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How sustainable is our current model of civilization?


Off-Topic Discussions

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According to what I could easily find on ye Int4rw3bz, admittedly a wikipedia article, 23 mW/cm2 seems to be the intended intensity at the collection/target point. Safety regulations set a limit of 10 mW/cm2, which means that you could stand on it and nothing much happens. So add in a dozen or so of these 23 mW/cm2 beams, which penetrate pretty well thanks to not getting interrupted by water, and you will have a rather sharp effect to deal with.

As for me protesting: Well, the defining streak of my political views is anti-authoritarianism and anti-totalitarianism. You should not be so surprised about my reactions. But hey, I am not saying it is impossible. Just put the schematics and software out as open source, and I am a happy camper. Allowing someone to put something like that in orbit without having it open source is sheer stupidity.


Sissyl wrote:
According to what I could easily find on ye Int4rw3bz, admittedly a wikipedia article, 23 mW/cm2 seems to be the intended intensity at the collection/target point. Safety regulations set a limit of 10 mW/cm2, which means that you could stand on it and nothing much happens. So add in a dozen or so of these 23 mW/cm2 beams, which penetrate pretty well thanks to not getting interrupted by water, and you will have a rather sharp effect to deal with.

You still miss the point... What effect ? You will just get soaked in quite harmless long wave microwave radiation, as your water molecules will stay nice and put.

Either you have short wave microwave radiation, and the beam never reach the ground; either you have long wave microwave radiation, and the beam does, going through the water molecules suspended in the atmosphere... and then through yours, without harming you.

It's the agitation of water molecules which gives to (the shorter lenght) microwaves their heating effect. Otherwise, they are as harmless as their closest (lenghtier wave lenght) neighbour the infrared radiation.

EDIT : going open source is nice, but how will you know that the program you peruse is the same that the one on the satellite ? Bwahahaha !


CBDunkerson wrote:
Sissyl wrote:
An extremely light cable several thousand miles long, yes. I haven't done the maths, no, but I doubt the media of the future won't either.

Yes... because everyone knows that while a feather falls slowly and gently to the ground, if you had a feather thousands of miles long it would plummet like a rock.

Make believe physics sez so!

Actually it would. Surface area to weight ratio is what drives air resistance. As size goes up, the ratio drops.

Drop a feather pillow. Notice how it lightly wafts to the floor.


I don't think there is really a problem with low-level microwave exposure, likely not even for pretty long periods. We live in an oxygen atmosphere, which is really a severely dangerous substance, just one we have adapted to. And I am aware that short-wave microwave exposure (like the ADS or microwave ovens) doesn't penetrate much, and damages by heating water molecules. That is not what I am talking about. ANY radiation will heat the exposed volume due to the energy imparted, and if there is enough, tissue will get burnt. With longer wave radiation, you can heat someone's entire volume, penetrate thin walls, and so on. Sure, you would not get the shorter wave water heating, but the exposed volume would still warm up, and with a high enough intensity, you could easily kill someone like that. And no, I would not be able to know about the software. I would just be justifiably opposed to any such project unless those implementing it can show sufficiently well that this is in fact the case.

As for thousand-mile cables, well, it may not be quite as simple as all that. If the cable snapped, the top would be unattached and start moving unpredictably, generally directed downward. It would clump and aggregate on its way down, and even though every section does not weigh much, it is specifically tough enough to withstand the forces involved. It would mean a chaotic tension game, but be aware that the entire cable's weight is what you'd need to account for. It will remain together, not strewn into convenient centimeter-long elements for easy dispersal. I would not compare the forces to a pillow or a feather. I would compare it to a whip of ridiculous weight and several thousand miles in length. My guess is that many someones will have a very bad day as it comes down.


Sissyl wrote:
I don't think there is really a problem with low-level microwave exposure, likely not even for pretty long periods. We live in an oxygen atmosphere, which is really a severely dangerous substance, just one we have adapted to. And I am aware that short-wave microwave exposure (like the ADS or microwave ovens) doesn't penetrate much, and damages by heating water molecules. That is not what I am talking about. ANY radiation will heat the exposed volume due to the energy imparted, and if there is enough, tissue will get burnt. With longer wave radiation, you can heat someone's entire volume, penetrate thin walls, and so on. Sure, you would not get the shorter wave water heating, but the exposed volume would still warm up, and with a high enough intensity, you could easily kill someone like that. And no, I would not be able to know about the software. I would just be justifiably opposed to any such project unless those implementing it can show sufficiently well that this is in fact the case.

