rapid prototyping and its applications in space

[no_way]

a couple posts on the blogs got me looking for the news on how far along the rapid prototyping methods are in the world, and its relation to anything that might be done on the moon.<br />First i stumbled on this<br />http://en.wikipedia.org/wiki/Selective_laser_sintering<br />and then, <br />http://www.xpress3d.com/Processes.aspx?sh=1<br /><br />It looks like there are plenty of methods and processes to try to apply for local parts manufacturing on the moon. I opened this thread to discuss the potential applications and approaches.<br />So which methods could be most suitable for using with refined lunar materials ? ISRU processes deal mostly with separating metals and stuff out from the regolith, such rapid prototyping methods could allow to make lots and lots of useful stuff in situ.<br /><br />I would really love to see a teleoperated robotic lander on moon which would test both metal extraction from regolith, and then some of these manufacturing methods.<br />

 

[spacefire]

if the cost of making limited production items drops, it will definitely have a lot of implications in the aerospace industry. <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>

 

[ruff_house]

I'm most interested in how the technology used in rapid prototyping could be applied to self replicating machines, (clanking replicators and van neran probes and such) the implications of which are huge.

 

[Swampcat]

I couldn't find any reference to "van neran probes." Did you mean Von Neumann? <div class="Discussion_UserSignature"> <font size="3" color="#ff9900"><p><font size="1" color="#993300"><strong><em>------------------------------------------------------------------- </em></strong></font></p><p><font size="1" color="#993300"><strong><em>"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."</em></strong></font></p><p><font size="1" color="#993300"><strong>Thomas Jefferson</strong></font></p></font> </div>

 

[ruff_house]

Oh man, yeah<br /><br />my bad. my very very bad. Crap. Sorry.

 

[kelvinzero]

I found this document online. Seemed fairly relevant though it is from 2005<br /><br />ISRU roadmap <br />from<br />http://www.lpi.usra.edu/lunar_resources/<br />http://www.lpi.usra.edu/lunar/strategies/index.shtml#resources<br /><br />worth a browse anyway. Not sure it was exactly the document I was looking for. I remember one with a large chart of readiness of a whole list of manufacturing technology and how they interrelated.

 

[eniac]

Self-replicating machines are a fascinating subject. There are no fundamental obstacles to producing one today, and the implications are indeed huge. The best reference I have found is this: http://www.molecularassembler.com/KSRM.htm. <br /><br />You can come at the problem from two different angles: 1) a few very versatile machines that can manufacture a large variety of parts (rapid prototyping), or 2) a large variety of different machines made from a small variety of parts (Lego model). The right combination of these two approaches, together with miniaturization, could bring down the mass and complexity of a minimum self-replicating system to a level where it could actually be built. <br /><br />Automation is the key to this, as all other processes are well established and implemented in the existing world economy, which is really one large example of a self-replicating machine. Any of the millions of microorganisms populating the Earth would be another, much smaller example. We'd need something in between.<br /><br />Although space manufacturing has been a considerable driving force for research into this area, it should be much easier to build a self-replicating factory right here on Earth. Once it exists, the design can then be modified for space and you can have it manufacture all the hardware and launchers to get it there, for free.<br /><br />Before you even get to space, you will have solved all of Earth's energy and resource problems, which is a nice little side benefit. <br /><br />Andreas<br /><br /> <div class="Discussion_UserSignature"> </div>

 

[no_way]

Well, i still consider full self-replication a bit of a stretch, and im looking at what would be doable right now.<br /><br />So consider a pilot ISRU plant on moon that is able to produce feedstocks of oxygen, aluminium and silica glass.<br />Also consider an existing space-adapted rapid prototyping plant using existing macroscale prototyping method, like laser sintering linked to above.<br /><br />It looks like it would enable tremendous capability buildup on lunar site without really shipping much mass up from earth at all. Basically all structural elements of buildings and vehicles could be built in situ, and thats the major part of mass for any lunar base concept.<br /><br />The thinking is: only massive parts would need to be made in situ, relatively lightweight stuff like electronics can be shipped up.<br /><br />A good thought exercise is looking at ISS and splitting its mass up to parts that could be produced using current rapid prototyping technologies and the ones that could not ( or would be too much trouble ). <br />Of course there would need to be design tradeoffs with mass and manufacturing tolerances, because obviously you are not going to get aerospace-grade parts from your laser sinterer.<br />

 

[no_way]

Another good thought excercise : can you come up with a general exploration rover design ( lunokhod-like capabilities ) that could be produced from lunar materials in 90% of mass, and replicated many times over ?<br />The sticking points of course are energy storage and production, but there are solutions for these too.

