Crops

louis · 2016-04-28 12:33:07

Leaving aside your personal story (though interesting) I don't agree Mars should go vegan. In any case this will soon be a non-debate because we will be able to grow artificial meat (in fact that is already being done). I imagine that is likely to be the way Mars goes: developing artificial meat industries and cuisine.

RobertDyck wrote:

what guinea pigs can eat
One concern: Vegans. The local chapter of the Mars Society had a wanna-be vegan, and I have a few vegan friends. When I talked about Mars being purely vegan, they liked that. But carnivorous members didn't. So I mentioned transporting fertilized chicken eggs, and hibernating cattle; but only after the settlement has a population of about 1,000. Carnivorous members liked that, but vegans didn't. Then the "Cabbage Girls" from PETA showed at an event where Elon Musk spoke. Elon said he isn't the "Overlord of Mars". Sorry Elon, I'm the one who stirred up the vegans.
One lady my age joined the local science fiction club. When I was in college, I found girlfriends there. I was a way for me to get to know a girl before screwing up the courage to ask her for a date. Membership of the club in early 1980s was several hundred, but in the 21st century it dwindled to a couple dozen. Most married or with someone. When a very pretty, single woman with common interests joined the club, I got interested. She was interested in spending time with me. She also was financially "stressed". She had a business walking dogs, vegan and glucose intolerant. (Not a good combination.) She also had a tiny older house. At one point she said her parents held the mortgage to her house, asked me to sell my house, pay off the mortgage of her house, and move in with her. Uh, what! That's forward. That's something a husband would do. I had spent some time with her, but we hadn't had a "date" yet, and hadn't even kissed. I wanted to get to know her first. Then I discovered she had a boyfriend; he lived in another province, flew into our city on statutory holidays. My house is tiny and older, but I completely paid off the mortgage. Equity in this house represents my entire life savings. She wants me to do basically kill myself, and became what? I'm sure she would kick me out of her house as soon as her boyfriend came back to town. So no. And to emphasize *NO*! I won't do that. She's still a friend, but just a friend. However, she's vegan. Purely vegan. She's also a Facebook friend so I get a lot of Facebook stuff. I have a politician friend who's vegan, and know several other activists who are vegan. They're quite passionate. Making Mars purely vegan would attract those people.
I've tried to be a politician. I won the nomination in my electoral district for one of the two major political parties in Canada for the 2008 federal election. That's when my serious problems began. Someone seriously buried me. But with the goal of attracting the most people, since Mars must be mostly vegan anyway, why not be purely vegan? That would attract the vegans to our cause?

RobertDyck · 2016-04-28 18:49:13

Ketchup recipe:
There are many on the internet, this guy claims his recipe is similar to Heinz.
Heinz Copycat Recipe

one 6-ounce can tomato paste
1/2 cup light corn syrup
1/2 cup white vinegar
1/4 cup water
1 tablespoon sugar
1 teaspoon salt
1/4 teaspoon onion powder
1/8 teaspoon garlic powder

Combine all ingredients in a medium saucepan over medium heat. Whisk until smooth.
When mixture comes to a boil, reduce heat and simmer for 20 minutes, stiring often.
Remove pan from heat and cover until cool. Chill and store in a covered container.

Alternate recipes: these have spices, but start with tomatoes instead of paste
All Recipes: Homemade Ketchup
All Recipes (again): Homemade Ketchup
Jamie Oliver: Homemade tomato ketchup

Last edited by RobertDyck (2016-04-28 20:29:40)

SpaceNut · 2016-04-28 19:13:01

You highlight indirectly the issue and that is we must be able to grow all these crops simutainiously and with stagered growing for some to all for a matched cycle of produce for all dietary needs....not to much of one and not to little of another but a blend to allow for complete meals...
The posts of 230, 233, 237 and the survival list need to be put into a context of germination, growth density to footage and term to full harvest times.....to be able to create the menus meals....