Okay. If you are going for the usual heating effect of electromagnetic radiation, you could also try a plain old huge parabolic mirror... In time, it will also heat what it is aimed to. Unless the aiming "point" is sidestepped of course (the microwave would be stealthier, I grant you that).

Could you link the page where you got technical specs ?

Not sure about the penetration power of microwave. The walls of my house are quite impervious to it : I have to go into the garden to get any signal on my cellphone. No time to look it up now though.

Oh, and I goofed : infrared lighht has got a shorter wavelenght that microwave, not the other way around. The closest to long wave microwave is radar.

Liberty's Edge

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CBDunkerson wrote:

Yes, natural gas releases CO2, but if we were using it only for backup night-time electricity generation total emissions would be low enough for atmospheric CO2 levels to begin (slowly) declining back towards natural levels.

DarkLightHitomi wrote:
Global warming is a natural process, even if humans have the largest effect on it right now (not saying I believe that)...

The term 'global warming' by itself just means that the globe is getting warmer due to ANY of the numerous things which can cause this. However, the term is currently used almost exclusively to refer to 'anthropogenic global warming'... warming caused by emissions of CO2 and other greenhouse gases due to human industry.

The term 'natural' is commonly used to refer to how things behave without human intervention. This was the usage I intended.

Ergo, no... global warming is NOT "a natural process" unless we are talking about some non-standard meaning of the terms.

I do hate semantic arguments.

DarkLightHitomi wrote:
...it is still a natural process and the planet is naturally going to get warmer, we are still in a very cold stage of the planet's cycle, it will get a lot hotter regardless of how much we help it along.

Ummm... no. A mere 15,000 years ago a large portion of the northern hemisphere was covered in sheets of ice more than a mile thick. Thus we are certainly not currently "in a very cold stage". Prior to the onset of AGW we were, in fact, at the peak of the current interglacial warm period. The natural progression would have been for temperatures to remain at around the level they had been for the past ~3000 years (with some minor variation up and down) for several thousand more years and then slowly begin descending towards another glaciation. That is, without AGW we would be looking at relatively stable, rather than warming, temperatures.

DarkLightHitomi wrote:
So no, there isn't going to be any decline in CO2 for a very, very long time, unless humans artificially reduce it somehow.

Not exactly. The atmospheric CO2 level declines every year when the northern hemisphere (which has more land) enters Spring and new plant growth pulls massive amounts out of the air. Further, if we reduced our current industrial greenhouse gas emissions by roughly 50% the atmospheric concentration would stabilize. If we reduce emissions by more than 50% then atmospheric concentrations would begin to decline immediately. It would take a very long time to return to ~280 ppm (the level which held steady with only tiny fluctuations for thousands of years before the industrial revolution) without some sort of artificial removal process, but there would be a small immediate drop followed by ongoing slow decline.

DarkLightHitomi wrote:
Natural levels are not some constant level that is somehow less then what it is now, as stated previously by others, the only debate about global warming is how much is humans vs how much is natural, so what makes you think that CO2 would decline, if CO2 would be increasing even without our help?

I know of no scientists who argue that the atmospheric CO2 increase from ~280 ppm to ~400 ppm was caused by anything other than human industry. If you believe such exist, please cite them. If you like I'll also be happy to show you the simple math which (like half a dozen other lines of evidence) proves that any such individuals are wrong. There are a handful of scientists (e.g. Spencer, Lindzen, Pielke, et cetera) who argue that some of the observed warming thus far (~0.8 C) has been due to some other factor. They just can't demonstrate what this magical other effect is. Or why the observed warming exactly matches the degree and 'fingerprints' expected of AGW.


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Sissyl wrote:


As for thousand-mile cables, well, it may not be quite as simple as all that. If the cable snapped, the top would be unattached and start moving unpredictably, generally directed downward.

If the cable is tight then the top will be pulled up.

Grand Lodge

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Sissyl wrote:

According to what I could easily find on ye Int4rw3bz, admittedly a wikipedia article, 23 mW/cm2 seems to be the intended intensity at the collection/target point. Safety regulations set a limit of 10 mW/cm2, which means that you could stand on it and nothing much happens. So add in a dozen or so of these 23 mW/cm2 beams, which penetrate pretty well thanks to not getting interrupted by water, and you will have a rather sharp effect to deal with.

