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Discussion of metallic hydrogen propulsion split from another thread.


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It has been persuasively argued that this discussion belongs in the KSP2 subforum because this is where the devs would expect to find feedback on this prospective game feature. And so, the thread has been moved. 

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Kerosene doesn't really need any great inventions to be a fuel, though (BTW, we're not really talking about propellant, it's fuel in this particular case). You can fill a bottle with its vapors and, if you can light it (the only really hard part), it'll fly. Or possibly explode. The reason is because kerosene has a fundamental property common to all chemical propellants - when combined with oxidizer, it undergoes an exothermic reaction. TL;DR: it burns. It was never in question, and, the whole point of extracting kerosene out of crude oil was to burn it. 

Metallic hydrogen does not have a property that would enable it to be used as fuel. Imagine where would we be if we through the trouble of making kerosene, only to find it didn't burn. That's roughly where we are with metallic hydrogen right now. It is, quite simply, not a viable means of energy storage.

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I am late to the party, but I found a great article for people who might not know what all the fuss on this thread is about: https://www.space.com/39370-what-is-bizarre-metallic-hydrogen.html

 

I believe Metallic Hydrogen propulsion is possible.

Because we can do both high pressure and high temperatures. The question is, how to get there.

and I think the KSP 2 devs have researched on the topic long enough to decide to put this in the game or not. They don't want to add magic parts. That's why we won't have Wormholes or Warp Drives. I think they did the research and concluded that it works.

also, why is there two threads on the topic, they should be merged.

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7 hours ago, The Doodling Astronaut said:

also, why is there two threads on the topic, they should be merged.

This topic was in the generic scientific section since the discussion on metallic hydrogen was mostly on its feasibility.

I opened the other one to have a place to discuss its addition to KSP2 and the result is that my topic was closed and this was brought back to this section.

 

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This MH 'debate' bewilders me a bit.  Yes I like the fact that KSP has a grounding in reality, but for it to expand to include interstellar travel several 'stretches' of what's currently possible for us have to be accepted.

I don't personally think it matters that we humans haven't solved the problems that prevent MH working yet, or even if it will ever be practical or possible for us to do so.  For gameplay reasons why can't we just accept that the kerbals managed to do it somehow?

Presumably the devs needed something to 'fill that niche' so, rather than inventing a purely fantasy "Musk-Bezos" drive that uses the negative vibes of business animosity to create anti-matter, they picked up on MH which 'could' at least actually work in theory if solutions to some currently insurmountable problems could be developed.

As long as they don't give the impression that MH is, or could soon be, a real working method of propulsion what's the problem?

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From my original post:

Quote

The responsibilities of an educational game

I always made clear that I don’t think the developers have any responsibility about the science, the engineering and the technologies they put in KSP2, sometimes even disregarding the whole thing as “an argument over the flavor text of some engine” and here’s why: I think it’s not a simulator nor an educational software, it’s a game. 

The “educational” part comes from the fact that somehow it helps you visualize and understand orbital mechanics, space travel and orbital maneuvering like no other book, academic lesson or expert can do, not from the accuracy of the presented setting (little green people messing with rockets in a miniature solar system).

That’s what I expect from the game and the standard I expect KSP2 to live up to.

That’s the difference I see between the ⅓ scale and the lack of orbital mechanics of other games or between any FTL or teleporting technology and metallic hydrogen or an eventual Kerbstein Drive which I expect to behave like respectively OP variants of chemical propulsion and Daedalus drives.

On top of that KSP2 is set in some generic “near future” and as a result of that is going to dabble with some very speculative science and engineering, if anything I think the standards for realism and scientific accuracy are expected to be lower than KSP1.

 

Realism vs gameplay

Another side of the metallic hydrogen debate is the realism vs gameplay argument, I never made a mystery that I put gameplay over everything else, that’s because of the aforementioned position of considering KSP a game first and, as a game, it’s already difficult enough to balance things like difficulty, engagement, level of grind and balancing without having excessive realism as a constraint.

After all I think the game has to “feel believable” while maintaining an enjoyable level of challenge and not just add a ton of boring chores and endless grind for the sake of extreme realism.

 

KSP1 is an already overly optimistic space game (not that's a bad thing) when making a sequel set into a "near future" they were bound to have some very speculative science and engineering that alone makes something like the "metallic hydrogen debate" only a question of time.

Half of the game is a scientific discovery or feasibility study away from becoming "bad science" it happened with metallic hydrogen and it will happen again with some other engine, colony or celestial body.

