Developing the cis-Lunar economy and infrastructure

JoshNH4H · 2012-01-19 19:57:38

Hop wrote:

JoshNH4H wrote:
I think the primary point that we're looking at here is that the concentrations of metals allegedly "discovered" by the LCROSS
Josh, the alleged 1.6% gold in the LCROSS ejecta is only one of several branches this thread has split into.

I was under the impression that the discussion of meteorites was a generalization of the discussion of the potential ores to be found in craters at the lunar poles, by way of questions regarding the accuracy of LCROSS's spectrometer in identifying metallic elements. Obviously this is a separate debate from communications with Earth, and that is one on which I can't much comment. Seeing as most meteorites which could form any ores are made of Iron, a fairly common element, isn't the question of whether meteorites can survive impact with the Moon moot?

Mark Friedenbach · 2012-01-19 20:39:28

Terraformer wrote:

Well, actually, what I was hoping to do was to work out what the minimum we'd need to set up Lunar fuel production to allow much greater masses to be transported to Luna, and from there, what we'd need to develop a thriving infrastructure...

Which would be a much more productive discussion, I think. Care to lead us down that path?

Terraformer · 2012-01-20 03:23:07

i will, later, after my Maths A-level exam

JoshNH4H · 2012-01-20 13:51:06

I suppose I will, if he's unavailable:

Obviously, the amount of energy needed to produce fuel depends in large part on what kind of fuel you want to produce. If you're looking to produce H2/LOX, it's going to be different from Methlox or equivalent fuels. I believe that methlox will be preferably to H2/LOX if Carbon is available, which it probably will be in the form of methane. However, for the launch from the Moon to Earth I think that ALICE fuel (e.g., a solid mixture of aluminium nanoparticles and ice, Isp ~300 (perhaps)) will be better because solid fuel rockets are simpler than liquid fuel and therefore would not need to be imported to the Moon when they wear out.

If methane is available, one just needs to split water to make oxygen. The stoichiometric ratio of O2 to CH4 is 2:1, meaning that 64 kg of O2 will be needed per kilo of CH4 (This reduces to 4:1). This in turn is equivalent to 4.5 kg of water being split per kg of methane. The delta G of formation of water is -237 kJ/mol. Assuming a 75% efficient electrolysis device, which is definitely reasonable, that's 316 kJ of electrical energy per mole of water split; This means 20 MJ/kg of oxygen, and 16 MJ/kg of fuel. The figures are similar for H2/LOX fuel, though slightly higher per kilo (18MJ/kg). I don't know what kind of production levels Terraformer wants to look at, but it's quite energy intensive to produce this.

On the plus side, the Hydrogen produced could be used to smelt Iron or help in the production of Aluminium (I'm thinking a palladium electrode which is suffused with hydrogen to help reduce the aluminium). I don't know about practicality, but with clever chemistry it might be possible.

Last edited by JoshNH4H (2012-01-20 13:51:31)

Terraformer · 2012-01-20 18:38:11

I believe there's plenty of Carbon Monoxide there (more than CH4 from the list, which no-one seems to be arguing with when it comes to volatiles), which means we're talking about producing Methane. We'll need to extract Oxygen from metal oxides, but that means that we'll have plenty of metal and silicon lying around the base to be used.

As to the required rate of production, that depends on the mass of the transfer vehicles, how often they're going to be used, and how much mass we need to import to both sustain and grow the base. If we're talking about transferring 20 tonnes of mass through a total delta-V of 12km/s every three months, we're going to need approx. 400 tonnes of fuel per quarter, so a production rate of maybe 35 tonnes a week (I don't have my calculator on me, so very approximate estimates). Say we go for twice that, so 10 tonnes a day, allowing us to import extra goodies. We'll be able to operate for maybe 20 hours a day, so we need a production rate of 500kg an hour. Say 20MJ/kg of fuel, meaning we need 10GJ of energy each hour. That works out at under 3MW, so maybe 5 tonnes for the power plant?

JoshNH4H · 2012-01-20 19:01:56

600 W/kg? That seems optimistic to me. Depending what stage of development you're on, 5 tonnes might be the mass you could get away with importing. I can't really say.

If you want to go from CO, the energy costs are going to be significantly higher. You can get CO to disproportionate to C and CO2, but there is an energy cost. On the plus side, it can be thermal energy, which is cheaper. After that, however, you also need to produce Hydrogen to make methane from the carbon. I suppose, if you have sufficient water and CO you can use the Water Gas Shift Reaction, though this will use up Carbon monoxide and water.