Have there been any long term tests for things such as genetic damage? Key thing I'm thinking of in comparison is the airline industry. While occasional flying is fine for the bulk of us, those who work in the skies for a living are exposed to more radiation than us groundlings due to the weaker atmospheric shield up there.

The other major issue with beaming power from orbit is the tremendous loss in efficiency.

A more practical issue is maintenance, for the same reasons they are more efficient, solar panels in orbit degrade about 10 times faster. And there's all the junk up there as well.

Liberty's Edge

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thejeff wrote:

Actually it would. Surface area to weight ratio is what drives air resistance. As size goes up, the ratio drops.

Drop a feather pillow. Notice how it lightly wafts to the floor.

A feather pillow has much lower surface area than the feathers inside it.

You are correct about weight (i.e. volume * density * acceleration due to gravity) increasing faster if an object's size increases proportionally in all three dimensions. This is known as the square-cube law... if one dimension doubles (2^1) then area increases by 4 (2 squared) and volume by 8 (2 cubed).

However, that isn't what I was referring to. I was talking about something long and thin... like the space elevator cable under discussion. A feather thousands of miles long... but no wider or thicker than an ordinary feather. Size increased in only one dimension. In such a case a doubling of length results in a doubling of area and a doubling of volume (ergo also weight)... and no change in the ratio.

Better example - take a roll of thin ribbon streamer and tear off a short piece and a much longer piece. They will fall at exactly the same rate. The length is irrelevant. Ditto for space elevator cable.


CBDunkerson wrote:
thejeff wrote:

Actually it would. Surface area to weight ratio is what drives air resistance. As size goes up, the ratio drops.

Drop a feather pillow. Notice how it lightly wafts to the floor.

A feather pillow has much lower surface area than the feathers inside it.

You are correct about weight (i.e. volume * density * acceleration due to gravity) increasing faster if an object's size increases proportionally in all three dimensions. This is known as the square-cube law... if one dimension doubles (2^1) then area increases by 4 (2 squared) and volume by 8 (2 cubed).

However, that isn't what I was referring to. I was talking about something long and thin... like the space elevator cable under discussion. A feather thousands of miles long... but no wider or thicker than an ordinary feather. Size increased in only one dimension. In such a case a doubling of length results in a doubling of area and a doubling of volume (ergo also weight)... and no change in the ratio.

Possible. Assuming we can actually build something that thin, but still strong enough for the purpose. Every design I see requires it to be much thicker. Meters at least.

And that we purposely build it to maximize air resistance. Not a wire, but a feathered structure. Which adds weight without adding strength.
I assume you'd only do that up above most of the atmosphere. Where it actually has to deal with wind in use, you need to minimize air resistance.


Country music

Grand Lodge

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thejeff wrote:
CBDunkerson wrote:
thejeff wrote:

Actually it would. Surface area to weight ratio is what drives air resistance. As size goes up, the ratio drops.

Drop a feather pillow. Notice how it lightly wafts to the floor.

A feather pillow has much lower surface area than the feathers inside it.

You are correct about weight (i.e. volume * density * acceleration due to gravity) increasing faster if an object's size increases proportionally in all three dimensions. This is known as the square-cube law... if one dimension doubles (2^1) then area increases by 4 (2 squared) and volume by 8 (2 cubed).

However, that isn't what I was referring to. I was talking about something long and thin... like the space elevator cable under discussion. A feather thousands of miles long... but no wider or thicker than an ordinary feather. Size increased in only one dimension. In such a case a doubling of length results in a doubling of area and a doubling of volume (ergo also weight)... and no change in the ratio.

Possible. Assuming we can actually build something that thin, but still strong enough for the purpose. Every design I see requires it to be much thicker. Meters at least.

And that we purposely build it to maximize air resistance. Not a wire, but a feathered structure. Which adds weight without adding strength.
I assume you'd only do that up above most of the atmosphere. Where it actually has to deal with wind in use, you need to minimize air resistance.

You're talking about carrying a lot of current. There's simply no pratical way to build an electrical cable that would be about 25,000 miles long. That's the essential problem with skyhooks as well. Lots of things that look great on theory, but run into real problems in the engineering end.

Don't forget the base of such a wire would have to be on the Equator. You'd still have the issue of getting the power from THERE to where you want it on the grid.

Liberty's Edge

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thejeff wrote:
Possible. Assuming we can actually build something that thin, but still strong enough for the purpose. Every design I see requires it to be much thicker. Meters at least.