We'd better get used to it.

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Not to get hung up on the beautifully productive debate that is going on... but it seems like adding metallic hydrogen rockets filled in for the beautiful plethora of other rockets the game seems to be missing.

Besides the Daedalus, where are any of the engines used in KSP:IE? In KSP 2 I have yet to see 1 allusion to anything like a liquid core engine, gas core engine, nuclear saltwater rocket, nuclear ramjet etc etc..... No new nuclear engines, no nuclear reactors to power nozzles and select propellants. They just look like a bunch of all-in-one engines... I'm happy to see Daedalus and Project orion but those are all we've seen from realistic engines when there are so many more to choose from. Meanwhile, we have metastable Met-H (sorry guys, it is not a thing and no reason to believe it will be) and the ever OP "torchship" which we haven't heard anything about how it works...

 

TL;DR: Met H is a missed opportunity to include a plethora of far more interesting and likely to exist engines and mechanics

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20 minutes ago, mcwaffles2003 said:

Besides the Daedalus, where are any of the engines used in KSP:IE? In KSP 2 I have yet to see 1 allusion to anything like a liquid core engine, gas core engine, nuclear saltwater rocket, nuclear ramjet etc etc..... 

We've seen exactly 3 nuclear engines (and heard that they'll come in different sizes) but also a radiation hazard icon in the VAB directly next to center of lift.

I think that we haven't seen the whole thing yet and the fact that in the last year we've only seen the original crafts that were used for the trailer only confirms that for me.

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21 hours ago, Bej Kerman said:

Kerosene isn't a propellant... until you invent the stuff you need to use it as a propellant.

MH isn't a propellant at all; Metastable MH is a potential propellant. So this isn't like not knowing how to burn Kerosene, it's more like discovering Crude Oil and not knowing how to refine it down into Kerosene.

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2 hours ago, Master39 said:

KSP1 is an already overly optimistic space game (not that's a bad thing) when making a sequel set into a "near future" they were bound to have some very speculative science and engineering that alone makes something like the "metallic hydrogen debate" only a question of time.

There's nothing optimistic about KSP1. Literally the only technology that is even slightly speculative is the RAPIER. Nuclear engines had been fired multiple times on the ground, you could slap the NERVA on a rocket and it'd work (in fact, that was the plan, until the whole thing got axed). All technology in KSP1 is Shuttle era at the latest, most of the rocketry is from the time Apollo, and smaller parts are more Mercury/Gemini in performance. It doesn't even have Space-X style advancements with reusability, being firmly stuck in the Shuttle-era mindset. 

The results are optimistic, yes, but nothing you can do in KSP1 couldn't be achieved IRL with Apollo-level tech. It'd just take more money and time than either the US or Soviets were willing to spend. I'd say, KSP1 is outright pessimistic, because it operates on a pre-Space X model of aerospace technology.

A "near future" sequel could've been futuristic just be featuring FFSC engines like the Raptor, souped-up NTRs and perhaps an early-tech direct fusion drive. KSP2 takes a very futuristic take on things, and metallic hydrogen propulsion in particular was known to be subject to be disproven by research even before it actually happened.

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56 minutes ago, Incarnation of Chaos said:

Metastable MH is a potential propellant.

A propropellant.

2 hours ago, Master39 said:

We've seen exactly 3 nuclear engines (and heard that they'll come in different sizes) but also a radiation hazard icon in the VAB directly next to center of lift.

10% of KSPI-E + 10% of Kerbalism

14 minutes ago, Dragon01 said:

There's nothing optimistic about KSP1

OptimismKsp1 + OptimismKsp2 = const

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2 hours ago, mcwaffles2003 said:

Daedalus, Orion.... what else? The torch ship?

The Nerv

 

15 minutes ago, Dragon01 said:

There's nothing optimistic about KSP1. Literally the only technology that is even slightly speculative is the RAPIER. Nuclear engines had been fired multiple times on the ground, you could slap the NERVA on a rocket and it'd work (in fact, that was the plan, until the whole thing got axed). All technology in KSP1 is Shuttle era at the latest, most of the rocketry is from the time Apollo, and smaller parts are more Mercury/Gemini in performance. It doesn't even have Space-X style advancements with reusability, being firmly stuck in the Shuttle-era mindset. 

KSP is "set" between the dawn of the space era and now-ish, and that is known and has nothing to do with the game being optimistic.

