Mission One: a one way ticket to Mars?

GCNRevenger · 2005-08-07 11:57:49

Oxygen supply isn't a big issue, humans don't need all that much, and it is relativly plentiful on Mars as long as you have energy to extract it. As far as energy goes, barring a sudden breakthrough with Fusion power, then medium/large fission reactors are non-negotiable, either we tell the enviromentalists/USAF-deathstar freaks to hush up, or else a self-sufficent Mars colony isn't happening.

And do you mean CO2 thermolysis rather then electrolysis Robert?

We also need to know alot more about the soil chemistry on Mars before we can start talking about seeding it with simple bacteria. If memory serves, there are peroxides in the soil, which obviously won't be good for bugs. For the forseeable future, there won't be any "outdoor" food growing.

Grypd · 2005-08-07 13:10:00

We also need to know alot more about the soil chemistry on Mars before we can start talking about seeding it with simple bacteria. If memory serves, there are peroxides in the soil, which obviously won't be good for bugs. For the forseeable future, there won't be any "outdoor" food growing.

Agreed from what we can tell the soil of Mars is actually extremely hazardous to plant life and incidentally us if we encounter out of a suit. But we can treat the soil to remove the extreme oxides and it can hopefully be turned into a decent substrate. Still a first sample return should give us a lot more knowledge about this and hopefully some answers as to what to try.

Another point to having a very good water supply next to our first bases is that it can allow us to use showers to remove the Martian fines from the outdoor excursions we send our astronauts. These fines will likely be high oxidants and sharp so we cannot really risk having too many into our habitats as they will prove a health hazard and having blind asbestos ridden astronauts does not exactly go well to the colony plan.

RobertDyck · 2005-08-07 14:05:09

Nope; not thermolysis, electrolysis. A thin membrane tube of zirconia requires an electric potential to move oxygen across. I'm sure heat plays a big role in breaking [tex:5861e12fbb]CO_2[/tex:5861e12fbb], but electrolysis moves oxygen. Heres]http://rtreport.ksc.nasa.gov/techreports/2001report/100/106.html]Here's a link.

I was talking about soil agriculture in a pressurized greenhouse. Plants can grow in 10kPa pressure absolute minimum but that's 100 mbar. Mars ambient is about 7mbar or 0.7kPa. Furthermore plants require lots of water to compensate for low pressure; the lower the pressure the more water. A sealed greenhouse can recycle or control water. Let humidity get high to reduce plant transpiration, and condense water on a cold surface, let it drip into plant trays. Lots of cold on Mars.

Controlling superoxides should be easy. Viking found superoxides neutralized by soaking soil in water, releasing oxygen gas. Soil rich in alkali feldspar would probably be alkali, but that could be neutralized by bubbling [tex:5861e12fbb]CO_2[/tex:5861e12fbb] under pressure in water soaked soil to form carbonic acid. Just like soda pop.

Asbestos, well that's another issue. We have to find what's there on Mars. Probably different patches have different soil, but microfibrous serpentine in the dust or fines would be asbestos. Not good. This is one reason I want to see a sample return mission launched in late 2011, the earliest launch window NASA gave for such a mission. It keeps getting pushed back, now the JPL web site doesn't even list a launch date at all. I think sample return is more important than Mars Reconnaissance Orbiter, especially the demonstration of In-Situ Propellant Production to return something from Mars.

Grypd · 2005-08-07 14:56:11

True all that is needed to create a colony is there it is just not exactly how we really want it so we have to basically terraform it.

Lot of good ideas for the various means to do base construction below, though a site aimed at moonbases they are reasonably adapted to what we need.

http://www.moonbase-italia.org/proceedings.htm]Moonbase a challenge

Still for plants the biggest problem is the low light level and the only means I can think of is to start to develop a plethora of species that can thrive in a low light condition. Unfortunatly there is no present cereals that do well in low light though this is not the case for root crops like potatoes or carrots.

John Creighton · 2005-08-07 15:11:34

True all that is needed to create a colony is there it is just not exactly how we really want it so we have to basically terraform it.

It is not exactly how you want it. I sometimes think that terreforming is a vast waste of precious resources but that is another discussion.