RobertDyck · 2016-04-28 21:07:59

Canning will be necessary. It was a fundamental skill that my mother just assumed every homemaker had to know and would use. We lived in a suburb, but had a large vegetable garden. Half of that garden was gone when my father built a double garage. But home canning means mason jars. Glass will be made on Mars, so mason jars. The idea crossed my mind that we could bring plastic jars from Earth, lower launch mass, polycarbonate. But there was a news sensation a couple years ago that water bottles and baby bottles made of polycarbonate leach BPA into food/drink. Ok, so not that. Polyethylene will only leach ethylene gas, which is released by ripe apples. So that's food safe. High Density Polyethylene (HDPE) is not as hard as polycarbonate, but quite hard. However, it's only rated for temperature up to 120°C / 248°F for short periods, 110°C / 230°F continuously. Canning requires boiling jars to sterilize them. A quick Google shows there are plastic jars.
Bernardin Home Canning: Plastic Freezer Jars
It says they're dishwasher safe. Dishwasher drying cycle would melt polyethylene, so these must be something else.

Produce used to be stored in a root cellar. It was chill, basically a walk-in fridge. So just build a walk-in fridge on Mars.

You will have produce that is available for short periods. For example, apples on the tree in my back yard all ripen over just a couple weeks. You could make cider, or apple juice, or store apples in cold storage (walk-in fridge). You also want to play with light levels and temperature to get trees to produce more than once per Martian year. One crop every 668.5991 solar days would be far too little. Two crops in that time would be more reasonable. Could you shorten the cold period, simulated winter, to trigger flowering? More than two crops per Martian year?

Last edited by RobertDyck (2016-04-28 21:09:21)

IanM · 2016-04-28 23:04:10

RobertDyck wrote:

Two crops in that time would be more reasonable. Could you shorten the cold period, simulated winter, to trigger flowering? More than two crops per Martian year?

You bring up a valid point, one which could jeopardize my calculations so far, including the one I'm making right now. I personally would have two growing seasons, and alternate the fields per crop for each growing season, as a form of crop rotation. The soil would thus be enriched, and my calculations wouldn't be completely discarded lol.

SpaceNut wrote:

Lima Beans 15 lbs, Soy Beans 30 lbs, Split Peas 15 lbs, Lentils 15 lbs, Total Legumes 75 lbs

That's an abridged count for legumes. I didn't have enough information about the "Dry beans" or "soup mix" to make any calculations. The preceding is, in any case, for a crew of 6 for 12 months. Extrapolated to a colony of 100 for 12 months, this is 500 lb Lima Beans, 1,000 lb Soy Beans, 500 lb Split Peas, and 500 lb Lentils, for a total of 2,500 lb of Legumes. From data sources aforementioned, this translates to 16.666 bushels of Lima Beans, 16.666 bushels of Soy Beans, 20 bushels of Peas. Statistics Canada pegs Lentils directly at 1,296 lb/acre (http://www.producer.com/2012/10/ranking … surprises/), leading to 0.39 acres of land devoted to their use. Experimental Quickpick peas over 1 year (http://www.purplehull.com/pdf_files/FSA-6057.pdf), had 1,019 lb/acre, which I'll round down to 1,000 for defensive pessimism. This results in 0.5 acres for their use.

As for the other legumes, Soy ranks in at 58 bu/acre (https://www.extension.iastate.edu/agdm/ … c2-20.html), thus needing 0.35 acres of land, and Lima Beans have 260 bu/acre on the pole (http://www.lsuagcenter.com/topics/lawn_garden/home_gardening/vegetables/expected-vegetable-garden-yields, w/ 130 rows/acre), thus needing 0.065 acres for their production.

This results in (a lot of) the legumes needing 1.305 acres to produce enough for 100 people; this combined with the 7.786666 acres for the grains results in the populace needing at least 9.09166 acres to have such basic food. A square mile to satisfy such needs for up to 7,039 people.

