mistermack

Well, I don't waste much time on such distant speculative articles, the title was more than enough for me. I'm posting about creating a shield for a space craft or station, and even that is speculative, but at least it's forseeable as possibly practical, given time. To do what?

It seems to me that it's probably revenge spamming, by someone who got banned. If it was easy, I'd restrict new members to just one post, in the first 24 hours temporarily. That might reduce the spam posting by a factor of five, because the new member could be banned on the first spam post. And longer term, it looks like an "I am not a robot" box is needed in the new member application form. Which would cut it out, unless it was some nutter doing it manually.

Me too, but that wouldn't justify dismissing every conspiracy theory, just because it is a conspiracy theory. Things like Watergate would never be blown wide open, and Nixon's "I am not a crook" would stand. Or the Bay of Pigs would go down as a noble failed Cuban revolution, not a botched CIA operation. And the world would still believe that Kennedy "stared down" Kruschev over Cuba, rather than giving way and agreeing to remove the nukes in Turkey. Not to mention "weapons of mass destruction" !! Actually, on this side of the pond, conspiracies have been going on for years unnoticed. When King Edward Vlll was knocking about with Wallace Simpson, and intending to marry her, not a word appeared in the British Press. The facts were completely hidden from the British, even though the American Papers were full of it. The history of the royal family is a history of conspiracies, right up to the present day, and the media are fully compliant. The advent of the internet has ruined that cosy arrangement now though, unfortunately for them. But not completely, they are still working around it.

Which generator? I was assuming that the real need for active shielding would be on more distant travel, not near Earth. Close to Earth there is natural shielding from the Earth's magnetic field. When you mentioned the power of the Sun at Mars, I assumed that you were addressing distant journeys. However, the James Webb is stationed much closer to Earth, but it's shield still produces very low temperatures : The sunshield is the size of a tennis court, which shows that you can shield more than just a tiny receptor. "The sunshield acts as large parasol allowing the main mirror, optics, and instruments to passively cool to 40 kelvins (−233 °C; −388 °F) or cooler,[6] and is one of the enabling technologies that will allow the JWST to operate.[10] The kite-shaped sunshield is about 21 by 14 metres (69 by 46 ft) in size,[11] big enough to shade the main mirror and secondary mirror, leaving only one instrument, the MIRI (Mid-Infrared Instrument), in need of extra cooling.[6] The sunshield acts as a V-groove radiator and causes a temperature drop of 318 K (318 °C, 604 °F)[12] from front to back.[11] In operation the shield will receive about 200 kilowatts of solar radiation, but only pass 23 milliwatts to the other side.[13][11]" The sunshield has it's own wiki page : https://en.wikipedia.org/wiki/James_Webb_Space_Telescope_sunshield

That's EXACTLY what I thought you'd say. If he was right. For once !

That's not surprising. Conspiracies DO happen. Some conspiracy theories are true, some are made up. I'm sure there are more made-up ones than true ones, but that doesn't change the fact that it's evidence that counts, not whether it's a conspiracy theory or not. Admittedly, some people would rather just dismiss them without evidence, but that makes as much sense as buying into them without evidence. People forget that some scandals that are now common knowledge started out by being dismissed as conspiracy theories, before the truth became undeniable. https://www.rd.com/list/conspiracy-theories-that-turned-out-to-be-true/

These problems are being met with today's tech, and were met with yesterday's tech too. One example of how efficient shading is in space is the Parker Solar Probe by NASA. The probe and all of it's equipment is designed to approach to within about four solar diameters of the surface of the Sun, and yet it's equipment is just shaded by a 4.5 inch thick carbon composite shield. At the other end of the temperature scale are the infra-red space telescopes. The Spitzer mission ran for about 20 years, and ended about 3 years ago. https://en.wikipedia.org/wiki/Spitzer_Space_Telescope It needed very low temperatures to operate. It ran it two stages, the cold and hot missions. In the cold mission the mirror got extra cooling from liquid helium, as well as protection by the sun shield. It operated at about 5.5 K. When the liquid helium ran out, they ran a 'warm' mission, just protected by the shield and operating at 28.7 K unaided. This allowed an 11 year extension of the mission, on restricted wavelengths at a constant 28.7K So shielding does work, it makes very low temperatures achievable, and of course, the tech moves on and improves all the time. High temperature superconductors can now operate above 90 K so the achievable temperatures in the shade in space won't need any extra cooling. Wikipedia says about superconductors " a superconductor has a characteristic critical temperature below which the resistance drops abruptly to zero.[1] [2] An electric current through a loop of superconducting wire can persist indefinitely with no power source.[3][4][5][6]" So at least in theory, you can maintain a magnetic field without any input power. In practice it will probably not be that easy, but it will be interesting how the technology progresses.