The scale, the simplified attitude control, the lack of life support or environmental hazards all of that makes the game optimistic, space stravel comes off as way simpler than IRL (again, nothing wrong with that, that's why I love the game).

 

15 minutes ago, Dragon01 said:

A "near future" sequel could've been futuristic just be featuring FFSC engines like the Raptor, souped-up NTRs and perhaps an early-tech direct fusion drive. KSP2 takes a very futuristic take on things, and metallic hydrogen propulsion in particular was known to be subject to be disproven by research even before it actually happened.

Don't correct other on vague concepts like "near future" vs "futuristic" it's a pointless discussion on semantics. For you fusion is on the fringe of NF while others call "the Expanse" that, replace "near future" with "true scottish pirate metal" and the concept doesn't change.

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37 minutes ago, Master39 said:

The scale, the simplified attitude control, the lack of life support or environmental hazards all of that makes the game optimistic, space stravel comes off as way simpler than IRL (again, nothing wrong with that, that's why I love the game).

Environmental hazards are there, just ask any Kerbal who trips over flat terrain or encounters one of the many surface krakens. :) 

Yes, space travel comes off as far simpler than it is, so does nuclear tech. This is beside the point, however. Metallic hydrogen is not a matter of optimism, anyway, since it's demonstrably wrong. If you think a wizard will someday pick you up and take you to the Moon, you're not optimistic, you're deluded. Space travel happens. Fusion happens. Metallic hydrogen metastability doesn't.

38 minutes ago, Master39 said:

Don't correct other on vague concepts like "near future" vs "futuristic" it's a pointless discussion on semantics. For you fusion is on the fringe of NF while others call "the Expanse" that, replace "near future" with "true scottish pirate metal" and the concept doesn't change.

Except that I said what it could have been, not what it has to be. DFD is a thing already, in a lab:
https://en.wikipedia.org/wiki/Direct_Fusion_Drive
Notice that this is a very primitive form of fusion drive. My point is that all the technology listed would have sufficed for a "near future" label. If you want to argue with that, you may say the lineup I presented would be "present day", as opposed to "near future", but calling this "futuristic" only tells me that you have no idea about where fusion research really stands.

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2 hours ago, Dragon01 said:

[snip]

Ok, let's strip all the examples so you stop arguing about those.

KSP1 already makes concessions on how some technology works.

KSP2 is set in the "near future"* and not "recent past" like KSP1.

KSP2 has a lot of speculative science and engineering probably with the same kind of concessions KSP1 already had.

A lot of speculative science and engineering in a setting where everything is OP compared to IRL means that everything is half a study/discovery away from becoming the next metallic hydrogen debate.

 

*devs words, not going to debate about what "near future" means, I've seen it used from a post SpaceX Starship setting all the way up to "the Expanse".

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34 minutes ago, Master39 said:

A lot of speculative science and engineering in a setting where everything is OP compared to IRL means that everything is half a study/discovery away from becoming the next metallic hydrogen debate.

You're still not getting it. Fusion works. Nuclear power works. This is not speculative science. Yes, there is some speculative engineering involved, but we're pretty sure all those things can be built, one way or another. Alcubierre drive is speculative science. Metallic hydrogen was (and now it isn't, it's bunk). Neither fusion nor fission are in this category. 

The technologies presented are not "half a study away" from becoming bad science. Metallic hydrogen was already on shaky theoretical grounds. Even the torch drive could be based on a real principle which had been tested in a lab. Source:
https://www.researchgate.net/publication/239590484_Advanced_Space_Propulsion_Based_on_the_Flow-Stabilized_Z-Pinch_Fusion_Concept
Not speculation, not magic, research

Here's a thought experiment. Suppose a politician (yes, this assumes a thinking politician, up there with metallic hydrogen on realism scale, but let's let just that one slide) plays KSP2. Would you rather have him see a metallic hydrogen drive and ask NASA "hey, why aren't you working on that", only to be told "that's because it's physically impossible", or a fusion drive, where the answer would be "because we'd need more money for developing it"?

Edited by Guest
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Guys, let’s not forget something-

Ksp2 is a game. A GAME. Should I make a big to-do about the sun in Minecraft? Ohh, the sun is SQUARE! It shouldn’t be a square! Why isn’t it round?!? So what if metallic hydrogen isn’t feasible? You don’t have to use it. No one is making you. You can completely ignore it, if you want.

