Discussion of metallic hydrogen propulsion split from another thread.

[magnemoe]

17 hours ago, Dragon01 said:

Pretty good, as with any thermal rocket technology. People who think nuclear has low thrust by definition are always thinking of NERVA, which was a hydrogen upper stage engine. If you use a heavier propellant you will have better thrust. Nuclear engines do not need to have low thrust, but their TWR will be lower than that of chemical engines, because they are heavier. 

Indeed, a liquid core NTR using water as propellant would have stats broadly similar to mH engines, without the need for unobtainium. 

Hydrogen has the benefit of being fast then hot because its light, the lightness also make trust fairly weak. Note that he LV-N in KSP is weaker because of balance. You could run an nerva on water or co2, but this would give you hydrolox ISP levels, it only make sense for ISRU. 
Liquid core and gas core has the benefit that the reactor don't touch the walls so it can run much hotter giving you higher isp and trust, downside is controlling an nuclear reaction in an blob of melted uranium  Its also open cycle, you will loose some uranium during trust. 
Finally it looks like you use reaction mass flow to keep the pile in place you are not doing rapid maneuvers with this also think you have to dump the core at end of burn. This might be unpopular in leo  
 

[kerbiloid]

5 hours ago, Codraroll said:

The game has RTGs burning forever, magic reaction wheels, parts that never deteriorate and stuff like that (even large metal claws that can grip soft foam fuel tanks without leaving marks), so a Kerbal Stabilization Procedure (TM) to create metallic hydrogen wouldn't be too far outside the question for me. 

We have dedicated mods to worsen the things.

But if use the metallic hydrogen, we just must use the huffnium-178m2 subnukes.

Edited July 24, 2020 by kerbiloid

[KerikBalm]

8 hours ago, Codraroll said:

Forgive me for waltzing into this thread as a layperson like a cow into a china store,

Very well, while this point has been brought up multiple times before, it is a long thread.

8 hours ago, Codraroll said:

wouldn't it be possible to assume some technology to stabilize hydrogen in a metallic form?

This would be equivalent to saying that future tech should be able to stabilize liquid water, and allow it to remain liquid in a vacuum.

The phase diagram of water is an intrinsic property of the substance, not subject to change.

[KerikBalm]

14 hours ago, K^2 said:

Ah, so it's also open cycle, got it. I thought LC was supposed to be closed cycle, making it very similar to SC. Yeah, with an open cycle, you don't have a heat exchanger, so there are ways to inject cooler layers between the really hot stuff and containment, giving you ability to push I_SP by at least a factor of "a few" compared to chemical. There are still limits, of course, but you ought to be able to get well above 1,000s with the right propellant mix and well designed reaction chamber and nozzle.

Well, if you want to do closed cycle liquid core, I suppose you can. If closed cycle gas core is a "lightbulb", then closed cycle liquid core would be some sort of liquid container.

A solid core NTR at 3200 K gives an exhaust velocity on H2 of 824 s according to atomic rockets, (yet they also say "A temperature of 2,300 to 3,100 K will produce approximately a specific impulse of 830 to 1,000 seconds")

So instead, I'll look at this:

https://en.wikipedia.org/wiki/NERVA#Reactor_test_summary

and use NRX A6 as the reference point: Chamber temp: 2406K, Isp: 869.

Since you can get up to about 4150K with Hf-Ta-C, you can have your liquid fission fuel encased in Hf-Ta-C, and heat that up to 4150K, which should result in sqrt(4150/2406) = 31.3% higher exhaust velocity, and thus higher Isp... which leads me to 1141 if a 24060K reactor gets 869.

This would be "clean", and would perform similar to a PSM engine mixed with liquid hydrogen.

Keep in mind, even if mmH/PSM existed, the only way to use it without melting the engine would be to dilute theexhaust with something else to prevent the engine from melting, so the "cesium doped" PSM engine is still ridiculous, and a less ridiculous PSM/mmH engine + lH2 diluant would perform about as well as a molten core NTR.

[Guest]

15 hours ago, magnemoe said:

Hydrogen has the benefit of being fast then hot because its light, the lightness also make trust fairly weak. Note that he LV-N in KSP is weaker because of balance. You could run an nerva on water or co2, but this would give you hydrolox ISP levels, it only make sense for ISRU. 

Not really, it gives you hydrolox-level Isp at a methalox-level thrust and with a propellant that is not hydrogen, which means storage is somewhat less problematic. Methane and ammonia NTRs would be superior to hydrolox chemical engines in every way besides cost.

