Hundred dollars a kg - Revision history

Hkhenson: /* Second approach */

2011-03-15T12:34:46Z

Second approach

← Older revision		Revision as of 12:34, 15 March 2011
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	==Second approach==		==Second approach==

	Getting to GEO, ~14 km/sec seems to require 2 stages. The question is "where to stage" with the practical problem of getting the first stage back to the takeoff point.		Getting to GEO, ~14 km/sec seems to require 2 stages. The question is "where to stage" with the practical problem of getting the first stage back to the takeoff point. By going into LEO the vehicle can be returned to the launch point after one or more orbits.

	Going back to the fundamentals of the rocket equation, single stage to orbit needs about 9 km/sec average exhaust velocity.		Going back to the fundamentals of the rocket equation, single stage to orbit needs about 9 km/sec average exhaust velocity.
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	A variant of this concept was reported here: http://www.foxnews.com/scitech/2011/01/25/nasa-exploring-lasers-beams-zap-rockets-outer-space/		A variant of this concept was reported here: http://www.foxnews.com/scitech/2011/01/25/nasa-exploring-lasers-beams-zap-rockets-outer-space/

			==Geometry issues==

			The long acceleration required for relatively low laser power means the laser needs to track the vehicle across several thousand km of the Earth's equator. The obvious approach is to place redirection mirrors in GEO, send the laser beam up to them and have the mirrors track the vehicle as it accelerates into LEO.

			This means the lasers need to be 30-40 deg to the east of the takeoff point. There are not many combination of takeoff locations on the equator and locations where 10-12 GW of power can be drawn from the grid.

			The US has one of them, Jarvis island for the takeoff and Sylmar or some other location on the Pacific Intertie for the lasers.

			The Maldives and Three Gorges Dam would work for China.

			Brazil and Spain or Portugal are another.

			Somalia and a location in India would work, but the grid infrastructure is light in India.

	==Other uses for a laser==		==Other uses for a laser==

Hkhenson: /* First method */

2011-03-15T12:25:08Z

First method

← Older revision		Revision as of 12:25, 15 March 2011
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	The normal rule of thumb for laser propulsion from the ground is a MW/kg or a GW/tonne. Because the laser stage is not fighting gravity or air drag, "pop up and push" needs only 4 GW for a 25 tonne payload.		The normal rule of thumb for laser propulsion from the ground is a MW/kg or a GW/tonne. Because the laser stage is not fighting gravity or air drag, "pop up and push" needs only 4 GW for a 25 tonne payload.

	==Second approach==		==Second approach==

	Getting to GEO, ~14 km/sec seems to require 2 stages. The question is "where to stage" with the practical problem of getting the first stage back to the takeoff point.		Getting to GEO, ~14 km/sec seems to require 2 stages. The question is "where to stage" with the practical problem of getting the first stage back to the takeoff point.

Hkhenson: /* Cost reduction */

2011-03-15T12:18:22Z

Cost reduction

← Older revision		Revision as of 12:18, 15 March 2011
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	The normal rule of thumb for laser propulsion from the ground is a MW/kg or a GW/tonne. Because the laser stage is not fighting gravity or air drag, "pop up and push" needs only 4 GW for a 25 tonne payload.		The normal rule of thumb for laser propulsion from the ground is a MW/kg or a GW/tonne. Because the laser stage is not fighting gravity or air drag, "pop up and push" needs only 4 GW for a 25 tonne payload.

	==~~Cost reduction~~==		==Second approach==
	~~Second method~~

	Getting to GEO, ~14 km/sec seems to require 2 stages. The question is "where to stage" with the practical problem of getting the first stage back to the takeoff point.		Getting to GEO, ~14 km/sec seems to require 2 stages. The question is "where to stage" with the practical problem of getting the first stage back to the takeoff point.

