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  1. Ignoring any mutually induced magnetization (which we can fold into the permeability), the magnetic field of two magnets is the sum of individual magnets' contributions. So while the net field seems to flow around the magnets, the rate of change of the magnetic field (which is what drives the eddy currents) is the same as if the second object wasn't a magnet. Another way you can think of is that the density of the fields of the original magnetic field is fluctuating within the magnet as you move the magnets closer or let them move further apart. If this didn't happen, the magnets would not be able to do work against each other, and that means they wouldn't be able to apply a force on each other. But to answer the more direct question, no, there would be no heat produced by a changing magnetic field in perfect vacuum. There would still be a loss to electromagnetic radiation, but that can be mitigated by changing the field more slowly. And if you have any sort of a gas, there would almost certainly be some amount of conductivity due to ionized particles, and that would result in a very, very tiny heat loss. But for any practical purpose, your losses are going to be in anything electrically conductive, which is the magnets themselves, any metal frameworks, and any circuitry you might be using (if this is meant for energy storage.)
  2. Heat comes from energy losses as work is being done against the system. When you move magnets around, that's usually in form of induced currents in anything conductive. Typically, even a superconductive magnet will have parts to it that are conventionally conductive, and moving magnets around will result in currents flowing through these, generating heat. That said, you can make magnets ridiculously efficient even when ordinary conductors are involved, which is a big part of why electric vehicles can get so many wins.
  3. Magnets, generally, don't like existing. Magnetic field has a lot of energy stored in it. The problem making stronger magnets is similar to trying to make a stronger pressure tank, but with additional challenges. Just like a pressure tank, a magnet can fail mechanically, literally tearing itself apart, but it can also fail on a phase-transition level, causing it to become something far less magnetic in an instant, dumping all that energy. And you basically only have the energy of chemical bonds to balance it, putting an upper limit on how high the stored energy can go.
  4. Seems like a good place to thank the moderation team, with @Vanamonde and @Gargamel in particular, but everyone's been great, really. If it all gets demolished in the interest of profit, goodbye, and thanks for all the fish.
  5. I don't think we have any radio data on it. Just visual spectrum magnitude estimates. That's part of why everyone's so excited. We're going to have every instrument watching this time. We're going to get full radio data, IR and UV observations from a number of ground and space observatories, and people will be checking gravitational interferometers and neutrino detectors to see if we pick up anything in the noise that might be correlated. I don't know if we'll get the signal on the latter two that is actually measurable, but I know that neutrino fluxes from supernovas with lower apparent magnitude have been picked up. So if neutrino flux and visual brightness are anything at all close to proportional, I think we'll get something. Gravitational I'm much less optimistic about, but maybe there's clever filtering people can do based on timing correlations? It'll be interesting to see what we get either way. At a minimum, I suspect we'll have a much refined estimate on the star's mass based on what we measure. And that might give us a better model for estimating the period of these events based on composition and proximity of the binary, letting us extend that measurement to more distant novas and possibly use them as a yet another candle. Since measuring intergalactic distances is still a pain, this might be useful to correlate with at least some nearby galaxies, and that could have ripples to the rest of the ladder.
  6. Zvezda, Poisk, and Rassvet have docking ports compatible with Soyuz and Progress craft. Pirs used to have one too, but has been decommissioned. While Chinese spacecraft started out heavily based on Soyuz, I don't know if they would have kept up with any modifications related to ISS and/or went off on their own path for their own station. Keep in mind that it's not just whether or not the ports themselves fit, but everything involved in aligning the two craft together for the docking to happen safely. If the ports themselves are identical, but the alignment guides are installed differently, you're not going to be able to dock. And even if the two systems are completely identical, and you want to take on the risk of manual docking, it's still something entirely untested with any number of potential problems arising. Honestly, if things were that dire, a better option might be a space walk.
  7. I mean, even if the Starliner was completely DOA, it's not like there is no way to get the crew home. They might be stuck on ISS longer than planned, but you could always work the rotation of the future launches in a way that gets them home soon enough, and lets the normal schedule resume shortly thereafter. Back when the Soyuz was having issues, people were even talking about adding extra seats to the dragon, which it's been designed to handle at least on paper, so something like that would be an option in a genuine emergency. It's just fun to poke fun at Boeing, and how they're trying to be nonchalant about the whole thing a little too hard, given all the RP disasters they're in the middle of. If it weren't for all the other problems the company has been having, we probably wouldn't even be discussing this beyond the, "Oh, they're going to take a closer look at what's up before heading home." And yeah, I don't think anyone currently aboard the ISS minds the mission extension. It's not like there's nothing to do or the crew is stuck alone without resources.
  8. Hypothetically speaking, if you were able to make a mirror that reflects any wavelength with near enough to 100% efficiency, you could build a tiny star that sits comfortably in an enclosure that fits in your pocket and can power your car, yes. The reason you can't has to do with how electrons in matter interact with electromagnetic radiation at such short wavelengths. I can see some kind of hypothetical superconducting degenerate matter being able to do that without flatly breaking known physics, but the kinds of pressures that involves already require being in a core of a star, so that seems entirely moot for any practical purpose.
