Mars first crew greenhouse

SpaceNut · 2007-01-13 21:23:54

This is a spinout topic of the recovery of waste:

Even though greenhouse might not be a prioirity for first missions to mars any effort to stay permanently will need to be more self sufficient.

These are a few thread where we had exstensive discusions on greenhouses in them One man one way suicide mission... and 4Frontiers

I wonder how much room two years worth of food would take compared to the facilities to grow new food? Seems to me that if they were serious about growing food, they'd need to bring along an agricultural specialist or two. Growing food is fairly labor intensive. You'd probably need a full time farmer to take care of the food needs. One person growing food is one less person exploring Mars.

A senerio of the need for quick return would be a lot longer than 9 to get back since it is a 26 month cycle for launching to mars. Which has the 2 month launch within window for flights.

Its could be worse if it were necessary to leave after the nine month journey out for the journey to get back with the ERV would only have a 9 month supply of food in orbit.

The powerpoint is very interesting, but how much power does this system take? It looks like two opaque greenhouses have 440 square meters. If the plants there are supplied by grow lights, I suspect that means a power demand of about 400 kilowatts (maybe half that if one greehouses is illumined when the other one is in a nighttime condition). That's a lot of power for recycling! And in duststorm season, the transparent greenhouse would have a pretty low productivity, so you'd have to light it a well or cut food and water production in half.
As for saving waste until the system is up and running, most of it is water, carbon dioxide, and nitrogen, and they should be pretty cheap to obtain. It'd be cheaper to haul a dozen kilos of "miracle grow" (I suppose they'll spend a hundred million dollars to refine the formula for Mars) and throw away a lot of the waste.

Just the means to make the dome will be an undertaking from insitu material.

Feeding the crew is important and while on the first stay we should at least experiment with growing of some foods regardless of the process by which we do it.

C M Edwards · 2007-01-15 12:35:01

The powerpoint is very interesting, but how much power does this system take? It looks like two opaque greenhouses have 440 square meters. If the plants there are supplied by grow lights, I suspect that means a power demand of about 400 kilowatts (maybe half that if one greehouses is illumined when the other one is in a nighttime condition). That's a lot of power for recycling! And in duststorm season, the transparent greenhouse would have a pretty low productivity, so you'd have to light it a well or cut food and water production in half.

An old reference I found for growing plants under lights recommends about 300W/m^2 lamp power, or only 190 kW for a 440 square meter greenhouse whose power system runs at 70% efficiency. Since the recommended fluorescent + incandescent combination is only 40-50% efficient, that 190kW would include at least double the amount of heat required, necessitating some sort of cooling system to shed the rest. So, make it an even 200 kW, easy, to run both greenhouses. That can be reduced to a little under 150 kW by keeping one half dark, but the dark half will still need heat even when there are no lights.

The minimum illumination to get a crop from flowering plants is about 130 W/m^2. (Some make do with less, some need more.) Martian sunlight can provide this, but not during the thickest dust storms, and not at latitudes above 70 degrees north or south. There’s also the pressure wall to consider, which is going to have to block a lot of light in order to provide a thick enough wall. Reducing pressure allows a thinner wall and/or bigger windows, but research indicates that you can only take the pressure so low before the corresponding decrease in absolute humidity and boiling point catches up to your crop. I believe transmission of only up to 85% of incident light is attainable through the greenhouse windows. (A greenhouse constructed of 100% transparent material is unattainable, IMHO.) That would increase the mass of the greenhouse (due to the accompanying thicker walls) and further restricts its useful range to about 60 degrees north or south. Still, windows don’t add as much mass as a 200kW dedicated powerplant, even with extra collector area to provide heat. That makes solar greenhouses competitive, even with these limitations.

The drop in light during an exceptionally thick dust storm isn’t 100%, so all that backup lighting would need to do is make that up. 100W/m^2 lamp power should be sufficient to keep up productivity during dust storms at the equator or keep the greenhouse going at higher latitudes – one third what’s necessary for growing under lights exclusively. Those lamps need not sit idle when not in use, either – artificial lighting is better than window light for many agricultural applications, because you can adjust it. Or, since dust storms tend to be seasonal, colonists can simply plan to adapt seasonally by laying in enough supplies to ride it out.

