the tiny cracks in the glass, and so makes it weaker.  Not entirely sure about that though.  What did you think of the post I just created before yours?

Its quite long. You seem to be talking about ponds, skylights and tenting. Lets me see if I got the idea. You want to put a tent above an ice pond. That might work. Lets say you put a dome above a crater filled it with water, and pressurized the dome just enough so liquid water can exist. I know 15 degrees centigrade is room temperature. So lets say we pressurized the dome so that the boiling point of water inside was one degree above room temperature or about 16 degrees centigrade. What pressure would you need to do that.

https://en.wikipedia.org/wiki/Boiling_point
This chart should be helpful:
water-pressure-boiling-temperature-2.png

Seems to be that if we raise the pressure under the dome to 0.5 psi or 0.034 bar, we could have a stable pond of water up to a temperature of 26.4 degrees Celsius or 79.6 degrees farenheight. I think we could have quite a big dome sustaining that pressure.

The atmospheric pressure on Mars is 0.087  psi, which would mean the dome would have to sustain a net pressure difference of 0.41 psi. Normal sea level pressure on Earth is 14.69 psi. So if we want, we can have a dome over a crater, a pond 26.8 meters deep, and underneath a sheet of plastic or glass, we have air at sea level pressure.

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#46 2016-01-01 14:27:15

Void
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Registered: 2011-12-29
Posts: 3,011

Re: Mars City - Your vision?

Your on the right track, but...

Your tent is for moisture retention only.  By other methods we prevent bulk boiling, but not small leakage of moisture from the covered pond into the tent.  You then perhaps use a method such as a compressor to recapture the small leakage of moisture.

I will go in steps.

You have your crater lake, it has ice on it.  You put the tent over it.  As long as the ice surface never rises to or above 0 DegC or 32 DegF, the triple point of water is never reached.  If the air inside the tent is a 100 % RH, you will not incur surface ice loss. Except:
During the night, moisture would condense on the inner tent wall, and so drop the tents humidity below 100%.  In this case, vapor will travel from the surface of the ice to the inner tent wall.  This is not well enough perfected in my opinion therefore.  In the day, that situation could reverse as sunshine drives frost from the inner tent wall to the surface of the ice, provided the surface of the ice was cold enough.  (It could get quite cold during the night).

So, and upgrade, would be to put a layer of plastic down on the surface of the ice.  Then during the night, that might serve as a vapor barrier to prevent evaporation from the surface of the ice to the inner tent wall.  This scheme could get into trouble during the day however, as if the surface of the ice builds up enough vapor pressure, the plastic coating could bubble up, and your transparency would suffer as those bubbles would collect opaque frost.

So, to do even better, think of a tile floor.  Your ice surface is going to be a mosaic of tiles.  Each tile is going to be a flat balloon, and you may fill the balloon with something, perhaps ice, maybe a transparent oil, or if you keep your lake warm enough, perhaps water.

For an  ice tile mosaic, you would have ice tiles encapsulated in a plastic balloon with a snug fit.

The tiles will get quite cold at night, and it is possible that during a daytime on Mars that inertia could be sufficient to prevent the encapsulated ice from having any ice melt or evaporate.  But if it did, it is encapsulated, and that by itself can keep the contents from evaporating since it is very unlikely that any melted water would get much above freezing, so the vapor pressure will not rise much above ambient, so the balloon can easily hold it's contents against evaporation, and the tiles will apply counterpressure over the water or ice below the tiles, preventing boiling/evaporation.

The tiles would float on the water.  Some moisture leakage would occur between the tiles, but your tent would be used to recapture that moisture.  You might employ some type of felt caulk between the tiles.


Personally, I am inclined to forgoe the transparent ice surface, and cover most of the lake with an opaque covering.  As I have said, Nuclear, Corrosive, Atmospheric, and Solar Energy of several kinds can supply the lake with life forces without making the whole surface a window.

