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#26 2011-12-24 07:22:19

Terraformer
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From: Ceres
Registered: 2007-08-27
Posts: 3,800
Website

Re: Developing the cis-Lunar economy and infrastructure

Well, I did suggest launching the water to EML1 and cracking it there, if possible... that ought to reduce boiloff (I don't know why you'd'place it in GEO...). Once the infrastructure is in place we can invest in a railgun.

If solar panels really are that easy to make, is there any chance we could bring back Ol' Neill's vision? smile

Louis, just how much is Lunar tourism going to cost? Even if the total cost is only twice their ticket to orbit, that will still be around 20 million dollars. How many people were on the list to go to the ISS, how many have already signed up for Bigelow's hotels... you must have researched this, surely?

When it comes to making ships, I think Lunar will be quite a good area. Gravity is quite useful when you're trying to build hulls, I'd think. Most internal outfitting will be done at Terra station (EML1) with the few things that need to be brought from Terra.

As far as exporting things to Terra goes, we need a means of getting the stuff to the surface in one piece, and something like the Dragon won't cut it - it costs say 80M to launch, with 4 tonnes down cargo. Our cargo will have a value of say 20k/kg, so 4 tonnes will be worth... 80M.


"I'm gonna die surrounded by the biggest idiots in the galaxy." - If this forum was a Mars Colony

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#27 2011-12-24 09:39:09

Rune
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From: Madrid, Spain
Registered: 2008-05-22
Posts: 191

Re: Developing the cis-Lunar economy and infrastructure

JoshNH4H wrote:

Before I go there, though, I want to mention something that should be number one on everyone's wish list for the Moon (Or Phobos, or both):  A fuel-less launcher.  If we're using the Moon primarily to make fuel, it's incredibly wasteful, both in terms of energy and production capacity to burn half of it (or potentially more, depending on the fuel) just getting there.  It doesn't make anything impossible or not viable as Zubrin has said, but it does make it less cost-effective.  A railgun with a connection between the rails and the payload made of plasma would be very energy efficient and pretty simple to build.  You could conceivably get away with one that was a kilometer long (acceleration would be very high, as would power consumption, but the potential benefits are astronomical, if you'll pardon the pun).  You could make the rails out of iron or aluminium, and incorporate the plasma generator into the device.

Well, in regards to fuel-less launchers, I would say that a space elevator seems like the obvious answer. First, it's actually doable on the moon with present day materials (IIRC, kevlar would do). And maybe with a little bit of thought devoted to it, you can manage to provide most of the mass through ISRU means (Basalt fibers, off the top of my head, jump to mind). Not so much with railguns, which are quite complicated pieces of technology with very tight margins and exotic alloys all over them (if not for the rails themselves, then for the electrical stuff that goes with them). A space elevator is mostly cable (>90% by mass), so just an automated cable factory and you can import the rest.

Also, even if you have to provide the same energy to the payload, you do so over hundreds of thousands of kms instead of one, which lets you use much simpler methods like solar panels (using either sunlight or beamed lasers) driving electric motors, and subjects the payloads to pretty much zero stresses. Humans might get bored, though... wink. Furthermore, unlike a railgun a space elevator is a conservative system, so you could actually pay the electric bill by importing as much mass as you export. Or turn a profit if you bring more stuff, but that seems less plausible (what do you pay it with, and where do you bring it from).

Oh, and there's also the facts that you can park things in a stable orbit without onboard propulsion systems, unlike pretty much any other method of launch. Just drop things at GLO, or the few suitable altitudes. To launch to earth or somewhere else you can't get away with such dumb payload, though, but that's a problem no matter what you use. All in all, railguns seem more suited for other applications. Like naval warships, or pitifully small gravity wells with little or no rotation (you know, 'cause then an elevator can't provide much free delta-v).


Rune. Happy "itsmybirthday" everyone!! And "nochebuena" tonight!!


