A Lunar Colony

dan_casale · Oct 12, 2005

Here is some information that I posted before the great forgetting. I have updated some of it in other posts. Fission – 20MW weights about 900,000Kg in two power plants: more information is near the bottom. Electrical power – 1.2MW: 1.2MW provides 1000Hp or about the average bulldozer’s horsepower requirements. Mechanical power could also be provided by Sterling cycle engines or Steam (water or other working fluid) power. Mechanical Steam power – No specs: Sunlight is concentrated to heat a working fluid to steam. The steam produces mechanical energy. The lunar shade is used to cool the steam back into working fluid. http://belizeone.com/BzLibrary/trust39.html http://www.sterlingsolar.com/ http://www.wikipedia.org/wiki/Steam_power http://quasiturbine.promci.qc.ca/QTHydrogene.html Solar electric - 8421 - 284w solar panels. (2.4MW) 1,001,053lbs $8,371,468. 1) A ring of solar panels is installed at the south pole. This allows half of the solar panels to be in sunlight at any given time. There are no moving parts for this configuration. 2) 4211 - 284w solar panels. (1.2MW) 600527lbs. $4,185,734. A large solar panel array is installed at the south pole. The array has sun tracking hardware that keeps the array pointed at the sun at all times. All the solar panels are used to maximum efficiency. Moving parts will require maintenance. 150,000 lbs of mounting and tracking hardware is included. http://www.nrel.gov/ncpv/pvmenu.cgi?site=ncpv&idx=1&body=world.html – suppliers and service providers. New Archi

scottb50 · Oct 12, 2005

Sounds to me like the only logical means is using water/solar and fuel cells. <div class="Discussion_UserSignature"> </div>

dan_casale · Oct 12, 2005

Nexium: />>As built, I suspect, solar power towers produce slightly less kilowatts per square kilometer than top of the line solar panels.<< Generally, solar thermal panels are considered to be 70% effecient. I suspect a large part of this is do to convection losses, because the vacuum type is about 80% effecient. Additionally wiring losses aren't a problem on the moon because high temperature super-conductors at the average lunar temperature, which can be found at about 2 meters. The problem with using the weight of Earth manufactured solar panels is that they are designed for Earth conditions. IE. 80MPH winds, hail, corrosive elements. On the moon there would be no wind. The hail would be replaced with high speed dust, that would poke holes in the panels. The corrosive elements are replace with more radiation, which isn't that big of a problem for Solar PV. kilendrial: Good post. But nuclear plants are shut down regularly for maintenance. I have never been able to find a schedule. But I believe it is about 1 or 2 months per year. I also think that your post underestimates the problem with dumping the waste heat. However, it might be easy enough to pump it into the lunar surface, but that would mess up the super-conductors (bummer). Another problem is that no power can be produced until the plant is completely assembled, whereas a solar PV system only requires 1 string to start producing power. Ideally the panels wouldn't be placed in a big square, they would be assembled into a long line. This would allow them to slightly extend the lunar day. --------------- What about using a thermal power tower. Waste heat is pumped into the lunar crust, then at night the heat is pumped from the sub-surface and used to turn generators, then radiated back into space. The mirrors would double as radiators for night time. The problem with using coolants is the possiblity of getting a

scottb50 · Oct 12, 2005

That's where we need to refine the mission we are talking about. I fully agree solar panels for use on the surface of the moon could be pretty minimalistic, like the roll up units on the ISS. The mass needed does not have to be all that much and it can be built in segments. Solar thermal, Nuclear ect., all would take a lot of ground work to start operation. With solar panels simply roll them out and plug them in. <div class="Discussion_UserSignature"> </div>

nexium · Oct 12, 2005

Hi Dan: The solar energy that falls on the solar thermal panel, may heat the working fluid with 80% efficency, but the turbine may be 80% efficient, the alternator 80% efficient, the step up transformer 95% efficient. At the other end, the mirror typically has it's effective area reduced to 70% because it isn't pointing directly at the sun. Dust and mirror impefections lose another 10% Some of the solar thermal panels are typically not illuminated at all. My guess is overall efficiency is 20 to 30%, less when some of the stearable mirrors are shaded. Neil