I currently am thinking of just a plastic sheet layed down over the ice and a pumice raft over it.
https://en.wikipedia.org/wiki/Pumice_raft

A pumice raft is a floating raft of pumice occasionally created by ocean-based or near-ocean volcanic activity.

It is rock or rock sand/dust with sufficient air filled cavities that it can float on water.

In this case, it would "Float" on ice.  I would simply put a plastic layer under it and above the ice to insure even better that the ice is very stable.  The pumice would be rather insulating, so the day/night and solar temperatures averaged under it, the ice should always be stable.

This is of course an upgrade from just putting regolith on the ice.  More effort, needed, but better results.  You are building a giant city on Mars, so I am guessing you can create artificial pumice.

*The pumice needs to be heavy enough to resist the wind however.  Or rather the surface area has to be kept low relative to mass, so maybe not pumice dust or sand, but maybe pumice pebbles.


Biologists suggest that animals and plants have migrated from island to island on pumice rafts.[1][2]

Astrobiologists have hypothetically linked pumice rafts to the origin of life.[3]

Last edited by Void (2016-01-01 14:42:11)


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#47 2016-01-01 14:34:46

Tom Kalbfus
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Re: Mars City - Your vision?

Wouldn't you want your subsurface habitat to be closer to room temperature rather than the temperature of ice water? 0 degrees Celsius isn't the most comfortable temperature to live in if the top of the pond is liquid rather than solid, as astronaut can swim to the surface in his space suit, and then enter an airlock to the outside of the dome to go outside.

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#48 2016-01-01 14:46:05

Void
Member
Registered: 2011-12-29
Posts: 3,011

Re: Mars City - Your vision?

Well for fresh water you can have a stratification which allows the water just under the ice to be 32 degF and the water at a bottom may be at 39 degF.  However you are right, even with good diving gear, 39 degF is nasty.

But study this it is a partial solution and will add more after it:

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

Description[edit]

A solar pond is simply a pool of saltwater which collects and stores solar thermal energy. The saltwater naturally forms a vertical salinity gradient also known as a "halocline", in which low-salinity water floats on top of high-salinity water. The layers of salt solutions increase in concentration (and therefore density) with depth. Below a certain depth, the solution has a uniformly high salt concentration.

When the sun's rays contact the bottom of a shallow pool, they heat the water adjacent to the bottom. When water at the bottom of the pool is heated, it becomes less dense than the cooler water above it, and convection begins. Solar ponds heat water by impeding this convection. Salt is added to the water until the lower layers of water become completely saturated. High-salinity water at the bottom of the pond does not mix readily with the low-salinity water above it, so when the bottom layer of water is heated, convection occurs separately in the bottom and top layers, with only mild mixing between the two. This greatly reduces heat loss, and allows for the high-salinity water to get up to 90 °C while maintaining 30 °C low-salinity water.[1] This hot, salty water can then be pumped away for use in electricity generation, often through a turbine of some sort.

So, they are doing this in a desert apparently and suffering lots of water losses from the surface due to evaporation, but the surface temp is 30 degC and the bottom gets up to 90 degC which would cook you diver eventually after it killed her/him.

So, that's not quite what we want, we don't want 30 degC open water on Mars, in fact we can't have that.

But here is a information about "Antarctic Dry Valley Lakes" which are natural solar ponds strangely enough!

http://antarcticconnection.com/informat … y-valleys/

The lakes are by far the most interesting and diverse habitats in the Dry Valleys. Organisms are found growing on and in the ice cover, in the water, and on the bottom of the lakes. Exploration of lake bottoms by SCUBA-equipped divers, including core sampling of bottom sediments, have disclosed the existence of algal mats on lake floors; in certain respects these are analogous to some of the Earth’s earliest life forms The mats produce gases which render them buoyant in marginal zones of the lake. There they form columns, which detach from the bottom, rise, and then work their way upward through the surface ice layers-as much as 5 meters thick-after which they dry out and blow away, sometimes to colonize in other locations.