In space, shading can be pretty efficient. If the mirror is one metre from the shaded equipment, then re-radiating might be significant. But if the mirror is 100 metres away, then very little will hit. And one kilometre away, it's going to be negligible. So you can easily site the mirror so that it's not a problem.

It seems like virtually any malady you look up, and read the known symptoms, a rash is included. Maybe it's quicker to list the disorders that DON'T include a rash, in the list of symptoms. The type of rash is more informative, than just whether there is one, or not. There's a big range that comes under the umbrella of "rash".

Yes, but not in the shade. You can reflect solar energy away for virtually no energy input.

Donald Trump can't have just suddenly developed this attitude of fixing things with a payoff. He must have been doing it successfully for decades, you don't start from nowhere. I wonder if he's got a little black book, of all the people he's paid off in the last fifty years? Imagine the carnage, if he goes down, and decides to take them all with him !

I'm going to display my physics ignorance here. Does a field require power? If no work is being done, is the power requirement just needed because of inefficiencies in the system? A bar magnet produces a field, but where is the power input? If the field isn't doing any work, the magnet doesn't need an energy input. Does that translate to electromagnets? With superconductors, you can have very low resistance, so you can have a huge flow of current with very little expended energy. So progress in the field of superconductivity means the prospect of bigger stronger fields, with smaller and smaller energy losses, as technology advances. And of course, space is very cold, so it favours superconductivity. That's how I see it at the moment, but I'm happy to be put right on the subject.

Why not? There are plenty of 'things' that can be made and handled outside of a shielded space. Especially using robotics, or remotely operated machinery. If there's a net loss of heat, it's doing a job. ------------------------------ On the question of detecting aliens from a heat signal, maybe the aliens would not want to be detected. If you are dumping heat via radiators, wouldn't it be possible to focus the radiated heat like a lazer, on infinity, so that you could only detect it if you happened to cross a tiny channel through space? And then you would just get an intense signal for a few fractions of a second, as you crossed the beam. So the odds of detecting aliens might be tiny, because that's the way they want it.

Can't we see a discussion between Ghandi and Stalin ? Ghandi " I will fight you with peaceful protest " Stalin " Good idea ". 😆

I'm not, I'm questioning the word's assumption that it will always be worse. And that IS good science.

Not really. Unless you can fix things without a scrap of evidence. Climate has always been a problem. And a benefit. And climate change has always happened, always been a problem, and a benefit. To fix anything, you would need to prove that current climate change, unlike past climate change, is all man made, and that the drawbacks outweigh the benefits. Shouting hysterically about every fire or tornado doesn't prove anything. Fires and tornados and hurricanes always happened, so did droughts and floods. It's laughable to be offered this sort of stuff as evidence of anything. The only evidence of future problematic climate change, over and above natural climate change, remains a bunch of models by some very committed activists. And the evidence that a bit of warming will be harmful is even weaker. Nobody EVER mentions the benefits, so how can you judge whether they would be less or more than the drawbacks? Dear me, you've missed the point by a mile. My posting isn't about the well-being of humans, it's about the existence or otherwise of other species, and their habitats.

The reason that I prefer population measures first, is because the climate problem is an hypothesis, whereas the population problem is very much a fact. We are causing extinctions because of land and sea use at a criminal rate right now, whereas climate may or may not become a problem a long time in the future, nobody knows. People think they know, but they don't. They are only convinced. Nobody knows the future, but you can know the present, and extinctions are happening today, were happening yesterday, and because of that, we can be very sure that they will be happening tomorrow. As well as extinctions, it's the destruction of habitats that I would like to see stop. Clearing more forests (with all the CO2 that that entails) and marginal land is causing damage and extinctions that will probably never be noticed, but will never be reversed.