In the beginning the universe was created. This has made a lot of people very angry and been widely regarded as a "bad move"

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#28 2011-12-24 11:35:34

louis
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From: UK
Registered: 2008-03-24
Posts: 7,208

Re: Developing the cis-Lunar economy and infrastructure

Rune wrote:
JoshNH4H wrote:

Before I go there, though, I want to mention something that should be number one on everyone's wish list for the Moon (Or Phobos, or both):  A fuel-less launcher.  If we're using the Moon primarily to make fuel, it's incredibly wasteful, both in terms of energy and production capacity to burn half of it (or potentially more, depending on the fuel) just getting there.  It doesn't make anything impossible or not viable as Zubrin has said, but it does make it less cost-effective.  A railgun with a connection between the rails and the payload made of plasma would be very energy efficient and pretty simple to build.  You could conceivably get away with one that was a kilometer long (acceleration would be very high, as would power consumption, but the potential benefits are astronomical, if you'll pardon the pun).  You could make the rails out of iron or aluminium, and incorporate the plasma generator into the device.

Well, in regards to fuel-less launchers, I would say that a space elevator seems like the obvious answer. First, it's actually doable on the moon with present day materials (IIRC, kevlar would do). And maybe with a little bit of thought devoted to it, you can manage to provide most of the mass through ISRU means (Basalt fibers, off the top of my head, jump to mind). Not so much with railguns, which are quite complicated pieces of technology with very tight margins and exotic alloys all over them (if not for the rails themselves, then for the electrical stuff that goes with them). A space elevator is mostly cable (>90% by mass), so just an automated cable factory and you can import the rest.

Also, even if you have to provide the same energy to the payload, you do so over hundreds of thousands of kms instead of one, which lets you use much simpler methods like solar panels (using either sunlight or beamed lasers) driving electric motors, and subjects the payloads to pretty much zero stresses. Humans might get bored, though... wink. Furthermore, unlike a railgun a space elevator is a conservative system, so you could actually pay the electric bill by importing as much mass as you export. Or turn a profit if you bring more stuff, but that seems less plausible (what do you pay it with, and where do you bring it from).

Oh, and there's also the facts that you can park things in a stable orbit without onboard propulsion systems, unlike pretty much any other method of launch. Just drop things at GLO, or the few suitable altitudes. To launch to earth or somewhere else you can't get away with such dumb payload, though, but that's a problem no matter what you use. All in all, railguns seem more suited for other applications. Like naval warships, or pitifully small gravity wells with little or no rotation (you know, 'cause then an elevator can't provide much free delta-v).


Rune. Happy "itsmybirthday" everyone!! And "nochebuena" tonight!!

Well, re lunar tourism, at a price tag of $10,000 per kg,  $20 million gets you 2000kg - that's a lot of mass I think for a 14 day trip I think. Of course, I would accept there will be some big capital costs at the beginning, but once you've got your 500kw PV panel facility up  there with the habs and the rovers and so on, well then that sort of price tag will generate huge revenues.  I think maybe the cost per person would actually be closer to $5 million. The multi-million price tag could definitely fall once the tourism industry becomes routinised. I don't think it's unreasonable to suppose the figure might fall eventually to $1 million - you're then getting closer to "world cruise" territory.

We should remember that the tourist shuttle will also be carrying cargo. I think the Moon will be perfect as a cemetery for cremated remains and as a location for Valentine Day messages.  No doubt there will be lots of other products and the lunar regolith, minerals and meteorites will also realise substantial sums, especially in the early years.  There will also be luxury foodstuffs and other products produced. 

http://science.howstuffworks.com/spaceshiptwo2.htm

Virgin Galactic, which I think is the best guide, claim to have 80,000 people on their waiting lists - with a price tag of $200,000 (though that is expected to fall).  I think on that basis we could envisage perhaps 8,000 people per annum being able to stump up for the lunar trip at a cost of $1-$5 million.  Anything between $8 billion and $40 billion.

I think space elevators are way in the future and shouldn't concern us now.  Now, the way to do it, is the Musk Method: cheap and cheerful rockets.


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#29 2011-12-24 12:29:53

Terraformer
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Re: Developing the cis-Lunar economy and infrastructure

Louis - it doesn't matter what the going rate for cargo is if you're talking about tourism so much as it matters what the going rate for passengers is. Cheapest I think is Dragon, which comes in at about 10M/person?

As for the market for tourism, we've already got information about orbital tourism to go off, from the ISS. Look at it, rather than making conjecture based on suborbital tourism.

Do remember that people want a return on their investment, so the capital cost has to be paid off sometime within the first 5-10 years of the operation. When you add in continuing costs, we're talking about having to generate 500M annually just to break even. While I reckon that's possible, the business case, just like the base, has to be nearly airtight.