As for saving waste until the system is up and running, most of it is water, carbon dioxide, and nitrogen, and they should be pretty cheap to obtain. It'd be cheaper to haul a dozen kilos of "miracle grow" (I suppose they'll spend a hundred million dollars to refine the formula for Mars) and throw away a lot of the waste.

Nitrogen conservation will be more useful than trying to recycle it. Grey water and black water waste will be well worth recycling, but not just for the water. The solid and solute content may prove an excellent source of nutrients for plant growth, once properly composted.

Shipping a dozen kilos of hydroponic nutrients might be worthwhile as well. The actual amount necessary for a given crop is remarkably small. Augmenting that with compost (you can use compost for hydroponics, too) would stretch that supply out for years.

Setting up a functioning greenhouse of any size larger than a room in the hab is going to require a lot more work than merely inflating a balloon and setting out some seeds in a tray. Greenhouse design is going to be tricky. IMHO, even the Mars Homestead project hasn’t given it all proper consideration, and they’d made more design progress than most.

...while on the first stay we should at least experiment with growing of some foods regardless of the process by which we do it.

It's definitely the sort of thing we should not wait to start doing. Likewise, we shouldn't throw all our seeds in the pot at once before we get some experience with the local growing conditions, either. So, starting small and building larger as we go is an excellent idea. By the end of the first martian year, we should know enough to start a full crop, but I would not count on it before then.

dicktice · 2007-01-15 14:51:40

I'd like an en route greenhouse produce growing discussion, as well thought out as the above, please. Desireable both for nutrition as well as occupational therapy during the trips out and back.

SpaceNut · 2007-01-15 16:52:48

Maybe if we knew more about the gardening on the ISS snow peas and how it is done would be a point of reference.

cjchandler · 2007-01-15 17:40:43

Why wouldn't a pressurized inflatable greenhouse work? Sort of like the biglow modules only less extreme and made out of Mylar film. Maybe an unpressurized sheet could be laid over the whole thing to protect it from dust and be easily replicable. That would also give it excellent insulation, if you had a lot of layers.

GCNRevenger · 2007-01-15 18:23:50

Multiple layers with a space between them. Pump the space full of a little Argon from Earth for insulation. UV and IR coatings for Mylar are available now.

cjchandler · 2007-01-15 18:56:49

Oh another thing, if your space suits are flexible enough and you bring a shovel, you could dig some ditches, then inflate the green house over them (the floor mylar would have to be pretty tough, and socks only inside ) then you have hydroponics tanks at a nice low weight.

C M Edwards · 2007-01-15 19:44:55

I'd like an en route greenhouse produce growing discussion, as well thought out as the above, please. Desireable both for nutrition as well as occupational therapy during the trips out and back.

One of the main difficulties with a Martian greenhouse large enough to support the crew isn't a mechanical problem at all, but rather the long lead times required to get it running on the necessary scale. So, yes, starting a garden en route is desirable and probably quite necessary.

For example, some plants have exceptionally long periods from seed to harvest or between propogations. Onions and other perrenial spices need growth periods as long as a year. Dwarf trees and bushes may not bear fruit until their second year. And so on.

Then there are the crops that will not store for six to nine months waiting for the crew to find time to arrive and build a greenhouse. Certain seeds will not keep this long, nor will potatoes and other crops that optimally cultivated from tubers or runners for better robustness. True, potatoes, strawberries and the like can also be grown from seed, but it's far less reliable. And refrigeration doesn't really help - not enough for nine months storage. (Grocery store potatoes will keep that long under refrigeration because they have been treated with chemicals to inhibit growth - not what you want if you intend to raise a crop of them.) If we want potatoes - a desirable cold-climate crop - on Mars, we're going to have to start growing them on the ship.

C M Edwards · 2007-01-15 19:49:02

I've mentioned a few times that I think we should have a dedicated crewman to operate the greenhouse, but that's really a bare minimum. The eventual establishment of a farm on Mars is so important to permanent settlement that I think we should go beyond that.