Terraformer · 2012-01-21 05:51:56

I thought making it from CO was energetically cheaper? Anyway, we won't really be losing anything by reacting it with water - we need the hydrogen and CO2 anyway. Perhaps with the addition of extra hydrogen we can get the reaction to proceed directly to Methane and Water. Anyway, it seems the reaction of Hydrogen and Carbon Monoxide is strongly exothermic - http://en.wikipedia.org/wiki/Steam_reforming, so we just need to get the Hydrogen. If there's abundant Carbon Monoxide, and we found a use for the CO2, we could make the entire Methane production a net energy gain...

Fuel production is going to be energy intensive - but there's no point going if we're not going to produce fuel. I don't know how much the support for the solar cells is going to mass; it needs to be able to turn to track the sun. I also don't know how much the fuel production and storage equipment is going to mass, though we should be able to store some in the Lander's fuel tanks.

JoshNH4H · 2012-01-22 00:20:53

I suppose you could react the CO on one hand to make C and CO2, and on the other hand with water to make CO2 and H2, then use the H2 to react with the Carbon to make methane. Energy costs would be primarily thermal, and significantly smaller than the energy costs of electrolyzing the water, though nonzero.

It seems like radiation resistant solar panels are heavier than the current state of the art, so I have no idea what you're looking at in terms of mass. I know that you can place the maximum of imported mass at 25 W/kg, which is the specific power of a very buildable nuclear reactor. That likely involves more mass than solar panels in this case, but I can't say by how much.

Terraformer · 2012-01-22 03:49:23

Eh? You need 3 moles of H2 and 1 mole of CO2 to produce 1 mole of Methane. The Water gas shift reaction produces CO2 and H2 in an equimolar ratio so if you produce your Hydrogen that way, you're looking at an excess of CO2. You need to add an extra 3 moles of H2 to get the stochiometry up, giving you 2/3 your required Oxygen in the process.

SpaceNut · 2012-01-22 09:28:06

Mark Friedenbach wrote:

Terraformer wrote:
Well, actually, what I was hoping to do was to work out what the minimum we'd need to set up Lunar fuel production to allow much greater masses to be transported to Luna, and from there, what we'd need to develop a thriving infrastructure...
Which would be a much more productive discussion, I think. Care to lead us down that path?

Lets assume that we are talking ALICE for fuel. That requires some ore collection sstem probably starting early with simple surface dust collection, sent via a transportation system to a refining plant, processed into the cylinder to attach to the rocket that we are using for lunar cargo lofting, but that assumes also a large quatity of water to make the mixture happen.....

A simple fuel to make at first after some ore collection is still a gaseous fuel system which should start with the waste recovery....

Terraformer · 2012-01-22 15:20:52

Well, which ones more energy intensive per km/s delta-V? My guess is ALICE. Methlox is probably the best to use, I'd think.

From the wiki article on steam reforming:

Steam reforming of natural gas or syngas sometimes referred to as steam methane reforming (SMR) is the most common method of producing commercial bulk hydrogen as well as the hydrogen used in the industrial synthesis of ammonia. It is also the least expensive method.[4] At high temperatures (700 – 1100 °C) and in the presence of a metal-based catalyst (nickel), steam reacts with methane to yield carbon monoxide and hydrogen. These two reactions are reversible in nature.
CH4 + H2O → CO + 3 H2
Additional hydrogen can be recovered by a lower-temperature gas-shift reaction with the carbon monoxide produced. The reaction is summarized by:
CO + H2O → CO2 + H2
The first reaction is strongly endothermic (consumes heat), the second reaction is mildly exothermic (produces heat).

So, we need 3 moles of H2 and 1 mole of CO to produce 1 mole of methane. If we're getting the Hydrogen by electrolysing water, we'll be getting 3/4 of the required oxygen as well. Since the reaction we're considering is strongly exothermic, perhaps we could use that extra heat to extract the additional oxygen from the soil, or perhaps the aid the electrolysis?

Mark Friedenbach · 2012-01-22 20:37:05

Silane/LOX is probably easier to do than ALICE, from a materials processing standpoint. Of course that's assuming that carbon is rare/hard to extract from the poles, otherwise methane/LOX would obviously be better.

I think more interesting than the chemistry (sorry Josh) is the infrastructure needs. What associated equipment, storage tanks, transportation infrastructure, etc. would be required? That's really what determines how expensive/difficult it will be to bootstrap.

SpaceNut · 2012-01-22 21:16:57

Silane ??? Monosilane chemical make up SiH4 silicon and lots of hydrogen not thinking that that is much better than methane or Alice...
other silane combination here at http://www.unibw.de/lrt10/forschung/projekte/silane

Found in clay, granite, quartz, sand

Melting Point: 1410.0 °C (1683.15 K, 2570.0 °F)
Boiling Point: 2355.0 °C (2628.15 K, 4271.0 °F)

That infrastructure starts with what is left behind each time we land and return to lunar orbit such as in the LEM a 2 stage unit which left its first stage on the surface.

