Going to Mars - Am I the only one?

Fledi · 2005-04-14 07:13:04

2. All that energy goes in as light and gets converted into heat, which then has to be removed from the greenhouse.

Isn't some of it needed to convert water and CO2 into O2 and sugar?

I agree on the rest though underground farming could work with nuclear plants providing the energy. But creating greenhouses should be cheaper in most cases.

clark · 2005-04-14 07:27:24

Weak light creates stringy plants, as they try to grow closer to the light source. Using available sunlight is optimal, however, given the unknown dust conditions, and the need to maintain outside surface areas clear for maximum solar light, it might make sense to just grow indoors.

Think about it, you are trading man-hours for maintanence of facilities, as well as increasing risk by placing the green house above ground, which may allow for a higher potential of a breach.

I'm also thinking there will be a greater reliance on GM crops, so they can be modified to thrive in the sub-optimal conditions (low light, low gravity). Plus, if you go the artifical light route, then you can utilize different light cycles- you have more control over the development and growth pattern of the plants.

There is a trade off of course, being energy intensive. But you would have a few thousands of people utilizing a nuclear reactor- I think there would be energy to spare, no?

GCNRevenger · 2005-04-14 07:57:50

Above-ground growing is best for a variety of reasons:

The biggest one, is that you don't have to rely on what space you have in caves or drilled tunnels, which will be at a premium. In order to make large farms, you will need signifigant room.

Using nuclear energy to grow plants would be difficult on a large scale. For the forseeable future, it is unlikly that any Martian settlement will have reactors any larger then submarine reactors, so you will have to be careful with what you spend the electricity on. Using it to grow plants en-masse probobly isn't practical.

They will however make lots of waste heat, so you can use that to keep the green houses warm during the Martian night and to thaw out subsurface water.

Making GMO crops that need less sunlight doesn't make alot of sense, since they would either produce less nutrient or wouldn't grow very fast, its a simple matter of thermodynamics. It makes more sense to develop plants that grow at lower pressures/temperatures or in saltier growing medium and use reflectors to increase sunlight as Rob suggests.

The risks involved with putting farms on the surface aren't that great, Mars is a pretty gentle world. No wind storms or anything that might pierce the plastic walls other then the occasional meteor, and that only rarely. Building small green houses en-masse and running them at reduced pressure will eliminate much puncture trouble.

srmeaney · 2005-04-14 08:20:14

Living underground offers something that living on the Surface does not. The ability to manufacture shelter as you go. If we live on the surface we will need a continuous supply of new habitat modules. The cost will stop colonization. Caves means we can grow our food under artificial lighting, Work in a "Safe environment" and pretty much expand the colony at the same rate that we expand the mine. I realize you all want your own little tin can house so you can all run off and do your own thing, but it aint gonna happen.

It also means we will be able to store water under a certain air pressure and temperature. Can you say indoor lake?

BWhite · 2005-04-14 08:27:03

There is a trade off of course, being energy intensive. But you would have a few thousands of people utilizing a nuclear reactor- I think there would be energy to spare, no?

Reactors need to be re-cored or abandonded and replaced once their fuel runs out. Navy ships go thropugh extended dry-dock and re-fit whenever a reactor runs out of fuel. IMHO, nuclear power is not a panacea for a decent energy budget, its a pre-requisiste.

Sunlight can be concentrated by inexpensive passive mirrors fed through light tubes and "supplemented" by grow lights run by the reactors. There will be no energy to squander, even with nukes.

Many years ago on a (defunct?) message board we discussed the sulfur lamp and LEDs are low power grow lights. Sulfur lamps look like a good choice (there is one in the Smithsonian) - - solid state, with no moving parts, full spectrum light (unlike LEDs) and power consumption comparable or better than LEDs which are damn efficient to begin with.

A necessary back up system, IMHO

= = =

The Moon, by comparison has an overkill of insolation.

Just no CO2 and little (perhaps no) accessible H20.