scottb50 · Oct 13, 2005

Either way you look at it thermal solar or Nuclear power just make no sense. Do you want to take 10 years constructing the infrastructure before you start putting people there? The idea should be to establish a stable facility and expand on it as more space is needed while conducting research and experiments, not building an elaborate facility before you open the doors. Solar thermal offers promise and would definitely be something to pursue, but to use it as a general power source would not be worth the trouble. The same with Nuclear, if we look at the currently available launch capabilities a 600 ton reactor would take hundreds of launches, when you figure the steam generators, turbines, construction materials and manpower to assemble it and operate it. I would stick to water, solar cells and fuel cells, it seems pretty simple to me. Use solar power to breakdown and store Oxygen and Hydrogen and produce electricity using fuel cells, recycle the water exhaust from the fuel cells and you have a self contained perpetual power source. If you need to bring water from Earth it will be to power engines and sustain people. <div class="Discussion_UserSignature"> </div>

Swampcat · Oct 13, 2005

"The same with Nuclear, if we look at the currently available launch capabilities a 600 ton reactor would take hundreds of launches, when you figure the steam generators, turbines, construction materials and manpower to assemble it and operate it." Hundreds of launches is probably a stretch, but this is getting to the point I was trying to make with stevehw33, to which he has not responded. My concern is not with nuclear power, per se, or the long term needs of a large colony/base, but with the initial build up. Nuclear power generation is a much more complex operation than solar and will require some technology develop to implement. Solar is relatively cheap, relatively low tech, simpler and has a track record of use in space so can be implemented with little or no technological development. I also agree with you that there is a need here to more clearly define the kind of colony/base/whatever that is being discussed. If a large city-sized community is envisioned, then the nuclear-first advocates have a much stronger case. I see problems with both sides of this issue, but it seems like the solar side has fewer initial roadblocks. <div class="Discussion_UserSignature"> ------------------------------------------------------------------- "I hold it that a little rebellion now and then is a good thing, and as necessary in the political world as storms in the physical. Unsuccessful rebellions, indeed, generally establish the encroachments on the rights of the people which have produced them. An observation of this truth should render honest republican governors so mild in their punishment of rebellions as not to discourage them too much. It is a medicine necessary for the sound health of government."Thomas Jefferson </div>

dan_casale · Oct 13, 2005

>>You're right. Hundreds of launches of course, more shows his state of mind rather than the facts. The Delta can lift 8 tons. It's not a heavy lift rocket compared to the Saturn and the Proton. The Russkies have just rolled out a 4 engine rocket whose lift capacity is enormous. Of course, getting all that mass to the moon is going to require a huge lift capacity rocket anyway. << From http://www.astronautix.com/lvs/saturnv.htm - Payload: 47,000 kg. to a: Translunar trajectory. From my previous post: ‘…single-cycle helium-Brayton plants of 10 to 50 MW provide a total capacity of 220 MW and the total mass is 9900 t, including a 10 percent design factor.’ http://lifesci3.arc.nasa.gov/SpaceSettlement/75SummerStudy/Chapt5.html 9900t / 47t = 210.6 (211) launches per 220MWp thus 2GWp / 220MWp = 5 reactors @ 211 launches each. So between 1053 and 1055 launches. 220,000,000W (220MW) / 9,900,000Kg (9900t) = 22.22 W/Kg energy density of single-cycle helium-Brayton plants. 190w / 14Kg = 13.57 W/Kg for solar panels (61% the energy density of nuclear.)

chriscdc · Oct 13, 2005

Well you were the one that implied that they needed the same level of purity. I'm sorry if you didn't realise that you had indicated that. You need to be alot clearer with what you say. I was then pointing out that the cost of the extra purification would put off the extra cost of production from the impure sources. So when did you become an expert on inorganic chemistry and manufacture? You have silicon in practically every molecule on the moon. You scoop up some regolith. Grind it (its nice and spiky anyway, so not much energy required). Place it in a solar furnace (practically no energy cost here). There are probably easier ways than this, but you then put the ions(nice lot of UV on the moon, or a simple cathode ray) as they sublime off, through a magnetic/electric field to seperate them out according to charge mass etc. Fiddle about with the vel of the particle so that when it collides, it will fall into a nice crystalline order. The great thing is that you can add dopants the same way, as well as collecting any of the other particles. Also the sorting process is solid state, so little can go wrong, except radiation will wear it down, very very slowly. You can't do this on earth because the massive cost of obtaining the vacuum - moon no problem. Similarly on earth it has to be a batch process, whilst on the moon it can be continuous. Then you could then store all the use full molecules that you need eg O2. The Solar furnace gets rid of you needing to supply the energy to break the bonds. It can build its own solar panels. This thing is half a Von Neuman machine. All this is based on earth tech, which is expensive due to the vacuums and non-passive energy sources. Sure it would be slow but it could go on forever. A robot could go on until its electronics fails. It could cover its own tracks and so re-arrange the dopants and fix any crystal damage caused by radiation and micrometeors. You could have this thing 'tending' its 'farm' of seve