The bottom water of these lakes can reach 25 degC which is suitable for a diver without a wet suit at all.  And it is powered by sunlight.  These lakes are natural solar collectors.

The price paid is having to deal with very salty water however, that is corrosive, but sometime corrosion can be your friend as well.

I am curious, I have been talking about this stuff for years.  How is it possible that you never read/understood it?

Last edited by Void (2016-01-01 14:58:14)


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#49 2016-01-01 21:07:46

louis
Member
From: UK
Registered: 2008-03-24
Posts: 4,709

Re: Mars City - Your vision?

Void - Just a suggestion...why don't you provide a kind of abstract at the top of your longer posts i.e. a few bullet points setting out the points you are detailing below?  I think that may help some readers e.g. me! 

Void wrote:

Well for fresh water you can have a stratification which allows the water just under the ice to be 32 degF and the water at a bottom may be at 39 degF.  However you are right, even with good diving gear, 39 degF is nasty.

But study this it is a partial solution and will add more after it:

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

Description[edit]

A solar pond is simply a pool of saltwater which collects and stores solar thermal energy. The saltwater naturally forms a vertical salinity gradient also known as a "halocline", in which low-salinity water floats on top of high-salinity water. The layers of salt solutions increase in concentration (and therefore density) with depth. Below a certain depth, the solution has a uniformly high salt concentration.

When the sun's rays contact the bottom of a shallow pool, they heat the water adjacent to the bottom. When water at the bottom of the pool is heated, it becomes less dense than the cooler water above it, and convection begins. Solar ponds heat water by impeding this convection. Salt is added to the water until the lower layers of water become completely saturated. High-salinity water at the bottom of the pond does not mix readily with the low-salinity water above it, so when the bottom layer of water is heated, convection occurs separately in the bottom and top layers, with only mild mixing between the two. This greatly reduces heat loss, and allows for the high-salinity water to get up to 90 °C while maintaining 30 °C low-salinity water.[1] This hot, salty water can then be pumped away for use in electricity generation, often through a turbine of some sort.

So, they are doing this in a desert apparently and suffering lots of water losses from the surface due to evaporation, but the surface temp is 30 degC and the bottom gets up to 90 degC which would cook you diver eventually after it killed her/him.

So, that's not quite what we want, we don't want 30 degC open water on Mars, in fact we can't have that.

But here is a information about "Antarctic Dry Valley Lakes" which are natural solar ponds strangely enough!

http://antarcticconnection.com/informat … y-valleys/

The lakes are by far the most interesting and diverse habitats in the Dry Valleys. Organisms are found growing on and in the ice cover, in the water, and on the bottom of the lakes. Exploration of lake bottoms by SCUBA-equipped divers, including core sampling of bottom sediments, have disclosed the existence of algal mats on lake floors; in certain respects these are analogous to some of the Earth’s earliest life forms The mats produce gases which render them buoyant in marginal zones of the lake. There they form columns, which detach from the bottom, rise, and then work their way upward through the surface ice layers-as much as 5 meters thick-after which they dry out and blow away, sometimes to colonize in other locations.

The bottom water of these lakes can reach 25 degC which is suitable for a diver without a wet suit at all.  And it is powered by sunlight.  These lakes are natural solar collectors.

The price paid is having to deal with very salty water however, that is corrosive, but sometime corrosion can be your friend as well.

I am curious, I have been talking about this stuff for years.  How is it possible that you never read/understood it?


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#50 2016-01-01 23:06:17

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 15,823

Re: Mars City - Your vision?

Maybe this will help

http://www.dullesglassandmirror.com/gla … lator.aspx

http://www.grayglass.net/glass.cfm/Flat … /conid/217

https://www.saflex.com/en/DownloadLibra … CHI_SAFETY

I am also wondering if progressively thicker layers of glass to support the weight above it with additional layers to spread the weight out on each layer might help....

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