Going to Mars - Am I the only one?

Martian Republic · 2005-04-14 16:40:08

I read somewhere that we need about three acres per person to be able to grow enough food for one person. If that is so, then growing enough food for a hundred people which would not be really that many people for a Mars colony. Then we would need about three hundred square acres to be able to feed our Mars colony. That going to be a pretty good size, before we even get to the place where people are going to be living at or working at, or anything else for that matter. So whether we farming above or below ground, it going to be a problem either way.

Larry,

Fledi · 2005-04-14 17:03:53

You could make several stories for the underground variant, where you have to place lights anyway. But I guess this will not reduce the problem by much.
It becomes even worse if you want to keep cattle for you need about 7kg of wheat for 1kg meat.
I wonder what the first martian cow will be like?

RobS · 2005-04-14 17:26:48

As I understand it, the folks at MIT interested in Mars construction concluded that cooling surface greenhouses is a major problem because radiation through the transparent bubble is not adequate. Cooling becomes an even bigger problem if the plastic bubble is inside a cave.

If you build a cave or tunnel, you will STILL need some sort of plastic liner to retain air, because rock has cracks and is never airtight.

Again, as I understand it, there are plenty of plastics that already exist on the commercial market that can handle Martian temperature swings. Robert Dyck has already posted about this on these forums. But if one is concerned about it, one could inflate a thin, expendible plastic bubble around the greenhouse. This outer layer could serve various purposes; to protect the main envelope against temperature swings and sand blasting, shield it against ultraviolet light, etc. The outer layer, like vinyl siding or a coat of paint, could be replaced every few years.

As the dust devils on Mars have demonstrated, you can blow dust off of structures. As GCN notes, it should be an automated process.

To protect greenhouses from damage, you bunch them all together cheek and jowl and bulldoze a dirt berm and rock pile around them, so no one drives into them (of course, if no one can get drunk behind the wheel, the danger of that is minimized). Near as I can tell, the danger from meteorites is precisely zero; the Martian atmosphere stops anything a few inches/centimeters across or smaller.

We know the level of insolation on Mars pretty well:

http://powerweb.grc.nasa.gov/pvsee/publ … power.html

About 40% of the year, insolation is reduced by dust. So your greenhouses have to be that much bigger and they won't grow much part of the year. It'd be a good time to plant winter wheat in them (which makes better bread anyway).

If you want more solar insolation during the half of the year when there is little dust, you can make your greenhouses taller. Rather than being a semicircle where height is equal to half of width, they could be semi-ellipses that stick taller. Air pressure will maintain their shapes either way.

The trick to make cheap reflectors are these, in my opinion:

1. Build greenhouses that are long north-south and narrower east-west. In other words, use a quonset hut shape, not a circular dome.

Before the sun rises, the entire dome is covered on the inside with insulation blankets, to retain heat. When the sun rises in the east, you lower the insulation blankets on the eastern side of the quonset hut (this can be done electrically, like raising and lowering shades on tracks). Leave them up on the western side. The insulation blankets are silvered on their inner surface. Sunlight that normally would pass over the tops of the plants hit the silvered blanket and are reflected back down on the plants (the shape of the inner semicircular surface is perfect for this). The insulation blanket does not have to have a smooth surface; it could be quite wrinkled, because most of the light would still be reflected downward.

About 10 a.m., the sun would have risen so high that the western blanket would start to shade parts of the greenhouse on the western side, so you'd lower the insulation on the western side. About 2 p.m. you'd raise the insulation blanket on the eastern side and reflect light downward that is shining in from the west. At sunset, the insulation would go up on both sides; the plants don't need to see the stars (though couples seeking a romantic view might want to lower the insulation blankets for a few minutes and enjoy the starry night together, until the bubble gets blurry from condensation at least!).

How much does this improve the energy situation? We can calculate it. The perimeter of a circle has a length = pi times d (diameter of the circle). This means that on the Martian equator, daily insolation is equal to the solar constant above the atmosphere divided by pi, because the light, rather than falling in a straight, flat line the width of Mars, is falling on a circular strip. In contrast, a greenhouse with efficient reflectors will capture just about all the sunlight that passes onto or over it, and if the greenhouse roof is a semicircle, this will equal the solar constant divided by 2 (because the sun is up during the day and down at night). Thus the improvement in available energy is pi/2 or 1.57.