Estimates vary, but however 'wide' and 'thick' it is, we are agreed that the length of the cable is irrelevant to its terminal velocity, yes?


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DarkLightHitomi wrote:


Space elevators, you could do better by making a "chain" up to geosync orbit with a counterweight (by chain I mean several large round rings stacked in a chain, with the elevator space in the middle), and have mag lev elevators do the lifting rather then cable. Though I would much prefer to not put people in such a thing until it's proven safe for cargo for a while.

Of course even just cargo would make space colonizing feasable.

No, you can't do better with a chain. The stress concentrations on a chain are significantly higher than they are on a woven fabric. We currently have no matieral that can handle the stress from gravity as a woven fabric. That is not counting stresses caused by wind, which a fabric will handle better by being more flexible.

Stop assuming you know better than the people doing research in the field. There is a reason experts are developing the technology or making the claims that they are. If you aren't willing to look into why and keep throwing out baseless claims you are a hinderance to science.


I seem to remember a story in a mid-eighties issue of Analog about terrorists planting a bomb on a space elevator because as the cable (materiel undefined) hit the ground it would function like a whip hundreds of miles long. Any basis in physics there?


LazarX wrote:
Sissyl wrote:

According to what I could easily find on ye Int4rw3bz, admittedly a wikipedia article, 23 mW/cm2 seems to be the intended intensity at the collection/target point. Safety regulations set a limit of 10 mW/cm2, which means that you could stand on it and nothing much happens. So add in a dozen or so of these 23 mW/cm2 beams, which penetrate pretty well thanks to not getting interrupted by water, and you will have a rather sharp effect to deal with.

Have there been any long term tests for things such as genetic damage? Key thing I'm thinking of in comparison is the airline industry. While occasional flying is fine for the bulk of us, those who work in the skies for a living are exposed to more radiation than us groundlings due to the weaker atmospheric shield up there.

The other major issue with beaming power from orbit is the tremendous loss in efficiency.

A more practical issue is maintenance, for the same reasons they are more efficient, solar panels in orbit degrade about 10 times faster. And there's all the junk up there as well.

I think it is quite important to be clear on what effect we are talking about here. In general, electromagnetic radiation has no proven/clear dangerous effect on human tissue at low intensities. That is the mobile phone brain cancer debate. I heard something about it a while back, but there is from what I know nothing clear yet. The next issue is shortwave radiation heating water molecules a la microwave ovens. Longer wave radiation doesn't have that. However, send enough energy into a volume, no matter what kind, and you will heat the volume if there is something there to heat. This is not the typical situation. When we make new technologies work, we limit such radiation and there are usually no reasons to consider this. The only situation you would want that is, say, if you wanted to kill someone. You know, the military does not need to follow OSHA guidelines for the working environment of enemy troops and all that? I feel pretty certain a Hellfire detonation exceeds safe working condition regulations...

I got my admittedly quick info from the wikipedia page on Space based solar power. I am quite willing to discuss it if anyone has better data.

I know it is a known problem with airline personnel being exposed to higher radiation levels, but that pertains to long term low intensity damage. This is short term high intensity.

Regarding loss of efficiency: the energy needs to get from space to the Earth somehow, right? If it can do so as long wave microwaves, you get much better efficiency than collecting the sunlight down on the surface. That is the entire point of the concept. Don't quote me on this, but 144% rings a bell.

But you are right on regarding degradation.


More country


Catprog wrote:
Sissyl wrote:


As for thousand-mile cables, well, it may not be quite as simple as all that. If the cable snapped, the top would be unattached and start moving unpredictably, generally directed downward.
If the cable is tight then the top will be pulled up.

My bad, should have been clearer. If the cable snaps, the top of the still tethered part of the cable will start sinking. I can just say it is a horrendously complex mathematical problem to chart the trajectory.


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Hitdice wrote:
I seem to remember a story in a mid-eighties issue of Analog about terrorists planting a bomb on a space elevator because as the cable (materiel undefined) hit the ground it would function like a whip hundreds of miles long. Any basis in physics there?

The cables they were thinking about in the 80s would be a problem. They imagined something like the steel cables on a suspension bridge, and when those snap it is dangerous. The current technology that is being developed is more of a wide ribon you can actually see through. They are testing it by launching balloons up to the point they may pop, and the ribon falls to the ground. Robots are sent up it to get readings of weather conditions so they can better model the stresses. These ribons are light weight and have high surface area, so their terminal velocity would not be that dangerous. They would still need large zones cleared in the event they fall, and because they can move with the wind they need even greater no fly zone around them.


