Mining Asteroids - Revision history

Hkhenson: /* Mining asteroids by Keith Henson */

2019-10-02T00:29:28Z

Mining asteroids by Keith Henson

← Older revision		Revision as of 00:29, 2 October 2019
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	=Mining asteroids by Keith Henson=		=Mining asteroids by Keith Henson=

	June 9 Draft temp post as a wiki for comment!		June 9, 2012 Draft temp post as a wiki for comment!

	''This article provides a rough analysis of mining an asteroid for gold and other high value elements (platinum group metals) for return to an Earth market. Given serious bootstrapping at an asteroid and the development of low-cost transport to GEO in the context of a power satellite or similar very large operations in space, it appears an asteroid-mining project could make money beyond the wildest dreams of avarice.''		''This article provides a rough analysis of mining an asteroid for gold and other high value elements (platinum group metals) for return to an Earth market. Given serious bootstrapping at an asteroid and the development of low-cost transport to GEO in the context of a power satellite or similar very large operations in space, it appears an asteroid-mining project could make money beyond the wildest dreams of avarice.''

Hkhenson: /* Mining asteroids by Keith Henson */

2019-08-06T21:45:04Z

Mining asteroids by Keith Henson

← Older revision		Revision as of 21:45, 6 August 2019
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			=Out of Date=

			This article needs updating. Not chemistry or economics, but the companies named. Planetary Resources and Deep Space Industries are gone.

			Keith Aug 6 2019

	=Mining asteroids by Keith Henson=		=Mining asteroids by Keith Henson=

Hkhenson: /* Process details */

2018-12-30T20:01:22Z

Process details

← Older revision		Revision as of 20:01, 30 December 2018
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	Back in 1990 Dr. John Lewis (now Chief Scientist for Deep Space Industries) did extensive experiments on digesting iron meteorite specimens in a CO pressure bomb, including the catalytic effects of adding other gases to the CO. (The work was done by Muralidharan and Freiser in the UofA's Strategic Metals Recovery Research Facility under funding from our Space Engineering Research Center.)		Back in 1990 Dr. John Lewis (now Chief Scientist for Deep Space Industries) did extensive experiments on digesting iron meteorite specimens in a CO pressure bomb, including the catalytic effects of adding other gases to the CO. (The work was done by Muralidharan and Freiser in the UofA's Strategic Metals Recovery Research Facility under funding from our Space Engineering Research Center.)

	While I think asteroid mining for gold and platinum is a ways off, it also seems to be a natural outgrowth of a large power satellite program. Indeed, it could provide some of the motivation to build the transport system for power satellites, if solving energy and carbon problems isn't enough.		While I think asteroid mining for gold and platinum is a ways off, it also seems to be a natural outgrowth of a large power satellite program. Indeed, it could provide some or all of the motivation to build the transport system for power satellites, if solving energy and carbon problems isn't enough.

	==Related Reference==		==Related Reference==

Hkhenson: /* Bootstrapping */

2018-12-30T19:55:36Z

Bootstrapping

← Older revision		Revision as of 19:55, 30 December 2018
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	It's going to take bootstrapping, but not an absurd amount. In this context, a 90% bootstrap seems feasible, especially starting from a plant sized to make Invar for power- satellite parts and already returning a few thousand tons per day of power satellite parts to GEO.		It's going to take bootstrapping, but not an absurd amount. In this context, a 90% bootstrap seems feasible, especially starting from a plant sized to make Invar for power- satellite parts and already returning a few thousand tons per day of power satellite parts to GEO.

	That much bootstrapping reduces the cost to $75 B for the startup.		That much bootstrapping reduces the transport cost to $75 B for the startup. Of course, a technology that allowed a smaller starting mass would be even less expensive.

