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No antennae radiate all the power fed to them!
rickman wrote in :
Lol, radiation resistance is from the signal energy *leaving* the antenna. It does not show up as heat! I already posted that I wasn't talking about radiation resistance as used in antennas. I just meant that some object, at some temperature, is limited in how fast it can get rid of its heat. (Also, assuming that even in space a thing may get heated a little by something, no matter how well someone tries to shield it, and that it won't take much to prevent a superconductor working). |
No antennae radiate all the power fed to them!
rickman wrote in :
You need to read up on the temperatures involved. Space is near absolute zero. I read less than an hour ago that the interstellar medium has latent temperatures of up to 100K. For a 'vacuum' it has a lot of stuff floating around in it, too. |
No antennae radiate all the power fed to them!
Lostgallifreyan wrote:
wrote in : There is no undiscovered magic in superconductors. There was no magic in any of the materials used for Gemini and Apollo either, but countelss things were learned just by using them out there. Care to name a few specifically from Genini and Apollo? And BTW, 99.9% of the materials used is aluminum. -- Jim Pennino |
No antennae radiate all the power fed to them!
Lostgallifreyan wrote:
rickman wrote in : You need to read up on the temperatures involved. Space is near absolute zero. I read less than an hour ago that the interstellar medium has latent temperatures of up to 100K. For a 'vacuum' it has a lot of stuff floating around in it, too. That is for energetic stuff floating around in some particular place. If you were causght in a CME it would be a lot hotter than that, but again that is stuff. The background temperature of space is 2.7 K. -- Jim Pennino |
No antennae radiate all the power fed to them!
|
No antennae radiate all the power fed to them!
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No antennae radiate all the power fed to them!
rickman wrote in :
You are aware that a standing wave still moves up and down, no? Ok, it looks like that is where I'm losing it. :) I look at some Youtube video shows that in a tank this is happening. So aht is it I see when a laminar flow hits a ceramic surface? Is it basically just a travelling wave that matches (in reverse) the speed of the flow? If that's all it is I'll let this rest. |
No antennae radiate all the power fed to them!
On 11/2/2014 3:08 PM, Lostgallifreyan wrote:
Jerry Stuckle wrote in news:m36209$kk3$1@dont- email.me: No, I don't think any part of the ISS is in "constant shadow". I believe it rotates as it orbits the earth, and different parts of it are in the shade at different times. I could be wrong, though - I've never been there :) Fair enough. I know that Apollo used to do the 'barbeque roll', but as far as I know there's less need of it on the ISS for whatever reason. Maybe they use the solar panels for shade part of the time, there's a lot of those... Or maybe it's in Earth's shadow often enough to get by... Or maybe it rolls constantly and I just had no idea. About particles, I don't know what sort of quantities there could be, or energies involved, but I'll settle for the realisation that an amount capable of causing heating would be long past rendering an antenna too noisy to use, probably. I suspect heating by remnant of mass coronal ejection might be the least of its worries. :) Not many particles in a vacuum :) -- ================== Remove the "x" from my email address Jerry, AI0K ================== |
No antennae radiate all the power fed to them!
Jerry Stuckle wrote in news:m36b58$oee$1@dont-
email.me: Not many particles in a vacuum :) Well, I can't argue. :) I just think that in some big reach of space where there is no sudden boundary between high material density, and high rarifaction, that occasionally some surprising exceptions to expected local conditions might occur. (And there was a time when 'space weather' was an unhead of concept). |
No antennae radiate all the power fed to them!
On 11/2/2014 3:58 PM, wrote:
Lostgallifreyan wrote: wrote in : Apples and oranges; we already know what will happen if one were to build an antenna from a superconductor. Fire up EZNEC and set material loss to zero; done. Yeah, anyone with a map could say a great deal about the shape of West Africa based on ocean travel. Again, apples and oranges as we know EXACTLY and in DETAIL what would happen. My point isn't so much about antennas, as about exploring the easy availability of cold environments for superconductors in space. Easy availability measured in thousands of dollars an ounce to get stuff there. Not having to lug heavy coolers up there might be an offer someone cannot refuse, and that someone might come back with all kinds of discoveries, things no models or predictions are going out there to find. The only thing that makes a superconductor different is the lack of resistance. We already know exactly what that means and what we would do with them if room temperature superconcductors were available. Here are a couple of things: electric motors and generators that would be very close to 100% efficient, small, light, and lossless power transmission lines, lossless transformers, big honking magnets. It's a little more than just no resistance. For instance, superconductors will "reflect" (for lack of a better word) a magnetic field. That's now a superconducting disk will levitate over a magnetic field. So just setting the resistance to zero doesn't necessarily cut it. There are other things to consider which EZNIC may not handle properly. -- ================== Remove the "x" from my email address Jerry, AI0K ================== |
No antennae radiate all the power fed to them!