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Sissyl wrote:
LazarX wrote:
Sissyl wrote:

According to what I could easily find on ye Int4rw3bz, admittedly a wikipedia article, 23 mW/cm2 seems to be the intended intensity at the collection/target point. Safety regulations set a limit of 10 mW/cm2, which means that you could stand on it and nothing much happens. So add in a dozen or so of these 23 mW/cm2 beams, which penetrate pretty well thanks to not getting interrupted by water, and you will have a rather sharp effect to deal with.

Have there been any long term tests for things such as genetic damage? Key thing I'm thinking of in comparison is the airline industry. While occasional flying is fine for the bulk of us, those who work in the skies for a living are exposed to more radiation than us groundlings due to the weaker atmospheric shield up there.

The other major issue with beaming power from orbit is the tremendous loss in efficiency.

A more practical issue is maintenance, for the same reasons they are more efficient, solar panels in orbit degrade about 10 times faster. And there's all the junk up there as well.

I think it is quite important to be clear on what effect we are talking about here. In general, electromagnetic radiation has no proven/clear dangerous effect on human tissue at low intensities. That is the mobile phone brain cancer debate. I heard something about it a while back, but there is from what I know nothing clear yet. The next issue is shortwave radiation heating water molecules a la microwave ovens. Longer wave radiation doesn't have that. However, send enough energy into a volume, no matter what kind, and you will heat the volume if there is something there to heat. This is not the typical situation. When we make new technologies work, we limit such radiation and there are usually no reasons to consider this. The only situation you would want that is, say, if you wanted to kill someone. You know, the military does not need to follow OSHA guidelines for the working environment of enemy troops and all...

Do you realize how large an area it would take, and how long it would take to do this? You are talking about baking someone from space by redirecting the power output from multiple power stations into 1 location. The time and effort that would require is rediculous, when they could just launch a missile from one of the many locations that can hit you at any time. The missile would probably have less collateral damage.


Wrong. The satellites need to have pretty exact precision to be able to hit the rectenna they are meant to send power to. There is also no reason to think it would take a long time. The human nervous system is pretty sensitive to heat, and holding a dozen or so satellite outputs there is likely a matter of seconds until the person fries. We aren't talking about doing more than raising the temperature of the brain a few degrees. If there is any point to this solar power scenario at all, the energy required is peanuts. Thus: Button pressed. Satellites direct their beams. Man somewhere dies in a few seconds. Satellites resume normal operation. Someone not targeted but nearby doesn't feel much of it at all. There is no significant collateral damage, except possibly the guy's mobile phone or laptop, perhaps some other electrical appliances are fried as well.

Liberty's Edge

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Because physics doesn't work that way.

You obviously don't know what you're talking about and have no interest in learning why you're wrong..


I am sure you will tell me, Krensky.


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Sissyl wrote:
Wrong. The satellites need to have pretty exact precision to be able to hit the rectenna they are meant to send power to. There is also no reason to think it would take a long time. The human nervous system is pretty sensitive to heat, and holding a dozen or so satellite outputs there is likely a matter of seconds until the person fries. We aren't talking about doing more than raising the temperature of the brain a few degrees. If there is any point to this solar power scenario at all, the energy required is peanuts. Thus: Button pressed. Satellites direct their beams. Man somewhere dies in a few seconds. Satellites resume normal operation. Someone not targeted but nearby doesn't feel much of it at all. There is no significant collateral damage, except possibly the guy's mobile phone or laptop, perhaps some other electrical appliances are fried as well.

From wikipedia"The Earth-based rectenna would likely consist of many short dipole antennas connected via diodes. Microwaves broadcasts from the satellite would be received in the dipoles with about 85% efficiency.[43] With a conventional microwave antenna, the reception efficiency is better, but its cost and complexity is also considerably greater. Rectennas would likely be multiple kilometers across"

Liberty's Edge

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Sissyl wrote:
I am sure you will tell me, Krensky.

I have. Repeatedly.

Grand Lodge

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Hitdice wrote:
I seem to remember a story in a mid-eighties issue of Analog about terrorists planting a bomb on a space elevator because as the cable (materiel undefined) hit the ground it would function like a whip hundreds of miles long. Any basis in physics there?

Not hundreds... THOUSANDS. What happens depends largely on where the break occurs. The real bad scenario is a break at or near the top which means the cable wraps itself around the entire Equator... and then some.