I don't think we're going to be able to get a mass driver or space elevator built within the first decade or so (would a space elevator reach to EML1?), but rockets will do fine for now.

ISRU solar power is something to look into, definately. More power is always good, and typically solid state means higher reliability. If it means we could leverage our initial 200kW supply into a 2MW supply without having to import much, we can grow the nascent space hamlet quicker, since imports can be dedicated to things like manufacturing equipment.

@Rune - is it your birthday today? If so, happy birthday. smile


"I'm gonna die surrounded by the biggest idiots in the galaxy." - If this forum was a Mars Colony

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#30 2011-12-24 18:46:57

louis
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From: UK
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Posts: 7,208

Re: Developing the cis-Lunar economy and infrastructure

Terraformer wrote:

Louis - it doesn't matter what the going rate for cargo is if you're talking about tourism so much as it matters what the going rate for passengers is. Cheapest I think is Dragon, which comes in at about 10M/person?

As for the market for tourism, we've already got information about orbital tourism to go off, from the ISS. Look at it, rather than making conjecture based on suborbital tourism.

Do remember that people want a return on their investment, so the capital cost has to be paid off sometime within the first 5-10 years of the operation. When you add in continuing costs, we're talking about having to generate 500M annually just to break even. While I reckon that's possible, the business case, just like the base, has to be nearly airtight.

I don't think we're going to be able to get a mass driver or space elevator built within the first decade or so (would a space elevator reach to EML1?), but rockets will do fine for now.

ISRU solar power is something to look into, definately. More power is always good, and typically solid state means higher reliability. If it means we could leverage our initial 200kW supply into a 2MW supply without having to import much, we can grow the nascent space hamlet quicker, since imports can be dedicated to things like manufacturing equipment.

@Rune - is it your birthday today? If so, happy birthday. smile

The information from the ISS is that people will pay millions of dollars for access to space, but of course getting ready for the ISS is a somewhat arduous process, whereas Virgin G is geared to making the experience as simple and enjoyable for the tourist as possible.

The reality is that governments like the USA's are already committed to forking out billions of dollars in space investment. All we are talking about here is diverting some of that (maybe 10 billion) into creating the lunar development infrastructure which, ultimately, would make all the subsequent lunar science missions much cheaper (as they could be incorporated as a marginal cost on top of the tourism operation).

I think with maybe 25 tours per annum we could certainly generate $500 million per annum through tourism and ancillary enterprises.    With 20 guests per tour, you are already at $500million per annum with a $1m ticket price.  With 100 guests per tour paying say $500,000  per guest we would be up to $1,250 million.  Then you could probably add in another $500 million from ancillary activities e.g. meteorite collection, taking cremated remains to the moon, Valentine love messages etc. The real question is - can we get the ticket price down to $500,000 ?  It doesn't seem that crazy to me once we have lunar fuel production and also reduce the mass per tourist to the bare minimum.

I've nothing against ISRU solar power, but does it make much sense on the Moon, if it was generating over a billion dollars' profit per annum? With that profit you can purchase and import huge amount of PV power, without going to the bother of setting up PV production on the Moon.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#31 2011-12-24 23:05:54

JoshNH4H
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From: Pullman, WA
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Posts: 2,538
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Re: Developing the cis-Lunar economy and infrastructure

Firstly:  With regards to the links that we're using as sources to say that lunar solar panel manufacture will be economical... who actually read the sources?  Between them, there was not even the slightest suggestion that anybody knew how to make a solar panel on the Moon that could generate even slight amounts of power.  The most succinct description of what we do and don't know was given in the second link. 

The Second Link wrote:

Known
The power incident on the Moon from the Sun is 1.36 kW/m2.  Even with a solar cell of 10% efficiency ( < typical terrestrial), significant power could be generated on the Moon ( 1 square kilometer ~ 1.36 gigawatts).  The resources in place on the Moon are conducive to fabrication of the solar cells.  There is plenty of real estate to devote to solar farms for supplying energy.

Unknown
We still need to determine the following: optimal solar cell structure and deposition technique, design of heating the regolith to melting temperature and heating of source material for deposition, method on connecting the solar cells into large arrays, finish rover design.

Summary: There is sunlight on the Moon.  The regolith is 42% by mass Silicon Dioxide.  There are no houses on the Moon to get in the way.  We don't know any of the specifics of the PV cells, things like what we actually want to make, how we're going to make it, and how we're going to get the things that we need to make it.