On 11/2/2014 6:06 AM, Lostgallifreyan wrote:
Jeff wrote in : ...or looking at it another way the dissipation in the radiation resistance is not in the form of heat it is the power radiated into space. Well, I did say I didn't know the terminology. On the other hand, I'm not talking about antenna's radiation resistance. The only thing I'm sure of here is that some body, at some temperature, can not emit heat faster than some rate, and that superconductors in space will warm up too fast to stay superconducting without support to cool them. What is going to warm them up? The point of using them for the antenna is because they have no resistance which means the signal is not turned into heat. This discussion looked like it had strayed some way from the earlier talk of antennas and radiation resistance. No, the topic was antenna radiating all the power fed to them. The other two things that happen to the power is to be reflected back to the source or dissipated as heat. Superconductors eliminate the heat dissipation. -- Rick |
No antennae radiate all the power fed to them!
rickman wrote in :
You are aware that a standing wave still moves up and down, no? Sorry about this.. even after my last post, I have a thought I can't drop easily. A few years ago someone showed me a speaker cone in a video, driven by AC current, and it had ferrofluid on it, but I think there was soem comment that any thixotropic fluid will do. It had peaks and troughs, in a sort of semi-random 2D form across the cone that held it. These peaks and troughs did not oscillate up and down on the spot, they stood rigid as merings peaks after drying in an oven. (Actually they did shift a little, but not a lot, and that was mainly due to erratic vibrations in the whole doings.) Anyway, would that effect not also be called a standing wave? |
No antennae radiate all the power fed to them!
Jerry Stuckle wrote in news:m36bbu$pou$1@dont-
email.me: I also don't know how steerable the solar panels are - but I would expect them to be somewhat steerable. That;s something I did see once, I think on a BBC article. They are a bit like louvre windows, fairly limited movement of each panel on its own axis, but enoughm given the gaps between their edges. And I think an entire branch array can be rotated on its own axis too, but I'm less sure about that bit. |
No antennae radiate all the power fed to them!
On 11/2/2014 4:55 PM, wrote:
Lostgallifreyan wrote: wrote in : There is no undiscovered magic in superconductors. There was no magic in any of the materials used for Gemini and Apollo either, but countelss things were learned just by using them out there. Care to name a few specifically from Genini and Apollo? And BTW, 99.9% of the materials used is aluminum. Much of the medical monitoring technology came out of the early space program, for one thing. So did advances in propulsion systems and remote controls (more than just model planes and cars) for another. -- ================== Remove the "x" from my email address Jerry, AI0K ================== |
No antennae radiate all the power fed to them!
rickman wrote in :
No, the topic was antenna radiating all the power fed to them. Specifically, doing it efficiently. :) Just being hard to match. Never mind the other bits, beginning to look like old ground already today. What I might be missing about my comment on some body at some temperature being limited in its rate of dissipation might be flawed anyway. Never mind the risk of confusion between an antenna's radiation resistance and what I'm trying to get at, there's another angle to this... Am I wrong? Could it be that just as an antenna is efficient regardless of size, IF you can feed it all the energy you're trying to transmit, is it also true that regardless of size, that hot body will also equally transmit all its heat? In other words, is the 'limit' analogous to matching, as in getting the heat from the bulk volume out to its surface? I'm hoping that answer(s) to this one might help solve a heap of confusion for me.. |
No antennae radiate all the power fed to them!