Water or CO2 are mostly good ISRU, but remember that they are pretty cheap. For a multiuse NTR launch vehicle, propellant costs will be important. Using them might be a good idea if methane stops being equally cheap for some reason.

[magnemoe]

41 minutes ago, Dragon01 said:

Not really, it gives you hydrolox-level Isp at a methalox-level thrust and with a propellant that is not hydrogen, which means storage is somewhat less problematic. Methane and ammonia NTRs would be superior to hydrolox chemical engines in every way besides cost.

Water or CO2 are mostly good ISRU, but remember that they are pretty cheap. For a multiuse NTR launch vehicle, propellant costs will be important. Using them might be a good idea if methane stops being equally cheap for some reason.

Yes you are right here. More interesting if other hardware like orbital rockets uses methane as you can refuel or just launch with little fuel in the tanks KSP style because of maximum cargo capacity. 
 

[SOXBLOX]

On 7/23/2020 at 4:44 PM, Codraroll said:

Forgive me for waltzing into this thread as a layperson like a cow into a china store, but if we're discussing this strictly in a KSP2 perspective, wouldn't it be possible to assume some technology to stabilize hydrogen in a metallic form? The game has RTGs burning forever, magic reaction wheels, parts that never deteriorate and stuff like that (even large metal claws that can grip soft foam fuel tanks without leaving marks), so a Kerbal Stabilization Procedure (TM) to create metallic hydrogen wouldn't be too far outside the question for me. 

While the real world seems to be sadly lacking in ways for metallic hydrogen to exist, there appears to be a pretty unison understanding of how it would behave if it did. Provided the right disclaimers were presented, I think its ground isn't so flimsy it warrants exclusion from a video game.

Exactly.

[KerikBalm]

On 7/23/2020 at 11:44 PM, Codraroll said:

Provided the right disclaimers were presented, I think its ground isn't so flimsy it warrants exclusion

The ground is very flimsy, and the cesium doped variant seems to be pure techno-babble.

I would not be so opposed if they had the right disclaimers, and as I've said before, I would be fine with it if they called it something like "liquid Explodium". After all, they say RTGs have "blutonium"

[Codraroll]

On 7/25/2020 at 8:10 AM, KerikBalm said:

I would not be so opposed if they had the right disclaimers, and as I've said before, I would be fine with it if they called it something like "liquid Explodium". After all, they say RTGs have "blutonium"

Wouldn't that be "Metallic Explodium"? Or at least "Metallic liquid fuel"?

But yeah, I agree there. If the problem with metallic hydrogen is that hydrogen can't be metallic, it shouldn't be a problem to come up with a similar substance that can be metallic and use that one instead. Take Minmus, for instance. Real-world physics wouldn't allow it to exist for very long if it was made of ice (at the very least, its mountains should come down pretty quickly), but as far as I can tell the official line is that it's made of a substance that just really looks like mint ice cream without actually being it (to everyone's great disappointment). Who knows what properties almost-mint-ice-cream has. Apart from phenomenal density, that is.

[Bej Kerman]

On 7/23/2020 at 10:44 PM, Codraroll said:

Forgive me for waltzing into this thread as a layperson like a cow into a china store, but if we're discussing this strictly in a KSP2 perspective, wouldn't it be possible to assume some technology to stabilize hydrogen in a metallic form? The game has RTGs burning forever, magic reaction wheels, parts that never deteriorate and stuff like that (even large metal claws that can grip soft foam fuel tanks without leaving marks), so a Kerbal Stabilization Procedure (TM) to create metallic hydrogen wouldn't be too far outside the question for me. 

While the real world seems to be sadly lacking in ways for metallic hydrogen to exist, there appears to be a pretty unison understanding of how it would behave if it did. Provided the right disclaimers were presented, I think its ground isn't so flimsy it warrants exclusion from a video game.

Exactly, eternally working OP RTGs and reaction wheels are just as silly as working mmH engines. If RTGs can work forever, why not mmH?

On 7/25/2020 at 7:10 AM, KerikBalm said:

The ground is very flimsy, and the cesium doped variant seems to be pure techno-babble.

  Please explain your viewpoints.

 

Edited July 27, 2020 by Bej Kerman

[KerikBalm]

1 hour ago, Bej Kerman said:

Exactly, eternally working OP RTGs and reaction wheels are just as silly as working mmH engines. If RTGs can work forever, why not mmH?

There was a thread on that...

No sense discussing that here.

