Author Topic: Critical Lunar Industrial Infrastructure  (Read 25485 times)

Offline sandrot

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Re: Critical Lunar Industrial Infrastructure
« Reply #20 on: 03/12/2008 03:35 PM »
If you want to use regolith for ISRU (I really liked the discovery that regolith may be vitrified applying a moderate dose of microwaves), you need to see how much regolith you have at the poles. There is infact a milder contribution to regolith formation due to thermal excursion.
"Paper planes do fly much better than paper spacecrafts."

Offline wingod

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Re: Critical Lunar Industrial Infrastructure
« Reply #21 on: 03/12/2008 03:39 PM »
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sandrot - 11/3/2008  11:37 PM

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wingod - 11/3/2008  7:14 PM

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sandrot - 11/3/2008  2:31 PM

Why do you start with solar power? That might be your first show stopper.

Solar power on the Moon (assuming a lunar polar location where there is 100% sunlight) is actually a no brainer.



Polar terrain is more rugged, not so easy to go around. Do you assume you land and use minerals in the terrain just around you?

Polar location assumes vertically mounted solar panels. And you need to perch them on the rim of a  properly exposed crater (peak of eternal light).

The south pole is much more rugged than the north and that is why I favor that location.  There are four sites there that are not in a bad area for travel down to the Mare Frigioris.  I have mapped out a couple of routes already.

Yep on the solar arrays and there are four locations where this is the case and in the north they are on easier terrain than in the south.



Offline wingod

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Re: Critical Lunar Industrial Infrastructure
« Reply #22 on: 03/12/2008 03:42 PM »
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sandrot - 11/3/2008  11:47 PM

To complete my previous post...

I don't see rovers going around scouting for minerals on solar power at the poles.

It is much better to get power from a nuclear reactor of some kind (see also related threads in Advanced Concepts). At least we can go further away from the poles. And, if you're not at the poles for the water, what's the point of being there? Sun tan? :cool:

Don't have to.  With adequate power, the highlands basalts make good feedstocks, which has always been assumed.

Power is the reason to be there, power without having to spend billions of dollars on developing nuclear power.  That has always been a show stopper before.  There are several areas that are in eternal sunlight and with emplacing a megwatt or two of power and with solar thermal, you have the basis for lunar industrialization.

Offline wingod

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RE: Critical Lunar Industrial Infrastructure
« Reply #23 on: 03/12/2008 03:48 PM »
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alexterrell - 12/3/2008  4:05 AM

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wingod - 11/3/2008  6:27 PM

Unless Spudis is right and there is a LOT of water, I do not think that we want to count on it.  Also, mining water at 35 degrees kelvin in the dark is a lot harder than anyone is currently thinking.  I am willing to forego it entirely, at least in the beginning.

Also, I do agree that robotics and regolith moving machinery is key in the early days as well.

The thermal environment at the lunar poles is benign enough to not worry too much about it.  

I do agree with a hab module, partially or fully buried.  However, I don't want to send up a lot of stuff that can be fabricated on the Moon, such as workshops.  The ISRU system must be able to create metals and with the metals we can make structures.  Micrometeorites are not a big deal for less than one year stays.

You are NOT going to deliver anywhere near a GW on a single launch or even a megawatt.

Solar collectors on buildings that are not sun pointing are useless in the polar regions due to the angles involved.  I do agree with brick sintering as well as a means to sinter a road as developed by Dr. Larry Taylor and his cohorts.

The next building has to be able to have an atmosphere to grow food as well.

Just some thoughts, good thinking everyone so far.



Clearly, identifying how much water there is should be the focus of exploration from ASAP till 2015. As for mining it: Light is not an issue if electricity is available. The diggers need to be designed to work at 30K. The tents are designed to house reusable landers whilst not being used. Tent's don't weigh much but help with thermal equilibrium. They can also pop out of a bag.

