jedcstuff

2008-10-24

More on a Solar Power Satellite demo project

Although the goal of beaming enough solar energy derived power down from space , as envisaged by Coyote's project, is not the first physical implementation of delivery of useful amounts of solar satellite derived power down to the earth's surface - as previously pointed out, that is already being done all over the world, wherever there is a satellite dish aimed at a communication satellite in GEO right now, getting a TV program's signal, is receiving solar energy picked up by solar panels located ing GEO and being converted into EMF energy and transmitted down to earth and being picked up on the ground at one's satellite dish, the usefulness being not to light a LED but to provide the information bandwidth to the receiving antenna - there would be huge leaps in technology advancement by the project envisioned by Coyote. That is because Coyote's project would deliver solar-derived useful power down to earth from a low earth orbit satellite, which means it adds the parameters of focusing a tracking beam linking two relatively moving points.

In the original concept of the Solar Power Satellite, the transmitter in space and the receiving antenna on the earth surface are relatively motionless, so the tracking requirements are much lower than those of a relatively fast moving focal area as exampled by beaming down from low earth orbit to a fixed location on the ground. Beaming gigawatts down from GEO to a rectifying antenna - usually called a "rectenna" - would need to be focused on an area with a diameter typically 12 miles in diameter, to keep the intensity of EMF energy no more than the sum energy of sunlight received anywhere on the antenna or in the beam coming down through the atmosphere, for safety reasons.

In the demonstration project, however, the rectenna needs to be quite small; thus the requirement to focus the EMF energy down to a much smaller area. This demonstration capability would be a major step beyond that currently being done by communication satellites in GEO at the present time.

And being able to track relatively moving focal site could thus enable delivery energy to the ground or in the air from a SPS in GEO, say, to a moving vehicle. In an age where fossil fuels usage on large scale could also hamper its use in large aircraft, such as commercial airliners and cargo planes, the ability to deliver energy to a moving vehicle in the prodigious amounts consumed by a large jet aircraft nowadays, means a much tighter beam and energy density focal area. Such large commercial jet aircraft would be shaped different from conventional aircraft, the swept back leading wing edges becoming a large flat area on top of the aircraft used as the rectenna to receive the power beamed from the SPS in GEO; such aircraft would also need much less energy to propel them since they would not need to lift the weight of the fuel for the trip nor the airframe needed for that; and that converts down to less engine power requirements, electrically propelled aircraft engines in this case; and in fact could be built as supersonic lighter than air vehicles - see my description of this kind of aircraft in my science fiction novel online, http://www.escalatorhi.com/techscifi/it's%20down%20to%20earth.html chapter 22 "A new kind of aircraft" about 3/5 down the long page; actually its description begins in the preceding chapter 21's end - such large commercial aircraft would thus be able to deliver people and cargo much as today's large jetliners, except without consuming expensive jet fuel nor its exhaust's atmospheric contamination of huge amounts of carbon dioxide greenhouse gasses each trip as done nowadays.

The ability to focus down to focal areas on a moving target bring up the old fears of misuse of the SPS for assaultive purposes, of course. The military uses of such a weapon have long brought caution to people regarding the establishment of SPS in space; memories of such destructive uses of loosed nuclear energy technology are still fresh in our minds, do we want to loose another strong genie out of the bottle too? Yet it is a case of the proverbial "playing with fire" risk; same as the use of fire that brought early man out of savagery; and also into the electrical age we now live in, which was once considered "electrical fire " - see the 1752 public impression of electrical energy "Electrical FIRE" http://www.escalatorhi.com/JimDabblingH/popelec1752.html - an energy of which somehow we overcame our fear of misuse; and so it now, for example, powers my refrigerator to keep my food from spoiling, and heats my house this cold night and will continue to heat it through the cold winter snows, since we generally learned to use "electrical fire" responsibly - do we want to go back to the days where we had no electrical power to use - I for one am not eager to go back to getting up in each morning in a freezing house to stuff firewood into the potbellied stove, nor to breathe the resulting smokey air outside all day either.

Similarly we ought to be able to responsibly use power beamed down from space; although we will have to do that consciously and deliberately, hopefully not after some warfare technology race to stimulate its development but rather its wisely intelligent responsible controlled usage by all nations potentially involved, even moreso than the International Space Station project has been. We hopefully have learned to be wise enough to quickly and responsibly learn to safely and responsibly utilize this potentially tremendous new 24/7 power source responsibly, carefully utilizing, instead of "playing with" this new kind of "fire," a next step for building a civilization based on cheap abundant continuous large scale energy to do our work for us, work far beyond the potentials of man's own muscles.

So all these kinds of issues can be explored by the project envisioned as a low earth orbit satellite speeding across the sky, beaming down less than a watt of solar-derived space power to a small area receiver on the ground.

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