Edited By BWhite on 1113488965

GCNRevenger · 2005-04-14 08:29:05

Except that digging tunnels underground is an EXTREMELY slow, difficult, and energy intensive process that it will never be practical for large-scale colonies. The space constraints imposed by a tunnel-town would be fatal to the idea.

As soon as we aquire a source of water on Mars, which there is in abundance at least at the poles, we will have everything we need to make polymers. And if you wern't a complete fool, you would know that polymers are the key ingridient in inflatable structures. No tin cans here.

GCNRevenger · 2005-04-14 08:31:56

Light pipes aren't the be-all/end-all either Bill, they take polymers to create as well, and if you have those you might as well make inflatable low-pressure greenhouses and forget the drilling underground stuff.

As far as growing stuff on the Moon, it may not be that nessesarry with Earth only a few days off. If you do want to, and water is available, then it is a matter of careful recycling of imported carbon and nitrogen, not an impossibility.

srmeaney · 2005-04-14 08:32:23

There will be one of the first colonization support industries. The mass production of Sulphur lamps for Illumination using Mars resources. It can even have its own cave. The problem is now going to be keeping the Air filtered and clean.

BWhite · 2005-04-14 08:32:56

As soon as we aquire a source of water on Mars, which there is in abundance at least at the poles, we will have everything we need to make polymers. And if you wern't a complete fool, you would know that polymers are the key ingridient in inflatable structures. No tin cans here.

Polymers have the added advantage of releasing fewer "daughter" particles as secondary radiation. Boron doped polyethylene is an excellent space construction material because it absorbs nasty radiation while aluminum, etc. . . will sometimes exacerbate the problem.

Plastic spaceships, at least the human inhabited sections, are the wave of the future, IMHO, as always.

GCNRevenger · 2005-04-14 08:40:31

Radiation on the surface won't be a big problem I don't think. Hydrogen doped polymers or putting a shallow layer of water in your ceiling ought to be enough.

Polymers will make up parts of spaceships that don't need excessive temperature or structural properties. Fuel tanks and the HAB module's walls are good applications. Unfortunatly, vehicles for ground launch do require some metals.

BWhite · 2005-04-14 08:41:56

Light pipes aren't the be-all/end-all either Bill, they take polymers to create as well, and if you have those you might as well make inflatable low-pressure greenhouses and forget the drilling underground stuff.

I am not (no longer?) a big underground guy. Using bulldozers to pile water ice laden reogllith on top of plastic habitats? Perhaps.

Nukes are essential but will not avoid the need to harvest as much sunlight as possible. Using mirrors aimed at a greenhouse is one step and using light tubes to funnel light from further away is another.

I am merely counting pennies and light tubes allow us to gather a few more cents. There is no panacea there.

= = =

Food growing on the Moon will be a very difficult business, I agree. Lunar insolation is ideal for industrial processes however.

Lunar solar furnaces can achieve fairly high temperatures with little capital investment.

= = =

Given the relative delta V needed for Earth to L1 versus Mars to L1 - - it seems possible (although far from assured) that a Mars colony might raise a few scraps of hard currency by selling food and water to Luna.

Absolutely Mars (together with Phobos/Deimos) could raise cash by selling food, water and fuel to as asteroid belt bound exploration mission.

srmeaney · 2005-04-14 08:46:03

Ten years ago I sent the wolves at NASA a suggestion that they could blow those little bubble Habitats in Space. I also suggested radialy extruded resin and silicate seal airlocks to interface directly with the rockface of tunnels so we could live underground.

Don't assume you know anything about me.

GCNRevenger · 2005-04-14 08:51:10

Ten years ago I sent the wolves at NASA a suggestion that they could blow those little bubble Habitats in Space. I also suggested radialy extruded resin and silicate seal airlocks to interface directly with the rockface of tunnels so we could live underground.
Don't assume you know anything about me.

Yeees I'm sure you did... whatever.

