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Nuclear Powered LEDs For Space Farming
DevotedSkeptic writes with an interesting article on possible lighting sources for growing food on the moon and other off-world locations. From the article: "... Agriculture remains the key to living and working off-world. All the mineral ore in the solar system can't replace the fact that for extended periods on the Moon or Mars, future off-worlders will need bio-regenerative systems in order to prosper. Here on earth, researchers still debate how best to make those possible, but nuclear-powered state of the art LED technology is arguably what will drive photosynthesis so necessary to provide both food and oxygen for future lunar colonists. ... Although during the two weeks that make up the long lunar day astronauts might be able to funnel refracted sunlight into covered greenhouses or subsurface lava tunnels, they will be left without a light source during the long lunar night. Current solar-powered battery storage technology isn't adequate to sustain artificial light sources for two weeks at the time. Thus, the most practical solution is simply to use some sort of Radioisotope Thermoelectric Generator, not unlike the one powering the current Mars Science lab, to power the LEDs that will spur photosynthesis in lunar greenhouses. ... On earth, Mitchell says it takes roughly 50 square meters of agriculture to provide both food and oxygen life to support one human. But, as he points out, who can say how productive plants are ultimately going to be on the moon, in gravity that is only one sixth that of earth?"
We should freakin know how well plants grow in gravity based on the nearly 3decades of shuttle experiments... Did this Mitchell not bother to look that up?
"Current solar-powered battery storage technology isn't adequate to sustain artificial light sources for two weeks at the time"
Oh rly? Use enough Tesla power packs and they'll be fine. Lithium is light.
"But, as he points out, who can say how productive plants are ultimately going to be on the moon, in gravity that is only one sixth that of earth?"
Other than the fact we know already and that plants could be grown in earth gravity in a centrifuge yeah, good point.
Sheesh.
Need Mercedes parts ?
Two technologies that would actually help would be massive bundle fiber optics, we have the tech now especially if mirrors are used to intensify the sunlight.
Nuclaer TEG's are all that work for lightweight probes, but for a real base station a much better heat exchange could be made on site to properly use the thermal output of the precious and heavy nuclear fuel.
I usually do not buy strawberry from south America (just because I like to support local farms and I tend to believe that it is healthier as well). I have strong problems to buy strawberries that come from Mars.
Last I checked, a lot of biological systems stop working when you dont have gravity. Especially things like immune systems. So if this is the case, I think light would be the least of your worries.
If you build a habitat at one of the lunar poles it will be possible to build photovoltaic power plants which are both in sunlight and close enough to the habitat to directly feed power to it with electricity transmission lines. Additionally, this makes it easy for a habitat to be accessible for polar orbiting spacecraft. Habitats anywhere else on the moon move way from the orbit of your vehicle with the rotation of the moon. If your landing site is on the equator, then you can use an equatoral orbut, but for landing sites away from the poles or equator the orbitor continually moves away from the landing site, requiring that place correction manoeuvres be done before landing or docking with a returning vehicle.
http://michaelsmith.id.au
Space Lunacy ....
We already have tomatos from Holland and Spain which all taste like crap. I don't even want to imagine what a moon tomato tastes like.
doesn't sound that big, tbh. is this super optimal?
world was created 5 seconds before this post as it is.
First, I've never heard the 50 sq meters (538 sqft) to sustain 1 human before. It's about the same area as an ultra-efficiency apartment. I assume that's for high-efficiency hydroponics. Interesting. I wonder if it'd be possible to grow some sort of edible algae to suppliment the more traditional crops? IE have an intense 2 week growing season, harvest when the sun goes down, then reseed when it comes back up? That would reduce the need to use your nuclear generator to keep the plants alive/in the proper growing cycle.
The gravity might mean you needing a slightly different breed, but given what I've seen with hydroponics/areoponics, I doubt that 1/6th gravity will have that much of a negative effect - but that would be something for the ISS to figure out!
I don't read AC A human right
...who can say how productive plants are ultimately going to be on the moon, in gravity that is only one sixth that of earth?
Or unproductive. Plants are complex biological systems which evolved over millions of years in one g. The moon is not magic.