On 11/2/2014 3:08 PM, Lostgallifreyan wrote:
Jerry Stuckle wrote in news:m36209$kk3$1@dont- email.me: No, I don't think any part of the ISS is in "constant shadow". I believe it rotates as it orbits the earth, and different parts of it are in the shade at different times. I could be wrong, though - I've never been there :) Fair enough. I know that Apollo used to do the 'barbeque roll', but as far as I know there's less need of it on the ISS for whatever reason. Maybe they use the solar panels for shade part of the time, there's a lot of those... Or maybe it's in Earth's shadow often enough to get by... Or maybe it rolls constantly and I just had no idea. I think the barbeque effect is because the capsule does not spread the heat very evenly. The temperature of space (including the sun's radiation) at earth's orbit is about the temperature of the surface of the earth. Here is the page where I found this. http://www.wwheaton.com/waw/mad/mad5.html ***** For the special case of a perfectly black, highly conductive sphere in the Solar System a distance R from the Sun, absorbing solar radiation from one side, but radiating in all directions equally, it turns out that the temperature drops with distance from the Sun as the square root of 1/R: T = 277 K (1 AU/R)½ ***** Assuming this equation is correct, the temperature of the object described is just 4 °C at Earth's orbit. Of course the earth is warmer because it is warmed from the inside as well as from the sun. Somewhere around 13 AUs the temperature reaches 77 °K, the boiling point of N2, which is much cooler than the critical temperature of a number of superconductors. -- Rick |
No antennae radiate all the power fed to them!
rickman wrote in :
I think the barbeque effect is because the capsule does not spread the heat very evenly. The temperature of space (including the sun's radiation) at earth's orbit is about the temperature of the surface of the earth. That fits. I think they were just averaging it on that basic principle. (And specifically, protecting the oxygen tanks above pretty much all else, if I remember the books right, I read a few at one point, over ten years ago). |
No antennae radiate all the power fed to them!
rickman wrote in :
Somewhere around 13 AUs the temperature reaches 77 °K, the boiling point of N2, which is much cooler than the critical temperature of a number of superconductors. Ok, but that goes with what I was saying about variable margins. Until there is much going on out that far, there will likely be a development more locally, of higher temperature materials that are useful enough somehow to justify putting them there. I don't doubt that shading them will help but that is more weight to haul out there too, so experiment will likely be needed to find compromises. The modelling might be harder than just doing it, starting small. |
No antennae radiate all the power fed to them!
On 11/2/2014 5:49 PM, rickman wrote:
On 11/2/2014 3:08 PM, Lostgallifreyan wrote: Jerry Stuckle wrote in news:m36209$kk3$1@dont- email.me: No, I don't think any part of the ISS is in "constant shadow". I believe it rotates as it orbits the earth, and different parts of it are in the shade at different times. I could be wrong, though - I've never been there :) Fair enough. I know that Apollo used to do the 'barbeque roll', but as far as I know there's less need of it on the ISS for whatever reason. Maybe they use the solar panels for shade part of the time, there's a lot of those... Or maybe it's in Earth's shadow often enough to get by... Or maybe it rolls constantly and I just had no idea. I think the barbeque effect is because the capsule does not spread the heat very evenly. The temperature of space (including the sun's radiation) at earth's orbit is about the temperature of the surface of the earth. Here is the page where I found this. http://www.wwheaton.com/waw/mad/mad5.html ***** For the special case of a perfectly black, highly conductive sphere in the Solar System a distance R from the Sun, absorbing solar radiation from one side, but radiating in all directions equally, it turns out that the temperature drops with distance from the Sun as the square root of 1/R: T = 277 K (1 AU/R)½ ***** Assuming this equation is correct, the temperature of the object described is just 4 °C at Earth's orbit. Of course the earth is warmer because it is warmed from the inside as well as from the sun. That's part of it. But it's also because the Earth doesn't radiate all that well, either. It holds a fair amount of the heat that strikes it. Air is a great insulator :) Somewhere around 13 AUs the temperature reaches 77 °K, the boiling point of N2, which is much cooler than the critical temperature of a number of superconductors. -- ================== Remove the "x" from my email address Jerry, AI0K ================== |
No antennae radiate all the power fed to them!
On 11/2/2014 4:20 PM, Lostgallifreyan wrote:
rickman wrote in : Sort of like wrestling a pig. You get all dirty and the pig enjoys it. That's the one I was trying to remember last week. :) Actually, I think it goes, "You both get dirty, but the pig enjoys it." -- Rick |
No antennae radiate all the power fed to them!
Jerry Stuckle wrote in news:m36d06$ui2$1@dont-
email.me: Assuming this equation is correct, the temperature of the object described is just 4 °C at Earth's orbit. Of course the earth is warmer because it is warmed from the inside as well as from the sun. That's part of it. But it's also because the Earth doesn't radiate all that well, either. It holds a fair amount of the heat that strikes it. Air is a great insulator :) Also, greenhouse efeect, skewing the ratio of heat gained vs heat lost... The UK just had a half-week of mid summer temps at Halloween. Never mind 'weather vs climate', these recordsd are being broken all the time now. |
No antennae radiate all the power fed to them!
