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Mining the moon for rocket fuel to get us to Mars
On May/31/2017 at 6:57 AM, Jeff Findley wrote :
In article , says... There is quite a lot of "exercise for the student" type problems here. There is a lot of work & study needed about lunar industrialization for sure including mining. One factor that may get some consideration down the road is the idea of what I'd call incremental industrial "densification". The idea being that lightweight gear is first sent up that has limited capacity for manufacture of the "heavy gear". Heavy feed stock ( steel, etc) would then be sent up subsequently for lunar manufacture. Enabling a heavy mfg. capability via bootstrapping. At this point my conjecture is pretty much a total hand wave, but I could at least see it as a possibility. Would need some math to determine if this would be preferable to just shipping up the heavy equipment directly. I suppose if the scale is massive enough the bootstrap approach might be the only really feasible one. Further study needed.... I think the "further study needed" is the key here. Researchers don't really know how they'd do this, so they're fishing for funding. Don't get me wrong, this is certainly worth doing some work on, but this is not a next 10 or 20 year solution. It's more like a next 25 to 100 year solution. But no, we'll do it all with SLS. Why waste money on studies? Flags and footprints. We couldn't possibly do anything differently than Apollo now could we? :-( The reality is there is so much between the SLS approach and the "living completely off the land" approach. I don't see "living off the land" becoming viable until you can start launching heavier bits like machine tools without resorting to making them out of aluminum, titanium, and unobtainium. Shaving every last gram off of payloads due to high launch costs is freaking expensive! It results in one-off payloads that might work, or they might not. To build a colony, we need to get to the point where we're buying machine tools "off the shelf" and simply shipping them to the moon and Mars. Run them in pressurized environments so astronauts can service them in "shirt sleeves". By then, astronauts will be selected for their skill at fixing machine tools, not for their ability to fly a fighter jet in combat or because they have the most college degrees. ****. I've got college degrees, but fixing machine tools, not my forte. :-) Alain Fournier |
#13
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Mining the moon for rocket fuel to get us to Mars
"Jeff Findley" wrote in message
... First, this isn't my "subject", it's the title of this article: Mining the moon for rocket fuel to get us to Mars May 14, 2017 8.04pm EDT ?Updated May 18, 2017 9.01am EDT http://theconversation.com/mining-th...-to-get-us-to- mars-76123 I saw this article (or a variation of it from another online publication) on Twitter. I replied something to the effect that this article glosses over all of the hard stuff, like the fact that the lunar soil and rock is horribly abrasive and that mining equipment isn't anything like the lightweight rovers that NASA/JPL has flown in the past. For crying out loud, JPL keeps using ALUMINUM for the rover wheels to keep them light, even though they're wearing holes in the things after less than 100 miles. Mining equipment can't be that weak! Anyway, I replied that mining equipment is *really heavy* because it's made of steel and hardened steel. The response by one Twitter follower was along the lines of, "That's why the mining equipment will be built on the moon from local materials". At that point, "I couldn't even". I mean WTF? So, to build mining equipment on the moon, you're going to build an entire freaking factory, from local materials?!?!? So, WTF are you going to use to mine the materials to build the factory?!?!?!? Don't get me wrong, I think *eventually* we'll be mining the moon for water to turn into LOX and LH2 (or possibly methane) to supply a fuel depot in lunar orbit. But, needless to say, I think the supporters of this notion are daft if they think it's going to happen in the next 20 years or so by building a freaking factory on the moon that's capable of building mining equipment that's not JPL class "toys" that wear out faster than you can build them. Jeff Yeah, I use a very simple first order approximation for this: the mass of the fuel you'll get from the Moon has to be greater than