If Slashdot were chemistry it would look like this:Cadaverine
Only 1/6th gravity, no atmosphere - why not use mirrors? You can afford some inefficiency, such cheap materials would mean you don't need to worry too much about replacement costs due to meteorite hits.
It doesn't always have to cost gazillions - I refer you to the Russian use of pencils.. :)
Insert
In fact current hydroponic systems reduce that space needed by 1/4. If money was actually spent on research they could further reduce the space needed to process Co2 and generate O2 by using plant material.
And WHY use nuclear powered? we could easily put up solar farms. yes you have to deal with the face that the lunar days are 28 earth days but storage can deal with that. You dont have weather to contend with, so every day period will be a perfect charging period.
I personally think go big or go home, launch and install a 20MW nuclear power plant if they want to go nuclear.
Do not look at laser with remaining good eye.
WE all want Moon Goats... What about the moon goats?
Do not look at laser with remaining good eye.
Are why I read Slashdot daily.
There is no lunar night. There's a dark side and a light side, and occasionally an eclipse.
On the Moon have the bases at the poles with a rotating solar collector to focus and direct the sunlight 24 hours a day except when the moon is eclipsed by the Earth.
Who needs light...
I would imagine it would be far far easier to breed (or use GM techniques) to make a crop plant that can deal with what is effectively a super short season than to attempt to light up the night. You could even store some of the daytime heat and smooth the "seasonal" temp transitions using a high heat capacity plastic mixed into the soil.
Given tundra based trees survive months with no usable light due to thick snow cover and natural summer annuals often only get light for growth for a few weeks a year this doesn't seem the biggest issue with moon farming.
Why do we need plants? Can't we just make machines that make food. Can't we make a machine more efficient than a plant?
Exactly! We should be setting up a farm on the moon. Just to test it out. Start small: 1 m2 of soil in a greenhouse.
The cost of such a mission is for a small part related to the cost of the boosters to get things in orbit and to the moon, and for a large part to the over-engineering that NASA is doing. That over-engineering is caused by a fear of failure. It's not like it's rocketscience to get anything to the moon. The fear of failure is the only thing that seems to hold us back.
If it costs 5000 $/kg to launch anything into a high orbit (which I will equate with getting it to the moon), a decent sized farm (1000 tons of material) would cost 5 billion $ in launch costs, which is nothing.
We could set up some practice greenhouses for a fraction of the cost. If failure is an option, that should be cheap enough in an age when more than that is spent on warfare every day...
So, what about the moon nazis? They aren't going to be happy about colonists setting up nuclear farms on their turf.
Yes, the moon nazis. The ones that set up that secret base on the dark side just before end of WWII.
Finally— tomacco! Do'h!
Easy solution- Legalize Pot if it's grown on the moon.
What if we were to accept the fact that Earth is the only planet we're ever going to have and manage our resources accordingly?
There just *might* be some Slashdot readers who have experience growing plants - whatever kinds of plants those might be - in places where they are hidden from natural sunlight, using artificial lighting for photosynthesis.
Don't forget to post as AC via Tor.
Thanks!
This is all about the moon's 14-day, Lunar–night power famine. The solution is simply to use solar power satellites sitting at one of the Earth-Moon Lagrangian points, where the solar collectors will be in perpetual sunlight. Perpetual power means always-on growing lights so the problem is solved without the need for RTGs, and their pretty horrible thermal inefficiency (not to mention the problem of where do you get all that Pu239 from).
The main problem with using solar power satellites for supplying power to the Earth (the huge cost of launching them into space) is neatly inverted in the Lunar context as, by placing a solar colony's power hardware in space, you have a large mass of hardware that doesn't have to be soft-landed on the moon, representing a substantial saving.
The 50 Sq meter comment bugs me. Its not like we are plowing the back 40 with mules. By now can't we think more 3d? if 50 sq meters would feed one human, how many humans would 1000 cubic meters feed (10x10x10 room)? A greenhouse dedicated to growing could have walls, even the ceiling used for growing. My imagination can think of many other problems, but in a low gravity environment space should not be one. If fact, why not have a module orbiting the Moon that is specific to growing food and just use gravity for the delivery...ah, just hit me, fuel for deorbit and landing would make it prohibative (rats).
