A Lunar Colony

[josh_simonson]

You're comparing apples and oranges here. Even though solar electricity is only 30% efficient, that doesn't gurantee that the incremental costs of upgrading or overbuilding the existing solar or nuclear energy supply is more expensive than building a dedicated optical system from the ground up.<br /><br />In the end system cost, utility, and complexity will be the metric by which these solutions will be judged, not efficiency.

 

[mlorrey]

Just so, but you've not made a business case for your position with any sort of numbers. I have. Try arguing with actual arguments, rather than just dismissals and empty assumptions.

 

[josh_simonson]

I'm just pointing out that raw efficiency in the use of sunlight is a worthless metric. We're not exactly short on sunlight or space to collect it in space. <br /><br />You also make a very bold and completely unsupported assumption that the two systems weigh exactly the same amount for a given area of collected light. This is certainly not the case. Your light concentrator will require many, fairly high quality mirrors that track the sun very accurately to reflect the light into the waveguide. That requires 2 actuated axis of movement and the intelligence to point in the right direction - per mirror. Photovoltaics only need to point in the general direction as the sun, and they don't need to be independantly aimed. <br /><br />Light collectors work just fine here on earth too, they can be used to solar thermal power, to enhance photovoltaics by shining more light on them, ect. However, the size, cost and complexity of the mechanism to point them at the sun accurately prevents their widescale use. <br /><br />In reality, once space assets reach the size to need such greenhouses, nuclear power will probably be the hands down winner on power density and cost. So really, this whole argument is moot. <br /><br />You can make all the ad hominems you want, I don't care. I'll happilly let others decide what to make of them.

 

[mlorrey]

Actually, josh, I pointed to a link that used quite a number of rather low quality and light flexible mirrors in a two dimensional sort of levelour system.<br /><br />BTW: Solar illuminance on earth at noon is 102,000 lux, or lumens per square meter. I'm discussing with a physicist friend how that translates to the lunar surface, with no atmosphere to glow or interfere, etc. but by the light piping technology, you would get 102,000 lux/1365 w, or about 75 lux per watt, at 100% transmission efficiency, down to about 48 lux/watt at the 60% efficiency typical of a light pipe with a 20:1 length:width ratio.<br />Now, lets look at using PV to produce electricity, and lights to convert it back to light: PV efficiency will range from 10-33%. If we build the panels using lunar materials, silicon, we are limited to 22% efficiency. So for each sq meter you are producing about 300 watts.<br /><br />The suggestion has been to use LEDs to deliver specific wavelengths to plants. LEDs range from 10-45 lumens/watt. This spells for not only a lot of solar panels, but a lot of LED panels as well. There is no way you can make an argument that the mass of the two together is less than the light piping AND more efficient. <br /><br />BTW: denigrating anothers ideas or methods is NOT ad hominem, so once again, I suggest you go do your homework and study up on what is and is not ad hominem before making such accusations.

 

[nexium]

One system that does most everything allows for well trained technicians who can jury rig to keep it going, but I want back up for the back up. Yes to a grid that can deliver survival amounts of power. Yes to nuclear. Yes to photovoltaic. Yes to fiber optic for illumination and for photosythesis. yes for parascopes that don't bring in the harmful radiation. Yes for the growing cubes that Josh suggested/ The top layer can be directly solar energized with fiber optics and parascopes. The lower floors should have several light sources including perhaps burning methane which can also prevent freezing and supply the plants with extra carbon dioxide. My guess is most plant types need 100 watts, plus per square meter, at least one hour out of each 24, for best performance later, during the budding, blooming and fruiting 14 days. Neil

 

[dan_casale]