As for the workshop, you have a chicken and egg dilemma. I don't think you can build in-situ a workshop without good working machinery. You can't have that without a workshop. Hence a small workshop, with inflatable working areas to start.

There's no single ISRU system. You start with mining, and end up with metal fabrication. Building the steps on the way will take a long time.

Solar cells can be positioned in space at 10 tons / MW. The only problem is unpacking them. I'd look at inflatable tubes for deployment - the bouncy castle approach.

Solar collectors on buildings are worthwhile if you cover them with thin film solar material. Even if their utilisation is 20% it makes sense. At the poles, it's the walls, not the roofs you cover.

Flat plate iron requires only a sintered regolith mold and a lifting device.  A lot of building can be built that way.

Solar collectors on buildings makes some sense but not as much as you think.  The problem is that you don't want the buildings in the permanent sunlit area as that is the most valuable property for power production.  You could do it in such a way as to have them mounted on the top of the structures but they still have to point at the sun.  At a loss factor of (cos 85) the output for flat plat solar is essentially zero.

Solar cells are only one part of a power distribution system.  A 250 kW inverter weighs 2 tons and if you go all DC you have a lot of problems with power losses.  An AC system makes a lot more sense.



Offline wingod

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Re: Critical Lunar Industrial Infrastructure
« Reply #24 on: 03/12/2008 03:49 PM »
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Kaputnik - 12/3/2008  6:23 AM

I'm just trying to picture life at the lunar poles. The sun will always be very low, about 90-degrees. That means that any building, hab, rover, etc, will cast a shadow that goes on forever, presumably. I'd love to hear the arguments that will happen when someone parks their rover in the wrong place!
The other thing that comes to mind is that the sun will always be in your eyes. I live quite far north (but nowhere near 90-degrees!) and at this time of year the sun is right in my eyes on the way home from work. It's bloomin' annoying!
But I'm sure NASA have thought of all of this.

The thermal environment at the poles is a LOT better than at the equator but the shadows will be interesting!



Offline wingod

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RE: Critical Lunar Industrial Infrastructure
« Reply #25 on: 03/12/2008 03:51 PM »
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alexterrell - 12/3/2008  10:41 AM

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sandrot - 12/3/2008  8:46 AM

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alexterrell - 12/3/2008  5:05 AM

[...]

Solar cells can be positioned in space at 10 tons / MW. The only problem is unpacking them. I'd look at inflatable tubes for deployment - the bouncy castle approach.

[...]


For the ISS we are at 15 tons / 65kW. Please recheck your numbers.

ISS (4.3 W/kg) is very low indeed. The figure I'm looking for is 10t/MW = 100 W/kg.

http://ieeexplore.ieee.org/Xplore/login.jsp?url=/iel5/9136/28987/01305402.pdf = 250W / kg.

This 2002 article from ESa expects 400W / kg. http://www.esa.int/esaCP/ESA2CKS162D_FeatureWeek_2.html

The POWOW concept http://www.aec-able.com/corpinfo/Resources/IAF%202000POWOW.pdf is now a few years old and gives 449KW from a 2488kg panel, or about 200W/kg

http://www.entechsolar.com/STAIF04.pdf gives a state of play. Figure 11 shows we're already above 100W/kg.

These papers were all done before nano solar.

And somewhere, but I can't find the link, there's an ESA photograph of a ~20m wide solar sheet, which looks as thin as foil.

Not sure about the weight of the lasers and ion engine. And as I said, the challenge is unpacking it.



You are forgetting the rest of the things that make a power system work.  The inverters alone are very heavy and require radiators themselves.

As for the solar power, maybe the Entech system makes sense, maybe not.  I tend to favor flat panel systems due to their ease of construction and longevity.



Offline wingod

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Re: Critical Lunar Industrial Infrastructure
« Reply #26 on: 03/12/2008 03:53 PM »
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sandrot - 12/3/2008  11:29 AM

No, the challenge is to make it stand. You're talking about a football field worth of solar panels vertically installed on the rim of a crater, with a SARJ equivalent to follow the 28 days lunar revolution.