SpaceNut · 2016-04-29 18:33:39

6 is the typical number for crew but we have discussed having as few as 4 and multiples of the 4 or 6 in a mars mission for the first few flights. So I think that what we have been working on is the first generation sizing of the enclosure based on what we need to grow in diversity of crops for a healthy diet most likely as a supplement on mission 1 but getting nearer to covering all needs as we gaining in population for a given mission.
Unless we are over growing from the start to allow for canning or other preserving methods then we will need to be able to change the sizing of the greenhouse as we grow the core size of the population that stays.....

IanM · 2016-04-29 20:42:41

Quite a lot of the acres involved in food production have to deal with grains, especially wheat. The shelf-life of refined flour is 1-2 years in a chilled airtight container, which is half to a full Martian year. If we do as I propose and manage to include two growing seasons in the Martian summer, this should not be much an issue, though it does mean that any overgrowth should be used for more planting, rather than milling.

RobertDyck · 2016-04-29 21:13:22

Storage Life Of Dry Foods

The Soft Grains
Soft Grains have softer outer shells which don't protect the seed interior as well as hard shelled seeds and therefore won't store as long. Hermetically sealed in the absence of oxygen, plan on a storage life of 8 years at a stable temperature of 70 degrees F. They should keep proportionately longer if stored at cooler temperatures.
The Hard Grains
The Hard Grains all store well because of their hard outer shell which is nature's near perfect container. Remove that container and the contents rapidly deteriorate. Wheat, probably nature's longest storing seed, has been known to be edible after scores of years when stored in a cool dry place. As a general rule for hard grains, hermetically sealed in the absence of oxygen, plan on a storage life of 10-12 years at a stable temperature of 70 degrees F. They should keep proportionately longer if stored at cooler temperatures.
Flours
After seeds are broken open their outer shells can no longer protect the seed contents and seed nutrients start to degrade. Don't try to store unprotected flours longer than a year. Hermetically sealed in the absence of oxygen, plan on a storage life of 5 years at a stable temperature of 70 degrees F. They should keep proportionately longer if stored at cooler temperatures.
Pasta
Pasta will store longer than flour if kept dry. Hermetically sealed in the absence of oxygen, plan on a storage life of 8 - 10 years at a stable temperature of 70 degrees F. Pasta should keep proportionately longer if stored at cooler temperatures.

Storage Life Differences
Depending on Temperature
Temp in °F In Years
---------- ---------
39.76 40
49.84 30
59.92 20
70.00 10
80.08 5
90.16 2.5
100.24 1.25

IanM · 2016-04-30 17:01:56

Let's see what happens with Wheat with a small settlement that starts out with 6 people and adds 12 people after every launch window. I assume that the colonists will not have kids until the settlement reaches a population of at least 100 at the earliest, thus negating any possibility of natural reproduction.

I assume that the wheat needs for the Original 6 would be imported with them for the first 6 months, which as SpaceNut said would be around 450 lb. However, afterwards they would need to grow their wheat. As I have calculated before, a colony of 100 would need 5.54 acres for their wheat per growing season; extrapolated to the 6, this would be 0.3324 acres, or 14,479.344 square feet. Each influx of 12 would add 28,958.688 square feet to this necessity. For clearer reference, 14,479.344 square feet is a square of slightly more than 120 ft by 120 ft, and 28,958.688 square feet is likewise a square of slightly more than 170 ft by 170 ft; however, the initial influx of 12 people would add to the initial 120 ft by 120 ft square 88 ft to each side, and the next addition would add slightly less than 61 ft to each side of that square, and so on, so it is entirely feasible for the colonists to overgrow to accompany potential future settlers, especially with the long shelf lives of flour that RobertDyck posted.

RobertDyck · 2016-04-30 22:19:36

I assumed it starts with a series of temporary expeditions of 4 people, all of whom return to Earth. The first expeditions leave infrastructure: habitats, solar panels, rovers, small plastic film greenhouses. Then the first permanent settlement starts with 12, then just supplies with the next launch window. Perhaps a change of 4 crew members. Then add 12 the next launch window. Could a settlement of 24 build habitat and life support for 100 in just one launch window? Of course I envision something like this...