	To analyze further, we have to assume a particular process. One proposed by Alexis Gilliland in the Rosanante book series was to use zone refining for the initial concentration step. (If you have never read them, the Rosanante books are the best fiction ever written about both space colonies and AI.)		To analyze further, we have to assume a particular process. One proposed by Alexis Gilliland in the Rosanante book series was to use zone refining for the initial concentration step. (If you have never read them, the Rosanante books are the best fiction ever written about both space colonies and AI.)
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	I will assume for this article melting the asteroid with an open-ended induction furnace, rolling the hot metal into thin sheet metal, followed by dissolving the metal in carbon monoxide under high pressure (i.e., the Mond process). The iron and nickel carbonyls will have to be reduced back to metals to recover the carbon monoxide.		I will assume for this article melting the asteroid with an open-ended induction furnace, rolling the hot metal into thin sheet metal, followed by dissolving the metal in carbon monoxide under high pressure (i.e., the Mond process). The iron and nickel carbonyls will have to be reduced back to metals to recover the carbon monoxide.

	How to separate ~~these liquids~~ in zero-g is a so far unsolved question. It may require artificial gravity (discussed below).		How to separate the liquid carbonyls in zero-g is a so far unsolved question. It may require artificial gravity (discussed below).

	The local structure could be made of iron or unprocessed metal or any alloy available from the output of the plant.		The local structure could be made of iron or unprocessed metal or any alloy available from the output of the plant.
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	2.5 million tons per day is about 29,000 kg/s. Melting this flow would take 29 GW, round to 30 GW. That is a lot of power, equal to three 5 GW power satellites before you take the 50% loss in transmitting power to the ground. A while ago I was in a Nucor minimill. The main melting furnace was 50 MW making this musing roughly 500 times larger.		2.5 million tons per day is about 29,000 kg/s. Melting this flow would take 29 GW, round to 30 GW. That is a lot of power, equal to three 5 GW power satellites before you take the 50% loss in transmitting power to the ground. A while ago I was in a Nucor minimill. The main melting furnace was 50 MW making this musing roughly 500 times larger.

	At 3 kg/kW, a power plant masses 3000 tons per GW. The asteroid 1986 DA swings out further than Mars, which would reduce the sunlight intensity to 1/4. The power output would swing ~~from twice to one half~~. Using the same kg/kW as near Earth, the power plant would mass 30 GW x 3000 t/GW or 90,000 tons. Virtually all of the mass could come from the asteroid.		At 3 kg/kW, a power plant masses 3000 tons per GW. The asteroid 1986 DA swings out further than Mars, which would reduce the sunlight intensity to 1/4. The power output would swing over the same range. Using the same kg/kW as near Earth, the power plant would mass 30 GW x 3000 t/GW or 90,000 tons. Virtually all of the mass could come from the asteroid.

	Assuming asteroid metal rolled thin enough to dissolve in a day, the high-pressure chamber will need to hold 2.5 million tons of crinkled-up sheet metal. At a density of 1000/kg/m^3, the reaction chamber would be 2.5 million cubic meters. As a cube, it would be around 136 meters on a side.		Assuming asteroid metal rolled thin enough to dissolve in a day, the high-pressure chamber will need to hold 2.5 million tons of crinkled-up sheet metal. At a density of 1000/kg/m^3, the reaction chamber would be 2.5 million cubic meters. As a cube, it would be around 136 meters on a side.
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	Moving high-pressure CO through a reaction vessel at a meter per second would be a path length of 86,400 m. It would require an area of 28.9 square meters, or 5.4 meters inside diameter. The pressure inside at 50 bar (~750 psi) would generate a hoop tension per meter would be 5.4/2 x 100,000 Pa/bar x 50 bar or 13.4 MPa. This is a large reaction vessel, but it's not completely beyond what has been constructed (on earth).		Moving high-pressure CO through a reaction vessel at a meter per second would be a path length of 86,400 m. It would require an area of 28.9 square meters, or 5.4 meters inside diameter. The pressure inside at 50 bar (~750 psi) would generate a hoop tension per meter would be 5.4/2 x 100,000 Pa/bar x 50 bar or 13.4 MPa. This is a large reaction vessel, but it's not completely beyond what has been constructed (on earth).