This is hardly a convincing argument for the feasibility of solar cells IMO.  I'm not arguing that they're impossible, but they're not going to get as high as 10% efficiency, even if we import the dopants.  That requires very high-tech facilities which have a tendency to require a lot of people and a lot of mass.

I proposed a railgun instead of a space elevator or something else because I thought that that was something that could be built within a relatively short period of time, totally in-situ.  A space elevator would either be pretty high mass or hard to make in situ, and deployment would be another issue entirely.  Long term it may be worth it, but short term IMO a railgun is the best choice in terms of rocket-less launch.

The fuel-splitting station would be at GEO because then you could have a single power transmission station from Earth, and save with all the expensive power generation equipment that you would otherwise need to bring up there.  Otherwise, the location of the fuel splitting station is arbitrary, but for some important factor which I'm sure exists but does not come to mind immediately.


-Josh

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#32 2011-12-24 23:20:54

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 28,750

Re: Developing the cis-Lunar economy and infrastructure

I really dislike all the quote blocks when its a complete post or to the previous posting when you are the next one to post too in response to its content.....

In response to "Those are all proposals and they haven't got to grips yet with the key issues of deposition - which on earth seems a pretty sophisticated process requiring sterile conditions. "

The moon is in a vaccum so sterile is done... deposition is more dependant on the layering materials and of which ones are to be used....plus to where the raw minerals come from....including printing them.

http://www.asi.org/adb/02/08/solar-cell-production.html

While high-efficiency solar cells can be made from a wide variety of semiconductors, lunar material scarcity rules out production of indium phosphide, gallium arsenide, copper indium selenide, or cadmium teluride solar cells. The available semiconductor material is clearly silicon. Candidate solar cell types are crystalline silicon and amorphous silicon. The most common soil material is anorthite, CaAl2Si2O8, which can be considered to be a mixture of calcium, aluminum, and silicon oxides: CaO + Al2O3 + 2SiO2.

If the solar cells are to be amorphous silicon cells made by the standard plasma deposition process, the silicon must be manufactured into silane (SiH4) gas. There are many different process sequences currently used for manufacture of silane. Dopants for a-Si typically are boron (diborane) and phosphorus (phosphine). The boron would have to be imported; this is also a small component. It also may be possible to dope the material with aluminum. Current technology amorphous silicon cells use indium-tin oxide, tin oxide, or cadmium sulfide for a transparent conductive surface layer.


http://thefutureofthings.com/news/7557/ … ction.html

Conventional CIGS solar cells are manufactured through a vacuum evaporation technique called co-evaporation. This process is not only time consuming, but comes at high costs. The process starts with the active elements of copper, indium, gallium and selenide heated and layered on a surface in a vacuum environment. The challenge in producing CIGS cells lies within this uniform composition of materials on a large scale using a vacuum.

Yang’s team completely eliminates the troublesome vacuum evaporation step. Their primary material, which consists of copper, indium and diselenide, can be easily applied into solar cells in three steps - dissolved into a liquid, applied and baked. The liquid consists of a hydrazine solvent, which is used to dissolve copper sulphide and indium selenide to create the constituents for the copper-indium-diselenide material. The absorbent layer of a solar cell would only be the CIGS material, which the researchers have created in solution form and which can be directly painted onto a surface of any size and baked.


http://newsroom.ucla.edu/portal/ucla/uc … 95100.aspx
other thin-film technologies, such as Cadmium Telluride (CdTe)


http://cen.acs.org/articles/89/web/2011 … brush.html

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#33 2011-12-25 14:04:17

RobertDyck
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From: Winnipeg, Canada
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Posts: 7,782
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Re: Developing the cis-Lunar economy and infrastructure

Terraformer wrote:

We know there are sheets of ice in polar craters which are at least 2m thick.

Are you talking about Mars or the Moon? Mars has a north polar ice cap we can see, and the ground penetrating radar on Mars Express found the south pole has an ice cap 3.7km thick! And it's so pure it can't be called permafrost, it's a polar ice cap, just covered in a skiff of dirt.