I think we should have a dedicated expedition to start the greenhouse.

C M Edwards · 2007-01-15 20:32:14

Multiple layers with a space between them. Pump the space full of a little Argon from Earth for insulation. UV and IR coatings for Mylar are available now.

I couldn't recommend that for a single-walled greenhouse of any size. Good design practice requires that if you have multiple pressure walls (which is what you're suggesting, even if they're only holding in a little argon), one of them should be strong enough to withstand the operating pressure all by itself.

I don't think we'll get that from a single sheet of Mylar.

You could make an exception for multiple layers combining their strength, but not if you're trying to make each one hold its own pocket of air. For example, The TransHab prototype used multiple layers in contact with each other, which worked well. But for all the hype about how TransHab was "triple hulled", it had just one pressure wall as far as the ASME's pressure vessel construction code was concerned.

SpaceNut · 2007-01-15 20:52:25

Nasa has not been idle on the subject and or this has gone under the radar...
Fruits for Their Labor

On the red Martian plains, inflatables offer an efficient use of materials and space. "You can bring something to Mars with a low mass and get a large volume," said Phil Fowler, a scientist with the Space Life Sciences Lab.
what an inflatable greenhouse is made of could hinge on research conducted by Jim Clawson from the University of Colorado. "I'm looking at the materials you would use for a greenhouse on Mars," said Clawson. The greatest threat to a greenhouse and its plants is the planet's intense ultraviolet radiation. "Mars' UV (ultraviolet rays) will harm most plants quite readily," said Clawson. The materials scientist is focusing on transparent plastics in an effort to find a balance between something that lets in a healthy amount of light while protecting plants from lethal UV.

C M Edwards · 2007-01-16 08:25:15

When the final design of the Mars greenhouse is finished, it's likely to be one of the most cleverly engineered units in technological history.

I think that article hit it, SpaceNut.

I am curious: a reasonable amount of data has started to accumulated from these depressurized growth experiments, enough to begin making educated estimates, but what I've seen to focuses mostly on growth rates and other metabolic indicators. Has anyone ever actually sown, raised, and harvested a crop from one of these things, then eaten it? Are there any measures of actual productivity under these conditions?

dicktice · 2007-01-16 09:39:47

I read somewhere that a complete human digestive system has been assembled from lab hardware. Also an old science fiction story involving a mechanical cow (to provide milk on the Moon, if memory serves). Such, one can only call them machines, could be used to test the feces produced from artifically digested produce grown experimentally under artificial, simulated expedition conditions--before exposing our tender tummies and guts by simply eating it to see what happens. "Best before ...?"

C M Edwards · 2007-01-16 11:27:28

You are a card, Dick!

To clarify: Do we really know this reduced pressure agriculture works?

PurduesUSAFguy · 2007-01-16 14:53:39

Unless you are talking about a greenhouse for a large permanent base, there is no way that ECLESS systems can beat the equivilent systems mass (ESM, this is the metric that all systems are compared with by NASA for a true apples to apples comparison) of a straight physio-chemical system.

Using straight physio-chemical processes you can get very good systems closure on oxygen and water, somewhere on the order of 93%. Also we couldn't forget that once your on the martian surface your swimming in CO2 which can be conceivably cracked to provide oxygen and atmospheric argon can be used as a buffer gas.

RobertDyck · 2007-01-17 06:59:46

This may be redundant, but we have discussed this before. There are a couple concerns with material selection: temperature, gas impermeability, transparency, UV resistance, and strength. I talked to a few researchers a few years ago and found no one knew what material to use, so I took on the task. Some people felt Tefzel was appropriate since that's the high-quality transparent film used for greenhouses on Earth, but Dr. Penelope Boston of the Ames Research Center told me she was concerned with UV resistance; she felt it wouldn't withstand the UV in Utah much less Mars.