	The yield strength of steel is up to 500 MPs. Stressed to 200 MPa, the wall thickness would be 1/15th of a meter thick, and the mass per meter would be ~5.4 m x pi x 1/15 x 7800 kg / m or 8.8 tons per meter. The whole pressure chamber would mass 762,000 tons, all of it from the local source. This is by far the largest piece of the processing plant.		The yield strength of steel is up to 500 MPs. Stressed to 200 MPa, the wall thickness would be 1/15th of a meter thick, and the mass per meter would be ~5.4 m x pi x 1/15 x 7800 kg / m or 8.8 tons per meter. The whole pressure chamber would mass 762,000 tons, all of it from the local source. This is by far the largest piece of the processing plant and about 3 times the initial plant mass estimate.

	==Process details==		==Process details==

Hkhenson: /* What it would cost to mine this asteroid */

2018-12-30T19:18:28Z

What it would cost to mine this asteroid

← Older revision		Revision as of 19:18, 30 December 2018
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	By rough analogy to the work Drexler and I did, the processing plant might mass 2.5 million tons (i.e., it process the plant mass in a day). That's a lot. Even by the standard of a half-million-ton-per-year power-satellite project, it would take 5 years to lift that much off the Earth.		By rough analogy to the work Drexler and I did, the processing plant might mass 2.5 million tons (i.e., it process the plant mass in a day). That's a lot. Even by the standard of a half-million-ton-per-year power-satellite project, it would take 5 years to lift that much off the Earth.

	Still, we can plug in numbers. A scheme I have worked on is to lift power parts to GEO using a combination of air-breathing rocket planes (Skylon) followed by arcjet tugs powered small power satellites ~~for lifting~~ 15,000-ton cargo blocks from LEO to GEO. The proposed cost is slightly under $200/kg. This is a LEO-to-GEO velocity change of about 4 km/s. It's probably possible (especially at this scale) to get the cost for transporting a mining and processing plant to 1986 DA down to $300/kg (a delta-V of around 7.1 km/s from LEO).		Still, we can plug in numbers. A scheme I have worked on is to lift power parts to GEO using a combination of air-breathing rocket planes (Skylon) followed by arcjet tugs powered by small power satellites. The arcjet tugs lift 15,000-ton cargo blocks from LEO to GEO. The proposed cost is slightly under $200/kg. This is a LEO-to-GEO velocity change of about 4 km/s. It's probably possible (especially at this scale) to get the cost for transporting a mining and processing plant to 1986 DA down to ~$300/kg (for a delta-V of around 7.1 km/s from LEO).

	That would cost $750 B for a 2.5-million-ton processing plant. Just for the transport cost, that's already twice the permitted capital budget.		That would cost $750 B for a 2.5-million-ton processing plant. Just for the transport cost, that's already twice the permitted capital budget.

Hkhenson: /* Bootstrapping */

2018-12-30T06:34:11Z

Bootstrapping

← Older revision		Revision as of 06:34, 30 December 2018
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	==Bootstrapping==		==Bootstrapping==

	Actually, $~~7.5 T~~ is not bad for a first cut.		Actually, $750 B is not bad for a first cut.

	It's going to take bootstrapping, but not an absurd amount. In this context, a 99% bootstrap seems feasible, especially starting from a plant sized to make Invar for power- satellite parts and already returning a few thousand tons per day of power satellite parts to GEO.		It's going to take bootstrapping, but not an absurd amount. In this context, a 90% bootstrap seems feasible, especially starting from a plant sized to make Invar for power- satellite parts and already returning a few thousand tons per day of power satellite parts to GEO.

	That much bootstrapping reduces the cost to $75 B for the ~~start up~~.		That much bootstrapping reduces the cost to $75 B for the startup.