Interesting article on the use of superconductors in the power grid.<br /><br />http://www.amsuper.com/products/htsWire/FaultCurrentLimiters.cfm<br /><br />and <br /><br /> <br /><br />Superconductor Fault Current Limiter Successfully Demonstrated for First Time in China Power Grid <br />Dec 20 - PRNewswire-FirstCall American Superconductor Corporation , a leading electricity solutions company, and China's Institute of Electrical Engineering (IEE) today announced that IEE has successfully demonstrated a superconductor-based fault current limiter -- essentially a high voltage surge protector -- for the first time in a power grid in China. The device was fabricated by IEE in collaboration with the Technical Institute of Physics and Chemistry and Hunan Electric Power Company utilizing "smart" high temperature superconductor (HTS) wire manufactured by AMSC. Since August 2005, IEE's fault current limiter device has successfully suppressed large spikes of current in the grid that were over five times the normal levels. Superconductor wires are considered smart because they possess unique physical properties that allow them to react instantaneously to current surges, passing electricity along at normal levels while also being able to recognize and then suppress large surges of electrical current. Suppressing spikes of electrical current is important because it prevents damage to expensive electrical equipment in power grids. Fault current limiters cannot be made from conventional materials such as copper wire. <br />According to Dr. Liye Xiao, Deputy Director of the IEE and Director of the Applied Superconductivity Laboratory at the Chinese Academy of Science, this project is an important step in demonstrating the value of these devices in greatly improving the reliability and stability of power grids in China. "Demand for electric power in China continues to grow dramatically year-over- ye

 

[chriscdc]

It is hardly appropiate to assume that you would need as much power as 70kg of TNT to move that much regolith.<br /><br />Firstly a large amount of the debris falls back into the crater and so raises the depth of the crater floor. So in reality far more regolith could be moved for that amount of energy.<br /><br />The second, is that the shockwave you mention would also carry a large fraction of the impact energy. <br /><br />Thirdly the impact causes the regolith to undergo phase changes. The regolith immediatly underneath would be vaporised and so when it expands, it causes the explosion that moves the majority of the regolith. Other regolith will melt and fuse, thus using more of the impact energy. <br /><br />Any other method of moving regolith would be far more efficient. Why partially melt regolith and then accelerate it to tens of meters per second when you could scoop most of it up with a trowel and accelerate it to only a few m/s at the most?

 

[nexium]

Dry soil as fine grained as regloth is rare on Earth. My guess is 0.07 kilotons of TNT would nor make a 100 meter crater. The soil blown with an upward vector the first micro second behaves like a thick atmosphere for the regloth blown upward the 2nd micro second, as 1/6 g gravity slows it's assent. Neil

 

[chriscdc]

I expect that such an impact would drill a deep hole in the regolith, afterall anti-bunker impact warheads have a mass of around a hundred times this but with a velocity of 1000 times less, yet they can still penetrate meters into earth. <br /><br />The energy of the impact travels faster than sound in regolith and so it would not transfer energy laterally until it slows enough. The regolith and the meteorite will converted to plasma by the impact, causing a high pressure coloumn of gas that will then expand outwards.<br />The crater is only the surface scar, with far more damage occuring underground. Actually I doubt much material went upwards, most material will be fused by the shockwave and thus taking up less space. A small amount will be expelled upwards whilst the majority of the crater heaves and then collapses downwards.

 

[chriscdc]

I'm not doubting the power or the impact or anything that I have heard from nasa. Just your assumption that you can work out the volume that can be moved via working out the Ke of the meteorite (your comments on showing that you need nukes not solar).<br />Also your assumption that a few tens of meters would be enough protection.<br /><br />Do you understand the importance of phase changes in the material? How much energy is required in the process of turning solid to liquid and then to gas. The explosive power of the impact comes from the change from rock to gas.<br /><br />You have an impactor hitting at 20km/s and this is far faster than sound in the regolith. This accelerates the grains, that move against each other causing friction, causing heat which then fuses the grains together.<br /><br />The point about the crater floor was that it was formed by processes happening underground and not by material being expelled by the impact.

 

[tap_sa]

If it takes the energy equivalent of 70kg of TNT to dig up a crater 3m deep and 100m wide on the Moon then we are lucky. One kg of TNT contains about 4.2MJ of energy while kg of ordinary diesel oil contains ten times as much. 4.2MJ is equivalent to 1.17kWhr (kilowatt-hour) so the explosive dig would need total of 82kWhr, meaning an excavator with 82kw power creates one crater every hour. Solar irradiance on the Moon is about 1367 watts, if we take a very poor 10% as a baseline for solarcell efficiency we'd need 600 squaremeters of such panels.<br /><br />Of course everybody knows that it has been/is/will always be <i>impossible</i> to set up a solarcell farm that big on the Moon, and if the digging of crater that big takes longer than one hour then it's all in vain anyways so solar power has no hope to power anything on the Moon, period.