Hkhenson: /* Rockets and lasers—pop up and push */

2011-03-15T12:16:54Z

Rockets and lasers—pop up and push

← Older revision		Revision as of 12:16, 15 March 2011
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	http://www.nss.org/settlement/ssp/library/CO2andSpaceResources.ppt		http://www.nss.org/settlement/ssp/library/CO2andSpaceResources.ppt

	~~==Cost reduction=~~= First method		=First method=

	There is another way that cuts the liftoff mass by a factor of five compared to rockets.		There is another way that cuts the liftoff mass by a factor of five compared to rockets.

Hkhenson: /* Cost reduction */

2011-03-15T12:11:00Z

Cost reduction

← Older revision		Revision as of 12:11, 15 March 2011
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	http://www.nss.org/settlement/ssp/library/CO2andSpaceResources.ppt		http://www.nss.org/settlement/ssp/library/CO2andSpaceResources.ppt

	==Cost reduction==		==Cost reduction== First method

	There is another way that cuts the liftoff mass by a factor of five compared to rockets.		There is another way that cuts the liftoff mass by a factor of five compared to rockets.
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	The normal rule of thumb for laser propulsion from the ground is a MW/kg or a GW/tonne. Because the laser stage is not fighting gravity or air drag, "pop up and push" needs only 4 GW for a 25 tonne payload.		The normal rule of thumb for laser propulsion from the ground is a MW/kg or a GW/tonne. Because the laser stage is not fighting gravity or air drag, "pop up and push" needs only 4 GW for a 25 tonne payload.

			==Cost reduction==
			Second method

			Getting to GEO, ~14 km/sec seems to require 2 stages. The question is "where to stage" with the practical problem of getting the first stage back to the takeoff point.

			Going back to the fundamentals of the rocket equation, single stage to orbit needs about 9 km/sec average exhaust velocity.

			A UK project by Reaction Engines is the Skylon. The people who designed it think they can get 12 tons into LEO. It gets up to 26 km and 2 km/sec on wings burning hydrogen and air. Back calculated from fuel consumption it has a truly remarkable 10.5 km/sec equivalent exhaust velocity.

			If the vehicle swaps internal oxygen for payload and the hydrogen is heated by 6 GW of laser, then a Skylon derived vehicle should be able to put 1/3 of its takeoff mass in LEO. For a takeoff of 300 tons (smaller than the smallest 747) and a vehicle mass of 50 tons, that means each launch would put 50 tons in LEO. Again given laser heating to 3000 deg K, 35 of that 50 tons should reach GEO. Using a entirely reasonable take off rate of 3-4 per hour, this transport system would put around a million tons per year in GEO. At 5kg/kW that would build 200 GW of new plants per year. It would only take a decade or two to get the world entirely off coal and nuclear power sources.

			A variant of this concept was reported here: http://www.foxnews.com/scitech/2011/01/25/nasa-exploring-lasers-beams-zap-rockets-outer-space/

	==Other uses for a laser==		==Other uses for a laser==

Hkhenson: /* How much lifted to GEO */

2009-08-31T03:23:55Z

How much lifted to GEO

← Older revision		Revision as of 03:23, 31 August 2009
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	==How much lifted to GEO==		==How much lifted to GEO==

	Five hundred [[gigawatt\|GW]] of [[solar power satellite\|power sat]]s at 2kg/kW requires 1 million tons (a billion kg) per year lifted to GEO ~~(perhaps~~ 2.5 times that if power sat mass can't be reduced below 5kg/kW).		Five hundred [[gigawatt\|GW]] of [[solar power satellite\|power sat]]s at 2kg/kW requires 1 million tons (a billion kg) per year lifted to GEO. More likely 2.5 times that if power sat mass can't be reduced below 5kg/kW).

	Do we have to lift that much mass? No. Extra terrestrial resources are a better idea, but there isn't time to develop the space industry to tap them. The economic effects (including famines) of the developing energy crisis are so bad that the large scale production of SBSP needs to come on line by 2015 to avoid economic collapse. Expect ET resources to be exploited by 2025 with this much activity in space.		Do we have to lift that much mass? No. Extra terrestrial resources are a better idea, but there isn't time to develop the space industry to tap them. The economic effects (including famines) of the developing energy crisis are so bad that the large scale production of SBSP needs to come on line shortly after 2015 to avoid economic collapse. Expect ET resources to be exploited by 2025 with this much economic activity in space.

