Why Jool like that? [SPOILER THREAD]

[Minmus Taster]

Spoiler

I myself have not been there yet but I've heard the planet actually has a ground now with a texture and everything. Is there a gameplay reason for this or is it a technical thing that people aren't supposed to see since heating is turned off?

 

[Drakenred65]

To avoid yeeting die to the gravitational singularity probably. Since that happened to Scott manley when he tried to find the bottom of the Mohole and fell through

Just now, Drakenred65 said:

To avoid yeeting  to escape velocity due to the gravitational singularity probably. Since that happened to Scott manley when he tried to find the bottom of the Mohole and fell through

 

Oops sorry 

[Strawberry]

Im hoping when we get resources there's gonna be some nice goodies to mine from the planet and Jool is now a mini neptune. I think itll be a super fun challenge to take off and land so Im hoping they keep it

Edited February 26, 2023 by Strawberry

[Kerbal3]

On 2/26/2023 at 2:44 PM, Strawberry said:

Im hoping when we get resources there's gonna be some nice goodies to mine from the planet and Jool is now a mini neptune. I think itll be a super fun challenge to take off and land so Im hoping they keep it

but then it's not a gas giant anymore, I'm hoping they are going to get rid of the surface eventually.

It's not a mini Neptune.

[K^2]

1 hour ago, Kerbal3 said:

but then it's not a gas giant anymore, I'm hoping they are going to get rid of the surface eventually.

The surface looks pretty intentional. We know that Intercept decided to stick to the metastable metallic hydrogen as one of the fuel types. It is based on an old, outdated hypothesis that hydrogen has a metallic state under high pressures that can be maintained under much lower pressures once achieved. While metallic state of hydrogen is pretty much a certainty under the right conditions, these conditions turned out to be far higher pressure at much lower temperatures than originally anticipated, and there is no longer a reason to believe that there is any metastability.

KSP2's Kerbol system is located in a different universe, one where materials have somewhat different physical properties to our own. This is inescapable from the fact alone that Kerbin has 9.8m/s² surface gravity with a 600km radius. The average density of Kerbin has to be about 58g/cm³. Densest known metal on Earth is osmium at 22g/cm³. We don't know of any materials that would reach 58g/cm³ even at the pressures in the Earth's core. Clearly, planets in KSP and KSP2 are made of some other stuff. Or, at least, stuff that behaves differently.

So circling back to the metallic hydrogen, the surface pressure of Jool is a little over 5MPa. That's a touch over 50 bar. The "air" density, however, is only 6.7kg/m³ at 200K ambient. Substituting that into the ideal gas law, we see that the atmosphere of Jool has an average molar mass of 2.23. Which means its' mostly hydrogen. In fact, this is a good fit for 90% hydrogen, 10% helium, <1% methane. In other words, Intercept probably took Jupiter's composition for the basis here. But now we get to the surface. On the real Jupiter, that hydrogen-helium soup turns into a supercritical fluid, which continues getting denser without a big change in its other properties until we get to (what we believe to be) liquid metallic hydrogen layer. That liquid metallic hydrogen "mantle" of the planet extends down to the core, which has a rather fuzzy boundary, resulting in no real solid surface. The transition from supercritical hydrogen to metallic is also likely to be a fuzzy one, meaning there are no sharply defined boundaries anywhere, but we can break down the broader regions into the solid icy/rocky core, liquid mantle of metallic hydrogen with helium droplets, supercritical lower atmosphere of molecular hydrogen and helium, and gaseous upper atmosphere of the same.

And now we get into the topic of metastability. If in Kerbal universe the hydrogen becomes metastable, what properties do we expect of this Jupiter analog? Well, we still expect the planet to have a liquid metallic hydrogen mantle. However, as the mantle circulates, the liquid metallic hydrogen that would reach lower pressure and temperature of higher altitudes instead of evaporating to a molecular hydrogen would instead solidify to its metastable metallic phase. This phase transition would expel much of the helium mixed into the composition, meaning the density of MSMH would be slightly lower than density of the liquid metallic hydrogen of the mantle. This is a very similar situation to what happens on Earth with all the molten rock in the mantle - the parts that solidify first near the surface form a lighter layer of various oxides that float on top of a molten metal-rich mantle. We end up with a solid surface. Except, on Jool, it's a solid surface of metastable metallic hydrogen. And indeed, the surface of Jool looks metallic.

Naturally, at a low enough pressure, we expect MSMH to sublime into molecular hydrogen. Apparently, in Kerbal universe that happens at around 200K at 5MPa of pressure. Which is fairly extreme, but reasonable enough for storage and transportation for use as fuel. And, well, Jool is the place you get it from. How we're going to be transporting it off the surface remains to be discovered. But in a world where MSMH exists at all, surface of Jool would be one place you'd find it, and indeed, a surface made of the stuff is exactly what you expect and predict based on extrapolating Jupiter analogue planet to Kerbal scale.