Jerry Stuckle wrote:
On 11/2/2014 4:17 PM, wrote: On Sunday, November 2, 2014 1:51:46 PM UTC-6, Jerry Stuckle wrote: No, I don't think any part of the ISS is in "constant shadow". I believe it rotates as it orbits the earth, and different parts of it are in the shade at different times. I could be wrong, though - I've never been there :) Hard to say.. Some parts away from the sun may stay dark during a daylight pass, but they may be lit on other passes, depending on the direction and angles to the sun. I suspect they want to keep the solar panels towards the sun as much as possible, but the panels themselves may be steerable to some degree. I've never been there in person, but I've been there via camera on many an orbit. Watching the planet from that platform can be good wholesome entertainment for the whole family. :) I also don't know how steerable the solar panels are - but I would expect them to be somewhat steerable. It wouldn't make a lot of sense to keep having to adjust the position of the entire ISS to keep the panels aimed at the sun. The station itself does not really appear to roll at all. Or at least that can be detected on a lit pass, and using the earth as a "roll indicator" of sorts. But if it keeps one direction pointed towards Earth, then it has to roll - one rotation per orbit. Which means the solar panels have to be steerable to some extent for maximum power. But anyone can watch for themselves as long as they are in contact, and not on a nighttime pass. The cameras they are using don't seem to be too sensitive at night. IE: I hardly ever notice the lights below on a dark pass. Of course, they zip around the planet in about 90 minutes time.. So quite a few chances during a day to see what parts of the station are lit, and which are not. Some cameras, like the one I'm watching right now do not show the station at all, while the one they were using a few minutes ago did. At this moment they are fixing to pass into darkness over the Atlantic. http://eol.jsc.nasa.gov/HDEV/ http://www.ustream.tv/channel/iss-hdev-payload The ISS rolls once per orbit keeping a constant attitude toward Earth. http://www.collectspace.com/ubb/Foru...ML/001224.html -- Jim Pennino |
No antennae radiate all the power fed to them!
rickman wrote in :
That's the one I was trying to remember last week. :) Actually, I think it goes, "You both get dirty, but the pig enjoys it." Precision in all things. :) It's right, I'm getting memories of the context I first saw that now. The guy it was used for was a troll according to many, but one that changed a great deal for the better. He was a lot younger though... |
No antennae radiate all the power fed to them!
Jerry Stuckle wrote:
On 11/2/2014 3:58 PM, wrote: Lostgallifreyan wrote: wrote in : Apples and oranges; we already know what will happen if one were to build an antenna from a superconductor. Fire up EZNEC and set material loss to zero; done. Yeah, anyone with a map could say a great deal about the shape of West Africa based on ocean travel. Again, apples and oranges as we know EXACTLY and in DETAIL what would happen. My point isn't so much about antennas, as about exploring the easy availability of cold environments for superconductors in space. Easy availability measured in thousands of dollars an ounce to get stuff there. Not having to lug heavy coolers up there might be an offer someone cannot refuse, and that someone might come back with all kinds of discoveries, things no models or predictions are going out there to find. The only thing that makes a superconductor different is the lack of resistance. We already know exactly what that means and what we would do with them if room temperature superconcductors were available. Here are a couple of things: electric motors and generators that would be very close to 100% efficient, small, light, and lossless power transmission lines, lossless transformers, big honking magnets. It's a little more than just no resistance. For instance, superconductors will "reflect" (for lack of a better word) a magnetic field. That's now a superconducting disk will levitate over a magnetic field. So just setting the resistance to zero doesn't necessarily cut it. There are other things to consider which EZNIC may not handle properly. Such as? In regards to magnetic levitation, a super conductor is a perfect diamagnet due to the Meissner effect. None of that has anything to do with antennas. http://hyperphysics.phy-astr.gsu.edu...ds/maglev.html http://en.wikipedia.org/wiki/Magnetic_levitation -- Jim Pennino |
No antennae radiate all the power fed to them!