The material I found was PCTFE. It's highly transparent, the only polymer more transparent is amorphous fluoropolymer, but anything amorphous isn't flexible enough for an inflatable. Besides, amorphous fluoropolymer is highly permeable, meaning air and water go right through. PCTFE is the most impermeable to water of any polymer, and highly impermeable to oxygen and nitrogen. There are some polymers more impermeable to oxygen and nitrogen, but they become brittle at temperatures ranging from -6°C to -70°C depending on the material. Mars gets colder than -70°C every night, and often colder than -80°C. The low recorded by Viking 2 was -111°C. The planetary record low measured by MGS was -140°C at the south pole in southern winter. PCTFE has a service temperature range of -240..+132°C. The hot spot recorded by MGS was +27°C last time I looked. The temperature in LEO can vary from -120°C to +150°C. That means even PCTFE can get hot and loose strength. An inflatable stored deflated in a bag can be transported to Mars, then just ensure it's cooler than +132°C before unpacking. In case you're interested something for the moon, its mean surface temperature is -153..+107°C but the extremes are -233..+123°C. This means PCTFE can handle the most extreme temperatures on the Moon or Mars. Suitable for a pup tent or greenhouse.

As for UV resistance, it's highly UV resistant. Teflon FEP has been well characterized, used on the outside of satellites in Earth orbit. PCTFE hasn't had as much work, but it's more UV resistant than Teflon FEP. The primary reason is it's so transparent that UV just goes through without interacting. PCTFE is sufficiently UV durable to last many years in either Utah or on Mars.

As for strength, the bursting strength for 1 mil film is 19.4psi; that pressure will cause it to burst. A film twice that thick will be twice as strong, so 2 mil film provides a sufficient safety margin. A "mil" is one thousandth of an inch, very thin. As a comparison, sandwich wrap is about 0.5mil thick, and the bag a mattress is delivered in is more than 5 mil. Note: 1 atmosphere (Earth at sea level) is 14.7psi.

One means that has been discussed many times is use multiple transparent layers, each sufficient to hold full pressure, and pressurized the gap. A pressure sensor can detect any leak in the gap. If you pressurized the gap lower than your interior pressure, but greater than outside, then an increase in gap pressure means your inner film has a leak while a decrease means your outer film has a leak. Redundancy with leak detection.

Service temperature of Mylar is -70..+150°C. Dupont's website says "it is also used at temperatures from -250 to +200°C when physical requirements are not demanding." That's excellent for Earth, but not good enough for space. Pressure will place the film under stress. You want to ensure the film doesn't crack in the shade. You can try to transport heat using air inside, stabilizing the temperature, but it's safest to ensure the enclosure can handle all temperature extremes of the environment.

The coatings for UV and IR protection are metals. Vacuum metallization dramatically reduced permeability. Dupont's website says it reduces Mylar permeability up to a factor of 100. Mylar is slightly less permeable to oxygen than PCTFE (6 vs 6.9 g/100 in[tex:bd8b48ee1a]^2[/tex:bd8b48ee1a]/24 hr/mil), and about the same permeability to nitrogen (0.9), but more permeable to water. It would be interesting to study how vacuum metallization affects PCTFE permeability.

Here's a web page I wrote: Greenhouse
Dupont's website: Mylar

C M Edwards · 2007-01-17 09:08:23

As for strength, the bursting strength for 1 mil film is 19.4psi; that pressure will cause it to burst.

PCTFE would definitely have acceptable properties for the windows of a pressurized greenhouse. Back when it was sold under the brand name Kel-F, was also extensively used in satellites. According to the 1965 edition of the Lockheed Space Materials Handbook (sorry, no link), PCTFE suffers greater percent loss of tensile strength than Teflon under UV radiation (15% vs. 6% under arbitrarily high – read “more than earth orbit” – UV illumination) and also more outgasing in vacuum conditions. It’s still pretty good, though – an excellent choice for windows in a pressurized greenhouse. You should also consider that its tensile strength increases remarkably as the temperature decreases, more than doubling at a lowest design temperature of -140 C.