Mars receives 500 watts per square meter; the Earth 1,000 after the thicker atmosphere's absorption is taken into account. Plants can grow adequately in September when, at 45 degrees north and south, the sun is up half the day and the sun never gets overhead. The sine and cosine of 45 degrees is about 0.7. I think that means that at 45 degrees north, plants get about 0.7 times as much sunlight in September as they would at the equator, or about 700 watts per square meter. On the Martian equator with reflectors, they can get 500 x 1.57 = 785 watt per square meter.

So from this I conclude that very simple reflecting surfaces on the inside of a quonset-hut shaped dome will give Martian plants roughly the same amount of solar energy as they receive on the Earth at mid latitudes. Terrestrial plants also have to deal with days of cloudy weather;martian plants do not.

-- RobS

RobS · 2005-04-14 17:35:02

There's a book called Space Settlements that describes the space requirements for a colony at L5. The follow data comes from that book. I would double the agricultural areas because it assumes twenty-four hours of sunlight at space levels, and the Martian surface is less:

Residential space 49 sq m per person
Work and other space:
Shops, Offices 3.3
Schools, hospitals, recreation 3.8
Service industry 4
Storage 5
Communication, waste treatment 4.2
Miscellaneous 2.9

TOTAL "inside" space: 72.2

Space Settlements say this about agriculture:

Sorghum 3.8 sq meters/person
Soybeans 23.5
Wheat 7.2
Rice 3.6
Corn 0.9
Vegetables 5.2
Subtotal: 44.2

Fish 2.6
Birds 0.8
Mammals 1.7

Transportation 12
Park space 10

TOTAL "outside" space: 68.7 sq m/person

-- RobS

GCNRevenger · 2005-04-14 20:27:47

"How have I underestimated anything? I never said it was going to be easy. As for pipe dreams, mine is about as plausible as your own- expecting polymer based plastics to withstand temperature extremes of that magnitude for any duration is sheer fantasy."

Ummm. You want to basically drill enough holes underground enough for acres and acres of farms. I am saying that your idea is not plausable, because digging underground is HARD, and you could not dig enough tunnel in any reasonable time, TBM mass, or energy requirement. It would take years and years, and you would need heavy machinery to either be built on Mars or imported from Earth.

I do happen to know a little about polymers, thank you very much, and they can be formulated to withstand the temperatures of the Martian night (which don't get as cold as your worst-case -225C near the equator I bet). Even plain old PVC, which can be made exclusively from Martian materials, is almost good enough with some dopants... Not that they would have to either with even minimal heating if properly insulated ... Even if not and you lose power long enough to risk the residual heat sink cooling off, then you are probobly dead anyway. You also underestimate the thermal capacity of rocks.

I want to stress another point, that the use of nuclear power must be applied sparingly: its going to be a long, long time before Martians could build their own large-scale power plants, so you are basically limited to the size of ones you can import from Earth. A power plant small enough to fit in one or two heavy cargo flights isn't going to make more then a few megawatts probobly, so you just don't have lots of electricity to spare.

It will be even longer then that before they could mine & refine Uranium, even if there is any to be had too. The huge amount of energy needed to operate a farm in complete darkness would be a horrible waste. Plus, operating it underground would be a big energy draw to keep the tunnels cool. A surface greenhouse, you could use the waste heat to keep them warm, which you can't do with a tunnel.

Polymer greenhouses can work just fine. There is nothing natural on Mars that is a puncture risk, they need little or no outside energy, and they can be built exclusively from native materials most likly. Maintenance won't be a big problem if the things are easy to make, since they would be expendable. A few pounds of polymer every couple of years just isn't a big problem. The biggest draw is that they are EASY, that you don't need major machinery or major Earth-imported hardware to build them.

The permafrost issue is more a problem for tunnels then greenhouses. If there is loads of water ice underground as MarsExpress and MRO suggest, then there aren't going to be any tunnel-farms. The heat, which you can't get rid of very well, will melt the surrounding ice and cause the tunnels to collapse. "Oops."

Grypd · 2005-04-15 15:00:49

Even at the equator the amount of light that Mars recieves is not perfect for growing plants even with the addition of additional light from Mirrors. Still benefits from increasing the atmosphere in an agriculture dome by increasing the CO2 concentration should cover for this. Heat could be provided by excess from the colonys nuclear plant and from heat exchangers removing the heat from the highly insulated Human areas.

