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KSK

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Everything posted by KSK

  1. Insta-frozen beer would suck and likewise, without a means of stirring the ingredients in transit, this thing would make a lousy ice cream maker. I suppose you could spray water into one portal and turn the other one into a snow maker.
  2. That makes sense - thanks. That's also a good point but as the STS program found out to its sorrow; 'it happened last time so it's fine' isn't necessarily a great reason to carry on doing it.
  3. So I read the follow up Twitter comments on the denting and they were… less than informative. Anyone on here care to weigh in? I mean, to me that looks bad, maybe worse if the denting happens with every propellant loading, but how bad is it really? How does stainless steel handle that kind of mechanical working, for example?
  4. It also improves spacecraft aerodynamics whilst reducing structural complexity and mass. After all, there's no need to equip your vessel with aero-control surfaces when Red Bull gives you wings. Ahem. Back to OP. The thread title is a bit of an overgeneralization but for this design of science-fiction SSTO, water landings probably do make sense.
  5. I don’t remember that part. I thought they were developed essentially as remote cameras by a news mogul? It’s been a while since I read it though so I could be wrong. Regarding entropy, I thought one deeper explanation for it came from statistical mechanics? Any given system will have far more disordered states than ordered states, so if it’s free to move between those states, it will tend towards greater disorder aka higher entropy?
  6. If you’re addicted to nicotine it’s probably a bad outcome. Otherwise: plantations and slavery, wasting productive agricultural land on narcotics, profiteering from human misery in the form of physical addiction to a substance which causes numerous lung diseases and lung cancer, practically writing the Big Corp playbook on spreading disinformation and discrediting any sources of information that could hurt said profiteering. Oh - and the cost to global healthcare systems of cleaning up after the profiteering. Need I go on? The tobacco industry has been and continues to be, a blight on humanity and a disgusting testament to the power of greed above all other considerations.
  7. Perhaps these sapient beings executed the first of their own who tried to encourage the widespread inhalation of addictive carcinogens for their personal profit? And the second. And the third. After the 10th execution, enthusiasm for smoking died out.
  8. Ahh, OK. I forgot about the overcharging part. I figured that provided the rods weren't hot enough to melt, they'd be fine. On the other hand - the rods can be made to release their energy in a single burst or gradually over time. Is there a lower limit to how gradual that release can be? Because I'm thinking that IR rods could be plugged into a safety system, which monitors their change in mass, and then causes them to 'vent' infra-red radiation if they get too massive. The need for a safety system might make them a little more difficult to use for some applications, but it should at least prevent them overcharging from exposure to ambient IR radiation. If you needed a technical explanation for the mass sensor, one way of building one might be to use a torsion balance to measure the gravitational force between the rod and an accurately known test mass. There are probably more elegant ways of doing it, or you could just handwave the details away if they weren't important to the story.
  9. Sunlight should do the job for UV, especially if you put your rod charging facility up in space. If you want to go full on sci-fi, build a Dyson Sphere around a star and use its entire output for charging UV-rods. Or optical-rods, or infrared rods. The solar spectrum is here - spectra for other stars will obviously vary. Infrared rods might be pretty decent energy sources and I would think most propellants would absorb infra-red radiation to some extent, given that infra-red spectroscopy is a pretty standard technique for fingerprinting molecules, particularly organic molecules. Heck you can see two big absorption bands for water in that diagram I linked to - both in the infra-red.
  10. The problem is that most materials don't absorb gamma rays terribly well, which will limit how efficiently a gamma-rod engine can convert gamma rays to heat and therefore to thrust. Whilst a sufficiently thick block of conventional solid propellant would certainly absorb the gammas, I'm not sure how evenly it would heat up, which might make it difficult to use in practice. In space, I guess you could dispense with propellant entirely and go with a pure photon rocket - you're not going to be short of photons with gamma-rods - but a photon rocket isn't much good for lifting stuff out of a gravity well, unless the photon source is intense enough to create a whole bunch of other 'interesting' problems. So for an SSTO, I would think you need a propellant that is reasonably good at absorbing gamma-rays both for ease of creating enough thrust and for making the exhaust safer. I wonder if a 'candy cane' propellant block would work? Layers of tungsten to at least partially absorb the gamma rays, sandwiched between thicker layers of a more easily vaporised material. Tungsten absorbs gamma rays, gets hot, vaporises rest of propellant. Or a block of propellant doped with tungsten particles might work better.
  11. That makes sense. Use the horribly unstable antimatter to make an energy source that gives you most of the bang for your buck but is substantially safer. As an aside, have you read Andy Weir's Project Hail Mary?