Lostgallifreyan wrote:
wrote in : Care to name a few specifically from Genini and Apollo? And BTW, 99.9% of the materials used is aluminum. Maybe I'm imagining too far back. What I'm getting at is that a lot of stuff we use on Earth came out of developments intended for, and used in, space. I think semicinductors in future will follow a similar path. To what extent I have no idea, but I think it likely. So again, I say that the use OUTside a space vehicle is no great leap once they're already inside one. It WAS transistor development that was pushed by the space race as tubes are very heavy in comparison and use lots of power. One more time, we already know EXACTLY how an antenna made of a superconductor would work, both on Earth and in space. -- Jim Pennino |
No antennae radiate all the power fed to them!
On 11/2/2014 6:02 PM, Lostgallifreyan wrote:
Jerry Stuckle wrote in news:m36d06$ui2$1@dont- email.me: Assuming this equation is correct, the temperature of the object described is just 4 °C at Earth's orbit. Of course the earth is warmer because it is warmed from the inside as well as from the sun. That's part of it. But it's also because the Earth doesn't radiate all that well, either. It holds a fair amount of the heat that strikes it. Air is a great insulator :) Also, greenhouse efeect, skewing the ratio of heat gained vs heat lost... The UK just had a half-week of mid summer temps at Halloween. Never mind 'weather Recorded temperatures have always set new records. Just considering one location, there are 365 days in a year and so 730 high and low records to test. We have been recording temperatures for roughly 200 years. What are the chances we *won't* set a new record for one of those dates in a given year? -- Rick |
No antennae radiate all the power fed to them!
Jerry Stuckle wrote:
On 11/2/2014 4:55 PM, wrote: Lostgallifreyan wrote: wrote in : There is no undiscovered magic in superconductors. There was no magic in any of the materials used for Gemini and Apollo either, but countelss things were learned just by using them out there. Care to name a few specifically from Genini and Apollo? And BTW, 99.9% of the materials used is aluminum. Much of the medical monitoring technology came out of the early space program, for one thing. So did advances in propulsion systems and remote controls (more than just model planes and cars) for another. True, but none of that came from throwing the stuff up into space just to see what would happen. -- Jim Pennino |
No antennae radiate all the power fed to them!
On 02/11/2014 21:00, rickman wrote:
On 11/2/2014 1:33 AM, wrote: rickman wrote: On 11/1/2014 8:18 PM, wrote: Wayne wrote: snip I was going to point out to Gareth that he is describing behavior in an antenna system, not an antenna. I doubt he will EVER understand the difference. But, I'm done now. No more. It does become tiresome correcting the same nonsense over and over again. Then there is no need at all to reply, no? Other than to prevent a casual reader from thinking his nonsense is reality, not really. Well, that and I really have a thing about deflating long winded gas bags. But that ain't gonna happen. In fact it is exactly these sort of responses that put air in his sails and keeps him going. In the end it makes you look pretty stupid too. Sort of like wrestling a pig. You get all dirty and the pig enjoys it. I doubt the casual reader would give his muddled nonsense the time of day, especially if they read the other stuff he posts. |
No antennae radiate all the power fed to them!
On 11/2/2014 3:58 PM, wrote:
Lostgallifreyan wrote: wrote in : Apples and oranges; we already know what will happen if one were to build an antenna from a superconductor. Fire up EZNEC and set material loss to zero; done. Yeah, anyone with a map could say a great deal about the shape of West Africa based on ocean travel. Again, apples and oranges as we know EXACTLY and in DETAIL what would happen. My point isn't so much about antennas, as about exploring the easy availability of cold environments for superconductors in space. Easy availability measured in thousands of dollars an ounce to get stuff there. Not having to lug heavy coolers up there might be an offer someone cannot refuse, and that someone might come back with all kinds of discoveries, things no models or predictions are going out there to find. The only thing that makes a superconductor different is the lack of resistance. That is far from true. There are all sorts of magnetic effects. We already know exactly what that means and what we would do with them if room temperature superconcductors were available. Here are a couple of things: electric motors and generators that would be very close to 100% efficient, small, light, and lossless power transmission lines, lossless transformers, big honking magnets. -- Rick |
No antennae radiate all the power fed to them!
Lostgallifreyan wrote:
wrote in : That is for energetic stuff floating around in some particular place. If you were causght in a CME it would be a lot hotter than that, but again that is stuff. The background temperature of space is 2.7 K. Ok, I just can't stop thinkling that stuff might get around out there in ways that are hard to predict, or sheild from. Get over it; we found out what's out there about a half century ago. -- Jim Pennino |
No antennae radiate all the power fed to them!