IanM · 2016-04-30 22:35:08

RobertDyck wrote:

Could a settlement of 24 build habitat and life support for 100 in just one launch window?

If I remember correctly, one launch window is ~26 months, roughly equivalent to 1.15 Martian years. If we incorporate two growing seasons into one Martian summer, I could see them supporting up to 50 for the next launch window, but I'd need some more calculations , and in any case point taken. For such expansion, however, I'd think that modularity would be key for the settlement. My apologies for any misunderstanding, I've kept assuming we're dealing with a somewhat mature settlement here, my bad. My wheat figures for a settlement of 6 and 18 still stand.

RobertDyck · 2016-04-30 22:54:34

Yea, my calculations were for a mature settlement as well. Perhaps the growth of the Mars Homestead Hillside Settlement is a bit ambitious.

Last edited by RobertDyck (2016-04-30 23:14:19)

IanM · 2016-04-30 23:02:03

Well, it's all about being over several launch windows: Even with the settlement of 6 expanding by only 12 per launch window, that's still 66 people after 11 years and 5 launch windows, and depending on when the floodgates open for second- and third-wave civilians to settle and expand the settlement, it could be significantly more.

louis · 2016-05-01 07:37:52

I am assuming your figures come from natural growing conditions on Earth (i.e.one crop per annum) . But if you grow wheat indoors under artificial light on Mars you can have 3 crops in one Earth Year (as the growing season is about 120 days). On that basis you can divide by 3 your area - that gives you about 4,800 sq foot. But you can further divide that by two I would say as I think we could have two tiers of dwarf wheat growing in a single hab. So that takes you down to 2,400 sq foot or just under 50 x 50 feet - maybe add on another 50% for access, storage and life support equipment = 3600 sq foot or 60 x 60 feet.

IanM wrote:

Let's see what happens with Wheat with a small settlement that starts out with 6 people and adds 12 people after every launch window. I assume that the colonists will not have kids until the settlement reaches a population of at least 100 at the earliest, thus negating any possibility of natural reproduction.
I assume that the wheat needs for the Original 6 would be imported with them for the first 6 months, which as SpaceNut said would be around 450 lb. However, afterwards they would need to grow their wheat. As I have calculated before, a colony of 100 would need 5.54 acres for their wheat per growing season; extrapolated to the 6, this would be 0.3324 acres, or 14,479.344 square feet. Each influx of 12 would add 28,958.688 square feet to this necessity. For clearer reference, 14,479.344 square feet is a square of slightly more than 120 ft by 120 ft, and 28,958.688 square feet is likewise a square of slightly more than 170 ft by 170 ft; however, the initial influx of 12 people would add to the initial 120 ft by 120 ft square 88 ft to each side, and the next addition would add slightly less than 61 ft to each side of that square, and so on, so it is entirely feasible for the colonists to overgrow to accompany potential future settlers, especially with the long shelf lives of flour that RobertDyck posted.

louis · 2016-05-01 07:54:16

I think 24 could build habitat and basic life support for 100 in just one launch window. How could that be done? I would say by using Mars materials - in particularly Mars bricks. Brick manufacture could be largely automated. Then use cut and cover techniques - i.e. dig a trench (with a robot digger) and then cover with Roman brick arches. After that you cover over the arch with Mars regolith. In terms of energy I think initially we will just import lightweight PV panels and batteries that will provide more than enough energy for the young community. That technique will provide plenty of hab space for living and for farming. The main issue I think is air locks. That needs more research. It might be that we can develop ice doors - so when you want a hab area sealed, you freeze water; when you want it unlocked you melt ice and then let the water drain away. Manufacturing air locks on Mars may be tricky - although perhaps materials like basalt could be used.