1 hour ago, Bej Kerman said:

 Please explain your viewpoints.

I already have, I am tired of just making the same arguments over and over.

So do you have an explanation for how it works or no?

[Bej Kerman]

20 minutes ago, KerikBalm said:

2 hours ago, Bej Kerman said:

Exactly, eternally working OP RTGs and reaction wheels are just as silly as working mmH engines. If RTGs can work forever, why not mmH?

There was a thread on that...

No sense discussing that here.

Quote

 Please explain your viewpoints.

I already have, I am tired of just making the same arguments over and over.

So do you have an explanation for how it works or no?

Thank you for explaining your viewpoints.

[SOXBLOX]

Perfect realism is both impossible and unnecessary in KSP 2. There is really no reason for objecting to mH in the game, while ignoring such defects as patched conics, infinite RTG power, the entire aerodynamics model, etc. Additionally, I count one, maybe two or three, people here who object to its inclusion. Many more of us do want it, or are fine tolerating it, the same way we tolerate Kerbol having the size of a red dwarf and the luminosity and spectrum of a G-type star.

I am fine with metastable metallic hydrogen being in the game. I do not want it renamed, dropped, or nerfed, and I will strongly object to any tampering with its position in the game.

Remember, for the purposes of those who want "realism" or "scientific accuracy" , the engine is a device with a high ISp and thrust, nothing more. You can ignore the flavor text where you want. If you don't want to use the engine, don't. Ignore it. Whining about it doesn't help anyone.

[KerikBalm]

[snip]

The point is that it seems like they just slung some buzzwords together, and I have yet to see any explanation as to how "cesium doping" is supposed to allow for magnetic confinement of ~6000k hydrogen.

It seems to me to make as much sense as saying they use a flux capacitor that modifies the phase variance to contain the exhaust.

If someone can explain how cesium doping is supposed to work, or provide the science behind it, I will withdraw my complaint.

Right now it seems to be prima facie techno-babble

Edited July 28, 2020 by Vanamonde

[Bill Phil]

21 hours ago, KerikBalm said:

[snip]

My understanding is that it’s intended to alter the bulk magnetic properties of the material - cesium was investigated as a working fluid for MHD generators and is used in some magnetometers.

Edited July 28, 2020 by Vanamonde

[kerbiloid]

52 minutes ago, KerikBalm said:

If someone can explain how cesium doping is supposed to work, or provide the science behind it, I will withdraw my complaint.

You need Red Caesium (tm). It's like Red Mercurym but Caesium.

[Guest]

4 hours ago, SOXBLOX said:

Perfect realism is both impossible and unnecessary in KSP 2. There is really no reason for objecting to mH in the game, while ignoring such defects as patched conics, infinite RTG power, the entire aerodynamics model, etc. Additionally, I count one, maybe two or three, people here who object to its inclusion. Many more of us do want it, or are fine tolerating it, the same way we tolerate Kerbol having the size of a red dwarf and the luminosity and spectrum of a G-type star.

Well, up in the KSP2 forum it's about 40 people who object to unrealistic/magical technologies, or at least don't want them to be in the game. Compared to that, 3 or 4 people do want bad science technologies to be included, even fewer are for outright technobabble.

Really, all "defects" you listed are approximations. It's ridiculous to compare them to including something that's not true on any reasonable level. Patched conics approximates reality quite well, except for a few specific situations. Metastable mH does not, IRL this effect does not occur no matter how you slice it. If you really want an example from KSP, it's how LF stands in for hydrogen, kerosene or hydrazine, depending on the engine (I really hope that KSP2 will address this, mods that add proper LH2 really make the game much more fun).

[SOXBLOX]

9 hours ago, Dragon01 said:

Well, up in the KSP2 forum it's about 40 people who object to unrealistic/magical technologies, or at least don't want them to be in the game. Compared to that, 3 or 4 people do want bad science technologies to be included, even fewer are for outright technobabble.

Really, all "defects" you listed are approximations. It's ridiculous to compare them to including something that's not true on any reasonable level. Patched conics approximates reality quite well, except for a few specific situations. Metastable mH does not, IRL this effect does not occur no matter how you slice it. If you really want an example from KSP, it's how LF stands in for hydrogen, kerosene or hydrazine, depending on the engine (I really hope that KSP2 will address this, mods that add proper LH2 really make the game much more fun).

Going bottom to top:

Fun is not quantitative. It is an opinion. I may not feel the same way. SPOILER ALERT:  I don't.

9 hours ago, Dragon01 said:

Metastable mH does not, IRL this effect does not occur no matter how you slice it.