fuel used to get the mass to mine it to the Moon, otherwise it's a net loss. Simply put, if you're going to extract say 100 kilotons of fuel from the Moon, you're going to have to use less than 100 kilotons of fuel getting your mining and processing equipment there, otherwise it's a waste. I think people look at in-situ fuel processing on Mars and figure the Moon makes even more sense. But processing atmosphere (even a thin one) to extract Carbon is far easier than mining the surface of the Moon. I do agree, at some point we'll process fuel on the Moon, but we're a LONG ways from there. -- Greg D. Moore http://greenmountainsoftware.wordpress.com/ CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net IT Disaster Response - https://www.amazon.com/Disaster-Resp...dp/1484221834/ |
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Mining the moon for rocket fuel to get us to Mars
On 17-06-05 04:06 , Greg (Strider) Moore wrote:
"Jeff Findley" wrote in message ... First, this isn't my "subject", it's the title of this article: Mining the moon for rocket fuel to get us to Mars May 14, 2017 8.04pm EDT ?Updated May 18, 2017 9.01am EDT http://theconversation.com/mining-th...-to-get-us-to- mars-76123 I saw this article (or a variation of it from another online publication) on Twitter. I replied something to the effect that this article glosses over all of the hard stuff, like the fact that the lunar soil and rock is horribly abrasive and that mining equipment isn't anything like the lightweight rovers that NASA/JPL has flown in the past. [snip] Don't get me wrong, I think *eventually* we'll be mining the moon for water to turn into LOX and LH2 (or possibly methane) to supply a fuel depot in lunar orbit. But, needless to say, I think the supporters of this notion are daft if they think it's going to happen in the next 20 years or so by building a freaking factory on the moon that's capable of building mining equipment that's not JPL class "toys" that wear out faster than you can build them. Jeff Yeah, I use a very simple first order approximation for this: the mass of the fuel you'll get from the Moon has to be greater than fuel used to get the mass to mine it to the Moon, otherwise it's a net loss. Simply put, if you're going to extract say 100 kilotons of fuel from the Moon, you're going to have to use less than 100 kilotons of fuel getting your mining and processing equipment there, otherwise it's a waste. Perhaps you on purpose ignored this factor in your approximation, but surely the *location* of the fuel must be considered? If you use 100 kilotons of fuel to send equipment to the Moon, most of that fuel is used up close to the Earth, and will not reach the Moon. If that equipment then produces 100 kilotons of fuel on the Moon, that fuel is on the Moon, which is "half-way to anywhere". You would surely have to use *much* more than 100 kilotons of fuel to deliver a payload of 100 kilotons of fuel from the Earth's surface to the Moon's surface. -- Niklas Holsti Tidorum Ltd niklas holsti tidorum fi . @ . |
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Mining the moon for rocket fuel to get us to Mars
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#16
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Mining the moon for rocket fuel to get us to Mars
"Niklas Holsti" wrote in message ...
On 17-06-05 04:06 , Greg (Strider) Moore wrote: "Jeff Findley" wrote in message ... First, this isn't my "subject", it's the title of this article: Mining the moon for rocket fuel to get us to Mars May 14, 2017 8.04pm EDT ?Updated May 18, 2017 9.01am EDT http://theconversation.com/mining-th...-to-get-us-to- mars-76123 I saw this article (or a variation of it from another online publication) on Twitter. I replied something to the effect that this article glosses over all of the hard stuff, like the fact that the lunar soil and rock is horribly abrasive and that mining equipment isn't anything like the lightweight rovers that NASA/JPL has flown in the past. [snip] Don't get me wrong, I think *eventually* we'll be mining the moon for water to turn into LOX and LH2 (or possibly methane) to supply a fuel depot in lunar orbit. But, needless to say, I think the supporters of this notion are daft if they think it's going to happen in the next 20 years or so by building a freaking factory on the moon that's capable of building mining equipment that's not JPL class "toys" that wear out faster than you can build