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KSK

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    Kerm Telegraph Maintenance Engineer
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    The North Grove, Duna.

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  1. Ahhh, good stuff. I was going to pitch in with some thoughts but glad you figured things out. Sorry about the late reply - it’s been a busy couple of days,
  2. That would make sense to me. Having just re-read the Atomic Rocket's page, it mentions two Mylar discs (uncoated as far as I can tell and not ribbons as per my earlier post. ) with an air gap between them, each having an aluminium ring around their rim, which acts as a temporary electrode and electrical contact with the permanent electrodes on the magnetic nozzle. Each pulse unit consists of the aluminium rings, Mylar discs and fuel pellet in the middle. The whole thing is vaporised in the explosion and the reason why Mylar is used is to keep exhaust products as light as possible, hence exhaust velocity as high as possible. This is all from a secondary source though - I'm sure that the actual papers go into a lot more detail and probably consider other designs like coated Mylar as well.
  3. That sounds a lot like Mini-Mag Orion if I'm reading you right. Wikipedia article here, Atomic Rockets article on this page. A significant challenge with it appears to be the hellaciously high magnetic field required. The design shown on the Atomic Rockets page uses a separate nuclear reactor which powers up a whacking great bank of capacitors, which are discharged through Mylar ribbons to the fuel pellet. And yeah - Mylar is normally an insulator but 70 mega-amps laughs at such petty distinctions and makes Doc Brown turn green with envy.
  4. Medusa always struck me as being even crazier than Orion. I’m also assuming that forward facing windows aren’t going to be a big feature of any Medusa craft. ”Please do not stare at the nuclear detonations with other eye.”
  5. The old TRIGA design is interesting too - the hotter it gets, the slower it goes. So much so that I don't think it physically can melt down. Public safety announcement - I recommend searching for "TRIGA reactor" if you want to know more, and not "TRIGA", which is distinctly not safe for work.
  6. Possibly? I thought New Armstrong was intended to be their moon rocket (makes sense with that name), whilst Jarvis is intended to be an upgraded upper stage for New Glenn, to make it fully reusable? If you’ll excuse the comparison, New Armstrong would be to New Glenn as Starship is to Falcon 9. You could be right though - I’m just guessing.
  7. I guess it’s the first step for Blue Origin, with New Glenn being the second and New Armstrong the third, assuming that NA is still more than a twinkle in Jeff’s eye. Pretty much on-brand that they don’t seem to have considered the wider ramifications though.
  8. Oh - forgot to say. If and when Blue Origin start putting New Glenn together, I’ll be watching this thread for news as avidly as I watch the SpaceX thread for Starship news. Sadly, at the moment I find it hard to get excited about Blue (got the blues you could say). Ongoing lawsuits (not the GAO appeal I hasten to add) don’t help. Also… I just don’t find Bezos particularly sympathetic or inspiring. Musk has his faults for sure - and I’m not convinced I’d want him as a boss - but in general I like his straight-talking SpaceX persona. Bezos? Well he built the right shaped rocket.
  9. Guilty as charged, I’ve been an unabashed SpaceX fan since before RATSat. With that said, if it had been Mr Musk pulling that insecure ‘look at meee!’ nonsense with Mr Shatner today, I’d be hard at work digging out a snarky one-liner to call out SpaceX instead.
  10. “We often see the customer as a nuisance.”
  11. Ahhh, that makes more sense to me. Thanks. For some professions, I would contend that that inability to control the conduct of others does determine how far you can get in your profession but I'd also agree that that inability is moot unless you're prepared to put in the work to begin with. I'm thinking of most of the creative/entertainment industries. For every JK Rowling out there, there are plenty of published writers (including well known ones whose work you'd find on sale in bookstores and the like) who still can't make a decent living purely from their writing. And behind each those, there are dozens more writers who are struggling to even get that far. I'd imagine that works for most of the other creative industries. You can be working your tail off, doing all the right things and maybe even doing pretty well. Hitting the big time though, depends on a large enough portion of a generally fickle public deciding that your stuff is da bomb and forking over their hard earned cash for it. But I'm nitpicking now or, at the least, cherry-picking.