spacester · Oct 13, 2005

Thanks for the numbers Dan. You know, if we keep "ignoring the energy density issue" like this, we just might make some progress. <img src="/images/icons/wink.gif" /> So we're looking at either getting approval to launch a nuke and its fuel to the moon in 10 launches of a HLLV which does not exist (how do you break a PWR into 10 pieces and put it back together?), or getting started with solar & fuel cells ASAP, or exploring other options. I don't know about you guys, but I ain't getting any younger. <img src="/images/icons/laugh.gif" /> <div class="Discussion_UserSignature"> </div>

dan_casale · Oct 13, 2005

>>I don't know about you guys, but I ain't getting any younger. << You just use the some old DNA and the transporter to get younger. Haven't you ever watched Star Trek, no wonder you don't have any grandiose ideas. *sigh*

craig42 · Oct 13, 2005

Apologies, I don't think I communicated myself clearly, let me try again. <blockquote>In reply to:<hr />We do NOT know if Si can be cheaply enough made there to be usable in solar cells. That is, would it use up more power to fabricate than it created? <hr /></blockquote> I completely agree the point that I'm making is if we don't know then Si could be made cheap enough or it might not be cheap enough. The fact we don't know doesn't mean it must be too expensive. <blockquote>In reply to:<hr />The uranium deposits are not necessary. Kg. for Kg. shipped-to the-moon enriched uranium<blockquote>In reply to:<hr />Oh you plan to ship it, not refine it in situ, that looks better. Assuming (somewhat arbitrarily) that the lunar base needs 4000kw daily. How much Enriched U235 will be needed yearly, and how many launches will that require? <blockquote>In reply to:<hr />It's called energy density, which you conveniently ignore<hr /></blockquote> Then allow me to directly address the issue of energy density now. I completley agree that solar has less energy than nuclear (61% of it in fact, thanks Mr Casale). What I do not see is how this is a problem, at the moment as far as I'm aware there is only a 5 landers and a few robots on the moon, plenty of real estate, especially at the poles for the first colony, which I am assuming this is. Are you discussing a latter day colony? In which case the occupation of valuable real estate by other colonies’ solar panels would make nuclear power necessary? Thank you for pointing out my failure to address the energy density, I can not possibly hope to absorb all information every time, please feel free to point out any other items I fail to address. It is the only way I can refine my arguments to address all problems, and it is better for it. Finally since th</blockquote></blockquote>

craig42 · Oct 13, 2005

So where are we setting up shop? Some candidates are; + = advantage - = disadvantage Earth/Near Side +convenient location for space elevator would significantly reduce launch costs +good Earth Links -Shielded from Solar wind/less He3 -Not shielded from Earths radio transmitters Far Side +Better for radio telescopes due to being shielded from Earth's radio transmitters +Not shielded from solar wind by Earth so perhaps more He3. -No direct communication with Earth Equatorial regions Oceanus Procellarum has been proposed by Shevchenko +Better radio communication +better likely hood of He3 +slight advantage in launching lunar material. -Not shielded from Earth's radio transmitters North Pole-(rim of) Peary Crater +parts of the crater rim are permanently illuminated by sunlight (except during lunar eclipses) +temperature conditions are expected to remain very stable at this location, averaging -50° C +possibly of valuable hydrogen deposits inside crater. -No launch advantage. South Pole Mt Malapert +is exposed to the sun most of the time +116km from shackelton crater (This crater is potentially valuable for astronomical observation. An infrared instrument would benefit from the very cold temperatures. A radio telescope would benefit from being shielded from Earth's broad spectrum radio interference.) +The nearby Shoemaker and other craters are in constant deep shadow, and contain valuable concentrations of hydrogen. +At around 5,000 metres elevation, it offers line of sight communications over a large area, as well as to Earth. +The South Pole-Aitken basin is located at the south lunar pole. This is the largest known impact basin in the solar system, and should provide geologists access to deeper layers of the Moon's crust. -No launch advantage. *edit to include E

barrykirk · Oct 13, 2005

One point about the location of a lunar colony. By the time we get back to the moon in 2018, the chinese may have already claimed all of the prime real estate.