Krensky wrote:

Basically the beams interfere with each othe and the overlaped area bgets the same amount of energy as a single beam would provide. The rest of the energy winds up in the non-overlapping areas.

See, Krensky, this here is what I don't understand. Yes, there will be some interference. Parts of the rays will cancel one another out. What you are talking about is precision counter-wave interference, and if you'll allow me to do so, I sincerely doubt a dozen satellites in geostationary orbits could acheive that close to the Earth's surface. I would even go so far as to call that level of precision physically impossible. So... if we have one ray, that's 23 mW/cm2. Adding in a second will not get up to 46, but close. Adding in more, this effect will grow bigger but not total. You know... adding more lamps in a room does not usually mean only the first adds to the lighting situation.

Then you say that the rest of the energy will wind up in the non-overlapping areas. Whew. For some reason, then, instead of going forward into the overlapping area, the photons will bounce off the overlapped area that is already occupied by photons and instead deviate to the areas where the photon density is lower? I would love to hear an explanation of this.


Caineach wrote:
Sissyl wrote:
Wrong. The satellites need to have pretty exact precision to be able to hit the rectenna they are meant to send power to. There is also no reason to think it would take a long time. The human nervous system is pretty sensitive to heat, and holding a dozen or so satellite outputs there is likely a matter of seconds until the person fries. We aren't talking about doing more than raising the temperature of the brain a few degrees. If there is any point to this solar power scenario at all, the energy required is peanuts. Thus: Button pressed. Satellites direct their beams. Man somewhere dies in a few seconds. Satellites resume normal operation. Someone not targeted but nearby doesn't feel much of it at all. There is no significant collateral damage, except possibly the guy's mobile phone or laptop, perhaps some other electrical appliances are fried as well.
From wikipedia"The Earth-based rectenna would likely consist of many short dipole antennas connected via diodes. Microwaves broadcasts from the satellite would be received in the dipoles with about 85% efficiency.[43] With a conventional microwave antenna, the reception efficiency is better, but its cost and complexity is also considerably greater. Rectennas would likely be multiple kilometers across"

Okay... you mean this could only be used to extinguish entire population centers, leaving only dead people and the entire non-electrical infrastructure intact? Sure lucky nobody would see a use for such a tool, phew.

Grand Lodge

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Sissyl wrote:
I know it is a known problem with airline personnel being exposed to higher radiation levels, but that pertains to long term low intensity damage. This is short term high intensity.

It's not short term when you're talking about beams being on 24/7. Remember that a lot more wattage is being poured into the environment than what is actually being received as power, about a hundred times more given an expected delivery efficiency of maybe one percent.


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Sissyl wrote:
Caineach wrote:
Sissyl wrote:
Wrong. The satellites need to have pretty exact precision to be able to hit the rectenna they are meant to send power to. There is also no reason to think it would take a long time. The human nervous system is pretty sensitive to heat, and holding a dozen or so satellite outputs there is likely a matter of seconds until the person fries. We aren't talking about doing more than raising the temperature of the brain a few degrees. If there is any point to this solar power scenario at all, the energy required is peanuts. Thus: Button pressed. Satellites direct their beams. Man somewhere dies in a few seconds. Satellites resume normal operation. Someone not targeted but nearby doesn't feel much of it at all. There is no significant collateral damage, except possibly the guy's mobile phone or laptop, perhaps some other electrical appliances are fried as well.
From wikipedia"The Earth-based rectenna would likely consist of many short dipole antennas connected via diodes. Microwaves broadcasts from the satellite would be received in the dipoles with about 85% efficiency.[43] With a conventional microwave antenna, the reception efficiency is better, but its cost and complexity is also considerably greater. Rectennas would likely be multiple kilometers across"
Okay... you mean this could only be used to extinguish entire population centers, leaving only dead people and the entire non-electrical infrastructure intact? Sure lucky nobody would see a use for such a tool, phew.

We can already mostly do this with bombs, and those are cheaper than the power loss from losing satalites for a few minutes.


A few seconds, Caineach. Not a building will be touched. No fires. Just... nothing living anymore. Walls do not protect particularly well. You would be safe inside a tank, though.


LazarX wrote:
Sissyl wrote:
I know it is a known problem with airline personnel being exposed to higher radiation levels, but that pertains to long term low intensity damage. This is short term high intensity.
It's not short term when you're talking about beams being on 24/7. Remember that a lot more wattage is being poured into the environment than what is actually being received as power, about a hundred times more given an expected delivery efficiency of maybe one percent.