I like the idea of Nuc power. We drive submarines and aircraft carriers with this power and if they can keep it safe and working 600 feet over the ocean, I think sitting on the moon would not be much bigger a problem (other then delivery). Fuel disposal would be much simplier (huge incenerator only 93M miles away), and I recall there is the building blocks for making fuel right there.
If NASA is looking for the right stuff to farm on the moon, I'm all in.
Life is a great ride, the vehicle doesn't matter
I think somewhere around $60M per piece, maybe even more given very limited availablity of plutonium-238. USA already ceased production of it::
http://www.spacepolitics.com/2011/09/11/senate-energy-bill-includes-no-pu-238-funding/
PU-238 can only be bought from Russians (as it was done in case of Curiosity power source):
http://www.slate.com/articles/health_and_science/science/2012/08/mars_rover_curiosity_its_plutonium_power_comes_courtesy_of_soviet_nukes_.single.html
Hovewer RTG will be producing heat and 100-200 W of electricity for 100 years.
I would say something like this is needed:
http://pesn.com/2012/08/22/9602166_Existence_of_1200_C_E-Cat_Test_Report_Confirmed/
http://archive.org/details/KSC-04PD-1312
I love Jesus, except for his foreign policy.
Notice the reasons that NASA was interested in a pen: Pencils could break and cause a hazard, and additionally were susceptible to a fast burn in the oxygen rich environment.
Pencils worked. They didn't work "just fine" they were a hazard, but nobody has a better system, until the pressurized pen.
While high tech for its own sake can be a bad idea often there's good reasons for new technology. The old tech may work but the new tech works better, more efficient, more reliable, less dangerously, etc.
As a simple example you've probably used, take optical mice vs ball mice. Yes ball mice work, however they have numerous problems. Optical mice work better. They are less susceptible to dirt, easier to clean, track on more surfaces, work at all angles including upside down and so on. As an extension, newer ones are getting even better, they have greater precision, track on even more surfaces, and so on.
So if you want, you can heat your water in your low tech "works just fine" fire pit with wood and a metal bucket. I think I'll heat mine in my high tech sealed water heater that is very efficient, safe, and convenient, because it works better.
... way better idea!
Current solar-powered battery storage technology isn't adequate to sustain artificial light sources for two weeks at the time.
This is simply wrong. Rechargeable batteries can easily hold a charge longer than two weeks. And once you have that, you have the ability to sustain light sources on battery power for two weeks.
Thus, the most practical solution is simply to use some sort of Radioisotope Thermoelectric Generator, not unlike the one powering the current Mars Science lab, to power the LEDs that will spur photosynthesis in lunar greenhouses.
No, it isn't. RTGs are limited by heat dissipation. Put enough isotope in one place and it heats up enough to melt. More and it'll eventually vaporize or perhaps even achieve criticality (such as the case with plutonium 238). A traditional nuclear plant scales better at high power levels.
So to get the scheme to work on a large scale, one needs a whole bunch of RTGs through the complex. That introduces all sorts of complexity issues.
Frankly, a better approach to me seems to be solar thermal with underground storage of heat. Heat up the fluid during the lunar day and draw down the heat during the lunar night.
Try spinning a raw egg. Now boil it and try again.
Solid centrifuges will spin for a very long time (nearly forever), but as soon as you put a gas in it the gas begins causing it to slow down. Gas at the rim is moving fast, Gas closer to the axis is moving slower.. When the two meet they average their speed --- and when the slower gas meets the rim it slows the rotation.
Same thing happens with the earth.. but so much of the earth is so nearly solid (and air such a thin layer) that the moon has more of an effect with the oceans.
Sharks aren't fish... they're a type of whale.
beowulf solarium made of these.
My ism, it's full of beliefs.
With a vacuum the problem is getting rid of excess heat.
Right now, that is done by outgassing, and radiation. Outgassing in any form is unsustainable.
If we're on the Moon, it would be nice to be as self-supporting as possible, it would be nice to have a rail-gun to get off the surface of the moon with no fuel, just energy.
