I'm going to say that getting hydrogen in required amounts for rocket fuel is probably more a matter of building the industry if you really want it-the problem of course is that I'm not sure how much we 'really want it'. Having the resources of a whole planet is very nice in theory, but how much do we actually have in fact? 1% of global GDP? .1%? And how big a payload are we gonna have to loft into orbit-just scientific satellites, or manned missions?
Let's do rocket engineering from the beginning
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Step 1 is I get the eggheads to work on a Light Gas gun instead of those silly rockets. Methane, gaseous hydrogen, and good old air are the only things needed to get up to at least 3 km/s with an option to get up to 7 km/s. You will still need a 'second' stage to get into orbit but that requires a ~1km/s kick stage while in orbit is much easier to do after all in theory.
Now it might look like a dead end technology as you won't be able to do maned anything with a space gun but it is important to remember at what stage we are at. There is no knowledge of hypersonic speeds, reentry dynamics, or even what space is like much less all the secondary research it opens up. And if you do manage to get it up then you have opened up a cheap way to get bulk payloads into space which will make future missions with rockets suddenly have more options on how to do long missions in LEO.
Now it might look like a dead end technology as you won't be able to do maned anything with a space gun but it is important to remember at what stage we are at. There is no knowledge of hypersonic speeds, reentry dynamics, or even what space is like much less all the secondary research it opens up. And if you do manage to get it up then you have opened up a cheap way to get bulk payloads into space which will make future missions with rockets suddenly have more options on how to do long missions in LEO.
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If I was truly insane I'd consider using ArO6F6 as my oxidizer. I'm not sure if that is even possible to safely make and handle or what its properties would be if it could be safely made, handled, and used.
That oxidizer molecule is going to look like a 20-sided die with a very unhappy Argon atom in basically a +18 oxidation state sitting in the middle of it and I know this despite having taken only two introductory college chemistry classes over 20 years ago.
When the thermodynamic cliff dive it's going to take happens PV=nRT tells me that the chamber temperature just increased by an order of magnitude before any of the heat released by the Argon atoms getting their electrons back is included or what the very hot oxygen and fluorine atoms are about to do to the things they're about to go oxidize and fluorinate is also included.
The chamber temperature is probably going to be higher than the surface temperature of the very large star we call the Sun.
I know ArO6 and ArF2 do exist as do a lot of other noble gas compounds. I don't know if ArO6F6 is possible.
en.m.wikipedia.org
That oxidizer molecule is going to look like a 20-sided die with a very unhappy Argon atom in basically a +18 oxidation state sitting in the middle of it and I know this despite having taken only two introductory college chemistry classes over 20 years ago.
When the thermodynamic cliff dive it's going to take happens PV=nRT tells me that the chamber temperature just increased by an order of magnitude before any of the heat released by the Argon atoms getting their electrons back is included or what the very hot oxygen and fluorine atoms are about to do to the things they're about to go oxidize and fluorinate is also included.
The chamber temperature is probably going to be higher than the surface temperature of the very large star we call the Sun.
I know ArO6 and ArF2 do exist as do a lot of other noble gas compounds. I don't know if ArO6F6 is possible.
Argon compounds - Wikipedia
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Are you sure that's not XeF6? I don't see anything about an argon hexafloride. Compared to Ar, the massive Xe will steal a good chunk of kinetic energy.
Sandy River DL
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Best be doing the launches from a remote uninhabited islad then. ClF5 is terrifying stuff.
Pineapple
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ClF5 is a lot less scary than ClF3
Sandy River DL
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Anything that generates hydrofloric acid as a combustion product is terrifying. Less so than both hydrochloric and hydrofloric acids? Yes, but still to be kept far away from anything you care about.
Pineapple
Punished Pineapple
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Well yeah people don't tend to stand directly under the rockets they launch.
Sandy River DL
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Yeah uh, that's not the big issue with Florine oxidizers...*side glance at all the early rocket failures*
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I was mentioning something truly insane. XeO4 (the nastiest oxidizer I'm aware of) boils at about the freezing point of water.
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There's a very good reason why I said:
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Mercury capsules massed about 1950kg with the escape tower and retro rockets. Vostoks were about 4,725kg at launch. So somewhere in that neighbourhood for early manned missions with a crew of one.
Scientific payloads could be smaller, but a society like the hypothetical one probably doesn't have anything much better than lead-acid and (maybe) nickel-cadmium batteries to power the satellite. Those are heavy, so developing solar panels would be a priority that (given our history) is probably already underway for reasons unrelated to space exploration. Until they get solar panels, they're stuck with batteries and would probably stuff their early satellites with as many as possible to make the satellites function for as long as possible.
The really tricky part is going to be the automated guidance and control systems. Analog electro-mechanical for guidance and electrical/pneumatic/hydraulic for controls is what I'm guessing they'd use.