Sure, the beams will be on 24/7. They will pour energy into their intended rectennas for almost all that time. But should the need arise, they can be diverted for a little while, once in a while. THAT exposure would be short-term. Exposure at the rectenna would be long-term.

Sovereign Court

Hitdice wrote:
I seem to remember a story in a mid-eighties issue of Analog about terrorists planting a bomb on a space elevator because as the cable (materiel undefined) hit the ground it would function like a whip hundreds of miles long. Any basis in physics there?

I remember a series of books about the colonization of Mars, and in that a space elevator is caused to collapse from terrorist activities, and in the book that came down with such force that the carbon steel turn to diamond or something like that. Mind you this was a space elevator, used to transport people and minerals from the planet to space, and so the cable would have been much thicker then just something used to transport energy. Also I seem to remember it wrapping around Mars' equator twice when it fell. Not sure how accurate that was, but most science fiction writers try to get the science right.

edit: This is the series


Comrade Anklebiter wrote:
More country

I'm noticing a distinct trend difference between our preferences in country music.


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Sissyl wrote:
A few seconds, Caineach. Not a building will be touched. No fires. Just... nothing living anymore. Walls do not protect particularly well. You would be safe inside a tank, though.

First, it would take them minutes to redirrect the satalites. You are talking about moving how the whole satalite is oriented, or at least a major transmitter. That takes time.

Second, the problems removing that much power from the grid for even a couple seconds would cause is huge. Do you realize that they have to coordinate bringing new generators online with every other generator on the same power grid? They reduce the output from 1 or more generators while the new one ramps up to not overload the system. 1 going out will cause the whole thing to trip. After the Great Northeast Blackout in 2003, they redisigned a lot of the system's failure modes, but that was caused by 1 generator creating a surge and causing a cascading failure. Unless you have a massive power bank that you send all of your power to first, decreasing your efficiency drasticly, you will blow out the power grid at least locally when you flicker the entire system.


Sissyl wrote:
LazarX wrote:
Sissyl wrote:
I know it is a known problem with airline personnel being exposed to higher radiation levels, but that pertains to long term low intensity damage. This is short term high intensity.
It's not short term when you're talking about beams being on 24/7. Remember that a lot more wattage is being poured into the environment than what is actually being received as power, about a hundred times more given an expected delivery efficiency of maybe one percent.
Sure, the beams will be on 24/7. They will pour energy into their intended rectennas for almost all that time. But should the need arise, they can be diverted for a little while, once in a while. THAT exposure would be short-term. Exposure at the rectenna would be long-term.

But they're LoS weapons. So, a satellite bank over the US is incapable of attacking Europe, Asia, Africa or South America.

Also, do you have any idea what a rectenna looks like? They're designed like that because the waves coming down are weak enough that they have to be amplified to be effective.

Another conceptual example.

You need a surface like this to actually turn the microwaves into something usable as energy. When the US government sends you a key to your new house directly underneath one, just don't move into the house.

Also, I find it ironic that you've advocated nuclear energy.


The plans I saw specifically stated that the beam would be able to change direction. Sounds to me like a pretty minor movement. And in an all solar power grid covering the entire world, with car batteries holding a night surplus, I doubt this energy draw would register much. Electricity grid today has very little storage capacity.

Grand Lodge

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I don't consider the stations use as death ray lasers to be a realistic concern. I do however have concerns with the long term effects of pumping gigawatts of microwaves into the environment. remember that 99 percent of the energy being beamed to the planet is just ending up as spillover. So you'll be using gigawatts in order to beam down megawatts.


Nuclear energy? What is ironic about that? The bombs were first made some decades before my birth. Sure, we would all be better off without them, but they exist. That is no reason to inflict new horrors on humanity. A weapon like this would be completely anonymous, be very profitable to use due to remaining infrastructure, and there would be no radiation fallout afterward that would prevent firing without serious thought.


LazarX wrote:
I don't consider the stations use as death ray lasers to be a realistic concern. I do however have concerns with the long term effects of pumping gigawatts of microwaves into the environment. remember that 99 percent of the energy being beamed to the planet is just ending up as spillover. So you'll be using gigawatts in order to beam down megawatts.

If that was true, do you seriously think space based solar energy would be a viable concept of any sort? Seriously? Microwaves are more efficient than sunlight, that is the entire point of doing this at all.