 

[bitbanger]

Fab @ Home is something that I find interesting.

 

[kelvinzero]

I think the big sticking point for the moon is the lack of water for smelting purposes. I dont know what the current status is concerning possible water at the poles, but we might be faced with shipping up all our hydrogen and creating our own water from lunar oxygen. Finding robust methods that do no use water at all would of course be wonderful.<br /><br />I think the energy production and storage outlook is pretty good. I have heard promising things about creating fields of solar cells using mainly local resources. For some processes all you need is heat, or more importantly a large heat differential. There we are in luck.<br />As for storing power there are a few possibilities. I wonder if simple thin spheres of aluminium could hold a useful amount of charge per weight? Or what about just a flywheel/ electric motor? You put power in to spin it up, and draw current off as you slow it down. Another low tech way to generate and store power would be a pressurised gas/stirling engine combination.<br /><br />Some of those might be dumb ideas but there just seem to be so many possibilities to explore.<br /> <br />I would really like to see an active forum discussing these possibilities. I have had a go at gathering some links here but it really doesnt seem to excite people as much as billion dollar rockets <img src="/images/icons/wink.gif" /><br /><br />ISRU links

 

[docm]

My take on water;<br /><br />~43% of the uppermost lunar regolith is O2. Take lunar regolith, put it in a solar heated reactor vessel @ />1000+ C. Much of the O2 comes off as free oxygen, some of which combines with trace hydrogen to make water. The output could be boosted by adding leftover hydrogen, if any, from lander fuel tanks. If H2 isn't used in the lander but methane is I suppose a process could be devised to use the H2 locked in the methane.<br /><br />Comments? <div class="Discussion_UserSignature"> </div>

 

[danhezee]

I think rapid prototyping is the difference between success and failure in any manned outpost on the moon or further. Imagine how many things will break or fail over a 1, 2, 5, or even 10 year period. Explorers will need a system to replace those parts. Also, I feel they will need a prototyping system like Bug Labs www.buglabs.net and Vex Robotics www.vexlabs.com. Those systems would allow explorers to create tools on the fly for problems they would encounter. <div class="Discussion_UserSignature"> </div>

 

[a_lost_packet_]

Rapid prototyping would certainly be an advantage. However, many critical components have exacting specifications. Rapid prototyping is designed to get a "hardcopy" of a concept, not produce a finished product to exact specifications.<br /><br />However, that being said, the technology is advancing. The biggest problem is materials. There are several types of prototyping materials and there are programmable tools that will churn out all sorts of parts out of durable materials like steel. So, a couple of different prototypers could be used to make simple parts and equipment replacements.<br /><br />But, all of that raw stock still has to get to the moon or be found there. True, it would save some freight for manufacturing simple components instead of having to stock them. Epoxies and polymers could be combined to produce a stock for a variety of components. But, the key is turning raw materials on the moon into material for a prototyper. If you can do that, then you save a lot of freight on shipping raw components. Finding native supplies of raw metals would be the best savings of all. You just have to figure out how to get them from the raw state to a finished state suitable for automated machinery and suitable for producing a component within design specs. <div class="Discussion_UserSignature"> <font size="1">I put on my robe and wizard hat...</font> </div>

 

[danhezee]

i looked at the fab @ home site and found this neat project www.reprap.org. RepRap is a self replicating rapid prototyping machine. of course it isn't self replicating yet but at least someone is trying. <div class="Discussion_UserSignature"> </div>

 