This reminds me of the case of Brazil. ( I don't know the current situation, but I read this a few years ago ). I expected the birth rate in Brazil to be sky high, what with a lot of rural people, and the strong influence of the Catholic Church. But I read that it had dropped dramatically. Not because they were killing babies, or forced sterilisation. It was surprisingly down to a few very popular soap operas on tv, which embraced the subject of family size in the drama plots. The effect on the birth rate was enormous. It dropped dramatically. I haven't checked the current situation, maybe it has all reversed again, but that was the story a few years ago.

I just found this about the ISS and heat regulation on it : The radiators are much as I guessed, large and thin and in the same plane. They are obviously up to the job. I wouldn't think that a less intensive living module would need so much cooling, as you wouldn't have such tightly packed equipment in such a small space. In a bigger unit, you could have air ducts passing through the solid shielding, warming the outer surface enough to radiate quite a lot of heat independent of radiators. Enclosing absolutely everything in ice was never my premise, and it was obviously suggested to combat radiation to protect humans, so I think you're over-stressing the original suggestion a bit. Having bits and pieces external to the shielding just makes common sense to me. If the living area of the station was ring shaped, you could have the ring shielded, and all sorts of other stuff in the centre, like radiative panels. If things were located close to the axis of rotation, the effect of artificial gravity would be very low, so they could be made of thin lightweight materials.

But you only need to shield living and working areas. And the ice can be encased in a reflective skin. Radiation in space can be pretty effective, as the radiators don't need to be robust or bear their own weight so you can make them very thin with a great surface area. And volume doesn't equate to greater heat generation. You will only generate small amounts from equipment, and obviously none from space heating, if you are having to dump heat. In any case, the living volume probably wouldn't be spherical or cylindrical, more likely ring shaped, with more surface area than a sphere or cylinder. Not if they are thin and flat and all in the same plane. And the point about space is that there is a lot of it. You can give a radiator an enormous surface area that would be impossible here on Earth. One problem would be getting cooling fluids from a rotating module to non-rotating radiators. I'm pretty sure you could get over that, maybe by having the fluids exit and re-enter along the axis of rotation. Since rotation is likely to be not much more than 1 rpm, I think it could be done ok.

You could use the heat to generate electricity with some fairly simple kit.

I've never heard of anyone worrying about shedding heat on a space station. Surely it's pretty simple to pump any excess heat through external radiators, if it was a problem? It could be radiated away or stored as a hot fluid in an insulated container. But this is ice frozen to minus 250 or more. On some distant solar system bodies there are mountains made of water ice, it behaves like rock does here on Earth, so you would think that supporting it's own weight, in artificial gravity of not much more than 1g would not be a problem. If necessary, it could be reinforced with metal, like concrete here on Earth.

You two seem to be talking at cross purposes. I agree with Moontanman that waste materials, or stores can be used on the outside of a giant space living module to absorb harmful rays. Once you get over the problem of sourcing heavy materials from space rather than Earth, then it should be easy enough to design effective protection. I don't get why the protection can't rotate along with the living area though. Wouldn't it be fiendishly complicated, to have a spinning living module, inside a non-rotating shield ?

You are talking as if there is only one "fitness". I think you have to include the effect of environment, as a driver of evolution. A new mutation might be neutral, or detrimental to fitness in one environment, but be very advantageous in another. If a new mutation allows an organism to better exploit a vacamt niche, then an evolutionary split can happen, with a new phenotype separating from it's cousins. Fitness and environment go hand in hand, so there are as many version of fitness as there are different environments.

The average American produces about 1,300 tons of CO2 in their lifetime. As well as producing kids who grow up to do likewise. One condom can stop that process in it's tracks. It's got to be the most CO2 saved, for the least money on the planet. The same applies to the rest of the world, to a lesser extent obviously. The world average is about 1/4 or the US average, but family sizes are a lot bigger in some countries. That was said as a joke I think, and not by me either.