  9. I don't think there was ever a Vandenberg launch that my area wasn't overcast for. I'll keep an eye out, but I'm pretty sure I'll only see clouds.
  10. I saw this dig by Futurism, and couldn't scroll past that title. Nothing new of substance, but sharing for the title anyways. https://futurism.com/the-byte/boeing-starliner-astronauts-stranded
  11. We all know that cats can survive a fall from an arbitrary height. Things they land on, however, aren't as lucky. This cat, evidently, fell from pretty high up. Possibly an airplane.
  12. That is wildly exaggerated, TBH. Your typical interplanetary transfer is in tens of km/s. A 2RPM rotation involves a rotation around a point 250m from the center of mass (this can be more or less than 500m of cable, depending on your counterweight, naturally) and has velocity w.r.t. combined CoM of only 50m/s. This is well within the mid-course correction burns you'll be doing anyways. Likewise, loss of gravity, while disorienting, is about as dangerous as riding on a drop tower at an amusement park. You do still have the spin of the rocket itself, but it's likely to be a fairly stable rotation and the resulting centrifugal effects will be minor enough for this to be at worst comparable to a slip-and fall on flat ground. You can never exclude a risk of injury in any sort of a fall, but you can also slam your hand closing a hatch, so you know. What is a real risk is the cable snap-back. Back of an envelope estimate, a lot of materials you'd consider for a cable would stretch by about ~10% before failing. You want a good safety margin, so you're probably going to be looking at a little less than 5%. Call it a 10m stretch from CoM, where the cable's most likely to snap. A fully-fueled Starship is 5kT, which means you're looking at 1/2 * 50MN * 10m = 250MJ of energy stored in the cables. It's not a LOT, but it's enough to get the tip of the cable flying at you at a decent speed. (Yes, I know the energy is split between multiple cables, but so is the mass of the cable you have to get moving...) With a very rough estimate of 20T of cables in there, you'd get something like 50m/s average speed, but the tip is likely to be traveling closer to the speed of a bullet. The odds of that tip hitting the ship are not zero, and it will absolutely slice clean through. There are safety measures you can take. The tension wave will propagate at the speed of sound through steel, which is on the order of a few km/s. That technically gives you enough delay for emergency severing of the cable. If you put accelerometers everywhere along the length of the cable, you can cut all the cables from the ship, causing both ends to snap together instead, resulting in very low chance of any part of the cable hitting the ship with significant velocity. You obviously want this system to be rock solid, but what emergency system isn't? And we are looking after a catastrophic failure, which is very unlikely to begin with. We build suspension bridges using essentially the same tech. All of that said, when people talk about testing a centrifuge on ISS, people do talk about small radius centrifuge. As mentioned earlier in this thread, we do now have strong evidence that even a sub-5m radius centrifuge is viable for artificial gravity with a trained crew. Especially if you don't mind ramping up the speed over a few days when the trip starts, and winding it down on arrival. And that is an entirely different structure. Something with a revolution period of about 4 seconds and compact enough to fit in the inner hull of the Starship. If we're going to see artificial gravity on a trip to Mars, that is far more viable than any tethered design. And it's also something we can comfortably test on the ISS with very reasonable expense. I mean, it's still a full sized module requiring some amount of orbital assembly with current launchers, but again, if we're looking at testing this for interior of a Starship, the best way to test it would be to assemble one within the Starship, dock it to ISS, and just keep it docked for a few months. What better proof of Starship's capability to take a crew to Mars could you possibly ask for?
  13. Our water never gets warm enough for a swim without a wetsuit. Otherwise, I'd probably be doing a lot of the same. There are a few bays not far from here that do heat up by end of July-August, but they all involve a bit of driving. And when the weather's good, also lots of standing in traffic to get to them. For anyone who doesn't mind a wetsuit and into surfing, though, these are some of the best locations. (Though, I suspect, same can be said about your area.)
  14. I really want a rogue planet Easter egg. Something that looks like a once habitable (or even industrialized?) world that got flung out of its ancestral home eons ago and has been floating through the void of space ever since, its atmosphere having condensed and subsequently frozen as vast "oceans" between the elevated areas that were once its continents. Because it would be far enough out from Kerbol, it would make sense for it to be uncharted and nearly undetectable, but it can also stay entirely fixed. Though, I do recall some speculation sparked by the discussion of the stellar movement being a factor Intercept is considering, potentially indicating Kerbol being part of a binary with a nearby star. That would both be a great excuse to bring in the nearby star system closer to Kerbol, as 0.1ly or even smaller distances aren't unusual for such configurations, and would allow the formerly rogue planet to be a Kerbol capture, still being absurdly far away and entirely uncharted until you put an effort into it, but nonetheless, being on orbital rails, making it a little easier to plan transfers to it. Again, not a bad way to bring all of the concepts and planet work already done by the authors of this thread into KSP1. (Edit: Though, I'll be honest. I'm growing more and more tempted to build an engine in Unreal as a proof of concept.)
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