You also need to see how thin film behave in space. The ESA article expresses interest in thin film but announces projects to test other kinds of solar cells.

Solar is not viable for rovers operating at the poles as humorously expressed by Kaputnik.


Agreed.  I would think that regenerative fuel cells would be the ticket for rovers and other machinery.



Offline wingod

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Re: Critical Lunar Industrial Infrastructure
« Reply #27 on: 03/12/2008 03:56 PM »
Again

Thanks for a lot of good replies, I just am trying to iterate here and give some of the thoughts that we have put into the effort.



Offline mwfair

Re: Critical Lunar Industrial Infrastructure
« Reply #28 on: 03/12/2008 04:10 PM »
The comment about flat plate seems valuable, relative to the notion of making iron beams etc to build structures.  Simple design is best, and igloos seem like the simplest of all buildings.  For this reason, flat plates, and bricks seem like the best starting point.  
Seems to me that the main resources to be used on the lunar poles, in order of both availability and utility, are time, mass, and sunlight.  Assuming the initial buildup process is autonomous or RC, we can take months just to build one building.  Time makes polar solar easier, since the 35% efficiency problem relative to  the motion of the sun doesn't matter, just take a 20 day siesta!  But the mass available on the moon is the sweetest thing, given enough time.  Who cares about structural efficiency, just make bricks or plate and pile them up.  If it takes months, so what?  Forget large batteries, these store energy in chemical form, but this requires mass.  Ignore the chemistry and build flywheels with bricks.  Seems to me a 3m diameter merry go round can store 1MWhr, enough at least to stay alive during said siesta!
Mike Fair

Offline sandrot

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Re: Critical Lunar Industrial Infrastructure
« Reply #29 on: 03/12/2008 04:25 PM »
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wingod - 12/3/2008  12:39 PM

[...]

Yep on the solar arrays and there are four locations where this is the case and in the north they are on easier terrain than in the south.


My point is: with solar we return to the moon just to be stuck in 4 places (I'm sure there are many more much interesting), and we have anyway to develop other technologies to move stuff around (rovers).

There can be more efficient approaches.

Regarding mobility, let's keep an eye on MSL.

Also, it is interesting to follow the DARPA sponsored Darpa Grand Challenge
  http://en.wikipedia.org/wiki/DARPA_Grand_Challenge

When I read one of the MER's has moved 40mm in one sol, I'm less than enthusiastic, thinking of what still needs to be done for the ISRU scout rovers.
"Paper planes do fly much better than paper spacecrafts."

Offline sandrot

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Re: Critical Lunar Industrial Infrastructure
« Reply #30 on: 03/12/2008 04:28 PM »
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mwfair - 12/3/2008  1:10 PM

[...]

Seems to me a 3m diameter merry go round can store 1MWhr, enough at least to stay alive during said siesta!

Not to turn you off, but building a balanced flywheel out of locally produced bricks seems a challenge to me.
"Paper planes do fly much better than paper spacecrafts."

Offline sandrot

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Re: Critical Lunar Industrial Infrastructure
« Reply #31 on: 03/12/2008 04:41 PM »
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mwfair - 12/3/2008  1:10 PM

The comment about flat plate seems valuable, relative to the notion of making iron beams etc to build structures.  Simple design is best, and igloos seem like the simplest of all buildings.  For this reason, flat plates, and bricks seem like the best starting point.  

[..]


I agree wrt the bricks, if we can make them microwaving regolith, which by all accounts seems to be a process not so power hungry.

Flat plate may be tricky to achieve, you need to have machinery as wide as the plate you want to build. And maybe iron is not the 1st choice (because of its melting point for once).

For structural elements I would look more into aluminum, as it is more pliable. Aluminum could be produced and stored in rolls. From the rolls you can automatically assemble trusses, as proven during an early STS mission.
"Paper planes do fly much better than paper spacecrafts."