One last note-sure, metallic hydrogen isn’t feasible right now. But...as humanity advances, and we make technological leaps and bounds, maybe we will be able to harness it someday. Think about this-only a hundred odd years ago, people though flight was a madman’s dream. Nowadays, it’s so common we don’t even think twice. And when you think about how much we have advanced even in just the last 30 years...I think it’s safe to say that in 200 years or so, we’ll be able to use metallic hydrogen. Just a thought, Mr. Fox.

Cheers.

-Lewie

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26 minutes ago, Dragon01 said:

You're still not getting it. Fusion works. Nuclear power works. This is not speculative science. Yes, there is some speculative engineering involved, but we're pretty sure all those things can be built, one way or another. 

The technologies presented are not "half a study away" from becoming bad science. Metallic hydrogen was already on shaky theoretical grounds. Even the torch drive could be based on a real principle which had been tested in a lab. Source:
https://www.researchgate.net/publication/239590484_Advanced_Space_Propulsion_Based_on_the_Flow-Stabilized_Z-Pinch_Fusion_Concept
Not speculation, not magic, research

Here's a thought experiment. Suppose a politician (yes, this assumes a thinking politician, up there with metallic hydrogen on realism scale, but let's let just that one slide) plays KSP2. Would you rather have him see a metallic hydrogen drive and ask NASA "hey, why aren't you working on that", only to be told "that's because it's physically impossible", or a fusion drive, where the answer would be "because we'd need more money for developing it"?

Flipside of that is Kids who'll play KSP2 in the actual thousands and start to wonder and research where on the scale of real each future tech is. You really want to give them one that is way on the edge to really inspire them to think and dream. They'll need some options that are at the magically end. This one the basic science of thrust is still valid not like a warp drive or magic portal just here is an idea on how to get higher ISP.

Frankly If Politicians get taken seriously saying things like "lets do this thing I saw in a computer game" then the problem isn't KSP.

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57 minutes ago, Dragon01 said:

 Yes, there is some speculative engineering involved, but we're pretty sure all those things can be built, one way or another.

You noticed I said "science and engineering" and not just science, impossible and impractical are basically the same thing.

 

1 hour ago, Dragon01 said:

Here's a thought experiment. Suppose a politician (yes, this assumes a thinking politician, up there with metallic hydrogen on realism scale, but let's let just that one slide) plays KSP2. Would you rather have him see a metallic hydrogen drive and ask NASA "hey, why aren't you working on that", only to be told "that's because it's physically impossible", or a fusion drive, where the answer would be "because we'd need more money for developing it"?

If you assume a thinking politician the problem does not arise, thinking people are usually pretty good at distinguishing a videogames from reality (despite what this whole debate may suggest), if you assume someone dumb enough to take a game about little green aliens building rocket as a scientific source being somehow in power then I think we'd have bigger problem than what he asks to NASA.

 

 

 

 

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As they brought the unnecessary MeH, they should add also the Cavorite.

As it's noticed above, they skipped a lot of intermediate realistic technologies from KSPI-E, but added a voodoo powder to magically fly without boring explanations.

Also a tank of Phlogiston would be great, to heat the Metal Hydrogen without engines-schmengines.

P.S.
Just to be clear: I'm all for the canned Phlogiston, interplanetary Aether, and Cavorite, and even MeH.
Say, substract the heat from a normal hydrogen to make it metallic, and store that heat as phlogiston.

Just it's another tale, and another story. Why mix it in any other way but a mod.

Edited by kerbiloid
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6 hours ago, Master39 said:

You noticed I said "science and engineering" and not just science, impossible and impractical are basically the same thing.

No. They aren't, and this is your most ridiculous statement so far. Impossible and impractical are not the same thing. Steam cars were impractical. Building a railway across the entire US was impractical. Tunneling under the English Channel was impractical. Landing rockets on their tail was impractical. Landing humans on the Moon was impractical (and it still is). Space airplanes were impractical (ditto). Reflying space rockets was impractical. One of the main themes I want KSP to teach is that impractical doesn't mean impossible. This is where KSP is allowed to make concessions to reality. Not to make the impossible possible, but to make impractical, practical. 

As for my analogy, evidently you missed my whole point. Again/ Here's a word of the day for you: Inspiration.

6 hours ago, mattinoz said:

Flipside of that is Kids who'll play KSP2 in the actual thousands and start to wonder and research where on the scale of real each future tech is. You really want to give them one that is way on the edge to really inspire them to think and dream. They'll need some options that are at the magically end. This one the basic science of thrust is still valid not like a warp drive or magic portal just here is an idea on how to get higher ISP.