  12. 1. Yes 2. Anything with heavy elements in - the heavier the better. Tungsten is good. Heavy elements pretty much suck as propellants though for a variety of reasons. 3. Cut hole in reaction chamber. Rivet gamma rod into hole. Make sure graser emitting end is pointing into chamber. Make sure not to weld gamma rod into hole in case it goes boom. Do not stare at grazer emitter with remaining eye. Possible problem - charging up gamma rods. From Wikipedia: "When a uranium nucleus fissions into two daughter nuclei fragments, about 0.1 percent of the mass of the uranium nucleus[9] appears as the fission energy of ~200 MeV. For uranium-235 (total mean fission energy 202.79 MeV[10]), typically ~169 MeV appears as the kinetic energy of the daughter nuclei, which fly apart at about 3% of the speed of light, due to Coulomb repulsion. Also, an average of 2.5 neutrons are emitted, with a mean kinetic energy per neutron of ~2 MeV (total of 4.8 MeV).[11] The fission reaction also releases ~7 MeV in prompt gamma ray photons." So about 3.5% of 0.1% or 0.0035% of the mass of a fissioning uranium nucleus appears as gamma rays. Therefore to charge up a 1g gamma-rod, would require the equivalent of fissioning about 28.5 kg of uranium. That's assuming a) that gamma-rods are perfect mass-energy converters, b) that all the gamma-rays from the fissioning uranium are captured and c) that no further gamma-rays are produced by decay of uranium fission fragments. We can take (a) as read for this discussion and I don't have any idea about (c) off the top of my head. (b) is a significant issue though because the gamma rays from the fission reaction are going to be emitted in random directions. So to completely capture the gamma-ray output from a fission reactor would require a shell of gamma-rods to be constructed around the reactor core, and each individual gamma rod will only capture a small percentage of that gamma-ray output. Long story short - you're going to need to fission a lot more than 28.5 kg of uranium to charge up a single 1g gamma-rod. There are other sources of gamma-rays of course, but a fission reactor seems like the most controllable and dependable one. On a more positive note - have some free worldbuilding for your gamma-rod setting.
  13. Propaganda to appeal to existing vested interests, corporate lobbying to enforce those interests, and internet influencers to mould public opinion in favour of the status quo. Talk is cheap. Talk which is merely telling people what they want to believe anyway is even cheaper.
  14. The best component is no com.... *BOOM* Aka, 'move fast and vaporize things.' At least anyone cutting corners with antimatter storage is only likely to cut them once.
  15. Agreed, and personally, I would have been in favour of an expanded home system for the kerbals in KSP2 and ditching all the interstellar stuff. Plenty of new planets, and the kerbal equivalent of asteroids, trans-Neptunian objects and even Oort cloud bodies for players that really enjoy long journeys, could have provided plenty of new stuff to visit without needing to go to other star systems. I honestly don't understand why the developers thought it was so important to keep the old home system from KSP1. New players wouldn't have cared, not having any point of comparison, and I doubt the existing player base would have been overly concerned, judging from the number of threads here about Gas Planet 2 and the like. IMO, interstellar travel with rockets (even the more speculative rockets that KSP will have) is silly or, more charitably, opens up a whole can of issues that I doubt that KSP2 will address in any particularly deep manner, given that including 'un fun' stuff like life support remains a contentious issue around here. But it is what it is.
  16. In no particular order. Can your antimatter containment system safely contain antimatter on Earth? If it can, then it can also deal with 1g constant acceleration, although you might also need to build in a decent safety factor to allow for jerk (rate of change of acceleration) if your spacecraft is likely to be making any rapid maneuvers. I say 'might' because I honestly don't know how that would work but I'm drawing an analogy with structures designed to handle dynamic loads vs static loads. I'm not sure that going lightweight on safety systems really matters that much vs going heavyweight. If the containment system fails and a ton of antimatter goes boom, then the mass of the containment system is essentially irrelevant. Quick calculation, 1000 kg of antimatter annihilates to release about 1.8x1020J of energy or the equivalent of a 43 gigaton nuclear detonation (assuming my powers of ten are all correct). Granted, that's not quite as dramatic as it sounds, since there won't be much of a blast wave in space but it's still a lot of energy to contain. Or, more likely, not contain. That's not to say that the storage system will be lightweight, it's just that the mass of the storage system has no direct bearing on how safely it can store antimatter. Miniaturizing an antimatter storage system for a missile might be a tricky engineering problem but the forces involved are likely to be small simply because of the smaller amounts of antimatter required. For example, to accelerate a gram of antimatter (or anything else for that matter) at 30g, requires 0.9N of force, which is pretty trivial. See above for comments on dealing with jerk, which is going to be a lot more important for a missile.
  17. The problem is that your spacecraft is a closed system. Unless you plan to harvest resources in-situ, then any mass you expend as propellant is mass that you're carrying with you. It doesn't matter whether your propellant is a tank of hydrogen, bioethanol made from corn grown on board, or corncobs grown on board, wrapped in tinfoil and fired out of a linear accelerator. If you're growing corn on a spacecraft then you'll be using up water, carbon dioxide and whatever other nutrients you're feeding it with. The increase in corn mass will be balanced by a decrease in water mass and carbon dioxide mass. There ain't no such thing as a free lunch, if you'll excuse the corny joke.