Offline mwfair

Re: Critical Lunar Industrial Infrastructure
« Reply #32 on: 03/12/2008 04:43 PM »
Assume a cylindrical building, 20k ft^2 = 160 ft diameter.  Lets say 10 ft tall  = 5000 ft^2 walls.  35% efficient wrt sun-in-view gives 1500 sq ft solar panel, which produces 6kW at 4W/ft^2.  Wow, not much.  But time is on our side, we just need enough to run a conveyor belt, an arm, and a laser sinter device.
Mike Fair

Offline wingod

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Re: Critical Lunar Industrial Infrastructure
« Reply #33 on: 03/12/2008 05:51 PM »
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mwfair - 12/3/2008  12:10 PM

The comment about flat plate seems valuable, relative to the notion of making iron beams etc to build structures.  Simple design is best, and igloos seem like the simplest of all buildings.  For this reason, flat plates, and bricks seem like the best starting point.  
Seems to me that the main resources to be used on the lunar poles, in order of both availability and utility, are time, mass, and sunlight.  Assuming the initial buildup process is autonomous or RC, we can take months just to build one building.  Time makes polar solar easier, since the 35% efficiency problem relative to  the motion of the sun doesn't matter, just take a 20 day siesta!  But the mass available on the moon is the sweetest thing, given enough time.  Who cares about structural efficiency, just make bricks or plate and pile them up.  If it takes months, so what?  Forget large batteries, these store energy in chemical form, but this requires mass.  Ignore the chemistry and build flywheels with bricks.  Seems to me a 3m diameter merry go round can store 1MWhr, enough at least to stay alive during said siesta!

I really like the idea about the flywheel.  However, I don't understand the 20 day siesta as the permanent lighted areas mean zero downtime.  With humans on the Earth to operate equipment during the human on the Moon off hours the overall efficiency of the industrial system is dramatically increased, something impossible for Mars.



Offline wingod

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Re: Critical Lunar Industrial Infrastructure
« Reply #34 on: 03/12/2008 05:57 PM »
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sandrot - 12/3/2008  12:25 PM

Quote
wingod - 12/3/2008  12:39 PM

[...]

Yep on the solar arrays and there are four locations where this is the case and in the north they are on easier terrain than in the south.


My point is: with solar we return to the moon just to be stuck in 4 places (I'm sure there are many more much interesting), and we have anyway to develop other technologies to move stuff around (rovers).

There can be more efficient approaches.

Regarding mobility, let's keep an eye on MSL.

Also, it is interesting to follow the DARPA sponsored Darpa Grand Challenge
  http://en.wikipedia.org/wiki/DARPA_Grand_Challenge

When I read one of the MER's has moved 40mm in one sol, I'm less than enthusiastic, thinking of what still needs to be done for the ISRU scout rovers.

Please take this in the spirit in which it is offered but I don't give a flying flip about more interesting places, the point is economic development, which completely changes how lunar operations play out.  With that power becomes the principle consideration and then a location that allows for mobility within that constraint, which to me, means the lunar north pole.

Rovers are trivial in the sense that we know how to do them and much better ones than something like MSL.  I really like the old LOTRAN from Eagle Engineering.  I am actually working with NASA Langely with their crane effort that is being built now for testing this year on moving regolith around.

The Russian rovers moved tens of kilometers per sol when they were on the Moon.

Offline wingod

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Re: Critical Lunar Industrial Infrastructure
« Reply #35 on: 03/12/2008 06:00 PM »
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sandrot - 12/3/2008  12:41 PM

Quote
mwfair - 12/3/2008  1:10 PM

The comment about flat plate seems valuable, relative to the notion of making iron beams etc to build structures.  Simple design is best, and igloos seem like the simplest of all buildings.  For this reason, flat plates, and bricks seem like the best starting point.  

[..]


I agree wrt the bricks, if we can make them microwaving regolith, which by all accounts seems to be a process not so power hungry.