  12. I really don't understand this need to prove sci-fi wrong which seems to come up a lot on your threads. I mean, I could understand looking at a bit of sci-fi and trying to figure out if it could be replicated in real life (and being disappointed if it couldn't) but chewing apart that same sci-fi just to declare that 'haha - they got it wrong!' seems particularly mean-spirited. As far as rotating tethers are concerned, if I was planning to write a story which involved one, I'd be overjoyed at reading this thread, and particularly @RCgothic's post which I referred to previously. Five hundred tons of spacecraft spinning on a 1km tether to create 1g of artificial gravity - and all using plain old steel rope? Fantastic! That gives me plenty of leeway to design and describe a fictional spacecraft knowing that the numbers are about right. If I need a more massive craft, I can go away and look for stronger tether materials to see if those craft would be feasible. The fine details of winch mechanisms, cable elasticity and hysteresis, damping vibrational modes on the tether, thermal properties of tether materials, effects of radiation on cable materials, etc. etc. ? Those I don't give half a damn about unless they're at all relevant to the story. For example, I might want to have the tether break or otherwise malfunction in a plausible way without making my behind-the-scenes spacecraft designers look like complete idiots for not thinking of the obvious failure modes ahead of time. Otherwise, I'm not going to care about the numbers at all. Mostly because the chances of my characters being in a situation where they need to explain those numbers in any detail are pretty slim. Partly because the more precisely I pin down a particular aspect of my spacecraft, the more constrained I am when talking about the rest of it. And partly because any numbers I put in the story are hostages to fortune for precisely this kind of nitpicking. (Plus it's tremendously easy to disappear down the rabbit hole of research, for the sake of a throwaway story detail, in lieu of actually getting any writing done. Ask me how I know.) At the end of the day, I'm writing a science-fiction story, not a monograph on spacecraft design. Unless the story requires a deep dive into the details, my aim would be to describe a plausible sounding tethered spacecraft with plausible capabilities, and to try not to include anything too boneheaded that would break my readers' suspension of disbelief.
  13. In no particular order. Always read the small print. If something looks too good to be true, it probably is. See above. 90% of internet adverts are garbage and/or dangerous. The rest are just after your money. Never be afraid to try something new just because it’s new. You may suck at it - but you might not. Sucking at something is the first step to not sucking at it. It’s okay to do something as a hobby and be happy with your level of competence at it. You don’t need to give it 110%, always push yourself to improve (insert your chosen trite self improvement slogan here). All jobs will have good days and bad days. All jobs will have parts that you like and parts that are drudgery. If you’re fortunate enough to have a choice, the trick is to pick the drudgery you can live with. Take pleasure in the simple things. Perfect is the enemy of good enough. Not every decision is worth endlessly agonising over. I personally disagree with the first item on @adsii1970’s list but the rest is golden.
  14. You’re contradicting yourself. Originally the a ship with the lighter tether was doomed if something went wrong, then it wasn’t doomed because it would require less propellant to recover from a tether break. Ditch the unhelpful ‘doomed’ language and I would say that both are correct. A less redundant tether system is lighter but riskier (tether might break) but the mass saved by using a lighter tether means that it’s possible to have a greater propellant reserve to recover from tether breaks. Theres’s also no reason why the two concepts (redundant tether and enough propellant reserve ) can’t be combined - but that extra mass requirement then has to come at the expense of a less capable spacecraft (in terms of achievable acceleration or delta-V) or a mass saving that has to be found somewhere else in the spacecraft design. Compromises. Compromises all the way down. Incidentally, there’s no irony in your last comments. The choice between using redundant systems (and therefore requiring a heavier spacecraft) or making the spacecraft repairable (and potentially lighter) has been understood since the earliest days of crewed spacecraft design. So far, redundant systems have mostly* been the preferred option, at least in US spacecraft. Making systems repairable in flight adds a whole other bunch of compromises to the design, not to mention the need to take along the necessary tools and spare parts - which add mass and also take up valuable storage space. *The ISS is a different matter of course but that’s a very long duration flight with a whole logistics chain to resupply it with consumables and spare parts.
  15. This is not an either/or scenario. Read @RCgothic's post again, since that's the most thoroughly worked out example on the thread. Looking at the tethered Starship example, there are several options for a lighter tether: Accept a less redundant system with a lower safety factor. Use lighter tether materials than steel ropes. Go for a lower artificial gravity than 1g. Any tether system is going to add mass to the spacecraft and there's always going to be a risk of something going wrong. This is not a binary choice between 'superheavy but redundant tether' and 'less heavy tether but doomed if something goes wrong'. This is a whole set of choices and trade-offs, depending on how much risk is acceptable.
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