  18. Yeah, bank cards and NMR magnets don't mix well. Ask me how I know. Back to the original question - there are limits on how strong a permanent magnet can be, which are down to both it's chemical structure and crystal microstructure. As a very loose analogy, picture a row of ordinary bar magnets lined up with all their poles aligned: N N N N N N N N [] [] [] [] [] [] [] [] S S S S S S S S Please excuse the bad ASCII art, but I think you can see what's going to happen here. Given half a chance, those magnets are going to rearrange themselves to: N S N S N S N S [] [] [] [] [] [] [] [] S N S N S N S N Unless there's some other factor constraining them. For a row of two or three bar magnets, that's not too tough, but the more magnets in the row, the harder it is to keep them all pointing in the same direction - which is what you want for the biggest overall magnetic field. As K^2 said, every magnet wants to tear itself apart.
  19. I'm not particularly sanguine about the practicalities of this proposal.
  20. Good question and I’m not enough of a geologist / geochemist to give a definitive answer. With that said: Minerals tend to be ionic, so they dissolve more easily in polar solvents. Water is an excellent polar solvent and it has unusually high melting points and boiling points for its molecular mass because of hydrogen bonding. That’s helpful because it’s liquid at a relatively high temperature and things tend to be more soluble at higher temperatures. Ammonia might work too but it’s not as polar and NH…N hydrogen bonds are weaker than OH…O hydrogen bonds, so ammonia has lower melting and boiling points than water. Both of which factors (I think) would make it a poorer chemical weathering agent. Hydrogen fluoride would be an excellent weathering agent in principle (given that the damn stuff etches glass) but is hellaciously reactive. I’d expect it to get locked away as fluoride minerals in short order, making it an ineffective weathering agent in practice. Non-polar solvents such as hydrocarbons aren’t much good at chemical weathering as they don’t tend to dissolve minerals. This is helpful when trying to extract them from the ground. Supercritical fluids (eg supercritical carbon dioxide) tend to be good solvents and might make decent chemical weathering agents. They’d be very location specific though as they need to be above a certain temperature and pressure. It’s also debatable whether life (at least as we know it, Jim) would be viable with supercritical fluids around - I imagine they’d do a pretty good job of dissolving any proto-cells as well as weathering rock. TL:DR I’m not sure that water is essential for weathering but it is a very effective and relatively benign weathering agent.
  21. I’m afraid I didn’t really grok the mathematical description but @kerbiloid’s more visual description? That I did get and I agree with OP - a tetrahedral planet would be a great setting for a science fiction story!
  22. Agreed. Radically different chemistry - sure. Radically different chemistry of sufficient complexity to support life - that’s a quite a bit more difficult. And whilst I’m reluctant to dismiss anything as outright impossible (because life is a tricksy thing and turns up in an incredible range of environments using an equally incredible range of nutrients and energy sources), as a species we’re pretty good at chemistry up to and including the more exotic ends of the Periodic Table. So yeah, my money would be on carbon based watery alien life rather than rock beasties.
  23. Probably from carbon dioxide and hydrogen. But yeah, this all gets messed up and back to front.
  24. More shower thoughts on Dune from a lapsed chemist. 1. Water and carbon dioxide are both very stable molecules. As a rule of thumb, if either of them are one of the end products of a chemical reaction, then that reaction is likely to be favourable and go to completion. 2. Aside. This is why hydrocarbons are so energy dense - they burn to two very stable molecules and release a shed load of energy in the process. 2. It is demonstrably possible to biochemically split water into hydrogen and oxygen, else we wouldn’t be here discussing this. 3. That being the case, I’d be reluctant to rule out the possibility of biochemically splitting carbon dioxide to carbon monoxide and oxygen [non-lapsed chemists feel free to chime in here]. 4. Carbon monoxide is poisonous to us but it’s also a versatile reactant for all kinds of chemical reactions, especially if you can also find some hydrogen from somewhere. Not necessarily a bad by-product to have around. 5. End result. I can imagine some critter in the Arrakan ecosystem which is capable of directly recycling CO2 back to oxygen without requiring water as a primary electron acceptor (as per Terran photosynthesisers). 6. Said critter probably wouldn’t be green (no chlorophyll, different wavelengths of light captured) so would be unremarked upon (compared to something green which would be very distinctive on a desert world.
  25. Hmmm. A carboxylic acid (or an aldehyde for that matter) can be reduced to a primary alcohol plus water by adding hydrogen. So, if the worms were capable of splitting water into hydrogen and oxygen (something equivalent to photosystem II in terrestrial plants) then I guess those aldehydes and acids could be a suitable hydrogen acceptor? Although that rather begs the question of where the all the water comes from. Possibly? Maybe? Hey look over there - a squirrel! But yeah, I don’t think aldehydes and acids are likely to be a source of oxygen on their own.
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