them. Jeff Yeah, I use a very simple first order approximation for this: the mass of the fuel you'll get from the Moon has to be greater than fuel used to get the mass to mine it to the Moon, otherwise it's a net loss. Simply put, if you're going to extract say 100 kilotons of fuel from the Moon, you're going to have to use less than 100 kilotons of fuel getting your mining and processing equipment there, otherwise it's a waste. Perhaps you on purpose ignored this factor in your approximation, but surely the *location* of the fuel must be considered? If you use 100 kilotons of fuel to send equipment to the Moon, most of that fuel is used up close to the Earth, and will not reach the Moon. If that equipment then produces 100 kilotons of fuel on the Moon, that fuel is on the Moon, which is "half-way to anywhere". You would surely have to use *much* more than 100 kilotons of fuel to deliver a payload of 100 kilotons of fuel from the Earth's surface to the Moon's surface. Not that much more really. And as I said, it's a first order approximation. There's a lot more math involved than simply this. But if you figure the delta V just to get to the Moon is approximately 12.52km/sec, and the delta-V from lunar transfer to surface is probably about 2.55, and 2.55 back out, so that's less than 1/2. Sure, you can probably play some numbers there (direct impact, etc.) but it doesn't change the first order approximation much. Again as a first order approximation, figure the energy used to land will be about the same as taking off. Now, figure if you want to go to Mars, from lunar transfer to Mars is approximately less than landing on the Moon, especially if you can use some aerobraking. So again, first order approximation, I stand by my analysis. -- Greg D. Moore http://greenmountainsoftware.wordpress.com/ CEO QuiCR: Quick, Crowdsourced Responses. http://www.quicr.net IT Disaster Response - https://www.amazon.com/Disaster-Resp...dp/1484221834/ |
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Mining the moon for rocket fuel to get us to Mars
First, I want to highlight that I'm not advocating fuel production on
the Moon; I am not competent to evaluate the difficulty of that. I'm only doubting the "first order approximation" that compares the amount of fuel needed to send the equipment to the Moon (from the Earth's surface, it is assumed) to the amount of fuel produced on the Moon. On 17-06-05 13:43 , Jeff Findley wrote: In article , lid says... Yeah, I use a very simple first order approximation for this: the mass of the fuel you'll get from the Moon has to be greater than fuel used to get the mass to mine it to the Moon, otherwise it's a net loss. Simply put, if you're going to extract say 100 kilotons of fuel from the Moon, you're going to have to use less than 100 kilotons of fuel getting your mining and processing equipment there, otherwise it's a waste. Perhaps you on purpose ignored this factor in your approximation, but surely the *location* of the fuel must be considered? If you use 100 kilotons of fuel to send equipment to the Moon, most of that fuel is used up close to the Earth, and will not reach the Moon. If that equipment then produces 100 kilotons of fuel on the Moon, that fuel is on the Moon, which is "half-way to anywhere". You would surely have to use *much* more than 100 kilotons of fuel to deliver a payload of 100 kilotons of fuel from the Earth's surface to the Moon's surface. So let's revise the original statement a bit. If the goal is to refuel a depot in lunar orbit, the fuel you mine, refine, and launch to that depot must exceed the amount of fuel it took to originally land the mining equipment, lander, and landing fuel when starting from roughly the same lunar orbit as the depot. I agree with that. Ignore the delta-V to get to lunar orbit, because it's the same for the 100 kilotons of fuel put in lunar orbit or the 100 kilotons of lunar lander, fuel, and mining equipment put in lunar orbit. How did you get from Greg's assumed "100 kilotons of fuel getting your mining and processing equipment there [to the Moon]" to "100 kilotons of lunar lander" etc.? The original statement assumed 100 kilotons of fuel would be used, in total, for transporting the mining equipment from (presumably) the Earth's surface to the Moon. The mass of that equipment, including whatever is needed to bring it from lunar orbit to the lunar surface, must then be assumed to be *much* less than 100 kilotons. -- Niklas Holsti Tidorum Ltd niklas holsti tidorum fi . @ . |