As the colony grows I think they should soon be in a position to manufacture their own energy production facilities: solar reflectors (e.g. polished steel parabolic mirrors which can concentrate solar radiation on to boilers) and steam boilers (with just a few parts imported from Earth). The steam boilers can then be used to generate electricity.

Producing enough water for life support should be relatively easy and basic water recycling should help.

As regards oxygen/earth air production, I imagine it would still make sense to largely import that equipment from Earth.

RobertDyck wrote:

I assumed it starts with a series of temporary expeditions of 4 people, all of whom return to Earth. The first expeditions leave infrastructure: habitats, solar panels, rovers, small plastic film greenhouses. Then the first permanent settlement starts with 12, then just supplies with the next launch window. Perhaps a change of 4 crew members. Then add 12 the next launch window. Could a settlement of 24 build habitat and life support for 100 in just one launch window? Of course I envision something like this...
http://www.marshome.org/images2/albums/ … l_TOT5.JPG
http://www.marshome.org/images2/albums/ … age022.jpg
http://www.marshome.org/images2/albums/ … age023.jpg

RobertDyck · 2016-05-01 08:09:05

louis wrote:

But you can further divide that by two I would say as I think we could have two tiers of dwarf wheat growing in a single hab.

Tiers? You can't grow tiers with natural light. If you use artificial light, you need power. What's the source of power? Solar panels? So solar panels that currently convert sunlight into electricity with 28.5% efficiency, then LED lights with overall luminous efficiency (including power supply losses) up to 22%. As opposed to ambient light that does not require any conversion, so 100%. Actually, glass is not 100% transparent, and a greenhouse needs a filter to remove UV, so it's 84-85% efficient. Mars has 47% as much light as Earth, so I said to build your greenhouses long and narrow, with a mirror along both long sides. The greenhouse would be twice as wide as high, and top of mirrors would be the same height above ground as the top of the greenhouse, so as much light comes from the mirrors as directly from the Sun, that doubles illumination. Long/narrow because light that reflects off a mirror at dawn will just shine into the greenhouse further down, move to perpendicular to reflection point at high noon, and further up the greenhouse at dusk. So mirrors do not have to track the Sun. Mirror angle will have the change with season, but that means change by 1% every second week. Very simple, no need for solar panels, no need for LED lighting. Manufacturing glass windows and mirrors is far less intensive than manufacturing solar panels and lights.

Besides, during power failure, ambient light just keeps going and going and going and...

GW Johnson · 2016-05-01 10:15:09

These lighting and stacking issues being discussed for greenhouses here, are exactly why I proposed the mushroom-with-a-glass-ringwall building shape for Mars buildings to be built of mostly-indigenous materials. All that was needed was a Mars-equivalent to concrete for the stone masonry center and ringwall columns, the cast roof plate, and the foundations.

If you build such a thing located in a slight depression (flooding isn't an issue currently on Mars), you can arrange aluminum panel mirrors about that depression to bounce sunlight in through the glass ringwall, with a geometric concentration of about 2 to approximate Earthly sunlight intensity. You might use as much as 3 to get some solar heating plus a little more UV through the triple glazing. In a climate that cold with a sun that dim, such an artificial crater ringwall is essential to make the building interior climate more easily equable.

That light is coming in essentially horizontally, so tiered planting beds become easily feasible. I'm not so sure you can do open-pan hydroponics this way, because you need to tilt the beds a little toward the essentially-horizontal light beams. But there ought to be a solution, even for hydroponics: maybe clear vessels with taller sidewalls?

The center column structure is a masonry tower, not pressure tight, but you could locate a prefab emergency pressure shelter in there. The roof cap is cast concrete with grade beams, much like foundations here, except that the beams are on top of the slab. The foundations are essentially the same as here, except that the lowest features could be "icecrete" instead of concrete. That stops air leaking away through the ground.