	To analyze further, we have to assume a particular process. One proposed by Alexis Gilliland in the Rosanante book series was to use zone refining for the initial concentration step. (If you have never read them, the Rosanante books are the best fiction ever written about both space colonies and AI.)		To analyze further, we have to assume a particular process. One proposed by Alexis Gilliland in the Rosanante book series was to use zone refining for the initial concentration step. (If you have never read them, the Rosanante books are the best fiction ever written about both space colonies and AI.)
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	I will assume for this article melting the asteroid with an open-ended induction furnace, rolling the hot metal into thin sheet metal, followed by dissolving the metal in carbon monoxide under high pressure (i.e., the Mond process). The iron and nickel carbonyls will have to be reduced back to metals to recover the carbon monoxide.		I will assume for this article melting the asteroid with an open-ended induction furnace, rolling the hot metal into thin sheet metal, followed by dissolving the metal in carbon monoxide under high pressure (i.e., the Mond process). The iron and nickel carbonyls will have to be reduced back to metals to recover the carbon monoxide.

	How to separate these liquids in zero g is a so far unsolved question. It may require artificial gravity (discussed below).		How to separate these liquids in zero-g is a so far unsolved question. It may require artificial gravity (discussed below).

	~~Local~~ structure could be made of iron or unprocessed metal or any alloy available from the output of the plant.		The local structure could be made of iron or unprocessed metal or any alloy available from the output of the plant.

	The power plant size depends on the heat capacity of iron at 25 J per mol per deg K. Iron is 56 g/mol, so to heat a gram of iron a degree K would take about 0.46 J, or 0.45 kJ/kg. The asteroid metal needs to be heated (1811 –164) deg K which takes ~741 kJ/kg. Iron takes 13.8 kJ/mol to melt it, adding 246 kJ/kg for 987 kJ/kg. Round up to 1 MJ/kg.		The power plant size depends on the heat capacity of iron at 25 J per mol per deg K. Iron is 56 g/mol, so to heat a gram of iron a degree K would take about 0.46 J, or 0.45 kJ/kg. The asteroid metal needs to be heated (1811 –164) deg K which takes ~741 kJ/kg. Iron takes 13.8 kJ/mol to melt it, adding 246 kJ/kg for 987 kJ/kg. Round up to 1 MJ/kg. (A million watt-seconds per kg.)

	25 million tons per day is ~~289~~,000 kg/s. Melting this flow would take ~~289~~ GW, round to ~~300~~ GW. That is a lot of power, three ~~years of output for a 100~~ GW~~/year~~ power~~-sat construction project~~.		2.5 million tons per day is about 29,000 kg/s. Melting this flow would take 29 GW, round to 30 GW. That is a lot of power, equal to three 5 GW power satellites before you take the 50% loss in transmitting power to the ground. A while ago I was in a Nucor minimill. The main melting furnace was 50 MW making this musing roughly 500 times larger.

	At 5 kg/kW, a GW masses ~~5000~~ tons~~, but that includes a 50% transmission loss~~. The asteroid 1986 DA swings out further than Mars, which would reduce the sunlight intensity to 1/4. The power output would swing from twice to one half. Using the same kg/kW as near Earth, the power plant would mass ~~300~~ GW x ~~5000~~ t/GW or ~~1.5 million~~ tons. Virtually all of the mass could come from the asteroid.		At 3 kg/kW, a power plant masses 3000 tons per GW. The asteroid 1986 DA swings out further than Mars, which would reduce the sunlight intensity to 1/4. The power output would swing from twice to one half. Using the same kg/kW as near Earth, the power plant would mass 30 GW x 3000 t/GW or 90,000 tons. Virtually all of the mass could come from the asteroid.