This can be manufactured on the moon. Producing solar cells of any efficiency from lunar materials should be the top priority.
As for living on the dark side, microwave beams up to lunar-orbiting satellites and back down to ground stations should be another priority.
The less we have to contract for from terrestrial corporations, and the more that can be produced on the moon, the bigger the techno payback we get.
Nuke power on the moon is so 20th century. Grow food using all-lunar technology. Generate air, etc., from moon tech. Then if/when we blow ourselves up the lunar colony won't need to worry about spare parts or resupply. Third priority, get to be able to fab robots from lunar materials. Chip fab should have some advantages in a vacuum environment, lots of other technologies needed or replacements for those technologies needed.
Primus: Space Farm
Escher was the first MC and Giger invented the HR department.
No, sharks are fish, look at the vertical tail.
There are resources of Uranium and Thorium on the moon itself, so it may be possible for lunar nuclear power to be self-sustaining. Of course, nuclear reactors need other materials as well, and I'm not sure if some of those would have to be brought in from earth (such as coolant in the form of water, sodium, or salts).
Grow your own meat without the cows in space. PDF, quick view.
I only look human.
My mother is a halfling and my dad is an ogre, so that makes me an Ogreling
"cost 5 billion $ in launch costs, which is nothing."
You sure you are not planning on a career in politics?
I only look human.
My mother is a halfling and my dad is an ogre, so that makes me an Ogreling
If you're setting up a farm on the moon, do you pressurize it to the equivalent of our atmosphere at sea level, or will half an atmosphere suffice? Do you use the same mixture that makes people comfortable, or do you bump the CO2 up to 10 or 15%? Do you use nitrogen, helium, or whatever you can cook out of the rocks to make up the rest of it? What about humidity? Temperature?
-jcr
The only title of honor that a tyrant can grant is "Enemy of the State."
If all you want is visible light, then an RTG is a horribly inefficient way to get it. As has been previously suggested, a full-blown fission reactor is a bit of a problem due to heat dumping and safety. Why not take the middle ground?
Use a powerful alpha-only emitter such as Gd-148 and a mix of phosphors to give you the spectrum and intensity you need. Alpha particles are stopped by almost anything, and as long as you don't inhale/ingest them, they're relatively harmless. Since you're talking a space environment and can generally trust the astronauts to not make too many errors in judgement, you could even use a beta emitter with a little shielding. We already have the phosphors to generate RGB, unless we've forgotten how to make them (think CRT - the electron gun is nothing more than an electronic beta emitter).
Tiller's Rule: Never use a word in written form that you've only heard and never read. You will end up looking foolish.
Can't believe you mentioned Russia and Space Mirrors without calling out their program to put orbiting mirrors in space for exactly this purpose...
http://www.nytimes.com/1993/01/12/science/russians-to-test-space-mirror-as-giant-night-light-for-earth.html?pagewanted=all&src=pm
http://en.wikipedia.org/wiki/Znamya_(space_mirror)
My God can beat up your God. Just kidding...don't take offense. I know there's no God.
Anyone who has grown cannabis under LED can tell you this. LEDs lack the raw lumens needed to penetrate thick foliage and reach lower branches. LEDs seem to work well enough for the vegetative growth phase but for flowering just can't put out as much raw light as HPS.
LED advocates will tell you the reduced lumens don't matter because the light is in targeted spectrums. That is great but it doesn't help penetrate the plant canopy. That isn't to say that you can't grow with led just that 1000w HPS will grow stronger and healthier plants than 1000w LED, albeit with more waste heat.
Some plants can't be cultivated indoors at all.
On the other hand, what you should probably be farming on a mars colony isn't tomatoes, it is algae.
Farms on the Moon? Why stop there, how about dairy farms in S.P.A.C.E?
How's about we run a few numbers?
If we assume that 50 square meters can feed one person, ( quite an assumption, IMHO ), and if we round down sunlight to 1,000 watts per square meter, then you need about 50 kilowatts of light, 8 to 12 hours a day, to support one person. Well, no, you need water, minerals and some energy too, but lets ignore that.