Flat plate may be tricky to achieve, you need to have machinery as wide as the plate you want to build. And maybe iron is not the 1st choice (because of its melting point for once).

For structural elements I would look more into aluminum, as it is more pliable. Aluminum could be produced and stored in rolls. From the rolls you can automatically assemble trusses, as proven during an early STS mission.

While I like Aluminum the problem is that it takes several hundred degrees higher temperature to get it out of solution with oxygen than Iron.  Also up to 1% of any regolith sample has Ni-Fe from asteroid impacts and that makes a really simple feedstock for the flat plate.  You don't need machinery, just a sintered mold to pour the liquid iron into.



Offline wingod

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Re: Critical Lunar Industrial Infrastructure
« Reply #36 on: 03/12/2008 06:02 PM »
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mwfair - 12/3/2008  12:43 PM

Assume a cylindrical building, 20k ft^2 = 160 ft diameter.  Lets say 10 ft tall  = 5000 ft^2 walls.  35% efficient wrt sun-in-view gives 1500 sq ft solar panel, which produces 6kW at 4W/ft^2.  Wow, not much.  But time is on our side, we just need enough to run a conveyor belt, an arm, and a laser sinter device.

That same square footage, turned toward the sun will product well over 100 kW.  That is the difference.



Offline sandrot

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Re: Critical Lunar Industrial Infrastructure
« Reply #37 on: 03/12/2008 06:22 PM »
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wingod - 12/3/2008  3:00 PM

[...]

While I like Aluminum the problem is that it takes several hundred degrees higher temperature to get it out of solution with oxygen than Iron.  Also up to 1% of any regolith sample has Ni-Fe from asteroid impacts and that makes a really simple feedstock for the flat plate.  You don't need machinery, just a sintered mold to pour the liquid iron into.

Here peaks of eternal light come handy... solar furnace?
"Paper planes do fly much better than paper spacecrafts."

Offline mwfair

Re: Critical Lunar Industrial Infrastructure
« Reply #38 on: 03/12/2008 06:28 PM »
Regarding rotating the solar panel to face the sun, I'd like to see an estimate of the mass ratio between turning mechanisms and the panel itself.  I bet it is at least 1:1.  If the superstructure available is ISRU, like the side of a brick wall, then the panel mass goes down.  But the mass of the motors, gears, bearings, and especially the cantilevered structure climbs fast, maybe with the square of the area.  So would you rather make one panel that rotates, or two that are fixed.  I'll take the two fixed.  
Lunar sol is almost 30 days.  Circumference of a circle is pi*d, but only the diameter sees the sun at any moment, so the geometrical efficiency of a circular building is 1/pi, a square building gets 25% sometimes, 35% max.  The siesta comment didn't really make sense, just an illustration that its okay if solar efficiency is low if time and mass are on your side.  If you have a small payload from earth, I suggest 1 fixed solar panel with a siesta, rather than either bringing a rotational base or second (or 3rd) panel.
I always prefer intrinsic numbers rather than extrinsic, its easier to show the whole system is viable.  If you insist on a certain total power number, the mass budget quickly climbs out of reason.  Better first to show a complete system, then scale it up.  Even still, I realize there is a minimum feasible power and mass requirement, no matter how long the timescale or how high-tech the ISRU.
Mike Fair

Offline sandrot

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Re: Critical Lunar Industrial Infrastructure
« Reply #39 on: 03/12/2008 06:57 PM »
Quote
wingod - 12/3/2008  2:57 PM

[...]

The Russian rovers moved tens of kilometers per sol when they were on the Moon.

Here what comes into play is the ability to move autonomously.

I see ISRU working better if we can deploy a "robotic community" where some stationary heavy machinery is fed/unloaded by rovers.

Although we can imagine robots accomplishing very complex tasks (imagine what they could do if they were just as intelligent as an ant or a termite), I believe they would work very well in manufacturing and storing elements for future human use.
"Paper planes do fly much better than paper spacecrafts."

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