The tanks from them would be a first step for liquid storage....

Waste recovery can get the carbon from plastics and such, that will be in the waste stream....

Engines can be reconfigured to become torches for smelting....

Back to Mark's ending question of infrastructure....
There are at least seven ISRU capabilities to refine regardless of where we go:
(i) resource extraction,
(ii) material handling and transport,
(iii) resource processing,
(iv) surface manufacturing with in-situ resources,
(v) surface construction,
(vi) surface ISRU product and consumable storage and distribution, and
(vii) ISRU unique development and certification capabilities.

Last edited by SpaceNut (2012-01-22 21:23:14)

JoshNH4H · 2012-01-24 19:35:44

Mark- Interesting is of course a matter of perspective.

That said, I'm not sure CH4/LOX is necessarily harder, especially given the volatile finds by LCROSS. It showed fair amounts of methane and carbon monoxide, I thought.

The problem with silanes is that you have to react or electrolyze your way to pure silicon, the complications of which would I imagine mirror those of obtaining Aluminium. Possible but probably not easy. As I was saying before, relatively simple chemical processes can be used to get to Methane, and at a lower energy cost, too. Methlox is also a much more familiar rocket fuel than silane-lox, which reduces development costs.

RGClark · 2012-02-23 07:05:31

Hop, I wanted to see what kind of payload we could get to Mars for a sample return mission using one of the current 20 mT payload launchers or the 53 mT payload Falcon Heavy. If you use aerobraking both for landing at Mars and for Earth orbit insertion, what would be the total delta-V to go from LEO to the Martian surface and back to LEO?
From this diagram I get a surprisingly low 10.2 km/s:

Delta-v budget.
Delta-vs between Earth, Moon and Mars.

http://en.wikipedia.org/wiki/Delta-v_bu … n_and_Mars

LEO to GTO: 2.5 km/s
GTO to Earth C3: .7 km/s
Earth C3 to Mars transfer: .6 km/s

Now notice for the delta-v's after this leading into Mars they all have red arrows indicating this part of the trip can be done by aerobraking. So this portion leading into Mars orbit and landing on the surface is only 3.8 km/s.

Then for the return trip:

Mars(surface) to low Mars orbit: 4.1 km/s
low Mars orbit to Phobos transfer: .9 km/s
Phobos transfer to Deimos transfer: .3 km/s
Deimos transfer to Mars C3: .2 km/s
Mars C3 to Mars transfer: .9 km/s

Now the delta-v's after this leading into Earth all have red arrows indicating this part of the trip can be done by aerobraking. So the return part of the trip can amount to only 6.4 km/s, for a total of 10.2 km/s for the round trip.

As for the heat shield for these Mars return velocities notice that the SpaceX Dragon's PICA-X heat shield was designed to withstand such velocities. It reportedly weighs only half of Apollo era heat shields which would put it at about 8% of the landed mass.

Bob Clark

Last edited by RGClark (2012-02-23 08:05:20)

SpaceNut · 2012-02-23 20:34:56

Phenolic Impregnated Carbon Ablator (PICA) was developed by NASA Ames Research Center in the 1990s and was the primary TPS material for the Stardust aeroshell.
http://en.wikipedia.org/wiki/Atmospheric_entry
I had not heard of the PICA-X but I see that it is an easier to manufacture PICA. The original PICA heat shield protected Stardust from temperatures as high as 2,500˚C as the spacecraft reentered Earth's atmosphere at more than 28,000 mph—faster than any previous manmade object.
http://www.nasa.gov/offices/oce/appel/a … -x_prt.htm

Now what size would the sample return lander want to be as we must budget the down mass of fuel to get it back on the path home.

Rune · 2012-02-24 09:03:28

Bob, from what I can tell, yeah, the delta-v would be that surprisingly small. Mars is not really that far away, energy-wise (at least some of the time). But take care, because a direct atmospheric entry from and interplanetary trajectory is not aerobraking, it's aerocapture, or direct entry. I don't doubt it can be done (direct entry is more than proved at this stage), but it implies a high degree of precision, and makes the heatshield a must. If instead, you captured propulsively into elliptical orbits (I recall Von Braun's mars mission budgeted 800m/s for capturing into a martian high orbit), you get most of the savings without any especial requirements, be them precision or heat protection. IMO, it simplifies the design greatly, especially in an unmanned mission that doesn't care if it has to wait in orbit.

As to Falcon Heavy's payload to Mars, it is supposedly 14mT for TMI. How much of that you can land, depends on the lander, but the rule of thumb for NASA's rovers and landers is about 30% of the weight goes into landing/cruise systems, IIRC. That's direct entry, of course, and it has been done plenty of times. With some spectacular failure rates, I might add.