	Assuming asteroid metal rolled thin enough to dissolve in a day, the high-pressure chamber will need to hold 25 million tons of crinkled-up sheet metal. At a density of 1000/kg/m3 the reaction chamber would be 25 million cubic meters. As a cube, it would be around ~~300~~ meters on a side.		Assuming asteroid metal rolled thin enough to dissolve in a day, the high-pressure chamber will need to hold 2.5 million tons of crinkled-up sheet metal. At a density of 1000/kg/m^3, the reaction chamber would be 2.5 million cubic meters. As a cube, it would be around 136 meters on a side.

	Moving ~~the~~ CO through a reaction vessel at a meter per second~~, it~~ would ~~move~~ 86,400 m~~/day and~~ require an area of ~~289~~ square meters, or 19.2 meters in diameter. The pressure inside at 50 bar (~750 psi) would generate a hoop tension per meter ~~of 20~~/2 x 100,000 Pa/bar x 50 bar or 50 MPa.		Moving high-pressure CO through a reaction vessel at a meter per second would be a path length of 86,400 m. It would require an area of 28.9 square meters, or 5.4 meters inside diameter. The pressure inside at 50 bar (~750 psi) would generate a hoop tension per meter would be 5.4/2 x 100,000 Pa/bar x 50 bar or 13.4 MPa. This is a large reaction vessel, but it's not completely beyond what has been constructed (on earth).

	The yield strength of steel is up to 500 MPs. Stressed to 200 MPa, the wall thickness would be 1/4 meter thick, and the mass per meter would be 60.3 m x ~~0.25~~ x 7800 kg / m or ~~118~~ tons per meter. The whole pressure chamber would mass ~~10.2 million~~ tons, all of it from the local source. This is by far the largest piece of the processing plant.		The yield strength of steel is up to 500 MPs. Stressed to 200 MPa, the wall thickness would be 1/15th of a meter thick, and the mass per meter would be ~5.4 m x pi x 1/15 x 7800 kg / m or 8.8 tons per meter. The whole pressure chamber would mass 762,000 tons, all of it from the local source. This is by far the largest piece of the processing plant.

	==Process details==		==Process details==

Hkhenson: /* What it would cost to mine this asteroid */

2018-12-30T05:37:51Z

What it would cost to mine this asteroid

← Older revision		Revision as of 05:37, 30 December 2018
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	Still, we can plug in numbers. A scheme I have worked on is to lift power parts to GEO using a combination of air-breathing rocket planes (Skylon) followed by arcjet tugs powered small power satellites for lifting 15,000-ton cargo blocks from LEO to GEO. The proposed cost is slightly under $200/kg. This is a LEO-to-GEO velocity change of about 4 km/s. It's probably possible (especially at this scale) to get the cost for transporting a mining and processing plant to 1986 DA down to $300/kg (a delta-V of around 7.1 km/s from LEO).		Still, we can plug in numbers. A scheme I have worked on is to lift power parts to GEO using a combination of air-breathing rocket planes (Skylon) followed by arcjet tugs powered small power satellites for lifting 15,000-ton cargo blocks from LEO to GEO. The proposed cost is slightly under $200/kg. This is a LEO-to-GEO velocity change of about 4 km/s. It's probably possible (especially at this scale) to get the cost for transporting a mining and processing plant to 1986 DA down to $300/kg (a delta-V of around 7.1 km/s from LEO).

	That would cost $750 B for a 2.5-million-ton processing plant. Just for the transport cost, that's already ~~more than ten~~ the permitted capital budget.		That would cost $750 B for a 2.5-million-ton processing plant. Just for the transport cost, that's already twice the permitted capital budget.

	==Bootstrapping==		==Bootstrapping==

Hkhenson: /* What it would cost to mine this asteroid */

2018-12-30T05:36:50Z

What it would cost to mine this asteroid

Hkhenson: /* Process details */ fixed typos

2017-12-27T18:56:17Z

Process details: fixed typos

← Older revision		Revision as of 18:56, 27 December 2017
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	While steel can hold the pressure, the inside lining can't be iron or nickel. Gold perhaps-- or plastic.		While steel can hold the pressure, the inside lining can't be iron or nickel. Gold perhaps-- or plastic.