RobertDyck · 2005-08-07 15:53:18

Potatoes come from the Andes mountains in South America, wheat comes from the middle east. Actually European agriculture appears to have started on the banks of the Black Sea when it was a fresh water lake, the Bosphorus opened about http://en.wikipedia.org/wiki/Black_Sea_ … eory]7,550 years ago flooding it with salt water from the Mediterranean. That flooded all their crop land, forcing people to migrate to Europe, Turkey, and the Middle East. Agriculture developed further in the Mesopotamian. However, that resulted in wheat and barley developing for sea level conditions, high pressure and high humidity, while potatoes developed for low pressure and dryer conditions. I read that wheat requires the same partial pressure of oxygen as humans. Fine, grow potatoes instead of wheat; that means fries instead of bread. I don't know about their light level requirements, but if wheat also requires strong light that's just another reason not to choose it.

Math time. The mean distance from Mars to the Sun is 227,940,000 km. The mean distance for Earth is 149,600,000 km. Light intensity varies by the inverse square of distance. If we use 1 AU for the distance from Earth to the Sun, Mars is 1.52366310 AU. Light intensity will be [tex:f0745072b1]\frac{1}{1.52366310^2}[/tex:f0745072b1] = 0.430746839 or roughly 43%. But the planet is a sphere, so light is spread out depending on latitude. Light at the northern tropic at summer solstice will be that intense, or the equator at spring & autumn equinox. Light per unit area on Earth also gets full intensity at the tropic in spring, or equator in summer, but not elsewhere. At the equinox (when axial tilt doesn't count) light will be spread out at higher lattitudes. Use a triangle, light per unit area will be 0.430746839 when the adjacent side is 0.430746839 as long as the hypotenuse, inverse cos 0.430746839 = 64.485° lattitude. So where on Earth is close to that? Fairbanks, Alaska, is 64.5° north so light there is equivalent to the Mars equator. Do crops grow in a greenhouse in Fairbanks? Trick question, there's a guy who closed himself in a greenhouse in Fairbanks to simulate Mars.

Fledi · 2005-08-07 19:31:01

Ever heard about the (yet failed) Russian space mirror projects during the 90's?
They were planning to light up urban areas by mirrors placed in space.
Now you would need a large mirror to project the required intensity to match Earth to a Martian surface, but with these ultralight light reflecting plastics it wouldn't be that much of a problem after all, if we can figure out how to inflate the structure.

Also space based power seems to be a better idea on Mars than on Earth since you will have to get the whole stuff to Mars orbit anyway. And leaving it somewhere on a Mars syncronious orbit would even be easier than landing the power source.

GCNRevenger · 2005-08-07 21:41:30

Space power on Mars is less good then on Earth, because there is only half the sunlight.

Surface-based reflectors, as RobS suggested using hinged reflective insulation covers (for the cold night) to double as concentrators, sounds like a good idea to me. Plant-growing lights might still be needed for dust storm times though. Sulfur vapor or LEDs perhaps.

Nuclear power is perfect for Mars, round-the-clock continuous electricity with no need for massive storage systems, gobs of waste heat for life support or industrial processes, reguardless if there is a dust storm or not... eventually when Fusion is available, Mars will have enough deuterium to become self-sufficent, no longer needing to import Uranium from Earth (which will probobly not be abundant on Mars).

Fledi · 2005-08-08 10:03:31

What matters is the energy to weight&cost ratio when you compare possible sources.
I'm pro nuclear, too, and if it proves to be the better option in this regard I'd happily agree to have nuclear plants on Mars, they are certainly the only sensible present option for anything beyond Mars.
It's just that placing a huge, but relatively light weight mirror in orbit vs. a nuke that is both heavier and has to be landed seems to be the better option for me at the moment.
You get sunlight from the mirror during most of the night, too, because of the high orbit and if you want to use it for elecetrical power generation you only have to heat up a large piece of insulated martian rock and use an appropriate fluid to propel a stirling engine day and night.

Longer sandstorms are probably still a problem though and maybe it would be a good idea to have a nuclear plant on reserve anyway, but we should not ignore any other option that is probably more efficient.

Edit: Why I was saying Mars based space power is better than Earth is because every energy source has to be transported to Mars, while if you compare Earth based nuclear vs. space power you don't have to lift the nuclear plants into orbit, so the cost question is very different.