	One million tonnes/years is in excess of 100 tonnes per hour. Will physics let us get under $100/kg? A [[moving cable space elevator]] only requires about 15 kWh to lift a kg from the surface of the earth to GEO (1.5 GW will lift 100t/hr). This is $1.50 at the high rate of 10 cents a kWh. Even if it cost $100 billion dollars to build, a capital cost of $10 billion a year lifting a billion kg is only ten dollars per kg. Unfortunately we don't have the cable – yet.		One million tonnes/years is in excess of 100 tonnes per hour. Will physics let us get under $100/kg? A [[moving cable space elevator]] only requires about 15 kWh to lift a kg from the surface of the earth to GEO (1.5 GW will lift 100t/hr). This is $1.50 at the high rate of 10 cents a kWh. Even if it cost $100 billion dollars to build, a capital cost of $10 billion a year lifting a billion kg is only ten dollars per kg. Unfortunately we don't have the cable – yet.

Hkhenson: /* Rockets or lasers? */

2009-04-24T17:10:17Z

Rockets or lasers?

← Older revision		Revision as of 17:10, 24 April 2009
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	Rockets are good for high thrust, but the {{wpalt\|Tsiolkovsky rocket equation\|rocket equation}} is a hard taskmaster when you need [[delta V]] that is a significant multiple of the exhaust velocity.		Rockets are good for high thrust, but the {{wpalt\|Tsiolkovsky rocket equation\|rocket equation}} is a hard taskmaster when you need [[delta V]] that is a significant multiple of the exhaust velocity.

	The root problem spaceflight has had all along is the rocket equation. All the problems flow from the fact that at best one part in 60 of the liftoff mass gets to GEO or lunar orbit. Here is the rocket equation in graphical form.		The root problem spaceflight has had all along is the rocket equation. All the problems flow from the fact that at best one part in 60 of the liftoff mass gets to GEO or lunar orbit. Here is the rocket equation in graphical form.

	~~http://en.wikipedia.org/wiki/File~~:Rocket_mass_ratio_versus_delta-v.png		[[Image:Rocket_mass_ratio_versus_delta-v.png]]

	And here is what is needed in delta V.		And here is what is needed in delta V.

Hkhenson: /* Rockets and lasers—pop up and push */

2009-04-21T02:34:14Z

Rockets and lasers—pop up and push

← Older revision		Revision as of 02:34, 21 April 2009
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	==Rockets and lasers—pop up and push==		==Rockets and lasers—pop up and push==

	~~This~~ is ~~a proposal~~ to combine the high thrust of rockets with the high exhaust velocity of ablation laser propulsion. It allows large payloads to be sent to GEO using relatively small lasers. The reason it works is that it matches the stage exhaust velocity to the mission velocity allowing small mass ratios.		The $100/kg proposal is to combine the high thrust of rockets with the high exhaust velocity of ablation laser propulsion. It allows large payloads to be sent to GEO using relatively small lasers. The reason it works is that it matches the stage exhaust velocity to the mission velocity allowing small mass ratios.

	Of the 14 km/sec needed to GEO, the rocket part of the pop up and push will provide about 2 km/sec.		Of the 14 km/sec needed to GEO, the rocket part of the pop up and push will provide about 2 km/sec.

Hkhenson: /* Rockets and lasers */

2009-04-21T02:32:41Z

Rockets and lasers

Show changes

Hkhenson: /* Rockets and lasers */

2009-04-11T02:11:31Z

Rockets and lasers

← Older revision		Revision as of 02:11, 11 April 2009
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	==Rockets and lasers==		==Rockets and lasers==

	The root problem spaceflight has had all along is the rocket equation. All ~~sins~~ flow from the fact that at best		The root problem spaceflight has had all along is the rocket equation. All the problems flow from the fact that at best
	one part in 60 of the liftoff mass gets to GEO or lunar orbit. Here it is in graphical form.		one part in 60 of the liftoff mass gets to GEO or lunar orbit. Here it is in graphical form.