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Mining the moon for rocket fuel to get us to Mars
On 17-06-05 16:09 , Greg (Strider) Moore wrote:
"Niklas Holsti" wrote in message ... On 17-06-05 04:06 , Greg (Strider) Moore wrote: "Jeff Findley" wrote in message ... First, this isn't my "subject", it's the title of this article: Mining the moon for rocket fuel to get us to Mars May 14, 2017 8.04pm EDT ?Updated May 18, 2017 9.01am EDT http://theconversation.com/mining-th...-to-get-us-to- mars-76123 I saw this article (or a variation of it from another online publication) on Twitter. I replied something to the effect that this article glosses over all of the hard stuff, like the fact that the lunar soil and rock is horribly abrasive and that mining equipment isn't anything like the lightweight rovers that NASA/JPL has flown in the past. [snip] Don't get me wrong, I think *eventually* we'll be mining the moon for water to turn into LOX and LH2 (or possibly methane) to supply a fuel depot in lunar orbit. But, needless to say, I think the supporters of this notion are daft if they think it's going to happen in the next 20 years or so by building a freaking factory on the moon that's capable of building mining equipment that's not JPL class "toys" that wear out faster than you can build them. Jeff Yeah, I use a very simple first order approximation for this: the mass of the fuel you'll get from the Moon has to be greater than fuel used to get the mass to mine it to the Moon, otherwise it's a net loss. Simply put, if you're going to extract say 100 kilotons of fuel from the Moon, you're going to have to use less than 100 kilotons of fuel getting your mining and processing equipment there, otherwise it's a waste. Perhaps you on purpose ignored this factor in your approximation, but surely the *location* of the fuel must be considered? If you use 100 kilotons of fuel to send equipment to the Moon, most of that fuel is used up close to the Earth, and will not reach the Moon. If that equipment then produces 100 kilotons of fuel on the Moon, that fuel is on the Moon, which is "half-way to anywhere". You would surely have to use *much* more than 100 kilotons of fuel to deliver a payload of 100 kilotons of fuel from the Earth's surface to the Moon's surface. Not that much more really. And as I said, it's a first order approximation. There's a lot more math involved than simply this. No kidding :-) But if you figure the delta V just to get to the Moon is approximately 12.52km/sec, and the delta-V from lunar transfer to surface is probably about 2.55, and 2.55 back out, so that's less than 1/2. What goes to the Moon (12.52 + 2.55 km/sec) is the mining and fuel-producing equipment. If that trip uses 100 kilotons of fuel, most of that is used near Earth (not close to the Moon) and the final part (landing, 2.55 km/s) is for a much smaller mass. Sure, you can probably play some numbers there (direct impact, etc.) Not my point at all. My point is just the ratio of fuel weight to payload weight, which is large for a trip from the Earth's surface to lunar orbit or lunar surface, whether you are sending fuel or mining equipment. If you are sending fuel, to be stored in lunar orbit, there is the advantage that it does not have to be landed onto the lunar surface, unlike the mining equipment. But the ratio between the delta-vees (12.52 vs 2.55 km/s) means that the landing cost is relatively small. Again as a first order approximation, figure the energy used to land will be about the same as taking off. What lands is the mining equipment, which must mass much less than 100 kilotons, if it took only 100 kilotons of fuel to send it from the Earth to the Moon. What takes off is the fuel that is produced (assumed to be 100 kilotons), plus whatever containers and propulsion it needs. So the take-off uses much more energy. (Plus one can potentially use electromagnetic launchers for launching the fuel from the lunar surface to lunar orbit, so the overhead in terms of containers and propulsion could be small.) Now, figure if you want to go to Mars, from lunar transfer to Mars is approximately less than landing on the Moon, especially if you can use some aerobraking. Right, which is why fuel in lunar orbit is so valuable, compared to fuel on the Earth. -- Niklas Holsti Tidorum Ltd niklas holsti tidorum fi . @ . |
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