Grypd · 2005-08-08 16:17:46

What matters is the energy to weight&cost ratio when you compare possible sources.
I'm pro nuclear, too, and if it proves to be the better option in this regard I'd happily agree to have nuclear plants on Mars, they are certainly the only sensible present option for anything beyond Mars.
It's just that placing a huge, but relatively light weight mirror in orbit vs. a nuke that is both heavier and has to be landed seems to be the better option for me at the moment.
You get sunlight from the mirror during most of the night, too, because of the high orbit and if you want to use it for elecetrical power generation you only have to heat up a large piece of insulated martian rock and use an appropriate fluid to propel a stirling engine day and night.
Longer sandstorms are probably still a problem though and maybe it would be a good idea to have a nuclear plant on reserve anyway, but we should not ignore any other option that is probably more efficient.
Edit: Why I was saying Mars based space power is better than Earth is because every energy source has to be transported to Mars, while if you compare Earth based nuclear vs. space power you don't have to lift the nuclear plants into orbit, so the cost question is very different.

There is also the need to provide maintenance. For a colony that is completely reliant on the technology powered by the electricity from the power plant. This means if something is wearing out and there is a need to do maintenance just driving a mile out to the nuclear plant or having to get a shuttle to fly up to an orbital soletta array is an important consideration. So with this principle in mind only having the power plants nearby is acceptable for an initial base or bases. A soletta array to help warm and power Mars is a great idea but not for any initial mission design.

GCNRevenger · 2005-08-08 17:11:41

If you have a nuclear reactor capable of providing most of the energy needs of a colony as backup for extended periods during dust storms, then why bother with the ungainly solar mirror? Just use the reactor for primary power. Dust storms can last for months, so unless you fancy letting the crops die, then you'll need enough power to run plant lights and heat to keep them warm. Many chemical and industrial processes need lots of heat energy, preferably at high temperatures, which are produced in great quantity by a reactor... and simply dumped as waste. Oh, and its portable too unlike a vast photovoltaic or solar/thermal collector array.

John Creighton · 2005-08-08 18:01:44

If you have a nuclear reactor capable of providing most of the energy needs of a colony as backup for extended periods during dust storms, then why bother with the ungainly solar mirror? Just use the reactor for primary power. Dust storms can last for months, so unless you fancy letting the crops die, then you'll need enough power to run plant lights and heat to keep them warm. Many chemical and industrial processes need lots of heat energy, preferably at high temperatures, which are produced in great quantity by a reactor... and simply dumped as waste. Oh, and its portable too unlike a vast photovoltaic or solar/thermal collector array.

This would be the best method initially. If mirrors can be constructed using local resources, then perhaps the nuclear reactor could be used to produce fuel for emergency back up generates. Perhaps this would provide a method for growth in the colony beyond what the power supply was initially intended to support.

RobertDyck · 2005-08-08 18:10:44

I have to agree with GCNRevenger on this one. A power supply close to the hab that can be maintained is important.

I also agree with mirrors to augment the greenhouse. Surface mirrors, not orbital. If you really need a bun to go with your soy-burger and fries, then mirrors can increase effective greenhouse illumination for wheat. Actually, I would use an aluminized curtain in the greenhouse, with spectrally selective coating on the windows. Mirrors could be simple flat mirrors that are adjusted once per week or two. A long, narrow greenhouse with the long end east-west could be augmented with mirrors on the north and south sides, the long sides. Mirrors at 45° would reflect light perfectly at high noon and spring/autumn equinox. At dawn light from sun in the east would shine into the greenhouse slightly to the west, but most of the light would still get in. At dusk the reverse, light from the west would be reflected slightly eastward but the west end would get direct illumination. You only need to adjust mirror angle with season.

Mars axial tilt is 25.19° so light will be inclined north or south by that much at the summer or winter equinox. Mirror angle is half that angle to ensure light gets in the greenhouse, so you need to adjust the mirror ±12.595° over a Mars year. Mars orbits the sun in 686.98 Earth days, but it's day is 1.025957 Earth days so that means 669.6 Mars days. It will take ¼ Mars year to move from equinox to solstice, so 167.4 Mars days to adjust mirrors by 12.595°. If you adjust the mirrors by 0.52667° each increment that only requires 1 adjustment per Mars week. Adjusting by 1.0533° each increment only requires adjustment every second week.