So far we've got ourselves a veritible napoleon complex... you jibbering about every which thing, mostly blithering nonsense, and claiming to be a sage of space and science.

srmeaney · 2005-04-14 08:54:51

Yeees I'm sure you did... whatever.

Throw your self out an airlock, you sidekick.

Martian Republic · 2005-04-14 09:23:28

Personally, I think it will be a combination of underground cities to cities on the surface. That there will be underground transportation system and above ground transportation system. Each one has there advantages and each one has there disadvantages. The advantages of the ones underground is you don't need space suits to move around in, but it will take a lot more effort to dig them out. The one above ground you will have to make a contingency plan for a dome deflating and space suit have to be available in sufficient quantities and other such safety equipment.

As far as nuclear power, if we are going to be building a colony of any size at all. We need to go with a full size nuclear power plant and we need to go with about three or four of them too. While we on the subject, we need to bring reprocessing plants to rework the nuclear material and be able to deal with the spent radioactive material after there through using it. While we are doing that, we need to add a nuclear powered water desalting plant and plasma steel plant for refining metals to a usable state for our Martian colony. Otherwise there no point in going nuclear, because you not going to take full advantages of what going nuclear can do for you, but you will still have the waist to deal with. As you say, they dry-dock submarines for several months, but we are not going to be able to dry-dock our Mars nuclear power back to Earth for servicing. So we may as well go with a big nuclear power plant that is designed for in house maintenance and being refurbished.

Larry,

Fledi · 2005-04-14 09:25:40

Hey let srmeaney talk, this is better than comedy.

clark · 2005-04-14 09:39:21

Hey let srmeaney talk, this is better than comedy.

Like when a clown cries, or a mime laughs?

I'm still of the opinion that artifical light and below ground growing areas provide more saftey and less maintenance versus above ground green house's. Even above ground, you will need to supliment the lighting to maximize production. In addition, the larger the base above ground, the more failure points you add to the base. You add additional surface area exsposed to the temp changes (wear and tear), and you have the ungodly maintenance issue of dust accumulating on any window. You will end up with hundreds of man0hours as they try to continually keep the windows clean.

That's the trade off.

Sure, nuclear won't solve all the energy problems, but at least nuclear plants can be automated to a greater degree. The most valuable resource (for a long time) on mars is simply man-hours.

Grow vats of soy, whatever. Create above ground parks for the social-psych factor. But for food production, you want everything controlled and the labor involved as low as possible.

SpaceNut · 2005-04-14 10:33:37

Well here is the wild temperature swings for the moon:
Moon's environment is definitely harsh. Without an appreciable atmosphere to distribute heat, most lunar regions swing from -180°C to 100°C as the Moon rotates in and out of sunlight every 29.5 days.

What might we expect for Mars?

Fledi · 2005-04-14 10:40:42

The temp changes on windows should not be that much because of a much thinner atmosphere and a constant temperature inside.

I'm thinking about how one of the mars rovers got cleaned by winds, we could also use that for cleaning windows.
Sure, we still need supplementary lights, but much less as in total darkness.

clark · 2005-04-14 10:54:59

The average temp is -63 (-81.4F) degrees celcius.

The range is 17 (62F) degrees celcius to -143 degrees celcius (-225.4F).

Above ground, you're going to be spending energy to maintain constant thermal temps. Matieral science is good, but long term exsposure to wide shifts in temps like this is hard to work around. Insulation, underground will reduce the wear and tear.

These temp shifts happen in hours, so there is more stress on the material.

GCNRevenger · 2005-04-14 11:32:28

You are woefully, radically, deeply understimating how hard it is to dig tunnels of signifigant size, especially with reduced gravity (hence less traction for heavy machinery). Building a whole farm under ground isn't going to happen, thats a pipe-dream.

You also forget that most of the exposed surfaces will be polymers, which should be pretty easy to make withstand those kinds of temperatures. If not, then you have multiple megawatts of waste heat from the reactor to keep them. Run the hot secondary coolant through piles of Martian rocks under the hydroponic trougths so they stay warm for a while even if the reactor goes offline or is needed for something else.