chriscdc · Oct 13, 2005

If you can't even manufacture solar cells from the moon, then is there really anypoint in going into space? Every other element ,apart oxygen, is going to be harder to get. Considering that you will have to get oxygen from the rocks you will end up breaking SiO2 and so getting some Si anyway. Seeing as SiO2 makes up a good proportion of the regolith then you are going to get alot of oxygen, just from the process of getting the oxygen. So on earth there is more power, that leaves out alot of contributing factors. You have the atmosphere which screws up many potential chemical reactions, that would otherwise be economic. The gravity is stronger than the moon, this results in more contact force thus more friction and therefore a larger constant force is required to keep something moving and so increasing transport costs. Seeing that you don't use any specifics, facts, figures in your arguments then everyone has to infer what you mean. You only ever seem to say that things are impossible whilst not showing why. I gave you an example of a system that would generate silicon panels from solar power alone, whilst using tech that we have at the moment. The lunar environment would negate the major costs of the systems on earth. It could take the silicon from any source of material that you supply it with. You on the other hand are assuming that you need nuclear power immediatly, that you could maintain such a system on the moon, that all the highly complex parts of the system will not be damaged by the environment, that the people on earth will be willing to continuously ship nuclear material up there. You will have no way to repair damage until a replacement part is supplied. Uranium is a finite resource anyway, so why use it in a situation where you have an unobstructed power source that will last the next 4.5billion years. Why do you even need to bet on which system will work, we are not going up there in the next 5 minutes

scottb50 · Oct 13, 2005

If you say Proton can take 100 tons to LEO I have no problem, where the problem comes in is getting it to the Moon, landing it and putting it to use. Then you have to consider 98% of that is the hardware that carries the actual payload and even putting 100 tons in LEO will only get you a few tons to the moon. The only way to do it is multiple launches of propellant and payloads to LEO and then going to the moon. <div class="Discussion_UserSignature"> </div>

kilendrial · Oct 14, 2005

Lets say that you have 100 people with a need for survival of 2 KW each (not very fun survival for sure…no computer games, no lunar joy-rides…only basic life support). You therefore need 200 KW of power generated by fuel cells for 14 days of night because of absence of light to power solar. There are a few questions to ask here. I found a system at fuelcellstore.com (under fuel cell systems , commercial, PC25) that has this exact output of 200 KW. How much would the fuel cell system cost? The site says contact them. How much would it weigh? PC25-20 tonnes(40,000 pounds). How much volume will it take up? 10' x 10' x 18' or 1,800 cubic feet or 50 cubic meters. How much fuel would it need stored to last 14 days at 200 KW (67,200 KWh)? It would be cool if the thing used H2 and O2 directly, but instead it uses an “anaerobic digester gas” of 60% CH4(methane) and natural gas. It uses 2,050 cft/h of natural gas and and 3,200 cft/h of the anaerobic digester gas. For 14 days, those figures are multiplied by a factor of 336. That means you would need to store 688,800 cft of the natural gas and 1,075,200 cft of the anaerobic digester gas. This is 20 olympic sized swimming pools (between both gases). How much energy would it take to store enough fuel assuming conversion from water? Are you going to use radiolysis, electrolysis, decomposition through thermal energy? If electrolysis, you can calculate using (200KW * 24 hours * 14 days)/(efficiency of the electrolysis process * efficiency of fuel cell process ). I found one source that says energy efficiency of electrolysis is 70% and fuel cell efficiency (only electricity) for our PC25 is 40%. So, you have to put 240,000 KWh into surviving one night. Distribute that energy over the 14 days of day-time. How much wattage will it require to be taken out of the system for power on average? 714 KW (almost a megaw