Water on the Moon has been a question for a very long time. Ground radar found dark patches at the Lunar poles that might be ice at the bottoms of craters. The theory was comets or carbonaceous chondrite asteroids would deliver ice, clay, tar, and other hydrated minerals. Water exposed to sunlight on the Moon would boil of, and that water vapour would slowly escape into space. However, ice at the bottom of a polar crater that never ever gets touched by sunlight might stay. In fact, water vapour from illuminated areas would move around the Moon until it achieves escape velocity, boiling during the 2-week "day" and freezing during the 2-week "night". If any vapour found its way to the bottom of a polar crater it would be captured in a cold trap.

Lunar Prospector had a neutron and gamma ray spectrometer specifically to look for this. The high speed neutron spectrometer would detect large chunks of ice, it found nothing. This doesn't mean there is no ice, it means if there is ice then it's the size of a grain of salt or smaller. The epithermal neutron spectrometer detected hydrogen, but that doesn't say what form it's in. It could be ice, clay, tar, or other hydrated minerals. Concentration was one cup over the area the size of a football field. Some scientists did not want to accept this, but that was the most concentrated spot they found.

Then NASA sent LCROSS. Its spent upper stage impacted the crater with the highest concentration of water that Lunar Prospector found. The probe followed, and measured debris thrown up by the impact. LCROSS detected 100kg of water in a total of 30 million kg of debris. That's a concentration of 3 parts per million. The instruments on Lunar Prospector could only detect soil contents 1 metre deep, but the impact of LCROSS dug several metres deep. And this concentration of 3 ppm was the most concentrated spot on the Moon.

Conclusion: there isn't any water on the Moon. Not any worth harvesting.

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#34 2011-12-25 14:23:23

RobertDyck
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Re: Developing the cis-Lunar economy and infrastructure

If you want ISPP on the Moon, then give up on hydrogen, carbon, or any hydrocarbon. There isn't any of those there. But in the late 1980s John Wickman came up with "Lunar Soil Propellant". He noticed solid rockets are based on aluminum powder and something that releases oxygen. There are plenty of aluminum oxide minerals in Lunar soil, so how can we use that? His idea was to smelt aluminum using the same techniques we use here on Earth. There isn't any bauxite on the Moon, but there is anorthite and bytownite. Sweden is currently harvesting those minerals at aluminum ore. The final stage of smelting aluminum is electrolysis of aluminum oxide, which releases a lot of oxygen. So he proposed using aluminum powder and liquid oxygen.

He actually built a proof-of-concept rocket engine for NASA. He tried a few combinations:

  • powdered aluminum mixed with liquid oxygen, as a mono-propellant. This worked.

  • powdered magnesium mixed with liquid oxygen. This is shock sensitive, if the fuel tank gets a good knock it will explode.

  • bi-propellant: powdered aluminum blown into the combustion chamber with compressed nitrogen gas, and a separate tank of liquid oxygen. This also worked, but the Moon doesn't have any nitrogen.

  • jet engine for Mars: powdered magnesium as jet engine fuel, with CO2 atmosphere. It worked, but requires Mars atmosphere.

The bi-propellant got my interest. His tests showed Al/LOX monopropellant is not shock sensitive, and combustion did not blow back into the fuel tank so it didn't explode. But bi-propellant is safer. Robert Zubrin's idea for ISPP on Mars was to bring a little LH2 from Earth. Learning from this, why don't we bring a little LN2 from Earth to the Moon?

His website is here: http://www.wickmanspacecraft.com/lsp.html

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#35 2011-12-25 22:02:12

JoshNH4H
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From: Pullman, WA
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Re: Developing the cis-Lunar economy and infrastructure

RobertDyck- What you say about lunar water makes a lot of sense given the evidence as you present it.  I'm just wondering if you have any scientist on record saying a similar thing, because I heard a lot of people that were very excited about the amount of water on the Moon.  I heard many who were talking about sheets of ice in the lunar craters.  This website indicates that ice concentrations vary between 6% and 100%, of course varying based on location.

I like the idea of a lunar soil propellant, and I am familiar with it (insofar as I've read all of wickman's page several times, do you have any more information on it?), but I believe that the Isp will be less than impressive, and this does matter when you have to design interplanetary rockets around a lower Isp.


-Josh

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#36 2011-12-26 12:11:56

Mark Friedenbach
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From: Mountain View, CA
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Posts: 325

Re: Developing the cis-Lunar economy and infrastructure

We know pretty with confidence that there are large, primarily H2O by weight ice deposits in the north polar region of the moon. Enough to fill one of the great lakes. I'm not at work so I can't pull up the paper citations, but these are pretty recent results.