Lostgallifreyan wrote:
rickman wrote in : You are aware that a standing wave still moves up and down, no? Sorry about this.. even after my last post, I have a thought I can't drop easily. A few years ago someone showed me a speaker cone in a video, driven by AC current, and it had ferrofluid on it, but I think there was soem comment that any thixotropic fluid will do. It had peaks and troughs, in a sort of semi-random 2D form across the cone that held it. These peaks and troughs did not oscillate up and down on the spot, they stood rigid as merings peaks after drying in an oven. (Actually they did shift a little, but not a lot, and that was mainly due to erratic vibrations in the whole doings.) Anyway, would that effect not also be called a standing wave? It would be called a scene from The Big Bang Theory; a speaker covered with plastic wrap with a water and corn starch mixture. -- Jim Pennino |
No antennae radiate all the power fed to them!
On 11/2/2014 5:49 PM, Lostgallifreyan wrote:
rickman wrote in : No, the topic was antenna radiating all the power fed to them. Specifically, doing it efficiently. :) Just being hard to match. Never mind the other bits, beginning to look like old ground already today. What I might be missing about my comment on some body at some temperature being limited in its rate of dissipation might be flawed anyway. Never mind the risk of confusion between an antenna's radiation resistance and what I'm trying to get at, there's another angle to this... Am I wrong? Could it be that just as an antenna is efficient regardless of size, IF you can feed it all the energy you're trying to transmit, is it also true that regardless of size, that hot body will also equally transmit all its heat? In other words, is the 'limit' analogous to matching, as in getting the heat from the bulk volume out to its surface? I'm hoping that answer(s) to this one might help solve a heap of confusion for me.. Hmmm... All things emit energy according to their temperature and their surface emissivity. All things also absorb energy according to their surface emissivity. Both processes are going on at all times. So an object loses or gains heat depending on its temperature and the temperature of the environment. That delta temperature sets the rate along with the surface emissivity. In space with the environment near absolute zero (ignoring radiation from the sun and other nearby objects) any object's radiation of heat will be near it's maximum potential and limited only by its absolute temperature. So yes, an object will lose heat according to it's temperature and that will be less at lower temperatures. But that doesn't mean a super conductor will warm up unless there is something heating it. -- Rick |
No antennae radiate all the power fed to them!
On Sunday, November 2, 2014 4:31:36 PM UTC-6, Jerry Stuckle wrote:
But if it keeps one direction pointed towards Earth, then it has to roll - one rotation per orbit. Which means the solar panels have to be steerable to some extent for maximum power. I'd have to watch a few full passes to see.. They have multiple cameras aimed in different directions, so I'm not sure if they actually roll once an orbit or not. For some reason, I'm thinking they don't.. Mainly because I don't recall the shuttle as rolling during orbits. They always flew upside down and maybe even backwards in orbit, with the cargo bays aimed at the planet. I think anyway.. I'd have to look into that more. Some cameras seem to aim forward, and some backwards like you are watching out the back of an old nine passenger station wagon. :| |
No antennae radiate all the power fed to them!
|
No antennae radiate all the power fed to them!
On 11/2/2014 4:11 PM, wrote:
Lostgallifreyan wrote: wrote in : The only external heat source in space is the Sun; solution, sun shade. Maybe not. I just did a bit of Googling for 'superconductors in space' minus quotes. There's a lot of statements abotu space missions ended because required helium or hydrogen coolant ran out, Yeah, the coolent ran out for the things that GENERATE a lot of heat and need to be cooled more than radiation can provide. Radiative cooling does not provide for a lot of cooling. and also of space having latent temperatures up to 100K, so a sun shade won't help a lot there with current materials. There really is no such thing as temperature in space as it is a vacuum. That is a gross oversimplification. The temperature of space is the temperature of the background radiation, even in a near vacuum. -- Rick |
No antennae radiate all the power fed to them!
On 11/2/2014 6:31 PM, wrote:
On Sunday, November 2, 2014 4:31:36 PM UTC-6, Jerry Stuckle wrote: But if it keeps one direction pointed towards Earth, then it has to roll - one rotation per orbit. Which means the solar panels have to be steerable to some extent for maximum power. I'd have to watch a few full passes to see.. They have multiple cameras aimed in different directions, so I'm not sure if they actually roll once an orbit or not. For some reason, I'm thinking they don't.. Mainly because I don't recall the shuttle as rolling during orbits. They always flew upside down and maybe even backwards in orbit, with the cargo bays aimed at the planet. I think anyway.. I'd have to look into that more. Some cameras seem to aim forward, and some backwards like you are watching out the back of an old nine passenger station wagon. :| Which means it rolls once per orbit. Otherwise it wouldn't be able to keep the same side facing the earth. -- ================== Remove the "x" from my email address Jerry, AI0K ================== |
No antennae radiate all the power fed to them!