Neither do endless RTG's, magic reaction wheels, or ultradense, physics-defying stars. As I pointed out, you can ignore the flavor text at your leisure. Or just don't use the engine.

9 hours ago, Dragon01 said:

Well, up in the KSP2 forum it's about 40 people who object to unrealistic/magical technologies, or at least don't want them to be in the game. Compared to that, 3 or 4 people do want bad science technologies to be included, even fewer are for outright technobabble.

I assume you refer to Kerik's poll on tech to be included in the game? Those questions were biased. Not a bad thing, but realistically, who here will vote for "aether screws"? "Bad science" is a shortcut around debate; it implies that anyone voting for "bad science" in a game is unscientific IRL. This is ridiculous, of course.

Edited July 28, 2020 by SOXBLOX

[KerikBalm]

[snip]

as I have mentioned numerous times, going back to the "worried about magic tech" thread, and page 4 of this thread. How does confinement of Cs allow for confinement of 6000k hydrogen?

Cesium won't be bound to hydrogen at that temperature, the hydrogen will not be confined even if the Cs is.

If the Cs (MW: 132) was somehow linked to the hydrogen (MW:1), then it would get terrible Isp, worse than the H₂O+mmH rocket. If we're relying on Cs ot readily give up its electron to make H-, then we still have the problem of a 1:1 ratio of Cs:H, getting absolutely horrendous Isp.

If they wanted a high Isp variant of mmH (pruple space magic), all they had to do was dilute the exhaust with lH₂, but they throw in magnetic confinement through Cs doping of the fuel, which makes no sense as far as I can tell, and seems to be pure technobabble.

Edited July 28, 2020 by Vanamonde

[Hannu2]

11 hours ago, KerikBalm said:

The point is that it seems like they just slung some buzzwords together, and I have yet to see any explanation as to how "cesium doping" is supposed to allow for magnetic confinement of ~6000k hydrogen.

It seems to me to make as much sense as saying they use a flux capacitor that modifies the phase variance to contain the exhaust.

If someone can explain how cesium doping is supposed to work, or provide the science behind it, I will withdraw my complaint.

[/quote]

I agree, but I think that economical realism is against us. KSP2 is intended to sell much more than KSP and it has to attract people who is not interesting in science or learning proper ways to fly in space. They want to have practically unlimited dv and fly to target by just heading nose to target and throttling and they want to read that kind of meaningless pseudoscientific jargon to get their immersion to game world. As far as I have understood there will be whole bunch of ridiculous scifi stuff in KSP2. At least I have to see what kind of game it is and can it be modded to be reasonable simulator instead of scifi fantasy full of graphical eye candy.

I can stand pseudoscientific jargon but I am sure that most of engines will have ridiculously overpowered performance compared to what is needed with near optimal trajectories. It is not fun for me. I want to use porkchop plots and plan maneuvers with Mechjeb. But I understand that there must be easy way for lazy people to see gorgeous planets. If it is true that just few percents of KSP players ever leave Kerbin's system, aesthetic work would be quite futile otherwise. And what is the most important to devs, sells will suffer.

[KerikBalm]

2 minutes ago, Hannu2 said:

They want to have practically unlimited dv and fly to target by just heading nose to target and throttling and they want to read that kind of meaningless

Well, if its something like a reasonable fusion drive, then taking a brachistochrone trajectory doesn't mean point at target, fire engines... you need very high thrust for that.

On one end of the scale, would be solar powered ion engine, thrusting on rails, but with a very low thrust. You don't just point at the target.

The supposed end game "torch ship" will likely be "point at target, engage".

Orions would be impulse trajectories, but very high velocity ones, htat may allow for "point at target, fire engines for a bit, arrive at target, fire engines to break".

My hope is that aside from the end-game torchship, and the purple space magic engines, that the remaining engines are realistic.

Orion drives would absolutely work.

Fusion drives clearly can work (we were getting net energy from fusion devices in the 1950's... the Russian Tsar bomba had 93% of its yield from Fusion). So an interstellar ICF drive seems fine to me. It could also be useful in-system for getting to outer planets quickly (like if there is a KSP 2 OPMN mod, and you want to go to Plock).

2 minutes ago, Hannu2 said:

As far as I have understood there will be whole bunch of ridiculous scifi stuff in KSP2.

...

but I am sure that most of engines will have ridiculously overpowered performance compared to what is needed with near optimal trajectories.