LCROSS chose to go to the south pole, and regardless chose a crater that we knew less about in hope of discovering things entirely new.

Last edited by Mark Friedenbach (2011-12-26 12:13:04)

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#37 2011-12-26 23:50:37

JoshNH4H
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From: Pullman, WA
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Re: Developing the cis-Lunar economy and infrastructure

Mark-

That was my understanding of the recent results, as well.  There is water on the Moon, and more than enough to use as rocket fuel.  Carbon is still considered to be very questionable, though, right?


-Josh

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#38 2011-12-27 01:25:34

Mark Friedenbach
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From: Mountain View, CA
Registered: 2003-01-31
Posts: 325

Re: Developing the cis-Lunar economy and infrastructure

IIRC various carbon-containing compounds exist on the south pole in ppm quantities (an extractable byproduct if you are going after something more abundant in the soil anyway, or if you're careful about recycling in how you use it so demand is low). This all of course from the LCROSS data.. but again I'm not at my desk so don't quote me.

It is entirely likely that the northern pole is filled with of volatiles of all kinds though. A methane-ice/regolith mixture is entirely possible, as far as I know, but we just don't have any data either way yet. Water ice is fairly unique in our ability to remote-sense it in permanently shadowed craters.

EDIT: BTW, even in the south pole things aren't so grim. LCROSS detected single-digit percentage water overall, and nearly pure ice in some layers/regions of the impact site.

Last edited by Mark Friedenbach (2011-12-27 01:29:51)

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#39 2011-12-27 05:22:16

Terraformer
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From: Ceres
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Re: Developing the cis-Lunar economy and infrastructure

If we have to, we can always use Silane... Isp around 300, but at least it's easier to store, and stretches the fuel supply.

We could really do with boots on the ground to check, though. Hey, perhaps a Lunar sortie could be pulled off when FH becomes operational?


"I'm gonna die surrounded by the biggest idiots in the galaxy." - If this forum was a Mars Colony

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#40 2011-12-27 10:20:45

JoshNH4H
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From: Pullman, WA
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Posts: 2,538
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Re: Developing the cis-Lunar economy and infrastructure

Mark- That sounds pretty much in-line with what I've heard in the past about current thinking on lunar volatiles.  If we're talking about rocket fuels, ppm of carbon is not enough.  That said, if we have large amounts of methane at the poles we don't even really need the water, seeing a you can get the oxygen for less energy by electrolyzing iron oxide.  This has been demonstrated a few times and they are trying to develop it commercially.  It also produces a lot of iron, which uys great for growing the colony, especially if you have methane to get carbon for steel.

Terraformer- I'm not aware of any test-goes of an engine running silane.  This makes me question very strongly the math of the person who came up with that number.


-Josh

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#41 2011-12-29 14:25:36

GW Johnson
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From: McGregor, Texas USA
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Re: Developing the cis-Lunar economy and infrastructure

Too bad we never really explored the moon during Apollo.  One landing per trip,  unable to dig deeper than half a meter with a little manual core sampler?  That didn't answer the two real questions (1) what all is there?  and (2) where exactly is it?  No two sites are alike,  not here,  not there,  not anywhere. 

It's time to go back with some men and robots together,  and visit maybe a dozen sites on the moon in a single trip.  That using landers,  based from orbit.  Stay for a while at each site,  and dig / drill deep.  Find out where the water really is,  how pure it is,  and how concentrated.  Are there any unexpected organics?  Are there any metals readily available? 

I think until you know the answers to those two deceptively-simple exploration questions,  you can't do any effective experiments toward in-situ resource utilization,  because you don't know what resources are there,  or where they are at your site.  And until you do some experimental bases doing ISRU,  colonies make no sense at all. 

I do think we need to return to the moon.  But to just repeat Apollo flag-and-footprints is just plain stupid.  We need to stop thinking like Apollo.  The worst mistake of all was one landing,  one mission.  Hindsight,  yes,  but it's past time to learn from those mistakes. 

GW

PS - I'd be careful of polymer materials exposed to sunlight on the moon.  UV destroys them,  so does radiation.  Both are quite worse there.  Solar PV is often proposed as polymerics replacing crystalline.  I don't even think that's a good idea here.