scottb50 · Oct 14, 2005

"Uranium is a finite resource anyway, so why use it in a situation where you have an unobstructed power source that will last the next 4.5billion years.">> uranium, just like oil is a finite resource, but with breeder reactor and even more advanced systems what we have could last indefinitly. I am all for Earth based Nuclear power, at least until we get the efficiency of Solar Power to where it can do the job alone. Once we start to go there it should be pretty quick when it is obvious that is the way to go. Technology will keep up, we just have to aim it in the right direction. How much would it weigh? PC25-20 tonnes(40,000 pounds). Maybe, I'm sure by the time we would need to take it to the moon, or Mars it would be a lot lighter and more efficient, especially after powering LEO stations and such. How much volume will it take up? 10' x 10' x 18' or 1,800 cubic feet or 50 cubic meters.... Here again with a directed effort it could probably be much smaller. What I have in mind is stacked units, one cell does hydrolisis the next produces power..., they're the same basic unit anyway and the heat generated from one will be offset by it's neighbor. How much fuel would it need stored to last 14 days at 200 KW (67,200 KWh)? />> You don't answer your question. It is not worth the trouble to launch hydrocarbons and Oxygen when it would be much simpler and safer to launch water. If you build a generic system that converts water to LH and LOX and stores it, and add more of the same units as needed you spread out the mass needed to be positioned at one time. <div class="Discussion_UserSignature"> </div>

tap_sa · Oct 14, 2005

"It's rather apparent that stating a nuke would weigh nearly 10K tons was rather silly" It would help to actually read what others write! From Dan's post: " single-cycle helium-Brayton plants of 10 to 50 MW provide a total capacity of 220 MW and the total mass is 9900 t "

chriscdc · Oct 14, 2005

Even if you could get the mass of the system down to 1800kg (are you sure that isn't a typo?) you still have several problems. You are in space, so any leak will probably end up with you losing a good portion of the coolant. No external atmospheric pressure to help counteract the internal pressure. Then you need a way to radiate the heat off. During the day the cooling is going to be substantially reduced as the surface heats up and the radiators begin to recieve more and more energy from the sun. The temperature of parts of the system will get to 300 degrees c easily. Just imagine the damage that would be caused to the system due to the temperature gradients found on the moon. Just imagine the damage to a hab that could be done, if a coolant tube leaks/explodes and debris punctures habitats. Also naval Reactors use enriched uranium, and so will make it harder to get political support. The reason that they can last for sometimes decades before refueling is because they have tons of fuel built into the reactor. This must put a limit on how much of a weight reduction you can make. Or you need storage for the uranium. There could be a reactor within the 1MWe range that you could get down on a lander, without having to develop a new heavy lander, with no assembly required. This could be useful. But in the medium term, these systems would rely on earth experitise and to do the majority of the construction. The colony could be self sufficient up until the reactor uses up its fuel, and it is at the mercy of the earth. It would mean that anyone going into space would have to come up with (the cost of) a new power source, if they can not pay for a nuke. Manufacturing solar panels on the moon would show that there is a system that you could export to any other lunar/asteroid/(to a lesser extent)mars colonies. I would rather go with a power system that you could make out of the ground that you are standing on, than relying on the goodwill of people

spacester · Oct 14, 2005

I suppose it was inevitable that we would reach this point in this thread. There are going to emerge two schools of thought as to how one goes about creating a lunar colony. There's the conventional way, the high-tech big business big government way, and there's The Other Way. What the poster whom I no longer directly address because he clearly cannot be bothered to read the thread but who has finally produced some numbers that more or less check out and so also the poster for whom I still hold out hope for being able to learn to play well with others does not understand because he clearly has not read the thread is that this thread was intended to talk about The Other Way. So the thread has been hijacked. Fine, indeed the terms of service say nothing about being rude, so be it. We can deal with this. Nuclear is king. All those who insist that only nuclear will suffice are the smartest, wisest, bravest and most well-endowed of all space advocates. Now, are the unhappy posters here happy? Now can we get back to talking about The Other Way without being drowned out by sheer volume of words? My strategy for discussing the need for a power supply was to establish a baseline Nuclear Capability that could be landed in the near term, and then analyze solar in relation to that. I wish folks would talk about the power lander I referenced earlier. It would really move the discussion along at this point. Let's talk about what we mean by The Other Way, for those that don't get it. I could go on and on and on but I'll cut myself off here cuz I gotta go to work. For now: The colony could be self sufficient up until the reactor uses up its fuel, and it is at the mercy of the earth. It would mean that anyone going into space would have to come up with (the cost of) a new power source, if they ca <div class="Discussion_UserSignature"> </div>