EDIT: The first satellite would probably be similar to Sputnik 1: a battery powered radio transmitter so you'd know it got up there and could track it.
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mouli
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This sort of hardware can run a basic Kalman filter-type localization system for navigation, assuming you can support hardcoded matrix operations. That gives you control state estimation and location (to an extent), and in turn can drive a basic feedback control system. I will also note that adaptive controllers of the model-reference sort can run on very basic electronics if you want to move up a generation, so controls aren't a huge leap here. As long as you just want 'space' and not to land on a comet or something. Extended Kalman systems and optimal controllers aren't all that accurate without iterative optimization.
Lemme know if you want sources or it seems a decent contribution to thread, this is in a sense my field.
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Any society that cares that much about non-fouled rocket exhaust isn't going to use anything other than kerolox or hydrolox for liquid rockets. Nothing else gives you the throw weight alongside relatively benign exhaust. It even cuts you out of solid boosters, because solid boosters have all sorts of other crap in their burn product.
That's a bit narrow, plenty of hydrocarbons burn at least as clean as kerlox, at least a few with respectable performance. (SpaceX and Blue Origin doing methalox, Vector was trying propene) If we're figuring less deltaV to orbit and also simpler technology demanding easier handling over maximum performance, HTP would be a clean oxidizer too.
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One side question: What's this society's current level of understanding of the physics of rocketry? If stuff like the Tsilovsky equation and the Oberth effect are already known then that's one less hurdle to overcome; the engineering just has to catch up with the physics.
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I think that's about where they'd be. Like us, circa 1925, minus all the military bullshit.
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Interesting. I figured they'd come up with something like a Dreyer Table capable of accepting remote inputs via radio to be the "brain" of an unmanned rocket because that's certainly doable.
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The main issue with hydrocarbons is refining the crudes into what you want precisely enough to be used in a rocket motor without blowing it up. Stuff like benzene and toluene shouldn't be too difficult even without access to crude oil. Something like RP-1 is an entirely different story.
With solids, I imagine those would mainly be used by this hypothetical society for launch escape systems in their space program, and not much else. Those need to be as simple as possible and work reliably every time. When one of those needs to be used, you've got bigger worries than a fouled up launch pad.
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They may be working on methalox, but every engine SpaceX has used to launch cargo has been kerolox. I expect methane is going to come along, but if we're talking a society around our 1925s, well, we were flying kerolox rockets in 1957 but nobody's used a methalox yet
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And I'd want no part of it (or any other strong acid with lots of oxygen in it) until someone else figured out how to keep it from corroding the materials it's stored in ... which didn't happen until someone figured out that adding a bit of hydrofluoric acid (which I'd also want no part of) is an effective corrosion inhibitor. That didn't happen for us until the 1950s.
For a society like the hypothetical one an engineer with my chemistry knowledge and a biology similar to ours isn't going to like any of the oxidizers and rocket fuels they can get except for ethanol ... and they're going to want drink that instead of feeding it to a rocket motor.
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Another oxidizer they might consider: sulphuric acid (H2SO4)
All the problems associated with strong acids apply. Then there's that sulfur atom. It's going to cause all sorts of trouble because it can attach itself to practically anything an oxygen atom can. You'll get all the combustion products you get with LOX or H2O2 plus sulfur soot, sulfur dioxide, along everything else that happens when sulfur replaces oxygen in a molecule ... and the list of "everything else" won't be pretty.
It might be about as good as perchloric acid performance wise, but I would feel sorry for anyone who gets stuck doing the static and shifting equilibrium performance calculations by hand to figure that out because H2SO4 is probably the biggest mathematical mess of all the so-far mentioned liquid oxidizers to solve. May the gods have mercy on their soul if the mix includes any or all of nitrogen, chlorine, or fluorine.
Aside: There used to be an Indianapolis architecture firm called A2SO4 ... someone had some chemistry knowledge and a sense of humour when they came up with that.
All the problems associated with strong acids apply. Then there's that sulfur atom. It's going to cause all sorts of trouble because it can attach itself to practically anything an oxygen atom can. You'll get all the combustion products you get with LOX or H2O2 plus sulfur soot, sulfur dioxide, along everything else that happens when sulfur replaces oxygen in a molecule ... and the list of "everything else" won't be pretty.
It might be about as good as perchloric acid performance wise, but I would feel sorry for anyone who gets stuck doing the static and shifting equilibrium performance calculations by hand to figure that out because H2SO4 is probably the biggest mathematical mess of all the so-far mentioned liquid oxidizers to solve. May the gods have mercy on their soul if the mix includes any or all of nitrogen, chlorine, or fluorine.
Aside: There used to be an Indianapolis architecture firm called A2SO4 ... someone had some chemistry knowledge and a sense of humour when they came up with that.