	The rotation of ~~1096 DC~~ is 0.149 day, making the period 12873.6 s. Omega is .0000488 radians per second. The outward end of an 86.4 km long object would be subject to an acceleration of ~0.02 m/s^2 or about 1/500th of a g, not useful.		The rotation of 1986 DA is 0.149 day, making the period 12873.6 s. Omega is .0000488 radians per second. The outward end of an 86.4 km long object would be subject to an acceleration of ~0.02 m/s^2 or about 1/500th of a g, not useful.

	I am assuming the asteroid has north and south polar boom stems installed and a C shaped structure to hold the induction furnace in place as it peels the slowly rotating asteroid. The sheet metal would go through rolling seals into the high-pressure processing chamber.		I am assuming the asteroid has north and south polar boom stems installed and a C shaped structure to hold the induction furnace in place as it peels the slowly rotating asteroid. The sheet metal would go through rolling seals into the high-pressure processing chamber.

	For the acceleration at the end of the pressure chamber to be raised to a g would take a rotational speed of omega2 = 10/86400. That gives a period of about 9.7 minutes. The dust, everything plus the iron and nickel carbonyls, would fall outward against the ~~counter current~~ flow of CO.		For the acceleration at the end of the pressure chamber to be raised to a g would take a rotational speed of omega2 = 10/86400. That gives a period of about 9.7 minutes. The dust, everything plus the iron and nickel carbonyls, would fall outward against the countercurrent flow of CO.

	Excess CO would go out the inward end, possibly with some dust, and against the flow of new metal ribbons. The outward end would provide a 1 g environment in which to sort out the liquid carbonyls by fractional distillation.		Excess CO would go out the inward end, possibly with some dust, and against the flow of new metal ribbons. The outward end would provide a 1 g environment in which to sort out the liquid carbonyls by fractional distillation.
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	A byproduct is finely powdered iron. An efficient way to use this as reaction mass would lower the cost of cargo return to the Earth. A co-product could be Invar, but in amounts far beyond what the largest possible power-satellite project could use.		A byproduct is finely powdered iron. An efficient way to use this as reaction mass would lower the cost of cargo return to the Earth. A co-product could be Invar, but in amounts far beyond what the largest possible power-satellite project could use.

	After removing the iron and nickel, sorting out the valuable elements from the stream will not be particularly challenging or energy intense, i.e., wet chemistry, ~~electrowining~~, ion exchange, etc. Of course, the plant will have to be configured to regenerate acids or other reagents needed in the process.		After removing the iron and nickel, sorting out the valuable elements from the stream will not be particularly challenging or energy intense, i.e., wet chemistry, electrowinning, ion exchange, etc. Of course, the plant will have to be configured to regenerate acids or other reagents needed in the process.

	While this looks like an extremely profitable mining operation, many questions need to be researched to refine the design and economic analysis. For example, at what rate does high-pressure carbon monoxide eat away the surface of asteroid metal? Do the other elements, particularly cobalt, retard the attack?		While this looks like an extremely profitable mining operation, many questions need to be researched to refine the design and economic analysis. For example, at what rate does high-pressure carbon monoxide eat away the surface of asteroid metal? Do the other elements, particularly cobalt, retard the attack?

	Back in 1990 Dr. John Lewis (now Chief Scientist for Deep Space Industries) did extensive experiments on digesting iron meteorite specimens in a CO pressure bomb, including the catalytic effects of adding other gases to the CO. (The work was done by Muralidharan and Freiser in the UofA's Strategic Metals Recovery ~~Reseatrch~~ Facility under funding from our Space Engineering Research Center.)		Back in 1990 Dr. John Lewis (now Chief Scientist for Deep Space Industries) did extensive experiments on digesting iron meteorite specimens in a CO pressure bomb, including the catalytic effects of adding other gases to the CO. (The work was done by Muralidharan and Freiser in the UofA's Strategic Metals Recovery Research Facility under funding from our Space Engineering Research Center.)