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#42 2011-12-30 07:51:04

Glandu
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From: France
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Re: Developing the cis-Lunar economy and infrastructure

+1 with GW on the last point. Though it depends on the polymer, resistant polymers are usually no the kind that are useful for other purposes. Most polymers are heat-vulnerable, cold-vulnerable, light-vulnerable. For radiations I'm less sure, but the very nature of polymers chemical structure makes me think most polymers are radiation-vulnerable too.


[i]"I promise not to exclude from consideration any idea based on its source, but to consider ideas across schools and heritages in order to find the ones that best suit the current situation."[/i] (Alistair Cockburn, Oath of Non-Allegiance)

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#43 2011-12-30 23:03:38

JoshNH4H
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Re: Developing the cis-Lunar economy and infrastructure

Another point on ISRU solar panels, though I hope I'm not belaboring it too much:  While 10% would give a lot of margin if you're talking about a PV panel made in a factory on Earth in the modern day, if all you have to work with is Silicon or a relatively basic plant for solar panel synthesis, this is highly optimistic.  I think that you would be talking about 5% efficient, at a maximum, with a small plant, even if you're bringing in dopants from Earth.  At that efficiency, you'd be just as well off using thermocouples with concentrated sunlight.

Then, you could also use concentrated solar power, using water as a working fluid.  It's not too complicated, isn't damaged by radiation, and works just fine on Earth.


-Josh

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#44 2011-12-31 07:21:58

Grypd
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From: Scotland, Europe
Registered: 2004-06-07
Posts: 1,879

Re: Developing the cis-Lunar economy and infrastructure

The Solar panel of choice on the Moon will be the silicon based versions.

The simplest design is the String ribbon silicon method. It has an efficiency of 13 to 14% but has managed to be made up to 18.3% in laboratory conditions. Still the efficiency of 13 to 14% is more than we need. The problem in the manufacture is its energy intensive.

Much more efficient cells are made by the use of Mono-crystalline silicon and the efficiency is about 17% but these cells are on a pure grown silicon crystal in which doping agents are emplaced. Much of these doping agents are found on the Moon but we may need to supply some of it for the first stages of lunar industrialisation. This though will not require too much mass sent to the Moon.

These make for very radiation protected cells but the more important principle is that we automate the process and that we can keep building more and more energy production. But the other point is that all items we have on the Moon will suffer degradation from the enviroment with these cells we can replace easily damage.


Chan eil mi aig a bheil ùidh ann an gleidheadh an status quo; Tha mi airson cur às e.

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#45 2011-12-31 16:14:07

Hop
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From: Ajo
Registered: 2004-04-19
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Re: Developing the cis-Lunar economy and infrastructure

RobertDyck wrote:

LCROSS detected 100kg of water in a total of 30 million kg of debris. That's a concentration of 3 parts per million. The instruments on Lunar Prospector could only detect soil contents 1 metre deep, but the impact of LCROSS dug several metres deep. And this concentration of 3 ppm was the most concentrated spot on the Moon.

Conclusion: there isn't any water on the Moon. Not any worth harvesting.

The October 2010 issue of Science had some articles on the LCROSS ejecta. Here are the published results:

N    6.6000%
CO    5.7000%
H2O    5.5000%
Zn    3.1000%
V    2.4000%
Ca    1.6000%
Au    1.6000%
Mn    1.3000%
Hg    1.2000%
Co    1.0000%
H2S    0.9213%
Fe    0.5000%
Mg    0.4000%
NH3    0.3317%
Cl    0.2000%
SO2    0.1755%
C2H4    0.1716%
CO2    0.1194%
C    0.0900%
Sc    0.0900%
CH3OH    0.0853%
S     0.0600%
B    0.0400%
P    0.0400%
CH4    0.0366%
O    0.0200%
Si    0.0200%
As    0.0200%
Al    0.0090%
OH    0.0017%

Lots more water than you indicate. Also a lot of carbon and nitrogen compounds.

But LCROSS isn't the most exciting find. The elevated CPR of India's Chandrayaan-1 lunar orbiter seems to indicate sheets of ice at least two meters thick. See: NASA Radar Finds Ice Deposits at Moon's North Pole.