[S_Coriolis]

Let's build colonies on Jool to mine metastable metallic hydrogen !

[Kerbal3]

1 hour ago, K^2 said:

The surface looks pretty intentional. We know that Intercept decided to stick to the metastable metallic hydrogen as one of the fuel types. It is based on an old, outdated hypothesis that hydrogen has a metallic state under high pressures that can be maintained under much lower pressures once achieved. While metallic state of hydrogen is pretty much a certainty under the right conditions, these conditions turned out to be far higher pressure at much lower temperatures than originally anticipated, and there is no longer a reason to believe that there is any metastability.

KSP2's Kerbol system is located in a different universe, one where materials have somewhat different physical properties to our own. This is inescapable from the fact alone that Kerbin has 9.8m/s² surface gravity with a 600km radius. The average density of Kerbin has to be about 58g/cm³. Densest known metal on Earth is osmium at 22g/cm³. We don't know of any materials that would reach 58g/cm³ even at the pressures in the Earth's core. Clearly, planets in KSP and KSP2 are made of some other stuff. Or, at least, stuff that behaves differently.

So circling back to the metallic hydrogen, the surface pressure of Jool is a little over 5MPa. That's a touch over 50 bar. The "air" density, however, is only 6.7kg/m³ at 200K ambient. Substituting that into the ideal gas law, we see that the atmosphere of Jool has an average molar mass of 2.23. Which means its' mostly hydrogen. In fact, this is a good fit for 90% hydrogen, 10% helium, <1% methane. In other words, Intercept probably took Jupiter's composition for the basis here. But now we get to the surface. On the real Jupiter, that hydrogen-helium soup turns into a supercritical fluid, which continues getting denser without a big change in its other properties until we get to (what we believe to be) liquid metallic hydrogen layer. That liquid metallic hydrogen "mantle" of the planet extends down to the core, which has a rather fuzzy boundary, resulting in no real solid surface. The transition from supercritical hydrogen to metallic is also likely to be a fuzzy one, meaning there are no sharply defined boundaries anywhere, but we can break down the broader regions into the solid icy/rocky core, liquid mantle of metallic hydrogen with helium droplets, supercritical lower atmosphere of molecular hydrogen and helium, and gaseous upper atmosphere of the same.

And now we get into the topic of metastability. If in Kerbal universe the hydrogen becomes metastable, what properties do we expect of this Jupiter analog? Well, we still expect the planet to have a liquid metallic hydrogen mantle. However, as the mantle circulates, the liquid metallic hydrogen that would reach lower pressure and temperature of higher altitudes instead of evaporating to a molecular hydrogen would instead solidify to its metastable metallic phase. This phase transition would expel much of the helium mixed into the composition, meaning the density of MSMH would be slightly lower than density of the liquid metallic hydrogen of the mantle. This is a very similar situation to what happens on Earth with all the molten rock in the mantle - the parts that solidify first near the surface form a lighter layer of various oxides that float on top of a molten metal-rich mantle. We end up with a solid surface. Except, on Jool, it's a solid surface of metastable metallic hydrogen. And indeed, the surface of Jool looks metallic.

Naturally, at a low enough pressure, we expect MSMH to sublime into molecular hydrogen. Apparently, in Kerbal universe that happens at around 200K at 5MPa of pressure. Which is fairly extreme, but reasonable enough for storage and transportation for use as fuel. And, well, Jool is the place you get it from. How we're going to be transporting it off the surface remains to be discovered. But in a world where MSMH exists at all, surface of Jool would be one place you'd find it, and indeed, a surface made of the stuff is exactly what you expect and predict based on extrapolating Jupiter analogue planet to Kerbal scale.

What about Jool's belts? Do they still make sense as the planet is currently?

[nejc]

Man I really hope this isn't the case permanently. We already have a planet with a dense atmosphere and a surface. It's Eve. Every other planet represents something in the real Solar System. A Jool with a surface would be redundant, and gas giants would have no representation.

I always hoped that the game could be expanded with balloon ships to explore and extract from the gas giant. Not land on it like on every other planet already. To me Jool was supposed to be special in the sense that it an eerie bottomless deadly pit. 

 

[TheRustedShackleford]

14 hours ago, K^2 said:

The surface looks pretty intentional. We know that Intercept decided to stick to the metastable metallic hydrogen as one of the fuel types. It is based on an old, outdated hypothesis that hydrogen has a metallic state under high pressures that can be maintained under much lower pressures once achieved. While metallic state of hydrogen is pretty much a certainty under the right conditions, these conditions turned out to be far higher pressure at much lower temperatures than originally anticipated, and there is no longer a reason to believe that there is any metastability.