And dust? Not a big problem, either some cheap PDMS hoses draped over the greenhouse with compressed CO2, or a more elegant electrostatic repeller. That failing, have a robot with compressed CO2 jets or something. Keeping the dust off is no where near as hard as drilling thousands of square meters of tunnels a few centimeters a day.

If nothing else, putting the greenhouses on the surface is ideal because its easy, minimal construction required.

BWhite · 2005-04-14 11:33:13

The average temp is -63 (-81.4F) degrees celcius.
The range is 17 (62F) degrees celcius to -143 degrees celcius (-225.4F).
Above ground, you're going to be spending energy to maintain constant thermal temps. Matieral science is good, but long term exsposure to wide shifts in temps like this is hard to work around. Insulation, underground will reduce the wear and tear.
These temp shifts happen in hours, so there is more stress on the material.

Insert an aerogel layer in the fabric. And if made in zero-gee, aerogel is quite transparent.

In my opinion, venting heat out of the human hab areas will be more difficult than staying warm. Largely unoccupied areas will need heat piped in but that heat can be scavenged from all the other hot areas of hte settlement.

We have discussed before the heat plumes that will likely rise continually from any habitat. And at a MarsHome workshop it was agreed that keeping any permafrost under the settlement from melting was quite critical.

Heh! Letting your Mars base sink because waste heat melted the permafrost into liquid water would ruin one's whole day. Heat disposal is a bigger problem if you dig deep.

clark · 2005-04-14 14:05:15

You are woefully, radically, deeply understimating how hard it is to dig tunnels of signifigant size, especially with reduced gravity (hence less traction for heavy machinery). Building a whole farm under ground isn't going to happen, thats a pipe-dream.

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. Not to mention the problems inherent due to the radical swings in temps between night and day.

Your flimsy tin can green house won't have much of a shelf life. So bravo, rebuild every 5 years and live in a constant state of perpetual maintenance as you track every last micro-fracture caused by degradation. The more surface area you expose yourself to, the more labor intensive the whole show becomes.

Oh, wait! That's right, the magic Co2 robots will solve everything.

You also forget that most of the exposed surfaces will be polymers, which should be pretty easy to make withstand those kinds of temperatures.

And what polymer would those be? I'm guessing something exotic, which is yet another brilliant way to add cost and complexity to the whole plan.

If not, then you have multiple megawatts of waste heat from the reactor to keep them.

And then you are beholden to making sure that waste heat goes to keep the shell intact. If you have a power interruption you may be looking at failure for the entire hab. This is stupid.

Run the hot secondary coolant through piles of Martian rocks under the hydroponic trougths so they stay warm for a while even if the reactor goes offline or is needed for something else.

Ingenious, now calculate the run off between your hot rocks and the surface temp at night on Mars. It won't last longer than a few minutes before the rocks are ice cold (not to mention cracking under the temp differential)

If nothing else, putting the greenhouses on the surface is ideal because its easy, minimal construction required.

And you save in the short term, but end up paying in the long term. You sure you don't work for NASA?

Bill,

Insert an aerogel layer in the fabric. And if made in zero-gee, aerogel is quite transparent.

Okay, on Mars, how are they going to build it? Requiring off-world products is unstable and only demonstrates that living off the land can't work on Mars.

We have discussed before the heat plumes that will likely rise continually from any habitat. And at a MarsHome workshop it was agreed that keeping any permafrost under the settlement from melting was quite critical.

Don't build on permafrost and this becomes a non-issue. Reinforce the foundation prior to construction.

Fledi · 2005-04-14 14:54:33

Considering how long a cup of tea stays hot in a thermos bottle I can't imagine that the temperature problem would be so severe with proper insulation.

clark · 2005-04-14 14:58:20

Pour your hot tea into your thermos, then shove it into the freezer.

A thermos works within a certain range, but it only acts to slow down heat exchange.

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Re: Going to Mars - Am I the only one?

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Re: Going to Mars - Am I the only one?

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