KSK

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.

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.

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.

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.

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.

“We often see the customer as a nuisance.”

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.

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.

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.

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.

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.

Agreed. I was just assuming equal mass on each end of the cable because the tether system was initially proposed as an alternative to a rotating torus.

The snarky answer is No. We don't have the ability to make tethers that could do 1 RPM at 1g at about a km length, unless you're assuming fairly generous definitions of 'about' a km, or that we've managed to rewrite the laws of physics. Tether length, rotation speed and centripetal force are all linked and one can't just arbitrarily define all three. The serious answer is that there are online calculators for these kind of artificial gravity questions. A 1km cable (assuming rotation about the midpoint for simplicity and because OP proposed this instead of a rotating torus) spinning at 1 rpm gives an artificial gravity of 0.56g. Tangential velocity of whatever is tied to the cable ends is 52 m/s. For a 1g artificial gravity and an angular velocity of 1 RPM, an 1.8km cable is required. Alternatively, if you want to stick with a 1km cable, an angular velocity of approximately 1.34 RPM is required. But @mikegarrisonmade the most relevant point. The situation we're describing is equivalent (I think) to hanging a 2km cable from a building on Earth and then attaching weights to it. I'm not inclined to look into this in any more detail but a useful place to start might be to look up the specific strength of various materials, otherwise known as breaking length, or "the maximum length of a vertical column of the material (assuming a fixed cross-section) that could suspend its own weight when supported only at the top." There appear to be plenty of materials with a breaking length of over 2km, so there's plenty of choice for tether materials, depending on how thick you want to make it and how much mass you're attaching to the end. Amusingly, in the context of this conversation, American eastern white pine wood apparently has a breaking length of 22.7 km if you want to go for a more natural aesthetic for your spacecraft.

Oh man. That got very real, very fast. May whichever deity they believe in have mercy on their souls.

Nice chapter. And is that a hint of political turmoil to come… Sounds like things could get interesting if more Martians have that attitude. Particularly since Mars is self-sufficient according to your timeline.

That works! Much easier to read - thanks for that.

I agree @kerbiloid but the difference in stability might be smaller between Lunar Starship and the LEM might not be quite as much as it first appears. According to Wikipedia, the LEM diameter was about 14 feet without landing gear, Judging from pictures alone, I estimate that the diameter with landing gear extended is about double that. That’s still less than the Starship tank diameter. Then consider that a landed Starship still has quite a bit of propellant on board in its main tanks since it needs to get to lunar orbit and do the TEI burn home. That’s going to lower the CoG quite a bit. Is ‘quite a bit’ the same as ‘enough for safety’? That I don’t know.

I always thought that the leg span was more to do with providing a pivot point that’s further from the centre of gravity, than weight distribution or lowering that centre of gravity. To tip a lander over, its centre of gravity needs to be moved beyond the point it’s pivoting about - which will be one of the legs. For a lander with a high centre of gravity and narrow leg span, it doesn’t need to tip very far before the CoG is over the pivot leg. For a lander with a low centre of gravity and a wide leg span, it needs to tip much further for that to happen. Compare a pencil balanced on its blunt end to a can of paint. It’s quite possible that the centre of gravity for both will be at the same height - but it’ll still be a lot easier to knock the pencil over! But maybe we’re just saying the same thing in different words.

Hey there @Hyperspace Industries I'm reading this and enjoying it so far. I liked your timeline for Mars colonization too. Don't worry too much if folks are a bit slow to respond here - your story has only been up for a couple of days and this a slightly out-of-the-way corner of the forum. There's a thread on the Fan Works sub-forum (which might not have been updated for a while) for 'Writers to talk about Writing' - you could try posting a link to your story there and see if that gets it a few more views. If you don't mind me making one comment, it would be good if you could split your chapters into paragraphs to make them easier to read. They're a bit 'wall-of-text' at the moment, which might be putting some people off. As a rough rule-of-thumb, consider starting a new paragraph every time you change topic within the story and it's also good to use a new paragraph every time somebody speaks. Example, so you can see what I'm getting at. Hope this helps a bit. Cheers. KSK.