tap_sa · Oct 14, 2005

"That appears to mean 9900 small tons. " What's a small ton, any relations to short, long or metric ton? Anyway in another post the 9900t was clearly written as 9,900,000kg. "I pointed out the weight of a modern, lt. wt. PWR was about 10 times less, perhaps even less than that, in the 50 MW range. " If you are talking about the French sub Amethyste then it's reactor produces 48MW of thermal power. It has 7MW electric engine to drive the propeller, the mechanical power from turbine shaft is a bit more but not much. Generators are very efficient, >95% efficiency is usual. Dan's 220MW was usable energy ie. electricity. You really should keep apples and oranges separated instead of picking whatever number is bigger when it suits the cause. Same thing with the SSTAR reactor. If you google around you'll find out that the reactor weighs 500 tonnes and is compact sure, but that is just the reactor. The 500t figure alone cannot be used to estimate kW/kg densities, it would be similar to boast solar thermal and talk only about the concentrating mirror. That's my 0.02 EUR on the issue in this thread, this is deviating too much into nuclear/solar debate only instead of moon base. A specific thread for the power issue alone would be in order.

kilendrial · Oct 14, 2005

"The colony could be self sufficient up until the reactor uses up its fuel, and it is at the mercy of the earth. It would mean that anyone going into space would have to come up with (the cost of) a new power source, if they can not pay for a nuke. Manufacturing solar panels on the moon would show that there is a system that you could export to any other lunar/asteroid/(to a lesser extent)mars colonies. I would rather go with a power system that you could make out of the ground that you are standing on, than relying on the goodwill of people a light second away." Do you really think you will be independent from Earth? With Uranium, you *might* need some interaction with earth for that purpose (disregarding on site radio-isotope mining) every 5 to 20 years. But, what if a fuel cell breaks? I also thought we were going to ramp up energy ability as needed so fuel cells (night time production) will probably have to be expanded at a linear rate with the solar ability and general size of the colony/settlement/city. Any expansion would then be tied to Earth unless you have a fuel cell factory as well. Are you going to go through the process of having the capacity to produce every spare part you need? Are you going to be using 10 to 20 year old computers also? Are you going to build computers plus solar cells plus fuel cells plus space craft? You are going to be tied to Earth somewhat for the foreseeable future. Anyway, if you could mine radio-isotopes on the moon, that is more viable for export than solar power and if you go for nuclear power yourself, you kill two birds with one stone as well just as solar power for both export and personal use would. It is more viable because of course it is my opinion that nuclear is better, and will have a even larger benefit for locations farther away from the sun. Other space expeditions will need a lot of stuff. Why is solar panels the only thing being considered? You could export a lot of things

dan_casale · Oct 14, 2005

stevehw33: 1) />>Wikipedia shows the Saturn V to have a total lift capacity of 118,000 pounds or about 60 tons. Just as I wrote.<< Thanks for providing your link. Happily your link and my link agree on the LEO capacity of the Saturn V rocket. However, after LEO comes Translunar trajectory, and after that comes "landed on the surface of the moon". Unfortunatly, I couldn't find a reference for how much the Saturn launch system was able to place on the surface of the moon. So yes, you are correct, my figure is too large. Also the quote is 47,000Kg. Your figure should also be in Kg. From this information I could speculate that 47,000 - ((118,000 - 47,000) / 6) = 11,833Kg to lunar orbit. This assumes that it takes 6 times the energy to leave LEO than to insert into Low Moon Orbit. Just a guess but (Total Mass of a Saturn V = 3,038,500 kg) 3,038,500 / 118,000 / 6= 4.29167. So 11,833 / 4.29167 = 2,757Kg to the lunar surface. This assumes that it takes 6 times the energy to lift off from Earth than it takes to land on the moon. If someone has better calcs please post them. 2) />>As no one is going to launch a huge space craft carrying hundreds of tons of materials to the moon, using current technologies, to build a lunar habitat, your point is moot. Rather, the lunar transfer craft will take quite some time to build in LEO and then take off towards the moon with its rather huge payload. Probly accompanied by 2-3 lander craft, as well, or to be joined later. << Either way is fine with me. The benefit of having a LEO shipbuilding facility will be come evident as we continue to spread outward. 3) />>From my previous post: ‘…single-cycle helium-Brayton plants of 10 to 50 MW provide a total capacity of 220 MW and the total mass is 9900 t, including a 10 percent design factor.’ http://lifesci3.arc.nasa.gov/SpaceSettlement/75SummerStudy/Chapt5.</safety_wrapper

craig42 · Oct 14, 2005

Agreed it’s best to ship the fuel in. Why do you not accept Casale's figures when they support your case? Is solar energy density even lower than that? Assuming (somewhat arbitrarily) that the lunar base needs 4000kw daily. How much Enriched U235 will be needed yearly to run the reactor, and how many launches will that require?

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