If this is a good idea (and I doubt it) the orbit of the particles would have to be limited so they are easy to steer round.
Horace Heffner wrote:
At 7:12 PM 2/9/5, revtec wrote:
God stuff is considered off topic in this forum, but I'm covinced that it
is central. Our perception of threats to our existance is directly linked
to our perception of God. Our attitudes toward "God sized" problems are
determined by our concept of God. The thermal condition of this planet is
set by the output of the sun. Compared to a one or two percent
fluctuation in solar radiation, anything humans can do down here is
totally irrelevant.
A more complete answer and some corrections, follow. Note last paragraph.
The objective of achieving even a 10 percent reduction in solar insolation factor seems to me to be feasible. This might be met by dispersing orbiting aluminum (or CaO, or lunar soil) nanopowder from latitudes 50 to -50, at, say, an altitude of about 800 km. This might be accomplished by deploying a ring of satellites that orbit between those latitudes, and then firing rockets in a direction normal to the direction of travel and a radial line through the earths center and such a satellite. The rocket firing would thus not change the orbit altitude, only the poles of the orbit. In this manner the nanpowder would be deployed at a constant altitude. During the firing the nanopowder would be deployed, possibly into the exhaust. It might be possible to design an electric rocket that uses the nanopowder as a reaction mass, and which runs on solar power.
It is presently possible to obtain metal nanopowders of dimension 8 nm. These then have volume of (8x10^9 m)^3 = 5.12x10^-22 m^3/particle, or 1.95x10^21 particles/m^3 of, say, aluminum. Aluminum weighs 2.70 g/cm^2 = 2700 kg/m^3. There is thus (1.95x10^21 particles/m^3)/(2700 kg/m^3) = 7.22x10^17 particles/kg.
If we assume that one such particle can reflect incoming photons of about 10^-6 m wavelength about 10 percent of the time within a radius of 10^-6 m, then each nanoparticle has the required coverage of Pi*(10^-6 m)^2 = 3.14x10^-12 m^2. This gives a coverage of (7.22x10^17 particle/kg)(3.14x10^-12 m^2/particle) = 2.98x10^6 m^2/kg.
The radius of the earth is 6.38x10^6 m, and if we deploy at 800 km then the effective radius of our deployment sphere is 7.18x10^6 m. Given that the area of the zone of a sphere is 2 Pi R h, the total deployment area is 2*Pi*(7.18x10^6 m)*((7.18x10^6 m)*sin(50 deg.)) = 2*Pi*(7.18x10^6 m)^2*(.766) = 4.96x10^14 m^2.
The total deployed mass is thus (4.96x10^14 m^2)/(2.98 m^2/kg) = 1.66x10^8 kg, or 166,000 metric tons.
Assuming the deployment of this amount of payload can get the price down to $10,000/kg, the cost of deployment is (1.66x10^8 kg)($10,000/kg) = $1.66x10^12. The price of, for a limited time, saving the earth when it is at the defined point of stress is about 1.7 trillion dollars.
The worst assumption in this rough first estimate is probably the assumption that an 8 nanometer particle can provide 10 percent reflection back into space of low infrared to visible radiation, radiation averaging about 10^-6 m wavelength, over an area about (10^-6 m)^2. If lunar soil is used, then much less energy is requred to get it into orbit and transport it, so there is no practical constraint the mass that can be moved in a multi-trillion dollar project.
Hopefully such a dispersal will be planned to occur at sufficient altitude that it will last long enough for us, or subsequent generations, to solve the global warming problem.
This is really a last ditch effort, and may be totally unnecessary. There is enough methane hydrate in the Northern hemisphere to meet all our needs for generations, probably well over 1x10^14 CF. If that gas can be produced and converted to hydrogen, without burning the carbon in the process, and all the carbon in the gas is converted to construction materials, the carbon dioxide in the earth's atmosphere hopefully would diminish at a sufficient rate to avoid runaway warming.
Elimination of all of mankind's energy consuption is about equal to a half of a tenth of a percent decrease in energy trapped by the greenhouse effect. Similarly, if we reduced the solar input by a similar amount, roughly 0.04 percent, we could double our energy use with no net effect - provided there were no additional greenhouse gases generated. It is the emission and retention of greenhouse gasses that is the problem, not the waste heat from energy generation/utilization. Annual world energy use is about 1/2000 the energy the energy the sun sends us each year.
The world energy consumption is about 400 quads/year, i.e. 400x10^15 BTU/y = 1.17x10^14 kWh/y, and is forecast to be about 470 quads in 2010. The world power consumption is thus roughly (1.17x10^14 kWh/y)/((365 d/y)*(24 h/d)) = 1.34x10^10 kW.
The sun puts out roughly a kW/m^2, the earth's radius is 6.38x10^6 m, so the earth presents about 3.2x10^13 m^2 cross section to the sun, thus obtains energy at a rate of about 3.2x10^13 kW from the sun. The total energy consumed by humanity is equivalent to an increase in solar insolation factor by about 0.04 percent, i.e. could be offset by a reduction of solar energy absorbed by about 0.04 percent.
However, since the energy provided by CF would for the most part *replace* carbon based fuel consumption, it is mostly an offset, thus global warming due to massive CF energy use would not occur. If we keep our nuclear plants and maintain our rate of energy consumption then it is a full offset, meaning no net change. A large reduction in CO2 generation would occur, and without change to the overall energy balance. This should eliminate the greehouse effect, provided methane release and high altitude water vapor concentrations have not pushed us to the no return level.
Depending on God to fix atmospheric environmental problems of our making, like acid rain, the greenhouse effect, massive storms, and huge forest fires, is not a reliable strategy for humanity. It is no more likely to be successful for us than relying on God to clean up any other environmental problems we have made, like Chernobyl, Hanford, Love Canal, West Virginia open pit coal mines, the Detroit River, Lake Erie, etc. It is rather like jumping in front of a speeding bus and expecting to be miraculously saved. As John F Kennedy said: "On this earth God's work must truly be our own".
Regards,
Horace Heffner