Rune. EDL on sensor-deprived Mars is scary.

louis · 2012-02-24 18:32:07

Rune - So how long is the wait? I seem to recall less than two months. Not too bad I think.

SpaceNut · 2012-02-27 19:01:22

Funny how this topic is being written of.
The cislunar econosphere (part 2)

Part 1

The article points to Lunar Oxygen

The to keep Nasascientists busy

Then again another topic of our discusions are 3D printing technology

Tieing this all up is a story on how Mining on the moon: gold, fuel, and Canada's possible role in a new space race

louis · 2012-02-27 19:25:11

SpaceNut wrote:

Funny how this topic is being written of.
The cislunar econosphere (part 2)
Part 1
The article points to Lunar Oxygen
The to keep Nasascientists busy
Then again another topic of our discusions are 3D printing technology
Tieing this all up is a story on how Mining on the moon: gold, fuel, and Canada's possible role in a new space race

Some interesting ideas there and a nice concept-map.

My one criticism would be that the focus on mining underplays what will be the really big revenue generator on the moon - tourism and associated lunar services. Tourism will far outweigh the other elements in the economy, at least for the first few decades.

Rune · 2012-02-28 07:45:50

louis wrote:

Rune - So how long is the wait? I seem to recall less than two months. Not too bad I think.

Didn't see that. Yeah, pretty much like you say. The thing is, it depends on how much velocity you shed each orbit (when your orbit intersects the upper atmosphere), which is limited by how much heat your spacecraft can handle. So no heatshield means a lot of drag passes, and the first ones are from long orbital periods, so they take longer. The decrease in precision required is because, since you are slowing in a lot of separate moments, you can make corrections after every one in case the atmospheric conditions change unexpectedly (like the atmosphere being more or less dense at that height on account of a solar storm blowing at that time, for instance).

As to real-world examples, Mars Global Surveyor took 4 months to get the high point of its orbit from 54.000km at capture to a mere 450. Mind you, they had no particular hurry, and a very fragile observation satellite with exposed instruments and such (and a bent solar panel, damaged during launch, that they weren't very sure of).

Rune. Of course, the US has demonstrated direct entry many more times than aerocapture (0, up to now) or aerobraking (a couple times). But the success rate is... let's say EDL is feared with reason.

RGClark · 2012-02-29 02:45:35

SpaceNut wrote:

Funny how this topic is being written of.
The cislunar econosphere (part 2)
Part 1
The article points to Lunar Oxygen
The to keep Nasascientists busy
Then again another topic of our discusions are 3D printing technology
Tieing this all up is a story on how Mining on the moon: gold, fuel, and Canada's possible role in a new space race

Thanks for those links, all very informative. I like the fact in that last one gold was mentioned on the Moon. LCROSS may have indeed detected gold but this detection is controversial. I wonder if the author was informed of some further information to firm up that detection.

Bob Clark

louis · 2012-02-29 17:25:37

Rune wrote:

louis wrote:
Rune - So how long is the wait? I seem to recall less than two months. Not too bad I think.
Didn't see that. Yeah, pretty much like you say. The thing is, it depends on how much velocity you shed each orbit (when your orbit intersects the upper atmosphere), which is limited by how much heat your spacecraft can handle. So no heatshield means a lot of drag passes, and the first ones are from long orbital periods, so they take longer. The decrease in precision required is because, since you are slowing in a lot of separate moments, you can make corrections after every one in case the atmospheric conditions change unexpectedly (like the atmosphere being more or less dense at that height on account of a solar storm blowing at that time, for instance).
As to real-world examples, Mars Global Surveyor took 4 months to get the high point of its orbit from 54.000km at capture to a mere 450. Mind you, they had no particular hurry, and a very fragile observation satellite with exposed instruments and such (and a bent solar panel, damaged during launch, that they weren't very sure of).

Rune. Of course, the US has demonstrated direct entry many more times than aerocapture (0, up to now) or aerobraking (a couple times). But the success rate is... let's say EDL is feared with reason.

Thanks for that - very informative.

I think it might make more sense to use more fuel/propellant to get to Mars more quickly and then do the orbital/aero capture over say a couple of months.

SpaceNut · 2012-02-29 21:43:59

That is fine for cargo unmanned missions but not for men as that is extra consumables for how ever long one would take to break.....

louis · 2012-03-01 19:46:21

SpaceNut wrote:

That is fine for cargo unmanned missions but not for men as that is extra consumables for how ever long one would take to break.....

Well I think you are probably overstating the consumables problem. Food is only 1.5 kg per person max = 90 kgs for two months. Most other consumables can be recycled to a pretty high degree of efficiency these days.

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Re: Developing the cis-Lunar economy and infrastructure

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