The center column and ringwall columns support the unpressurized structure under its own weight during construction, to include piling 1 to 3 meters of regolith on top of the roof slab. You wet this regolith as you emplace it, and let it freeze, to form ice between the particles, making it quite strong of itself. All of this weight exceeds the blowout force for full 1 atm pressurization when done.

With triple glazing emplaced in preformed niches in the ringwall columns, foundation ring, and perimeter of roof slab, it's fairly well insulated. You maintain reduced pressures between the layers, with built in low-pressure alarms. Lower between panel pressures allow you to control stresses in flat glazing panels. And it's pretty much sheltered from solar and CGR radiation, because of the ice in the regolith cover on top. Locate your solar PV panels and communications gear up there. The icy regolith makes a firm base to hold it.

This kind of construction could be emplaced anywhere on Mars. If you don't have a handy shallow depression in which to place it, dig one with a bulldozer-equivalent. You need the artificial crater ringwall around it for good solar bounce and concentration.

Like I said, all we really need to do this is a Martian concrete. Being able to make transparent glass in situ would help, but we don't initially have to have that capability. Bring the glass and the steel rebar from Earth.

But, making concrete and icy regolith requires lots of in situ water. See why I keep insisting on locating buried glaciers for best base locations?

GW

Last edited by GW Johnson (2016-05-01 10:19:05)

RobertDyck · 2016-05-01 10:23:45

Radiation is *NOT* an issue for plants. Anything that blocks sunlight works against a greenhouse.

louis · 2016-05-01 14:53:28

Yes - tiers (I referred to artificial light). Energy will not be a problem on Mars. At a rough guesstimate I'd say PV panels at 20% efficiency need to cover a minimum area of 240 feet by 240 feet or 73x73 metres to generate the wheat for 6 people. 73x73 metres is 5329 square metres, which is a lot of panelling but we now have ultrathin and lightweight solar panels - down to 5 grams per sq metre. Let's assume that with protective screening that's 10 grams per sq metre - that gives us 53290 grams or 53 kgs. Obviously there would be associated equipment (cabling, inverters, and battery storage to ensure an even power supply). I expect that could all come in at under 2 tonnes, maybe even under 1 tonne.

By using artificially lit indoor farming you avoid a lot of difficult construction work in producing the surface structures - instead you can use diggers to dig out suitable hab space for indoor farming.

RobertDyck wrote:

louis wrote:
But you can further divide that by two I would say as I think we could have two tiers of dwarf wheat growing in a single hab.
Tiers? You can't grow tiers with natural light. If you use artificial light, you need power. What's the source of power? Solar panels? So solar panels that currently convert sunlight into electricity with 28.5% efficiency, then LED lights with overall luminous efficiency (including power supply losses) up to 22%. As opposed to ambient light that does not require any conversion, so 100%. Actually, glass is not 100% transparent, and a greenhouse needs a filter to remove UV, so it's 84-85% efficient. Mars has 47% as much light as Earth, so I said to build your greenhouses long and narrow, with a mirror along both long sides. The greenhouse would be twice as wide as high, and top of mirrors would be the same height above ground as the top of the greenhouse, so as much light comes from the mirrors as directly from the Sun, that doubles illumination. Long/narrow because light that reflects off a mirror at dawn will just shine into the greenhouse further down, move to perpendicular to reflection point at high noon, and further up the greenhouse at dusk. So mirrors do not have to track the Sun. Mirror angle will have the change with season, but that means change by 1% every second week. Very simple, no need for solar panels, no need for LED lighting. Manufacturing glass windows and mirrors is far less intensive than manufacturing solar panels and lights.
Besides, during power failure, ambient light just keeps going and going and going and...
http://www.superlaugh.com/1/ebunny2.gif

Last edited by louis (2016-05-01 14:54:02)

GW Johnson · 2016-05-01 17:58:16

Radiation may not be an issue for the plants in the greenhouse, but it is an issue for the gardeners. We cannot forget about that.

The more sunlight and heat enters the greenhouse during the day, the lower the solar PV power requirement we must satisfy, and the easier this is to do.