We will ensure that the Human parts of the colony will be under a good degree of radiation protection even if sandbags under a brick covering. And to ensure that heat from such bases does not leak into the regolith and cause subsidence in a permafrost area we will insulate the areas very thoroughly. This will make the Human areas a sweatbox unless we can provide a form of air conditioning and using a heat exchanger to move this to the agriculture domes above does make sense.

Still we will benefit from modifying the plants we grow like incresing the chlorophyll count to increase light efficiency or by modifying the chlorophyll themselves. Probably making for not green plants but almost black but it will be good practice for designing plants to operate outside the domes in the martian wild.

srmeaney · 2005-04-15 19:14:59

Finaly, someone who sees the value of an underground colony.

Mars republic, you refered to tunnels linking underground colonies. At hypersonic velocities, the air pressure wave of a maglev will rupture the tunnel. Unless you run the transport in a vaccuum.

Are nuclear reactors sufficiently small to drive a train? Or would we have to go with a power grid?

Fledi · 2005-04-16 04:57:42

I recall my father telling me, that he was once in an underground farm in Russia when he was studying there. They used mercury vapor lamps with several 100kW for a single Lamp for lighting there.
They were using the farms to help supply some far north cities with food, so underground farming is possible.
I don't know whether they built them into permafrost (unlikely) or found some hard rock to dig the tunnels in, but why wouldn't we be able to do the same on Mars?
Though it might be a lot cheaper to simply costruct some greenhouses.

Dook · 2005-04-16 07:42:47

Living on mars is difficult enough without all this craziness about excavating and living in underground caverns.

If you are going to make things more difficult on yourself there has to be a tremendous benefit, some reason to make the extra cost and burden worthwhile. There simply is none.

Martian Republic · 2005-04-16 11:01:00

I recall my father telling me, that he was once in an underground farm in Russia when he was studying there. They used mercury vapor lamps with several 100kW for a single Lamp for lighting there.
They were using the farms to help supply some far north cities with food, so underground farming is possible.
I don't know whether they built them into permafrost (unlikely) or found some hard rock to dig the tunnels in, but why wouldn't we be able to do the same on Mars?
Though it might be a lot cheaper to simply costruct some greenhouses.

It might eventually be possible to grow food underground on Mars. But, it going to take a lot of digging to do that. Did your father also tell you how long it took them to dig out enough area so that they could grow enough food to be able to make a serious difference on the food supply of that northern city? If it took them forty or fifty or even sixty years or longer to dig it out. Well, that could be a problem on Mars where we need it as soon as we get it. Also we have the equipment on hand to dig out that much area underground here on Earth and we can build the power station to power the hole thing. We can setup large massive labor camps in the hundred or even thousands to do projects like that too. On Mars we can not. After we setup our first major city on Mars, then that might be a viable possibility or some variation of that on Mars.

I personally believe that we will eventually have a combination of both type of city’s on Mars as the population on Mars increases. We will eventually have both an underground and above ground transportation, but will probably be hundred to two hundred years or more into the future when we may have hundreds of thousand or even millions of people on Mars. But, on the short term, we will probably be building most of our city on the surface with only minor digging into Martian mountain side or down into the ground, because of the labor factor in digging out that much area to build a city underground like that. We also may be doing digging for mining purposes too, but it would depend on what kind of mining that we are doing to as to whether we are actually digging hole or mining the air or surface deposits. For the first forty or fifty year after we land on Mars, major infrastructural project are going to be few and far between, because of the resources need to build them. That one reason I favor building one major city where you have a massive labor pool to draw from to build major infrastructure that need to be build to have a healthy economy on Mars. Now we may have to scatter a few people out in mining colonies to get resources and we may have research laboratories scattered around Mars, but out main city should be our number one focus for any effort for us to stay on Mars permanently. That where you would build your space port, which would be like an air port, your manufacturing and main farming communities.

Larry,

Fledi · 2005-04-16 11:27:03

I don't know how long it took them to dig the caves, but I doubt they did it with labor camps, at least not the way my grandparents were digging. The tunnels would be too unsafe and small that way.

Underground digging could be automized almost completely, so it would not be that labor intensive and you could just let the machines dig around. It is a good way to create radiation safe living places at the beginning, though it might still be too much work for farming.