You don't need outright magic, though. Science provides you with "magic-like" propulsion aplenty, if you want very speculative. Flow-stabilized Z-pinch fusion can theoretically give you performance on the level of Epstein drive, and fusion in this method is far more stable (5000 times more) than normal Z-pinch, so this method might actually be easier than what we've been trying so far. Science is far less restrictive than people assume. 

Besides, metallic hydrogen isn't even on the "magic end", performance wise. It's a fairly pedestrian middle-ground engine, sitting well below more realistic options such as the GCNR or fusion drives. Based on the numbers they gave, it could easily be replaced by liquid core nuclear rockets, they match the required performance almost exactly. 

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13 hours ago, Lewie said:

One last note-sure, metallic hydrogen isn’t feasible right now. But...as humanity advances, and we make technological leaps and bounds, maybe we will be able to harness it someday. Think about this-only a hundred odd years ago, people though flight was a madman’s dream. Nowadays, it’s so common we don’t even think twice. And when you think about how much we have advanced even in just the last 30 years...I think it’s safe to say that in 200 years or so, we’ll be able to use metallic hydrogen. Just a thought, Mr. Fox.

Let's use a possibly illustrative example here:

Instead of talking about metastable metallic hydrogen, let's use metastable water.  You take normal water and heat it up without letting it boil and vaporize to several hundred degrees Celsius (at least 500 Kelvin) and then by abusing it's metastability you store it in a normal water bottle, still with all that heat energy.  You then connect that water bottle to a rocket nozzle, and pump it out, letting it revert to steam at some high PSI as it exits the nozzle, producing thrust.

Depending on how hot you can make it stable at, you could get great thrust and ISP - similar to say a nuclear salt-water engine, if you could keep it metastable at high enough temperatures. Better in fact, as you wouldn't be losing some Uranium as propellant.  You'd have to work on keeping the heat in the tanks, but vacuum is a great insulator and I'm sure you could work out something - especially since the normal problem is getting *rid* of heat.  Since it's metastable you don't have to worry about keeping the tanks all that strong, so the only weight penalty would be insulation.

Does this sound useful?  Does it sound reasonable to put in a game?  Could you say 'as humanity advances, this may one day be possible'?  Or does it sound ridiculous and something you wouldn't want in a science-based game?  Here's the thing however: there is actually *more* evidence that this would be possible than metastable metallic hydrogen - after all, you can keep water metastable a couple of degrees above boiling.

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7 hours ago, Dragon01 said:

Besides, metallic hydrogen isn't even on the "magic end", performance wise. It's a fairly pedestrian middle-ground engine, sitting well below more realistic options such as the GCNR or fusion drives. Based on the numbers they gave, it could easily be replaced by liquid core nuclear rockets, they match the required performance almost exactly. 

And that's exactly why it isn't a big deal, the educational portion of the game, teaching orbital mechanics, is not touched.

 

7 hours ago, Dragon01 said:

No. They aren't, and this is your most ridiculous statement so far. Impossible and impractical are not the same thing. 

"Let's define as impractical things that have already been done and demonstrated not so impractical after all, completely forgetting that for every single of those projects there were probably tens of other ideas that were even more impractical"

 

22 minutes ago, DStaal said:

[...]

Ok, I give for granted that's impossible as a premise because I think it doesn't change the argument that much, but let's remember that we've just been able to create the thing in a laboratory (maybe) only once or twice and the evidence and data about its metastability are really fresh.

It's beyond dishonest talking about it like it's something that's been disproven without doubt half a century ago.

Especially doing so much noise about KSP2 (that, just a reminder, is a videogame about little green aliens messing with cool rockets) when basically every other usually reliable source of information has a lot of catch-up to do on the argument.

 

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27 minutes ago, DStaal said:

Does this sound useful?  Does it sound reasonable to put in a game?  Could you say 'as humanity advances, this may one day be possible'?  Or does it sound ridiculous and something you wouldn't want in a science-based game?  Here's the thing however: there is actually *more* evidence that this would be possible than metastable metallic hydrogen - after all, you can keep water metastable a couple of degrees above boiling.

Like I said, it’s a game. And it’s not even a ‘science based game’. (Jool’s moons are impossible, we all know that). A game. Ksp is a much more realistic then other space games out there, so what if there are a couple engines that are speculative? A game. A GAME. It doesn’t hurt you. Don’t worry...the mean metallic hydrogen won’t bully you. 

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