Fledi · 2005-08-08 18:13:07

Yep, dust storms and the maintenance issue are making space mirrors look as a less good option than at first look.
Nevertheless, it would still be a good supplementary power source, you can use the heat energy of the nuclear plant, that would have to be converted to light first for other things like melting ores while the mirror shines at the greenhouse.

As for mobility, I have to disagree, there is probably no easier way to move a power source as to simply redirect the beam elsewhere.

Edit: Good point Robert, there are not many points left to argue for space mirrors with this. Maybe that a high orbit mirror could still deliver light at night and the surfaces of the ground based mirrors could be eroded fast by dust storms.

Argh, good job all destroying my wonderful space mirror fantasies.

GCNRevenger · 2005-08-08 19:01:28

Martian greenhouses will need all the help they can get to retain heat during the frosty nights, so I think that it makes sense to design the focusing mirrors to double as insulating shrouds during the night. Half-bury the inflated tubes in the Martian soil to suppor them and help retain heat, and have curved mirror-finish aluminum shrouds that cover the top half, hinged at the sides of the tube and meeting at the top. Open them differing amounts of the day to absorb maximum sunlight, then close them at night. Perhaps put piles of rocks in the tube to help moderate the temperature via passive means, and to maintain temperature for a little while if power is interrupted.

"As for mobility, I have to disagree, there is probably no easier way to move a power source as to simply redirect the beam elsewhere.

You've gotta have a collector on the ground if you want to make effective use of that energy for anything except growing plants. That sure isn't portable.

"then perhaps the nuclear reactor could be used to produce fuel for emergency back up"

Pure storage means are never going to be practical for anything except very short time frames, like hours or days. Stored systems running for weeks, like dust storms, is out of the question.

srmeaney · 2005-08-08 19:05:36

At twenty billion per person it would go something like this: China sends two people to live on Mars and resupply them with food every year. In return these two would send fifty tonnes of scientific samples in the earth return vehicle that is used to send them fifty tonnes of food.

China refuses to share with America or anyone else.

USA sends Team to Mars to collect own samples. Small war on Mars.
Both nations declared idiots.

Galactic loss of face for both parties. Plant two flags and come home.

Commodore · 2005-08-08 19:27:46

If we can't depend on solar energy for greenhouses because of distance and dust storms, and are going to lose oodles of heat energy to the traditional greenhouse designs, why not bury and insulate the hell out of the things and grow everything with lamps?

GCNRevenger · 2005-08-08 20:06:29

Since we'll probobly be using nuclear power on Mars, and because nuclear power plants can only convert a portion of the heat they produce to electricity, nuclear plants will have oodles and oodles of leftover waste heat.

Since lighting sources would consume lots of electricity, which is much harder to make (between three and twnety times as hard depending on configuration) then heat energy with nuclear reactors per-watt, then it makes sense to trade electric-hungry buried greenhouses for heat-hungry exposed surface ones. Surface ones are also easier to make in very large volumes/areas then buried ones, which would either require tunneling or heavy structural support to deal with the weight of overlying soil.

BWhite · 2005-08-08 20:32:53

Semi-buried greenhouses could receive sunlight supplements through use of inflatable mylar coated passive collectors spread around outside the facility and possibly light tubes, some of which have attained rather high transmission percentages.

Set up a few dozen inflatable mirrors focused on light tube collector plates and a substantial amount of sunlight can be gathered, far more than just what falls on the greenhouse "naturally"

Back on the old CivCult Mars forum we revisited this topic endlessly.

The sulfur light (they have some in the Smithsonian) is a solid state (hard to break) energy efficient full spectrum light for back up reliability.

GCNRevenger · 2005-08-08 20:58:35

Too much digging. Just put it above ground with night-insulation shutters that double as concentrators in the day.

RobertDyck · 2005-08-09 01:32:47

I keep saying the greenhouse is your backup life support when the reactor goes down. Water electrolysis or direct carbon dioxide electrolysis can generate oxygen but need electricity. If you make the greenhouse dependant on electricity you have a single critical point, if it fails you suffocate. An ambient light greenhouse will provide oxygen when there's no power at all. The mirrors I describe are simple, no complicated tracking mechanism to break when it gets clogged with fines. An adjustment that only moves 1° every second week can be moved by hand, go out in a spacesuit to turn a knob or a crank. Or just move a support to the next notch. If the greenhouse only depends on artificial light a couple weeks, once per year then what's the chance the reactor will fail the same time?