[kelvinzero]

Im cant exactly say I like your idea docm, it might just be all we have <img src="/images/icons/smile.gif" /><br /><br />I wonder if there is some way of flowing oxygen over a really large amount of regolith in the hope it will find a volatile to react with. For example would oxygen migrate between an anode and cathode tens of meters apart under the lunar surface.<br /><br />--<br /><br />I think the idea behind the original post was that moon regolith might a good prototyping material. Some of it is very very fine and all of it is very very dry. Sort of how I imagine the contents of a laser jet cartridge.<br /><br />You could probably extract super fine elements (eg using static charge?) and you could probably also sort it into grades according to how magnetic it was.<br /><br />

 

[eniac]

"I think the big sticking point for the moon is the lack of water for smelting purposes."<br /><br />I don't think smelting requires water. Most of the metal oxides in regolith can be reduced with silicon (http://www.molecularassembler.com/KSRM/Figures/3.53.JPG), which in turn can be produced from silicon dioxide by electrolysis (http://www.freepatentsonline.com/4292145.html). <br /><br />In the Lackner-Wendt cycle referenced above, carbon and hydrogen are used for silicon dioxide reduction, most likely because the process was designed for Earth dirt. In theory, both carbon and water are conserved and recycled in the process, in practice there will be losses. With a little bit of chemical ingenuity, I believe that the use of carbon and hydrogen can be entirely avoided in the extraction of the most important materials from lunar regolith: Al, Ti, Fe, Si, Al2O3, SiO2. These materials can make up the bulk of any machinery or structure. Aluminum can substitute for copper, titanium can substitute for iron (except in magnetics), alumina makes an excellent ceramic material for insulators and crucibles, silicon dioxide is great for glass, and silicon has use in solar cells and electronics. Basalt, basalt fiber, and sintered regolith (for bricks) are examples of materials that are quite versatile, yet require no chemical processing at all.<br /><br />"As for storing power there are a few possibilities. I wonder if simple thin spheres of aluminium could hold a useful amount of charge per weight? Or what about just a flywheel/ electric motor? You put power in to spin it up, and draw current off as you slow it down. Another low tech way to generate and store power would be a pressurised gas/stirling engine combination."<br /><br />I don't think electrostatic charges are good for energy storage. Flywheels, though, are perfect. With natural vacuum expensive enclosures can be omitted. A rotating sling could have dual use for energy storage and launching payloads.<br /><br />Andreas<br /> <div class="Discussion_UserSignature"> </div>

 

[eniac]

"I wonder if there is some way of flowing oxygen over a really large amount of regolith in the hope it will find a volatile to react with."<br /><br />It is easier than that. You heat the regolith and all the volatiles will come out as gas. That's what being volatile means.<br /><br />It is likely, though, that the amount of regolith processed for materials simply does not contain enough volatiles to meet the need of human habitation, so hydrogen and carbon, at least, will have to be imported. From comets, perhaps, or asteroids.<br /><br />Andreas<br /> <div class="Discussion_UserSignature"> </div>

 

[kelvinzero]

Here are those links for the one click generation <img src="/images/icons/wink.gif" />molecular assembler link<br />freepatentsonline link<br /><br />the oxygen flow idea was a long shot. It would be nice if you could go for the easy stuff across hundreds of cubic meters of regolith at once by poking a rod in the ground.<br /><br />I'll have a look at those links.

 

[eniac]

This link should also be of interest: http://www.asi.org/adb/02/13/02/silicon-production.html<br /><br />Particularly the second half, which describes a process with much lower temperatures than Lackner-Wendt, and no carbon nor hydrogen required. Instead, potassium flouride (neither element is common on the moon) is used and recycled, which should be easier to do with minimal loss. As far as I can tell, much the same materials are produced, namely aluminum, titanium, iron, silicon and oxygen. It also has the advantage of producing silicon through flourosilane, which should yield high purity silicon for solar cells directly without further purification. Pretty clever, but I don't know how practical.<br /><br />Andreas<br /> <div class="Discussion_UserSignature"> </div>