Now LED's are at about 100 lumens per watt. Spread that out over a square meter and you have 100 lux. Sunlight is right around 130,000 lux,. So you need about 1,300 watts to light up one square meter to the same intensity as sunlight. Very roughly.
Solar cells and inverters and wiring have an end-to-end efficiency of around 10%. So you need about 13,000 watts of collected sunlight to light up one square meter of hydroponics.
So we need about 13 meter-square panels at right-angles all the time to the Sun to get 13,000 watts during sunny days on the Moon. Let's round that down to 10, as sunlight is a bit more potent there.
Now sunlight is only there about 2/3 the time, and off for like 10 days, so we need batteries, let's say those are 75% efficient, round-trip through the batteries and diodes and inverters.
So we're back up to about 20 meter-square panels to light up one meter. To light up 50 square meters, one person's worth, that's ONE THOUSAND SQUARE METER STEERABLE PANELS.
That's an awful lot of hardware. I'm not sure one person could maintain 1,000 panels-- wiping off the dust, checking the steering motors, repairing meteorite damage, freeing vacuum-welded joints, swearing at al the dust they've stirred up walking from panel to panel, etc, etc, etc.
Doesn't leave much time for farming, among other things.
And oh, where are you going to get the water for 50 square meters of whatnot growing?
Are there slugs on the moon ? If not, how long will they take to slither there ? For as long as the slugs are kept away, they'll surely have a better rate of growth than my garden.
The DOD is looking at some thorium reactors. By having small ones (10 MWe) they can bring these in via chopper, put them in a hole, and then provide power for bases, esp. FOB. These would then be easy to destroy if being overrun. Now, what is the advantage of this for the moon and mars? Ppl do not get too upset about thorium being sent up to space. The amount of uranium that would be needed to power it would be minimum. And one of the nice advantages is that the thorium reactor in sodium would have little to no chance of water in either locations. In addition, the 800C can be used not just to provide power, but also a number of chemical reactions and industrial operations (i.e. metal smelting for casting purposes). In addition, it provides the heat for the base without needing any real shielding.
I prefer the "u" in honour as it seems to be missing these days.
I mean, I grow some plants that require lots of sunlight but that for reasons beyond my power cannot be cultivated in the open air.
If the NASA sends me a couple of these atoms, I can assure them that I will use them on my plants, that I will keep a serious control of its growth and that I will tell them if some unexpected toxic byproduct appears in them.
Why can't
Which atmosphere? Earth's where a space station would have a very tiny gravitational effect on? Or the atmosphere in the space station which has very little mass for stealing angular momentum from the rigid part of the space station (assuming it stays subsonic...).
There are effects that can slow down the rotation if close enough to Earth to still experience a tiny bit of atmospheric drag, radiation pressure, or stuff like imperfect docking and venting of gases, etc, and uneven pull of Earth's gravity requires some station keeping if trying to keep an exact orbit. The point is, the idea that it would slow down any significant amount just due to gases within the space station is completely wrong. The angular momentum would have to go somewhere, and heat doesn't work either, as you would need bulk movement. The fact rigid rotation gives different tangential velocities doesn't affect this, for solid or gas, or for the tidal effects on the Earth-Moon system.
Regardless of the size of your lunar farm, you will still need to provide light to the plants during the two weeks of darkness that is the lunar night. Further, if you are going underground to protect yourself, and the plants you live on, from radiation, then you will need to provide all the light all the time.
Ergo, the nuclear-powered LEDs. Or perhaps LEDs based on batteries that can capture solar energy during the long lunar day (assuming we develop the know-how for developing such batteries.)
Nuclear Powered LEDs For Space Farming
Why just nuclear power? I'm not against it, but there has to be other sources (exclusively or in combination thereof). For example, molten salt power generators. These are highly effective at capturing heat for a very long time. I'm sure that by the time humanity can build such things, we would have also developed salt compounds with much higher heat retention, and ceramics for insulators much better than what we have today.
Similarly, we can think of solar powered batteries that capture immense amounts of energy during the long lunar day. There will be a point in the future where this technology will be leaps above what we have today.