 

[scottb50]

so solar power has no hope to power anything on the Moon, period....<br /><br />Sure it does, I just hope we do more with it than dig craters. I doubt there is much call for them anyway. <br /> <div class="Discussion_UserSignature"> </div>

 

[mlorrey]

Solar panels are very useful on the moon, but are only more cost effective than nuclear if they are actually manufactured on the moon from lunar materials (and produced in large quantities to justify the manufacturing infrastructure). <br /><br />People shouldn't get so worked up over ONE observed meteor impact on the moon. Big whoopie doo, satellites observe dozens of high altitude fireballs from meteorites every day. It doesn't say anything about the actual strike rates for any given area of the moon.

 

[scottb50]

With a thin film collector array you could easily build a huge field on the moon or even Mars. My idea is individual arrays that service one or more hydrolizers. Any failure does not affect other systems and cross-tying to other systems can still assure continued use. Say a rock knocks out an array others supply the hydrolizers while repairs are made.<br /><br />If nothing else this impact points out the obvious possibility for it to happen anywhere and anytime and the need to plan for it. The real problem is Stations in LEO are probably in more danger because of the Earths gravity. Not to say the danger is that great to begin with, but since it exists there has to be a probability of rock A impacting Station B. <br /><br />I say everything is built inside identical Modules connected to one another, the more Modules the more redundancy. With every Module having triple redundancy pretty much any problem in one Module could be coped with safely.<br /><br />As for producing arrays on the moon I would think it would require way too much equipment, which would have to be brought from Earth. I would think a rolled array, or a bunch of them could be sent on just about any launcher. Stimulate the economy, the more launchers the cheaper and safer they get until it's simple and safe to get to Space. Cheap would be nice, but two out of three isn't too bad.<br /><br /> <div class="Discussion_UserSignature"> </div>

 

[chriscdc]

Steve can you give a link as newscientists article has disappeared, and in all the other news articles, they say that the crater was 3m across and only 0.4m deep.<br /><br />http://www.space.com/scienceastronomy/051223_moon_meteoroid.html

 

[tap_sa]

...and 'high energy density' means .... what?

 

[scottb50]

http://www.hydroelectrolysers.com/<br /><br />Plug in solar to supply the electricity and you could produce an infinite amount of Hydrogen and Oxygen that can be used to run fuel cells from which you get electricity to run your facility and equipment. I may be wrong, but I think the big coal mining machines use electric motors.<br /><br />If you have enough available power you can run whatever you want. Need more power? Add more solar panels, hydrolizers, fuel cells and water.<br /><br /><br /><br /> <div class="Discussion_UserSignature"> </div>

 

[mystex]

Forgive me if this has been covered allready but I've been slogging through the threads and it seems everything is more concerned about power generation than about first getting to the moon. <br /><br />In my opinion we would be better off to send a satalite to the moon to start off with. This sat could be placed in geosyncronous orbit where we could scan for the best site to start with. <br /><br />It would also serve as a relay link for a telerobot presence on the moon. With a geosyncronous satalite in a polar orbit around the moon we would have a continual connection and would be able to teleoperate robots continually. <br /><br />As for the whole dig or bury underground argument why not start off with the assumption that there will be access tunnels under any settlement if its done in a dome. These would allow for subways and the running of utilities easily through out. <br /><br />Initially the basalt removed to excavate these could be used to build habitats above ground and to start working on a dome.<br /><br />If this was done inside a crater the rock removed through boring could be used to start out sealing up the crater. Once the crater was sealed construction of an over head dome could be accomplished. <br /><br />I had read in one of the posts of having a central cylindar in the dome. This would be perfect to add stability to the dome and would also allow for a housing the recieveing and launching facilities for earth moon transit. Once the dome and cylindars were up multiple levels could be added to the dome perhaps leaving open central areas close to the cylindar. <br /><br />For a power source an initial collection of solar cells from earth would be a start but from then on they could be built on the moon from native materials. Instead of light tubes fiberoptics could be used to send and direct light into buildings and different areas. <br /><br />Fiberoptics could be easily produced from native materials. <br /><br />The dome could probably be anchored by fusing the

 

[mlorrey]