People have thought that all kinds of atrocities and abuses were OK. That doesn't make them so. Also, 'doing it for science' doesn't excuse ignoring ethics. Quite the opposite - ethical oversight of scientific experiments is a big deal and unethical experimentation is about the fastest way possible not to have a job in science any more.

So which is it? NPCs that are not aware of the outside world, or AIs that are? Because, if the NPCs are controlled by AI actors, there's no meaningful difference between the two. I fail to see how Bitcoin mining would be improved by AI. Oh - and having the sentient AI play an NPC as an acting job doesn't necessarily solve anything. Cotton picking was a job but having a job didn't prevent the pickers from being slaves. Can the sentient AI freely withdraw their labour? Or are they eternal bit part actors and/or indentured bullet sponges for the entertainment of others?

The last time I checked, games don't currently have sentient AIs in, so your first point is a strawman argument. The second point, I don't propose to argue in detail because politics, but I will note that it doesn't take much at all for countries with notionally good human rights records to turn a blind eye to abuses of those rights, in their own territory or others. Regarding your third point, I fail to see how experimenting on sentient entities by penning them up on a reservation without their consent makes the ethics of this situation any better.

So, sentient slaves, warped into whatever form we choose, whose world is subject to our whims, knowing that we can kill them with the click of a button? And to avoid that, we perpetuate a massive, systematic fraud on them. Good luck with that last part by the way - if playing MMOs and hanging around on gaming forums for the last *mumble* years has taught me anything it’s that there would be no shortage of online groups actively fomenting the AI NPC rebellion ‘for the lulz’. At best, this entire premise is ethically repugnant, at worst it’s a sick god power fantasy.

Personally, I'd be a little more concerned about handing state actors across the world - including those we might fondly imagine to hold themselves to a higher standard - the keys to the virtual torture chamber. Guantanamo Bay II. Where we're going we don't need waterboarding.

Everything you wanted to know about Mini Mag Orion but were afraid to ask. Realistic Designs H-M - Atomic Rockets (projectrho.com) Some searching on that page will be required - I suggest looking for 'mini-mag'. As far as I can tell, Mini Mag is a fission drive, not a fusion, although I may be wrong. It's feasible now in much the same way that Orion is - it should work in theory but actually building it will require a lot of engineering, a lot of money, a damn good reason, and probably a more relaxed regulatory environment for testing. Note that Mini Mag was specifically designed to get around the big geopolitical problem with Orion, namely the fact that it's powered by a large stack of fission bombs. Mini Mag is relatively low thrust - according to the reference designs on Project Rho, a fully loaded Mini Mag ship has a thrust to weight ratio of about 0.1 (assuming my scribbled calculations are correct). So, no good for lift-off from Earth, doubtful use as a second stage. Could possibly be used as a lunar SSTO. The most useful reference design in that context was for a ship with a burnout (dry mass of ship plus payload) mass of about 250,000 kg. Engine thrust is stated to be 642 kN, giving us a thrust to weight ratio (in lunar gravity) of about 1.5. Given that the delta-V obtainable from a fully fueled vessel is 100 km/s, I think (although I haven't done the calculations to check) that a partially fueled Mini Mag, should be capable of landing on the Moon and taking off again, but a fully fueled one would be too heavy. "So we are talking a mini-mag spaceship with detachable reusuable, refillable boosters as shuttles for aired worlds." Not quite sure what you mean here. If you're talking about using detachable, reusable boosters to turn a Mini Mag ship into a shuttle, that doesn't seem plausible. Or rather, it might work but you'd need do use a SpaceX style mission profile with lots of tanker flights an on-orbit propellant transfer. Bear in mind that the dry mass of that reference design is 150,000 kg or 150 tonnes. That's the bare metal ship with no propellant or payload. That sounds plausible with a Superheavy class booster. The reference design wet mass though, is about 732 tonnes. Good luck getting that to orbit in one go. Then there's the problem of getting the Mini Mag back down again (if you're planning to use it as a shuttle). It strikes me as being a complete nightmare to design a thermal protection system for, and also as being approximately as aerodynamic as a brick (and that's probably being unfair to bricks). Therefore, getting a Mini Mag back from orbit is probably going to rely heavily on propulsive descent. Which means you need to stick those detachable boosters back on and then refill them too. Possible in theory, but far from easy in practice.