Regarding strength, Robert, you keep expressing the strength of materials in terms of psi internal pressure. I don’t think that’s sufficiently informative. The burst pressure of a greenhouse window is going to depend on its size. I can get a window of Saran Wrap to withstand 19.4 psi if I just make it small enough. I think you should consider expressing strengths in terms of yield strength, not internal pressure, for a better comparison with other materials.

Here's a web page I wrote: Greenhouse

That’s pretty good! I’ve already put it in my favorites.

I also tried my hand at greenhouse design with a set of articles for the New Mars Wiki. John Creighton did a great one, too. Reading back over them, I’ve found a few mistakes that I intend to go back in and edit out when I get time. (The lighting level is underestimated, the suggested pressure is too high, etc.) (I’d love help with it, BTW.) But the section on greenhouse structure does address size considerations.

Attaining the necessary window size for a solar illuminated greenhouse is going to be a problem for almost any transparent material, especially anything with layers thin enough to be inflatable. I don’t think layered PCTFE alone will prove to be a sufficient building material. We’re going to need to reinforce it with something.

Tom Kalbfus · 2007-01-17 10:17:18

Multiple layers with a space between them. Pump the space full of a little Argon from Earth for insulation. UV and IR coatings for Mylar are available now.

The Martian atmosphere is a fairly good insulator already, not for nothing is it called a laboratory vacuum. If you were to place a greenhouse in Antartica the insulation requirements would be quite strenuous, as you would have a much thicker atmosphere carrying away heat from the greenhouse surface. I think any greenhouse you built in Antartica would have more than sufficient insulation than what would be required of Mars.

dicktice · 2007-01-17 10:34:41

"An inflatable stored deflated in a bag can be transported to Mars, ..."

Unfolding and refolding: not a trivial detail in itself, both with regard to the planetary greenhouse (upon landing), and the subject of inflation (en route) and deflation (prior to aerobrake) and re-inflation of a possible inflatable habitat mother ship (in orbit).

RobertDyck · 2007-01-17 17:28:55

"An inflatable stored deflated in a bag can be transported to Mars, ..."
Unfolding and refolding: not a trivial detail in itself, both with regard to the planetary greenhouse (upon landing), and the subject of inflation (en route) and deflation (prior to aerobrake) and re-inflation of a possible inflatable habitat mother ship (in orbit).

Well, I was thinking simply don't. Attempting to deflate an inflatable for atmospheric re-entry is quite difficult. Especially when you have to pack it into an entry vehicle with heat shield. The little mission architecture I came up with is a dedicated, reusable interplanetary spacecraft that can go from Earth orbit to Mars orbit and back, then a separate lander. I don't know about the long term durability of TransHAB; will it suffer from repeated micrometeoroid strikes eventually compromising it's micrometeoroid shield? If durable then use it for the habitat, otherwise use a metal hull.

The lander can use a simple capsule and make the surface habitat all inflatable. The surface habitat doesn't need a micrometeoroid shield, just a scuff and sand storm shield. Micrometeoroids will not survive entry through Mars atmosphere. Larger meteorites might, but the sand bag layer on the roof will stop them. Actually, you don't want a foam layer for the surface habitat that could accumulate water frost, [tex:6004a9cd01]CO_2[/tex:6004a9cd01] frost, or worse of all fines. I'm thinking the outer layer should be Goretex. Goretex fabric is used for the outer most layer of spacesuits, as heavy as canvas. To be technical, it's 400 denier Orthofabric; a double layer fabric with Goretex face, Nomex backing, and every 3/8" two threads of Nomex are replaced with Kevlar threads in both the weave and fill directions. Fine, use the same stuff.

I guess one view is that a trip of only 6 months for an adventure as great as a trip to Mars, I can withstand living in a can and eating re-hydrated rations. You wait 'till you get to the surface for luxuries like greenhouse space or fresh produce.

dicktice · 2007-01-18 04:25:43

Well--as a devotee of space travel, per se, I would like to make the trip as enjoyable as possible from the start. So, if deflating the spacecraft habitat is as impractical as you say (no surprise), I'd be willing to give up the economical expediant of aerobraking, and exchange the throwaway shield for even larger inflatable living quarters, at the expense of carrying enough additional fuel to match orbits, on arrival, with Mars.