Pathfinder Roleplaying Game Subscriber
LazarX wrote:
I don't consider the stations use as death ray lasers to be a realistic concern. I do however have concerns with the long term effects of pumping gigawatts of microwaves into the environment. remember that 99 percent of the energy being beamed to the planet is just ending up as spillover. So you'll be using gigawatts in order to beam down megawatts.

Well, according to the wikipedia article, the solar pannels will have an only a 16% estimated transmition loss.


I would also like to add that to any specific geostationary position, more or less exactly half of Earth's surface should be visible.


Irontruth wrote:
I'm noticing a distinct trend difference between our preferences in country music.

What do you mean?

I love Emmylou Harris!

Grand Lodge

Pathfinder Adventure Path, Campaign Setting, Companion, Roleplaying Game, Tales Subscriber
Caineach wrote:
LazarX wrote:
I don't consider the stations use as death ray lasers to be a realistic concern. I do however have concerns with the long term effects of pumping gigawatts of microwaves into the environment. remember that 99 percent of the energy being beamed to the planet is just ending up as spillover. So you'll be using gigawatts in order to beam down megawatts.
Well, according to the wikipedia article, the solar pannels will have an only a 16% estimated transmition loss.

You're not reading the article correctly. You're probably getting that figure from this line.

Between 1969 and 1975, Bill Brown was technical director of a JPL Raytheon program that beamed 30 kW of power over a distance of 1-mile (1.6 km) at 84% efficiency.[34]

That's 16 percent loss based on a transmission distance of 1 mile. From 26,000 miles you're going to have a lot more spreading. For full disclosure, my data is heavily based on a NASA publication dating from when this idea was first floated around during the 70's about the same time as the NERVA project. Technological changes since then, may have changed things.

Either way, the startup for this isn't going to be cheap, and we're going to have to get a lot better at space construction if this is going to work.


Small mercies and all that.


Pathfinder Roleplaying Game Subscriber
LazarX wrote:
Caineach wrote:
LazarX wrote:
I don't consider the stations use as death ray lasers to be a realistic concern. I do however have concerns with the long term effects of pumping gigawatts of microwaves into the environment. remember that 99 percent of the energy being beamed to the planet is just ending up as spillover. So you'll be using gigawatts in order to beam down megawatts.
Well, according to the wikipedia article, the solar pannels will have an only a 16% estimated transmition loss.

You're not reading the article correctly. You're probably getting that figure from this line.

Between 1969 and 1975, Bill Brown was technical director of a JPL Raytheon program that beamed 30 kW of power over a distance of 1-mile (1.6 km) at 84% efficiency.[34]

That's 16 percent loss based on a transmission distance of 1 mile. From 26,000 miles you're going to have a lot more spreading. For full disclosure, my data is heavily based on a NASA publication dating from when this idea was first floated around during the 70's about the same time as the NERVA project. Technological changes since then, may have changed things.

Either way, the startup for this isn't going to be cheap, and we're going to have to get a lot better at space construction if this is going to work.

Actually, my comment should be 15% and came from

wikipedia wrote:


Earth-based receiver

The Earth-based rectenna would likely consist of many short dipole antennas connected via diodes. Microwaves broadcasts from the satellite would be received in the dipoles with about 85% efficiency.[43] With a conventional microwave antenna, the reception efficiency is better, but its cost and complexity is also considerably greater. Rectennas would likely be multiple kilometers across.

I'm reading through the referenced study now, and am having a hard time finding where that claim came from. I may also be interpretting that incorrectly, and they may be refering to only the efficiency of the conversion through the reciever, and not accounting for losses in atmosphere.


Pathfinder Roleplaying Game Subscriber

I just noticed that the graph on the wikipedia page comes from the study above, and includes a 99.6% transmition efficiency. Haven't found where they come up with that number in the study yet - too distracted by more important stuff.


Just because you guys haven't argued in 18 or so hours doesn't mean I'm not going to still post country songs in here.

Liberty's Edge

Pathfinder Comics Subscriber; Pathfinder Adventure Path, Campaign Setting, Companion, Modules, Pawns, Roleplaying Game, Tales Subscriber

I see your country songs and raise you a gnos yrtnuoc.

Grand Lodge

Pathfinder Adventure Path, Campaign Setting, Companion, Roleplaying Game, Tales Subscriber

I trump you all with Slim Whitman's "Indian Love Call"

*Heads explode*

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