I agree on the one big city first approach, we need to achieve a high recycling rate as soon as possible. That might work better in larger settlements.

MarsDog · 2005-04-16 13:09:15

http://www.vegansociety.com/html/environment/land/]On Earth only 274 M^2 (16.5m (54 feet) meter square) for potatoes

Add some reflectors to increase energy to Earth levels.
And you could have a very dense population of Irish immigrants ?

srmeaney · 2005-04-17 17:40:15

If there is going to be substantial Science teams, then it is cheaper to provide a few with mobile habitat/labs and send them to many sites rather than to deploy stationary habitats to those sites.

Martian Republic · 2005-04-17 18:34:17

Finaly, someone who sees the value of an underground colony.
Mars republic, you refered to tunnels linking underground colonies. At hypersonic velocities, the air pressure wave of a maglev will rupture the tunnel. Unless you run the transport in a vaccuum.
Are nuclear reactors sufficiently small to drive a train? Or would we have to go with a power grid?

Yes, to have vacuum tub underground, that would be one way to deal with the hypersonic velocities of a levitated train system on Mars. But, the infrastructure to do that would be so big that it would be at least a hundred years or more after we first land Mars to get a big enough population with big enough industrial capacity to do something like that. But, in the short term, it would be just a pipe dream of some future development project.

As to your second question.

No, we will not be putting nuclear power plants levitated trains systems. We would either have it running of electric power grid system or we may be using some form or permanent magnet system where we wouldn't have to much electricity to run our levitated train system. The Japanese levitated system repulsion system which is a little bit faster than the German levitated system of attraction. I heard they would theoretically max out at around 350 to around 375 or something like that. There is an American World War II Veteran that came up with an idea of using permanent magnates for generating most or the power to power that levitated train system. Which would have a great energy saving feature to it and I heard that it would theoretically top out at about 600 miles an hour. If he has in fact, figured out how to use permanent magnets, you would not have to generate too much power to run it. You would only have to control the permanent magnets as they cross each other to start or stop or control the speed of the levitated train system. It worked on system of extending and retracting magnates and such things. He planning on put the rails on cone so it would be self-leveling for low maintaince.

This is definitely not a short term project or even near term project for that matter for any Mars colony. But, once you have two major city on Mars say maybe three or four hundred miles away, they would be less than an hour away by the super train system.

Larry,

Martin_Tristar · 2005-04-17 20:15:51

Cheaper to build above ground development they tunnelling miles and miles through the martian soil. We need to build and layout two or three sizable outposts within 30 kms from each other and point one as the principal settlement for government and authority management. We need as a grid of communication and global positioning satellites (GPS) in geostationary orbit around Mars to provide the correct information and monitoring facilities for all the ongoing probes and droid surveying of the planet.

In order to get to this stage of mars settlement evolution we need a vast fleet of cargo transports (unmanned and / or manned ) that would bring the necessary cargo to the settlements as well go further into the solar system for exploration and resource collecting purposes.

We don't need to waste time and resources making things difficult for the development of the planetary resources for mars and the expansion of human settlement into space.

Fledi · 2005-04-18 17:20:12

Why do you think we should begin with several settlements? It seems to me that making one base bigger and more redudant is a better option since you can share the infrastructure.

Haven't seen any figures comparing surface settlements to underground ones, but I won't insist on having it done below the surface if it proves to be less efficient.

Grypd · 2005-04-18 18:24:05

There seems to be a problem with peoples ideas what surface structures are. Maybe its the name. But even the metal sided huts or similar that will be one of the first structures constructed on Mars will be partially dug in and definitly covered by bagged regolith to provide radiation protection.

There is no need to dig hundreds of metres underground when it is simpler and more cost effective to go only so far and to add other materials to provide long term radiation protection.

Martin_Tristar · 2005-04-18 18:48:30

Fledi,

Good saying "Don't put all your eggs in one basket" , our colonization approach should be development on that saying because we want to limit all risks associated with colonization and improve the benefits. You can plan the settlements with standard modules (living quarters, recreation areas ) and specialized modules. ( government / authorities areas, large spaceport, manufacturing / mining areas, agriculture and more.) Also with 3 settlements apart approx. 30kms ( 20 miles ) then we could explore outwards another 30 kms safety that equals 120x120 = 1440 sq kms area not 360 sq kms from a single settlement.