Geosynch is nowhere near close enough to do a lunar observation mission (note that the lunar rotation period is one month). Terran geosynch is more than 200k miles away from the moon.<br /><br />Furthermore, Clementine and other missions have already closely mapped resources on the moon. Having a lunar GPS and satphone service on the same satellites would be a big help at some point, but that requires having a lot of people operating on the moon in many locations, prospecting widely, to make it a profitable endeavour.<br /><br />Digging is really not necessary. As we now know, the crater depth of even relatively rare impacts observable from earth do not exceed 1 meter depth. Burying inflatable hab modules and spent fuel tanks under 2 meters of spent regolith should be completely sufficient for all but the rarest impact events, and so long as modules have pressure hatches, then dealing with blowouts shouldn't be a problem.<br /><br />Fiberoptics are far less efficient than much much wider light tubes at transmitting light. They are both essentially similar devices, and while lasers transmit through fibers well, this is only because laser light is collimated and coherent. Normal light interferes with itself in a fiber and the transmission efficiency of broad spectrum light is very very poor.<br /><br />As for nuke reactors, I'd suggest instead of that large French reactor, to use US Navy submarine reactors. Their design, size, and reliability seem ideal for the application.

 

[mlorrey]

On the contrary, lunar maps at resolutions down to 1-5 meters have been made, they just are not publicly available on the web as of yet.

 

[scottb50]

Forgive me if this has been covered allready but I've been slogging through the threads and it seems everything is more concerned about power generation than about first getting to the moon.....<br /><br />It's all inter-related. If you have electrical power you have the means of doing everything else you want to do. I doubt you could get too far without it. <div class="Discussion_UserSignature"> </div>

 

[mystex]

I do hope you will all continue to forgive what probably seem like stupid questions.<br /><br />Would it not be possible to send up an automated factory to build solar cells during the early stags of the colony? I mean since we're going to have teleoperated robots digging it out why not have them start manufacturing solar cells with the silica in the regolith?<br /><br />That way we could start mounting the solar cells and start powering up systems and things before we get there. With this we could start off with a small power supply that would be ramped up as we go. By the time we have a small place established and send up our first team to have a more hands on approach we would have a significant amount of solar cells constructed, mounted, and powering the local power grid.<br /><br />Like I said though I know my ideas probably aren't as well thought out as a lot of yours. But I think possibly they might be somewhat valid.

 

[craig42]

<blockquote><font class="small">In reply to:</font><hr /><p><br />Would it not be possible to send up an automated factory to build solar cells during the early stags of the colony?<p><hr /></p></p></blockquote> To be fair no one really knows the answer until we send one up and try using it. <br /><br />ASE Americas has plans to build a <br /><br />fully-automated solar cell manufacturing line Both GT Solar and Energy Conversion Devices Inc. claim to have developed automated machines to produce solar cells. The later of which produces 25 million watts per year. This ability of an annual bootstrap is key pillar of the pro-solar crowd. Especially if you can build another machine with In-situ materials.<br /><br />Of course it depends what you mean by an 'automated factory' if you simply want to pour in feedstock one end and have finished solar cells pushed out the other then I see no reason why these process can't be adapted for Lunar use.<br /><br />If in however you want to gather regolith, extract the necessary materials (A-Si alloy and Stainless Steel for the ECD inc model) and the delivery and installation, as well as the technicians, and the managers etc. Then you’re probably going beyond the realm of current technology.<br /><br /> I certainly think that you could certainly have an automated a production line.<br /><br /> Unless of course these machines require large amounts of hydrogen or some other resource the moon lacks.<br />

 

[why06]

I'm sorry... this is a fairly long discussion... and while I did not read more than the first five pages I had an idea about how to support this hole opperation from the get go. Before any mining opperations or tourrism buisness takes off.<br />Why don't we sell moon rocks...you know any a left-overs and extras from the initial building of the colony.<br /><br />I know I would pay $20.00 at least for a small piece of moon rock, for no other reason than to simply know where it came from.<br /><br />While reading this I've heard many great ideas and I do not know weather this has been discussed or not but, I'll try to read the whole thing eventually. I just wanted to post this before I forgot. <font color="orange"></font> <div class="Discussion_UserSignature"> <div>________________________________________ <br /></div><div><ul><li><font color="#008000"><em>your move...</em></font></li></ul></div> </div>

 

[mystex]

Craig thats exactly what I had in mind. I mean it would make sense to have multiple automated lines, ones for proccessing the regolith and others for processing the refined materials in to what we would need. <br /><br />If we could have different automated factories producing things from the regolith that we required for building habitats then we could send those up first with teleoperated robots to gather the regolith and do some basic construction. <br /><br />Then we would be able to send up crews to start building with the proccessed materials. Would certainly make things easier I would think.