	While I think asteroid mining for gold and platinum is a ways off, it also seems to be a natural outgrowth of a large power satellite program. Indeed, it could provide some of the motivation to build the transport system for power satellites, if solving energy and carbon problems isn't enough.		While I think asteroid mining for gold and platinum is a ways off, it also seems to be a natural outgrowth of a large power satellite program. Indeed, it could provide some of the motivation to build the transport system for power satellites, if solving energy and carbon problems isn't enough.

Hkhenson: /* Process details */ updates

2015-05-07T15:29:20Z

Process details: updates

← Older revision		Revision as of 15:29, 7 May 2015
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	While steel can hold the pressure, the inside lining can't be iron or nickel. Gold perhaps-- or plastic.		While steel can hold the pressure, the inside lining can't be iron or nickel. Gold perhaps-- or plastic.

	The rotation of 1096 DC is 0.149 day, making the period 12873.6 s. Omega is 0000488 radians per second. The outward end of an 86.4 km long object would be subject to an acceleration of ~0.02 m/s^2 or about 1/500th of a g, not useful.		The rotation of 1096 DC is 0.149 day, making the period 12873.6 s. Omega is .0000488 radians per second. The outward end of an 86.4 km long object would be subject to an acceleration of ~0.02 m/s^2 or about 1/500th of a g, not useful.

	I am assuming the asteroid has north and south polar boom stems installed and a C shaped structure to hold the induction furnace in place as it peels the slowly rotating asteroid. The sheet metal would go through rolling seals into the high-pressure processing chamber.		I am assuming the asteroid has north and south polar boom stems installed and a C shaped structure to hold the induction furnace in place as it peels the slowly rotating asteroid. The sheet metal would go through rolling seals into the high-pressure processing chamber.

← Older revision		Revision as of 05:36, 30 December 2018
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	The next question is how much extraction plant would it take to process an asteroid such as 1986 DA.		The next question is how much extraction plant would it take to process an asteroid such as 1986 DA.

	Back in the '70s, Dr. Eric Drexler and I designed a solar powered plant to vapor deposit aluminum or steel (See "Vapor-phase Fabrication of Massive Structures in Space "). We worked out that the plant could vaporize its own mass in aluminum every eight hours.		Back in the '70s, Dr. Eric Drexler and I designed a solar-powered plant to vapor deposit aluminum or steel (See "Vapor-phase Fabrication of Massive Structures in Space "). We worked out that the plant could vaporize its own mass in aluminum every eight hours.

	Separating metals might take two or three times ~~that much~~ plant, especially given the weaker sunlight in the asteroid belt. I have previously considered a 50,000-ton processing plant able to provide power-satellite Invar (35% nickel) construction sheet. I sized it to produce its own mass in nickel every 50 days processing a metal asteroid such as 1986 DA [http://lists.extropy.org/pipermail/extropy-chat/2009-March/048350.html] and slide 90 [www.nss.org/settlement/ssp/library/CO2andSpaceResources.ppt]. The delta V between GEO and this asteroid can be as low as 140 m/s.		Separating metals might take a two or three times larger plant, especially given the weaker sunlight in the asteroid belt. I have previously considered a 50,000-ton processing plant able to provide power-satellite Invar (35% nickel) construction sheet. I sized it to produce its own mass in nickel every 50 days processing a metal asteroid such as 1986 DA [http://lists.extropy.org/pipermail/extropy-chat/2009-March/048350.html] and slide 90 [www.nss.org/settlement/ssp/library/CO2andSpaceResources.ppt]. The delta V between GEO and this asteroid can be as low as 140 m/s.