This kind of "mushroom" building that I described can serve as more than just a greenhouse. That same basic construction pattern can also serve as living quarters, and any other human function. "Trick it out" inside in any way that you need.

GW

RobertDyck · 2016-05-01 18:18:35

louis: When engineering anything, you have to plan for the worst case. With a bicycle, failure means you stop and walk. A habitat on Mars provides air to breathe, lack of life support means death. You can't evacuate back to Earth until the next launch opportunity, which could be many months away, and multiple months in space before you're back on Earth. Ambient light greenhouse is the only life support system that provides oxygen during complete power loss. Any other system makes power a single point of failure. Talk to GW Johnson about "single point of failure".

GW Johnson: I've posted many times that the atmosphere of Mars blocks heavy ion galactic cosmic radiation. Documents from NASA say 90% at a high altitude location, like Meridiani Planum, and 98% at a low altitude location like Elysium Planetia. GCR is solved by landing on Mars. Beta radiation is blocked by epidermis of human skin, and easily blocked by a single sheet of plastic film. Alpha is blocked by a piece of aluminum foil, or metalized coating on greenhouse windows. That metal is there to block UV radiation, UV-C is dangerous but easily blocked by the same coating that NASA has put on spacecraft and station windows since Apollo. That same coating blocks Alpha. There's negligible X-rays in space, the little that exists is blocked by that same metalized coating. That leaves proton, light ion, and gamma. All blocked by regolith, but all easily manageable. By putting 2 metres or more regolith on the roof of a habitat, that blocks radiation from the hab. Which means radiation in a plastic film greenhouse is equal to a spacesuit. To limit radiation exposure to equal a nuclear reactor worker in the US, limit time outside (including greenhouse) to 40 hours per week. Is that really bad? That's a work week.

Radiation on the surface of Mars is half that of ISS. So no regolith on the roof at all is still a manageable risk. A science mission would do something like Mars Direct, which would include sandbags to be filled with regolith and piled on the roof. Not 2+ metres thick, but a lot more than nothing. So the fact radiation on the surface of Mars with no radiation protection what so ever is half that of ISS, then this makes a science mission quite feasible.

Last edited by RobertDyck (2016-05-01 20:08:19)

SpaceNut · 2016-05-01 19:38:31

http://science.nasa.gov/science-news/sc … eenhouses/

In recent experiments, supported by NASA's Office of Biological and Physical research, Ferl's group exposed young growing plants to pressures of one-tenth Earth normal for about twenty-four hours. In such a low-pressure environment, water is pulled out through the leaves very quickly, and so extra water is needed to replenish it.
But, says Ferl, the plants were given all the water they needed. Even the relative humidity was kept at nearly 100 percent. Nevertheless, the plants' genes that sensed drought were still being activated. Apparently, says Ferl, the plants interpreted the accelerated water movement as drought stress, even though there was no drought at all.

scheduled to launch in mid-2020 and land on the Red Planet in early 2021. The investigation, known as the Mars Plant Experiment (MPX), could help lay the foundation for the colonization of Mars, its designers say.

http://www.engineering.com/DesignerEdge … -2021.aspx

Greenhouse Design for the Mars Environment: Development of a Prototype, Deployable Dome

http://www.techtimes.com/articles/11796 … -rover.htm

The experiment would use Earth air and water to keep a batch of flowering plants alive for 15 days and see how they're affected by otherworldly conditions.
MPX would employ a clear "CubeSat" box — the case for a cheap and tiny satellite — which would be affixed to the exterior of the 2020 rover. This box would hold Earth air and about 200 seeds of Arabidopsis, a small flowering plant that's commonly used in scientific research.

SpaceNut · 2016-05-01 19:44:57

One of the problems of the topic is that many are chosing to jump to the end when we have built up the infrastructure to not only delever the mass we want to mars but also have the landing capability of scale....

At one point we started topics that were the gradual steps of toe hold, foot hold and so on but its seems hard as of late to stay on topic....