SpaceNut · 2007-07-12 07:39:51

Lots of details as to what they eat and how much has been sent to the station and more...in this link

NasaExplores lessons

Since the ISS was first inhabited, over 10,000 meals have been eaten, and over 6,804 kilograms (15,000 pounds) of food have been sent to keep the residents healthy.
In a 180-day mission (6 months), given a 10-day rotating menu, the same meals will be served 18 times-and that's why nutritionists and astronauts take great care when planning the foods that travel into space; nobody wants to be bored with dinners.
American food stored on the ISS is prepared at the Space Food Systems Laboratory at Johnson Space Center in Houston, Texas. The food is designed to stay fresh for 9 to 12 months

ASEN 5016 Lecture 5: Nutrition and Temperature Regulation

Average male astronaut over 30 daily energy requirement is 2875 cal
3. Water Supply in Space
Total Daily Consumables ~22.5 kg per person per day (including hygiene water)
Total estimated consumables per person per year ~8213 kg
· Food = 219 kg
· Oxygen = 292 kg
· Potable Water = 1132 kg
· Hygiene Water = 2008 kg
· Laundry Water = 4562 kg
Water = Greatest single mass consumable (~7702 kg/person/year for a ‘high end’ system, which is only ~5.5 gal/day)

Article section in qote is what I am bring to the attention of all.

Achieving Solar Space Energy - An Interview With the Space Solar Power Institute's Darel Preble

2. During your presentation you spoke about the decline in nutritional value of the world’s agricultural products, could you please explain that dynamic.
Preble: Sure. Let's examine wheat and rice - the worlds top two grains. At doubled carbon dioxide levels, plant-available nitrogen decreases 40 to 50 %, resulting in reduced nutrition from forage and grasses grown under doubled CO2. Wheat grown at doubled CO2 declines in protein content by 9-13% and produces poorer dough of lower extensibility and decreased loaf volume.
Hence flour, produced from wheat grain developed at high temperatures and in elevated CO2, degrades. “The nutritive value of rice was also changed at high CO2 due to a reduction in grain nitrogen and, therefore, protein concentration.” The protein content of rice declines under combined increases of temperature and CO2. Iron and zinc concentrations in rice, important for human nutrition, would be lower.
(By not eating whole grain products and eating "junk food" we have voluntarily reduced our nutritional intake by even more, so this is cumulative. We are becoming increasingly overfed, but undernourished.) Ruminants, including cattle, sheep, oxen, buffalo, deer, - the source of nearly all the milk and half the meat the world eats - will gain weight much more slowly grazing on forage growing under doubled CO2. CO2 is expected to reach doubled levels by mid century, under business as usual assumptions.

SpaceNut · 2007-07-22 09:27:00

While I know that this image

is about power I could not help but see the simularity in this one

Multi-storey glasshouses the future of farming?

http://verticalfarm.com/

SpaceNut · 2007-08-13 08:29:45

Keith Cowing's Devon Island Journal - 10 July 2007: Back to the Arctic

Once again I am headed north to Devon Island, the home of the Haughton-Mars Project. This is a place many have come to call "Mars on Earth" for its similarity to terrain on Mars. Due to this similarity - and a number of other factors (including its isolation) a wide range of scientific and engineering activities are conducted here in an effort learn how to live on other world such as the Moon - and Mars - and perhaps elsewhere.

Is any of this research really helping to allow for a manned trip for Mars?

noosfractal · 2007-08-13 17:46:54

Is any of this research really helping to allow for a manned trip for Mars?

From what I've read they are researching:

Suits
- Wear & tear
- What you can/can't do in a suit
- Accidents per month, accident type
- Emergency procedures

Human Factors
- Team size
- Team composition
- Team structure
- Adaption to 25 hour day
- Remote healthcare

Hab design
- Time and motion studies (esp. working with experts @ 40 min. comms. delay)
- Lab equipment, computing requirements
- Routine EVA facilities (esp. "dustlock" issues)
- Life support loop closure
- Waste handling

New Mars Forums

Announcement

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