	(The high mass estimate was due to including a full-scale power satellite and a substantial habitat for several hundred plant operators and their families.)		(The high mass estimate was due to including a full-scale power satellite and a substantial habitat for several hundred plant operators and their families.)
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	The assumed market was Invar for second-generation power satellites. It's a tiny 10,000-ton per day pilot plant by comparison to a serious gold mining project. Out of ten million kg/day, it would recover ~7.5 kg of gold and around 30 kg of platinum group elements worth about $700 million a year. That's just noise in the context of $700 B per year from power satellite construction.		The assumed market was Invar for second-generation power satellites. It's a tiny 10,000-ton per day pilot plant by comparison to a serious gold mining project. Out of ten million kg/day, it would recover ~7.5 kg of gold and around 30 kg of platinum group elements worth about $700 million a year. That's just noise in the context of $700 B per year from power satellite construction.

	To recover 625 tons of gold per year given gold at 0.75 ppm would mean processing 900 million tons per year or about 25 million tons per day. 1986 DA at 22,000 million tons would last at that rate for 24 years.		To recover 625 tons of gold per year given gold at 0.75 ppm would mean processing 900 million tons per year or about 2.5 million tons per day. 1986 DA with a mass of 22,000 million tons would last at that rate for 24 years.

	This is about the right project size for 1986 DA given that processing plants for mines usually use up an ore body in 25-30 years. For example [http://www.mercatorminerals.com/s/MineralParkMine.asp]		This is about the right project size for 1986 DA given that processing plants for mines usually use up an ore body in 25-30 years. For example [http://www.mercatorminerals.com/s/MineralParkMine.asp]
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	The first step in concentrating metals from low-grade ores is often the most expensive. The amount of valuable metals in an asteroid is not much different from a current gold mine processing 3-ppm ore. It will take a different method from crushing rock; asteroid iron is on a par with giant anvils.		The first step in concentrating metals from low-grade ores is often the most expensive. The amount of valuable metals in an asteroid is not much different from a current gold mine processing 3-ppm ore. It will take a different method from crushing rock; asteroid iron is on a par with giant anvils.

	By rough analogy to the work Drexler and I did, the processing plant might mass 25 million tons. That's a lot. Even by the standard of a half-million-ton-per-year power-satellite project, it would take 50 years to lift that much off the Earth.		By rough analogy to the work Drexler and I did, the processing plant might mass 2.5 million tons (i.e., it process the plant mass in a day). That's a lot. Even by the standard of a half-million-ton-per-year power-satellite project, it would take 5 years to lift that much off the Earth.

	Still, we can plug in numbers. A scheme I have worked on is to lift power parts to GEO using a combination of air-breathing rocket planes (Skylon) followed by ~~ground~~ powered ~~arcjets~~ for lifting 15,000 ton cargo blocks from LEO to GEO. The proposed cost is slightly under $200/kg. This is a LEO-to-GEO velocity change of about 4 km/s. It's ~~probable~~ (especially at this scale) to get the cost for transporting a mining and processing plant to 1986 DA down to $300/kg (a delta V of around 7.1 km/s from LEO).		Still, we can plug in numbers. A scheme I have worked on is to lift power parts to GEO using a combination of air-breathing rocket planes (Skylon) followed by arcjet tugs powered small power satellites for lifting 15,000-ton cargo blocks from LEO to GEO. The proposed cost is slightly under $200/kg. This is a LEO-to-GEO velocity change of about 4 km/s. It's probably possible (especially at this scale) to get the cost for transporting a mining and processing plant to 1986 DA down to $300/kg (a delta-V of around 7.1 km/s from LEO).

	That would cost $7.5 ~~T for a 25~~-million-ton processing plant. Just for the transport cost, that's already more than ten ~~times~~ the permitted capital budget.		That would cost $750 B for a 2.5-million-ton processing plant. Just for the transport cost, that's already more than ten the permitted capital budget.

	==Bootstrapping==		==Bootstrapping==