Also we can have a large population on the surface then with a single settlement and also have a larger droid presence ( under human control ) on the surface as well. Also requires more cargo transports and human centric transports from earth to mars thus creating a large space infrastructure around earth and on moon to manufacture the cargo transports, and human transports and explorer vessels and other special purpose vessels.

Commodore · 2005-04-18 19:03:34

Why do you think we should begin with several settlements? It seems to me that making one base bigger and more redudant is a better option since you can share the infrastructure.

No one settlement will have practical access to all the various resources needed. A base cutting blocks of polar ice here, large deposits of x mineral there, a space port on one of the big volcanos, all tied together by robotic rovers at first, maglev trains later. The beginings of an economy.

Besides, its going to be a while before scouting expeditions can travel far. Spreading out settlement will mean more of the planet can be covered.

Fledi · 2005-04-19 18:18:27

Good points all, looks like we are just talking about other phases of settlement. I was referring to the very beginning, where the main task would be to keep life support systems going.
Of course at some point it will become more useful to go out and found several settlements, but obviously we will not land simultaneously at 3 different places and begin everywhere from nothing.

About underground structures I was wondering if it would be of advantage to go some meters below ground where the pressure from surrounding rock would even out the overpressure of the air in the tunnel. So you wouldn't need to have much of a support structure (just some layers of air proof material).

Martin_Tristar · 2005-04-19 19:36:47

FLedi,

After the explorer / survey phase of Mars is complete around 2035 ( single vessels type landings ) when we go for settlement phase starting 2040- then it should be in multiple locations using a fleet of unmanned cargo transports ( 4-6) and 1-2 human transports for the ground personnel. including a portable solar array cargo transport and packable space station transport and one other vessel a satellite transport for orbit placement of communication and other satellites for martian orbit.

Our modern version of a "wagon train for the new promised land" each human transport carries up to 6 landing pods each, each pod has supplies for 6-8 people. The pods can be used as emergency escape modules as well. As many as 2 droids for surface work per human would also arrive to commence construction work on the planet, some general work other specialized like a droid cranes, dozers,diggers and more.

While the first fleet nears the red planet, another unmanned cargo fleet would be uinder development for the next cargo run to the planet. Currently we don't have any the infrastructure required to launch the settlement missions successfully and we need to build the infrastructure including the large volume of resources required including the large variety of droids required for the explorer through to construction activities on the martian surface.

Alot of work ahead !!!!!!!!!!!

Fledi · 2005-04-21 10:32:37

I see a possible problem in going for that small settlements. It might prove to be difficult to effectively produce nuclear power on that scale.
But then maybe I'm wrong an the solar arrays would be sufficient for energy production.
Also you would have to make very miniature construction droids or have larger ones shuttling between the settlements.

GCNRevenger · 2005-04-21 11:10:25

Actually its the other way around, it would be hard to efficently produce nulcear energy on a large scale. It will be a long, long time before early Martian settlers to actually build a nuclear power plant, even if the basic componets were shipped from Earth to weld together on Mars. So, the reactor must be small and light enough to fit on the largest cargo vehicle (idealy no more then ~40-50MT), preferably with the Uranium loaded. We are quite a bit further from producing Uranium or reprocessing Plutonium, even if there is any natural Uranium on Mars to be had.

Solar power will probobly be important for industrial power, but their usefulness will be limited due to less light from the Sun and loss of efficency due to dust/dust storms. They shouldn't relied upon to keep everybody alive and fed.

Martin_Tristar · 2005-04-21 22:27:15

First the Solar Power Array is in orbit getting continous light from the Sun. The solar array use a concentration mirror system to increase the light level increase the available useage. Next, the supplies for each settlement are dropped from cargo transports in orbit to each base, until permanment transport is established.

All local droids are client-server architecture based designed with some automated systems. Each Base has a group of telerobotic trained personnel to manage and oversee the movement of supplies and expansion of base facilities.

Fledi · 2005-04-25 09:33:09

Martin, the more I think about your idea the better I like it.
It is scaleable and you can direct the power beam wherever you want, which is most useful when a small outpost has a short-time need for a large amount of energy.
I guess you would use something like microwaves for getting the power to the ground, as has been proposed for earth based microwave plants.

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