There is always some drift and we all expect it to a degree...

I think with a step by step gradual grow of size of crew and expectation of resupply by a greenhouse we can achieve the goal of going to mars to stay after the first few crews...

louis · 2016-05-02 12:00:07

I agree about worst case planning. That's why you would already have enough food in the form of dried, frozen and vaccuum packed that would already be at the surface when your 6 colonists arrived. I really don't think emergency oxygen would be a problem. One would land several separate kits able to make oxygen from water and have a good stock of oxygen candles for immediate emergency use. The thing about PV panels is they are NOT a single point of failure. You can have several different systems. As long as you have battery storage (again, there won't be a single battery) your power will not fail. Even in dust storms there is still light getting through (I think 20% of annual average is the worst I have seen), so as long as you have a significant over capacity (over the average requirement that is), that will not be a problem.

I don't doubt that natural light agriculture is possible, but I think in the early stages of the colony it makes more sense to go with artificial light (a) precisely because there is less likelihood of crop failure - conditions will be optimal (b) because the construction effort required is far less (i.e. we won't need sophisticated pressured environments over huge areas - we can use simple cut and cover techniques) and (c) because humans will be fully protected from radiation in the case of indoor farming,and so can about their work in light suits rather than protective gear.

RobertDyck wrote:

louis: When engineering anything, you have to plan for the worst case. With a bicycle, failure means you stop and walk. A habitat on Mars provides air to breathe, lack of life support means death. You can't evacuate back to Earth until the next launch opportunity, which could be many months away, and multiple months in space before you're back on Earth. Ambient light greenhouse is the only life support system that provides oxygen during complete power loss. Any other system makes power a single point of failure. Talk to GW Johnson about "single point of failure".
GW Johnson: I've posted many times that the atmosphere of Mars blocks heavy ion galactic cosmic radiation. Documents from NASA say 90% at a high altitude location, like Meridiani Planum, and 98% at a low altitude location like Elysium Planetia. GCR is solved by landing on Mars. Beta radiation is blocked by epidermis of human skin, and easily blocked by a single sheet of plastic film. Alpha is blocked by a piece of aluminum foil, or metalized coating on greenhouse windows. That metal is there to block UV radiation, UV-C is dangerous but easily blocked by the same coating that NASA has put on spacecraft and station windows since Apollo. That same coating blocks Alpha. There's negligible X-rays in space, the little that exists is blocked by that same metalized coating. That leaves proton, light ion, and gamma. All blocked by regolith, but all easily manageable. By putting 2 metres or more regolith on the roof of a habitat, that blocks radiation from the hab. Which means radiation in a plastic film greenhouse is equal to a spacesuit. To limit radiation exposure to equal a nuclear reactor worker in the US, limit time outside (including greenhouse) to 40 hours per week. Is that really bad? That's a work week.
Radiation on the surface of Mars is half that of ISS. So no regolith on the roof at all is still a manageable risk. A science mission would do something like Mars Direct, which would include sandbags to be filled with regolith and piled on the roof. Not 2+ metres thick, but a lot more than nothing. So the fact radiation on the surface of Mars with no radiation protection what so ever is half that of ISS, then this makes a science mission quite feasible.

GW Johnson · 2016-05-02 12:16:56

RobertDyck:

I'm not very worried about GCR either, not even very much while flying around in space. It's big solar flare events that worry me, because while lower-energy radiation, the huge quantities can be fatal within hours or even minutes.

With respect to this stuff, Mars is more like the moon, no magnetic field to turn this stuff aside. I worry that with such a thin atmosphere and the huge quantities of radiation, that dangerous amounts will get through. These are erratic and occasional events, and people need a place to hide for a few hours while they pass.

The thick regolith roof covering I propose is not so much only a radiation shield, it is also easily-available thermal insulation, plus also at least some protection against small meteorites. Or thrown debris from some other bad event, like an equipment explosion or a vehicle crash.

GW

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