As for cold, the thin Mars air looses heat very slowly. I asked an engineer to do a thermodynamic analysis of a greenhouse. She didn't have time for all the refinements I wanted, but found a single layer inflated greenhouse without any spectrally selective coating will get too hot during the day and too cold at night. It would loose more heat to the cold ground than to air.

RobS · 2005-08-09 02:26:48

I think the MIT people studying Mars colonies also concluded that greenhouses will have a problem of getting rid of heat, not of being too cold. The atmosphere conducts very little away and plastics can stop escape of infrared pretty efficiently.

The dust storm season lasts about 1/3 of a Martian year and results in as little as 1/4 of as much insolation at the ground level. That's too low for most crops, except shade crops (and there aren't many of them). But greenhouses will be able to produce oxygen if you plant shade loving plants. Impatiens (the flowers) grow well in incredibly shaded areas under trees. Geraniums manage as well. I'm sure there are more useful plants that handle low light, but I don't know which ones they are. The ideal crop would be one that adds nitrogen to the soil or otherwise enriches it, and maybe even produces something edible to humans.

If one sets up 1/3 more greenhouses than normal, one will be able to store human food for the dust storm season. Then during storm season plant a green manure to enrich the soil, or shade plants that herbivores will eat, and store the extra fodder to increase milk and meat production later, when you are concentrating on human food crops.

-- RobS

srmeaney · 2005-08-09 03:35:59

I think the MIT people studying Mars colonies also concluded that greenhouses will have a problem of getting rid of heat, not of being too cold. The atmosphere conducts very little away and plastics can stop escape of infrared pretty efficiently.

There is always the option of a ground spike. A metal pipe driven deep through the greenhouse floor to exchange energy with the Martian Permafrost. The problem will be pressure loss. A Porus groundspike allows continuous pumping of warm air into the permafrost.

Continuous cycling of Greenhouse atmosphere by pumping in Mars atmosphere to the Pressure of Sea level earth, while pumping out hot atmosphere is also an option.

Grypd · 2005-08-09 10:59:37

The trouble with heating a permafrost is it melts and you get sinkage. So any heat exchange to a Martian permafrost has to be carefully done. Still it should be possible to get heat flow reversed during the Martian night by a heat exchanger and get some return.

There are certain plants that benefit though from a very warm enviroment this is in the form of the sea weeds and algae. Heating that amount of water would be very energy intensive but with luck we should get a decent return in the form of food.

Still a lot of work to be done on this whole genre.

Grypd · 2005-08-09 12:19:03

The single greatest problem for growing plants on Mars is unlike the Earth the planet Mars recieves undiluted light from the Sun. A greenhouse on Mars will have to act like the Earths atmosphere and this means it will have to give almost complete Uv protection especially of the most harmful Uv b and Uv c ranges of the spectrum. Artificial lighting will have to be used as all currently in use Uv protections for greenhouses also reduce the most important light ranges this being red and blue. Uv is fatal in even medium doses to plants

Artificial lighting for plants though has recently gone through a bit of a major advancement with the creation of Cheap very efficient LEDs. If we put into a greenhouse LEDs in the range of between 80 to 96% red and 6 to 20% blue the majority of most plants needs can be met. If we also change the atmosphere in the greenhouses to higher than normal CO2 and warmer tempatures with a good nutrient supply then good yields should be possible.

Another advantage is that LEDs are long life items and also reasonably easy to create in an automated fashion. Solar cells are an example of a similar technology and there automated creation has been explored in many previous threads. If the materials to make greenhouses can be found on Mars and there creation automated then Food should not be a problem for Mars settlers.

Another technology in its infancy but with obviously important benefits is automation of a greenhouse farm and the computer providing control of the enviroment and needing as little human intervention as possible. The Japanese seem to be the masters at this as they are now routinely building such automated farms under sky scrapers and similar buildings. These Japanese Farms are examples of 100% artificial light enviroments with automated enviromental controls.

one final advantage to a more automated enviromental farm is the reduction of the risk of spreading disease between farms and the risk of a famine.

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