KSP2's Kerbol system is located in a different universe, one where materials have somewhat different physical properties to our own. This is inescapable from the fact alone that Kerbin has 9.8m/s² surface gravity with a 600km radius. The average density of Kerbin has to be about 58g/cm³. Densest known metal on Earth is osmium at 22g/cm³. We don't know of any materials that would reach 58g/cm³ even at the pressures in the Earth's core. Clearly, planets in KSP and KSP2 are made of some other stuff. Or, at least, stuff that behaves differently.

So circling back to the metallic hydrogen, the surface pressure of Jool is a little over 5MPa. That's a touch over 50 bar. The "air" density, however, is only 6.7kg/m³ at 200K ambient. Substituting that into the ideal gas law, we see that the atmosphere of Jool has an average molar mass of 2.23. Which means its' mostly hydrogen. In fact, this is a good fit for 90% hydrogen, 10% helium, <1% methane. In other words, Intercept probably took Jupiter's composition for the basis here. But now we get to the surface. On the real Jupiter, that hydrogen-helium soup turns into a supercritical fluid, which continues getting denser without a big change in its other properties until we get to (what we believe to be) liquid metallic hydrogen layer. That liquid metallic hydrogen "mantle" of the planet extends down to the core, which has a rather fuzzy boundary, resulting in no real solid surface. The transition from supercritical hydrogen to metallic is also likely to be a fuzzy one, meaning there are no sharply defined boundaries anywhere, but we can break down the broader regions into the solid icy/rocky core, liquid mantle of metallic hydrogen with helium droplets, supercritical lower atmosphere of molecular hydrogen and helium, and gaseous upper atmosphere of the same.

And now we get into the topic of metastability. If in Kerbal universe the hydrogen becomes metastable, what properties do we expect of this Jupiter analog? Well, we still expect the planet to have a liquid metallic hydrogen mantle. However, as the mantle circulates, the liquid metallic hydrogen that would reach lower pressure and temperature of higher altitudes instead of evaporating to a molecular hydrogen would instead solidify to its metastable metallic phase. This phase transition would expel much of the helium mixed into the composition, meaning the density of MSMH would be slightly lower than density of the liquid metallic hydrogen of the mantle. This is a very similar situation to what happens on Earth with all the molten rock in the mantle - the parts that solidify first near the surface form a lighter layer of various oxides that float on top of a molten metal-rich mantle. We end up with a solid surface. Except, on Jool, it's a solid surface of metastable metallic hydrogen. And indeed, the surface of Jool looks metallic.

Naturally, at a low enough pressure, we expect MSMH to sublime into molecular hydrogen. Apparently, in Kerbal universe that happens at around 200K at 5MPa of pressure. Which is fairly extreme, but reasonable enough for storage and transportation for use as fuel. And, well, Jool is the place you get it from. How we're going to be transporting it off the surface remains to be discovered. But in a world where MSMH exists at all, surface of Jool would be one place you'd find it, and indeed, a surface made of the stuff is exactly what you expect and predict based on extrapolating Jupiter analogue planet to Kerbal scale.

This explanation was more informative and entertaining than any science class I've ever taken. Thanks!

[Strawberry]

On 3/1/2023 at 5:06 PM, K^2 said:

And now we get into the topic of metastability. If in Kerbal universe the hydrogen becomes metastable, what properties do we expect of this Jupiter analog? Well, we still expect the planet to have a liquid metallic hydrogen mantle. However, as the mantle circulates, the liquid metallic hydrogen that would reach lower pressure and temperature of higher altitudes instead of evaporating to a molecular hydrogen would instead solidify to its metastable metallic phase. This phase transition would expel much of the helium mixed into the composition, meaning the density of MSMH would be slightly lower than density of the liquid metallic hydrogen of the mantle. This is a very similar situation to what happens on Earth with all the molten rock in the mantle - the parts that solidify first near the surface form a lighter layer of various oxides that float on top of a molten metal-rich mantle. We end up with a solid surface. Except, on Jool, it's a solid surface of metastable metallic hydrogen. And indeed, the surface of Jool looks metallic.

I seriously doubt that the surface is metallic hydrogen, for starters I dont think solid metallic hydrogen is even practically possible? The pressures for liquid metallic hydrogen are already insane, to get it to a solid Id imagine would take much more. Also Im pretty sure if you landed on solid metallic hydrogen your ship would just explode, hydrogen is super reactive. Not to mention it just doesnt look like metallic hydrogen, metallic hydrogen is shiny and reflective whereas Jools surface is rocky.