Then, there is the issue of efficient energy consumption. We now have light bulbs (and other light-emitting technology) that are far more effective than what we had two decades ago (and certainly from the time the first light bulb was invented.)
So if we were to extrapolate in the increased efficiency of energy production and energy consumption, we might find that nuclear-powered LEDs are not (or will not be) the only game in town.
Aside this, we are forgetting the role of genetic engineering. Humans will need "normal" light levels if they want to avoid genetic engineering on themselves. But edibles do not have to have that restriction. Chances are we will have to engineer plants, algae and edible protists, maybe plakton, and who knows, higher-order animals, so that they can economically thrive at lower light environment.
In Larry Niven's "Known Universe" series of books, the Puppeteers genetically re-engineered their home world plakton so that it could carry photosynthesis with just the infrared band (out of necessity after they moved their world away from their dying star.)
And in a more realistic scenario (realistic as far as sci-fi is concerned) in James Corey's "Leviathan Wakes", humanity has taken to the belt and the Jovian/Saturnian moons. In one the Jovian moons (don't remember which), humans grow cattle and crops engineered to thrive under very low light (reflected and augmented by large orbital lenses). And on the Belt, settlers feed on food alternatives made out of yeasts and fungus - cheese and beans as the books tale.
It would seem to me that, at least at the early stages of Solar colonization, humans will have to depend on possibly engineered protist sources for proteins and fats rather than animals. I guess that will be a vegan's dream come true ;)
If you need to grow plants for food/oxygen off-world, that means you have people there.
If you have people there, that means they're going to be doing other stuff.
If they're going to be doing other stuff, that means they're going to need power.
If they're going to need power, you should just have a power generator which pumps out electricity, and channel some of that electricity to the LEDs providing light for your hydroponics lab. There's no need to put an RTG inside each LED.
Especially considering that most of the energy given off by an RTG is thermal (the RTG aboard Curiosity gives off about 2 kW of thermal energy, about 110 W of which is converted to electricity). With an RTG inside each light source, every minor light source is also a major heat source, and your heating/cooling problems become that much more complicated. With all your power centralized in a few places (for redundancy), you can centralize heat pumps which deliver only as much heat only where needed.
I don't know how useful a RTG would be, considering the weight, containment, and materials needed to set them up. Not to mention that they are good and fine for powering a small rover or voyager spacecraft, but to get one on the scale needed to power lighting, computers, and all the other electronic and electrical devices needed on a moon base would seem a bit prohibitive. I don't know the efficiency of this type of reactor, but since this is Slashdot, I bet someone here does.
I know there are some issues with LFTR designs (notably the pipe material), but wouldn't that be a better design for something on the moon? I believe there is a fair bit of thorium in lunar rocks, which would make for a good start to a mining operation. And, in addition to providing power, it can be used to separate water (or ice, if there is indeed some on the moon) into hydrogen and oxygen for fuel and breathing.
I get that RTGs are a tested technology and LFTRs would be relatively new (new designs at least), but overall, wouldn't it be a better fit for an isolated base like one on the moon?
The only people who will be living and working in space in the near future are the people serving the space tourist, what possible economic model would support sending people in to space to mine asteroids or any other work that can be done by robots. Even now with our crude robots there is no economic justification for sending people into space, the space shuttle was a way to make sending stuff into space 100x more expensive by insisting people went along for the ride, and the international space station simple researches sub-staining people in a space station, or maybe sending people to mars for flag planting engineering stunt, look what we can do exercise. In the far future who knows what will happen, people could choose to live in space simply because they can, who knows.
Until we develop some new methods of storing power, I'm afraid we're stuck with the nuke. You're going to need heat/power for the people during the night. Though insulation and thermal mass with stored solar heat should work for the heat. But that's for a larger base.
Actually building something like a solar thermal power station using molten salts and a storage tank big enough for 2 weeks is a large enough undertaking that you'd have to be refining the salts ON the moon.
Solar panels in multiple sites - like 4 solar farms around the face of the moon would theoretically be doable, but the moon is 'only' 1/4 the diameter of the earth; you're still looking at shipping power distances greater than any single power run on Earth. Probably easier to build the huge thermal storage tank.
I don't read AC A human right