On 11/2/2014 6:11 PM, wrote:
Jerry Stuckle wrote: On 11/2/2014 3:58 PM, wrote: Lostgallifreyan wrote: wrote in : Apples and oranges; we already know what will happen if one were to build an antenna from a superconductor. Fire up EZNEC and set material loss to zero; done. Yeah, anyone with a map could say a great deal about the shape of West Africa based on ocean travel. Again, apples and oranges as we know EXACTLY and in DETAIL what would happen. My point isn't so much about antennas, as about exploring the easy availability of cold environments for superconductors in space. Easy availability measured in thousands of dollars an ounce to get stuff there. Not having to lug heavy coolers up there might be an offer someone cannot refuse, and that someone might come back with all kinds of discoveries, things no models or predictions are going out there to find. The only thing that makes a superconductor different is the lack of resistance. We already know exactly what that means and what we would do with them if room temperature superconcductors were available. Here are a couple of things: electric motors and generators that would be very close to 100% efficient, small, light, and lossless power transmission lines, lossless transformers, big honking magnets. It's a little more than just no resistance. For instance, superconductors will "reflect" (for lack of a better word) a magnetic field. That's now a superconducting disk will levitate over a magnetic field. So just setting the resistance to zero doesn't necessarily cut it. There are other things to consider which EZNIC may not handle properly. Such as? In regards to magnetic levitation, a super conductor is a perfect diamagnet due to the Meissner effect. None of that has anything to do with antennas. http://hyperphysics.phy-astr.gsu.edu...ds/maglev.html http://en.wikipedia.org/wiki/Magnetic_levitation Are you sure? I haven't seen anything one way or the other on it - although I'm sure it's been studied. Can you point at some studies to that effect? -- ================== Remove the "x" from my email address Jerry, AI0K ================== |
No antennae radiate all the power fed to them!
On 11/2/2014 6:17 PM, wrote:
Jerry Stuckle wrote: On 11/2/2014 4:55 PM, wrote: Lostgallifreyan wrote: wrote in : There is no undiscovered magic in superconductors. There was no magic in any of the materials used for Gemini and Apollo either, but countelss things were learned just by using them out there. Care to name a few specifically from Genini and Apollo? And BTW, 99.9% of the materials used is aluminum. Much of the medical monitoring technology came out of the early space program, for one thing. So did advances in propulsion systems and remote controls (more than just model planes and cars) for another. True, but none of that came from throwing the stuff up into space just to see what would happen. No, but they all came from the space race (Mercury, Gemini and Apollo programs) - which was your question. And since then, there have been all kinds of experiments on various orbiting objects such as MIR, Skylab, the space shuttle and ISS. Many discoveries are coming out of it - although I don't know offhand what's been put to use yet, since there is no manufacturing in space. But thinks like perfectly round ball bearings and new ways to make pharmaceuticals come to mind. -- ================== Remove the "x" from my email address Jerry, AI0K ================== |
No antennae radiate all the power fed to them!
rickman wrote in :
Recorded temperatures have always set new records. Just considering one location, there are 365 days in a year and so 730 high and low records to test. We have been recording temperatures for roughly 200 years. What are the chances we *won't* set a new record for one of those dates in a given year? True, it's no great deal intself. And given the Maunder Minimum soem big excursions can be expected, especially as the sun isn't following its usual 11-year pattern. On the other hand I remember people asking me in 1983 about glonal warming, and me insisting that it did not just mean warmer, but wetter, stormier, as well. There's no doubt that compared to thiry years ago this has happened across most of thwe world. For a real balance of 'records', we need to know how often the record for quietest, or closest approach to average, conditions occured, and I have never heard the like. :) Generally, if news is not exciting, it is not considered as news. Also, even when we had unusual cold recently, it is arguable that climate conditions don't cause a strong enough gradient to keep a strong division of temperature with lattitude, and similar things can be said about the wandering of the jet stream. Too many things look new, an the rate of broken records is increasing when it ought to be decreasing if things were generally stable. |
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