Orion drives are ridiculous, but yet perfectly feasible. I'm looking forward to them. If its OP'd, but realistic, I'm ok with it.

mmH and Cs-doped magnetically confined mmH in particular, seem to not be realistic at all.

As to the other interstellar engines, I was giving them the benefit of the doubt, and witholding judgement due to a lack of details.

2 minutes ago, Hannu2 said:

At least I have to see what kind of game it is and can it be modded to be reasonable simulator instead of scifi fantasy full of graphical eye candy.

Well, the thrust on rails thing used for the fusion drives is a great addition, because it should also mean that we can get thrust on rails ion drives, and the ion drive thrust can be nerfed to a reasonable level (no more ion powered mun and minmus landers), since burns could be done at higher than 4x physics warp.

[Guest]

6 hours ago, SOXBLOX said:

I assume you refer to Kerik's poll on tech to be included in the game? Those questions were biased. Not a bad thing, but realistically, who here will vote for "aether screws"? "Bad science" is a shortcut around debate; it implies that anyone voting for "bad science" in a game is unscientific IRL. This is ridiculous, of course.

Ah, but that was the point. Metallic hydrogen is in the same category as aether screws. Both are confirmed, by experiment, not to work. The "debate" is just a bunch of people refusing to believe the latest experiments, because they don't fit their worldview, exactly this sort of thing happened around the time aether got disproven, too. Ideally, we'd just forget metallic hydrogen rockets were ever thought possible, and we'll move on to developing technologies that actually work. Any work that persists in promoting an outdated worldview is counterproductive, which is best shown by the fact there's such a vocal minority trying to defend such an obscure theory as metastable metallic hydrogen, just because KSP2 devs wanted to include it in a game. Aether, at least, was a major part of scientific worldview for decades, while this is just a bit of high pressure science trivia that was completely obscure until Nertea decided to include it in early FFT (I strongly advised him against it back then, but it was before the experiments that disproven it, so my arguments were weaker).

KSP is a game about science. Yes, anyone wanting to include bad science in that is most likely, more or less, unscientific IRL, or at least doesn't care either way. The belief that people will not take KSP2 seriously is very, very naive. It's not slapstick with explosions anymore, despite marketing videos not quite dropping that notion. KSP1 even has a version meant for teaching. It's a serious rocket game that uses some light slapstick to make itself seem more approachable.

1 hour ago, Hannu2 said:

I agree, but I think that economical realism is against us. KSP2 is intended to sell much more than KSP and it has to attract people who is not interesting in science or learning proper ways to fly in space. They want to have practically unlimited dv and fly to target by just heading nose to target and throttling and they want to read that kind of meaningless pseudoscientific jargon to get their immersion to game world. As far as I have understood there will be whole bunch of ridiculous scifi stuff in KSP2. At least I have to see what kind of game it is and can it be modded to be reasonable simulator instead of scifi fantasy full of graphical eye candy.

Metallic hydrogen doesn't let you do that, though. It's only a modest improvement over a solid-core NTR, and pretty much equivalent in performance to a (reasonably realistic) liquid core NTR. Our technobablium drive isn't even a very good engine, compared to the realistic stuff. Ironically, fusion torch and antimatter drives that they talked about are pretty much realistic, if far-fetched. A flow-stabilized Z-pinch engine is a real thing, and its theoretical performance is well within "point and burn" territory (seriously, that thing's crazy, but apparently the princple works). 

Edited July 28, 2020 by Guest

[Hannu2]

1 hour ago, KerikBalm said:

Well, if its something like a reasonable fusion drive, then taking a brachistochrone trajectory doesn't mean point at target, fire engines... you need very high thrust for that.

Yes in principle, but no in practice. I am quite sure there will not be tools to calculate that kind of trajectories and execute maneuvers. At least I may calculate it once by hand, then program help program and use it couple of times and then think it is too tedious, if there will not be Mechjeb like mod which can make such operations automatically.

 

1 hour ago, KerikBalm said:

My hope is that aside from the end-game torchship, and the purple space magic engines, that the remaining engines are realistic.

Orion drives would absolutely work.

Orions and fusion drives may be somewhat realistic. However, what is purpose of them in planetary flight simulator? Only interesting thing in spaceflights is try to achieve goals with limited resources using optimal trajectories. Otherwise it is very boring to fly easily from sphere to another. Such propulsions could be usable on interstellar operations or business trips, but they are even more boring. They are turn nose to target, hit red button and use extreme timewarp -operations. It is also hard to believe that anyone could ever make interesting content so much that it do not fit in one solar system. And if can, player's lifetime is not enough to find all interesting places.