Im pretty sure the surface is just intended to be like a standard gas giant core, a rocky mixture of ice and metal. There's a pretty big explanation you could go for for why Jools solid core is so large, its a mini neptunes. Mini neptunes are gas giants smaller then neptunes, and larger then super earths. There cores are much larger relative to other planets. I think Jool could go with some oceans for its surface to make some more sense, but besides that I think its cool.

[K^2]

2 minutes ago, Strawberry said:

I seriously doubt that the surface is metallic hydrogen, for starters I dont think solid metallic hydrogen is even practically possible?

In the real world, unclear. Certainly, not under these conditions. But we're talking about the KSP2 universe, where we know that one of the planned future tech engines is based on metastable metallic hydrogen. It was a hypothetical state of hydrogen which was later disproven by better models, but when it was predicted, based on these earlier faulty models, it would have been a solid under the conditions not unlike these on the surface of Jool. Again, this material doesn't exist in the real world, but it's part of the KSP2 tech, which means it exists in that world, and the only plausible source of it is on Jool. Given all of the physics of this fictional material, it would make sense for Jool's entire surface to be made of it.

[Strawberry]

2 minutes ago, K^2 said:

In the real world, unclear. Certainly, not under these conditions. But we're talking about the KSP2 universe, where we know that one of the planned future tech engines is based on metastable metallic hydrogen. It was a hypothetical state of hydrogen which was later disproven by better models, but when it was predicted, based on these earlier faulty models, it would have been a solid under the conditions not unlike these on the surface of Jool. Again, this material doesn't exist in the real world, but it's part of the KSP2 tech, which means it exists in that world, and the only plausible source of it is on Jool. Given all of the physics of this fictional material, it would make sense for Jool's entire surface to be made of it.

I mean we know that metallic hydrogen can be manufactured and will be manufactured in game. Making the surface solid metallic hydrogen seems weird and wrong and I dont know what it adds. Also metallic hydrogen is still believed as possible?? Its just the metastable aspect thats questionable.

Edited March 3, 2023 by Strawberry

[K^2]

Just now, Strawberry said:

I mean we know that metallic hydrogen can be manufactured and will be manufactured in game. Making the surface solid metallic hydrogen seems weird and wrong and I dont know what it adds

*shrug* I don't know what that does in terms of gameplay or aesthetics. I'm just channeling my inner physicist. If a metastable phase of metallic hydrogen was to exist, and a planet had a liquid metallic hydrogen mantle under a mostly-molecular hydrogen atmosphere, and the temperature at the interface was below the melting point of MSMH, then a crust of MSMH would surely form.

But it's a game, and the developers can go into any number of directions with that. All I know is that the above would make sense with the known Kerbal cosmology and that there are people on the dev team that were definitely thinking along these lines. Whether it's actually the intended structure is just a guess. It's entirely possible that these people got overruled based on much the same concerns that you raise.

[Vl3d]

You guys can justify whatever you want, I'll just say this: I don't like that Jool has a surface now.

[Tazooka]

1 hour ago, Vl3d said:

You guys can justify whatever you want, I'll just say this: I don't like that Jool has a surface now.

Jool had a surface in KSP 1 originally. But it was patched out

I'm assuming the same will happen here with KSP 2

[Strawberry]

I personally like that Jool has a surface because its a good subversion of expectations, you expect it to be infinite depths but when your curiosity makes you plunge a probe into it and you get awarded by discovering a surface. It also presents a very interesting challenge from taking off, Jool is not only very big and has a thick atmosphere, the majority of engines also dont work on its surface, making it very hard to get off from the surface.

[K^2]

8 hours ago, Tazooka said:

Jool had a surface in KSP 1 originally. But it was patched out

I'm assuming the same will happen here with KSP 2

Unlike KSP1's smooth sphere, KSP2's Jool surface has features and dedicated material texture. It looks like too much effort for a placeholder. Granted, it's entirely possible that it was something that was considered, then got abandoned, so it's still possible that it will be cut, but I'm leaning towards it being one of the places intended for colonies mining for unique resources.

Return from Jool would be by far the most challenging mission. What is better graduation than that into future tech, which would make the subsequent climbs out of gravity wells trivial?

[nejc]

WIth Jool having a surface we have no suface-less planets in the system. To me that removes something unique. I'm all for mini Neptunes in other systems, but I'd like the main system to be an analogue of the real Solar System, and we have 4 suface-less planets here and no mini Neptunes.

I hope this is eventually patched.  I would be disappointed though if there are no mini Neptunes in other systems.

Edited March 7, 2023 by nejc