Last edited by Hop (2011-12-31 16:14:51)


Hop's [url=http://www.amazon.com/Conic-Sections-Celestial-Mechanics-Coloring/dp/1936037106]Orbital Mechanics Coloring Book[/url] - For kids from kindergarten to college.

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#46 2011-12-31 18:58:50

Terraformer
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From: Ceres
Registered: 2007-08-27
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Re: Developing the cis-Lunar economy and infrastructure

What strikes me most about that list is the 1.6 percent of Gold and the 1 percent of Cobalt. Lot's of economic potential there, and possibly a byproduct of normal volatile production...

There seems to be enough CO to produce Methane, so storage is a lot easier. If we can work out viable solar thermal rockets (nuclear is politically out), we can get Ammnia to use in them, offering upwards of 600s Isp. Not high enough thrust probably to use in flyby's, but for other missions (Venus?)...


"I'm gonna die surrounded by the biggest idiots in the galaxy." - If this forum was a Mars Colony

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#47 2012-01-01 10:16:41

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
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Re: Developing the cis-Lunar economy and infrastructure

Looking at the LCROSS list,  I see potential there.  5.5% water is intriguing,  to say the least.  Carbon compounds seem to be in short supply.  There's a bunch of minerals and metals that could be useful,  perhaps in minable percentages. 

It would be really slick to set up some sort of fuel processing station using the water to create hydrogen and oxygen,  and carbon shipped in from somewhere else (not Earth) to create methane.  This thing could be mostly-automated,  as might some sort of mineral/metal mining rig.  Vanadium in particular is necessary for high-alloy steel. 

Don't count nuclear stuff out "politically".  That crap will have to be resolved,  because nuclear power for electricity and propulsion will be necessary to do anything significant beyond Mars.  Those destinations are just too faraway not to use it,  and too interesting not to go.  Reducing Isp potentials and frontal thrust densities is not the way to get there,  excepting extreme-slowboat trajectories entirely unsuitable for human travel. 

I think the moon is a really convenient,  safe place to the the nuclear propulsion work that would take us way beyond where we were with NERVA 4 decades ago.  And it did everything but actually get flown.  We know it works,  better than chemical rockets.  I think it would power a dandy reusable single-stage "landing boat" for Mars.  Something tough as an old boot,  capable of landing in rough (interesting) terrains,  and flyable hundreds if not thousands of times. 

All these ideas,  plus doing real astronomical science,  are pretty good arguments for going back to the moon.  Can't pitch it as "exploration" because we've already been there,  but we could pitch it as a piece of the larger effort support exploration of Mars and those other faraway destinations.  That's how the Dutch East India company justified planting its initial settlements in the Indonesia region.  Good argument then,  and now. 

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#48 2012-01-01 16:21:30

Terraformer
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From: Ceres
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Posts: 3,800
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Re: Developing the cis-Lunar economy and infrastructure

To be perfectly honest, I don't mind waiting until we have mature Lunar, Venus, and Mars colonies before mounting our first manned missions to Jupiter and Saturn. No need to hurry, the Martians will colonise in due time. Besides, just how low can we get the trip time using only chemical and solar thermal - if it's under a year to Jupiter, we've no need for nuclear to colonise.

I wouldn't say Carbon is in short supply - look how much Carbon Monoxide there is! We'll need to mine some Iron Oxide, though, to get the additional Oxygen required. But that just gives us Iron for building with...


"I'm gonna die surrounded by the biggest idiots in the galaxy." - If this forum was a Mars Colony

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#49 2012-01-01 16:40:56

Adaptation
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Registered: 2011-11-22
Posts: 42

Re: Developing the cis-Lunar economy and infrastructure

Just a few points.

There's gold in them craters, enough to fund allot of fun and all the extra Hg will make refining the gold blissfully simple. 

Linear motors make a real nice low tech low cost alternative to rail guns. 

Original imported solar arrays could be retrofitted onto insitu concentratiors.  Production multijunction cells are already more than 40% efficient, and both silicon and multijunction cells are even more efficient under concentrated light so-long as they are kept cool.  Composite solar systems (concentrated pv coupled with heat recovery) are claiming over 70% efficiency.

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#50 2012-01-02 02:42:43

JonClarke
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From: Canberra, Australia
Registered: 2005-07-08
Posts: 173

Re: Developing the cis-Lunar economy and infrastructure

I don't believe there is significant gold or mercury in lunar craters.  Not without good evidence.

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