 

 

1 hour ago, KerikBalm said:

Fusion drives clearly can work (we were getting net energy from fusion devices in the 1950's... the Russian Tsar bomba had 93% of its yield from Fusion). So an interstellar ICF drive seems fine to me. It could also be useful in-system for getting to outer planets quickly (like if there is a KSP 2 OPMN mod, and you want to go to Plock).

Fusion nuclear reactions are of course well known real things, but you have to accept quite much technomagic in material physics, magnetic confinement tech etc. to get fusion work as propulsion device. Same with Orion, it is very hypothetical concept even though it is based on some physics. As far as I know there is not any applications expect some forms of nuclear bombs. I expect also that current fusion bombs may be little on large side from Orion optimal.

 

 

1 hour ago, KerikBalm said:

Orion drives are ridiculous, but yet perfectly feasible. I'm looking forward to them. If its OP'd, but realistic, I'm ok with it.

mmH and Cs-doped magnetically confined mmH in particular, seem to not be realistic at all.

I like too more if overpowered magic drive have properties known to belong fusion and is called fusion instead of completely fictive descriptions. But it is not requirement of my entertainment. Reasonable balancing to give realistic like technical challenges is. And unfortunately it seems that KSP2 will not give it at vanilla, at least without personal restrictions. And if there is too much such restrictions, there is no point in tech tree.

 

1 hour ago, KerikBalm said:

Well, the thrust on rails thing used for the fusion drives is a great addition, because it should also mean that we can get thrust on rails ion drives, and the ion drive thrust can be nerfed to a reasonable level (no more ion powered mun and minmus landers), since burns could be done at higher than 4x physics warp.

Thrust under high time acceleration and realistic ion engines would be very nice.

[Guest]

4 minutes ago, Hannu2 said:

Fusion nuclear reactions are of course well known real things, but you have to accept quite much technomagic in material physics, magnetic confinement tech etc. to get fusion work as propulsion device. Same with Orion, it is very hypothetical concept even though it is based on some physics. As far as I know there is not any applications expect some forms of nuclear bombs. I expect also that current fusion bombs may be little on large side from Orion optimal.

Not really, there are perfectly serviceable "suitcase nukes" (SADM, most notably) and of course Davy Crockett the "nuclear bazooka" (actually a recoilless rifle). It's been tested and it works, with a charge much smaller (and dirtier) than you'd like for Orion. The concept itself was tested, too, using conventional explosives. There's nothing wrong with Orion, aside from the fact that it requires setting off a bunch of EMP and fallout-inducing nukes. 

Fusion is harder, though not impossible. Experiments with a "direct fusion drive" have been done. It works, but is a power hog. The current thinking is that we're not building big enough, and the trouble with building big is that it's very expensive. See ITER for at attempt at fusion along these lines. The problems with it seem solvable at the moment, and serious studies have been done, without assuming anything magical other than a source of money.  

[Hannu2]

10 minutes ago, Dragon01 said:

Metallic hydrogen doesn't let you do that, though. It's only a modest improvement over a solid-core NTR, and pretty much equivalent in performance to a (reasonably realistic) liquid core NTR.

Do you mean speculated real world hydrogen or dev's choice in the game? Latter can be of course whatever. I do not care much such details in this kind of situations. I think there is no need in thrusters more effective that NTR or fission powered ion engines in space exploration game, which models the civilization which makes first probes and manned excursions to bodies in their solar system. It takes probably hundreds or thousands of years development from that point to get those futuristic technomagic engines which makes it possible to colonize the whole system and make regular fast tourist and business traffic between planets.

 

10 minutes ago, Dragon01 said:

 

Our technobablium drive isn't even a very good engine, compared to the realistic stuff. Ironically, fusion torch and antimatter drives that they talked about are pretty much realistic, if far-fetched. A flow-stabilized Z-pinch engine is a real thing, and its theoretical performance is well within "point and burn" territory (seriously, that thing's crazy, but apparently the princple works). 

I disagree. In my opinion it does not make idea realistic if some concepts are taken from real science, like fusion or antimatter, but every practical aspect is assumed to be technomagic. It also breaks the story. Why in the heck supercivilization able to build fusion powered machines and product and handle industrial quantities of antimatter has not investigated their whole solar system thousands of years before. It is as credible as astronauts in first manned rocket sent to investigate celestial crystal sphere of Moon would notice that "hey, you do not believe this, our planet is not flat disk but ball".