What would the Kerbol System look like if all the planets used real-world physics equivalent?

[Findthepin1]

Like Vall would be slingshotted out of Jool's SOI and into Kerbol orbit, also Bop would, Eve would become a Venuslike horridly hot place with high pressure from the evaporated oceans, Laythe may gain a ridiculously thick ozone layer due to ionization or whatever from Jool's radiation, etc. What do you think?

[soulsource]

The question is: Do we ignore that various bodies in the Kerbol system obviously are of a much higher density than normal matter would be under the same gravity? If not, than most bodies in KSP would probably explode, as their very fabric would try to release all strain it experiences the moment real-life physics would set in...

If we ignore this, and just assume that Kerbols planets are made out of black magic, then: Well, fellow KSP players, to the numerics mobile!

[Sky_walker]

Completely differently. Planets don't use any realistic densities to begin with. Kerbin would probably have a neutron star in a core, Jool wouldn't be a gas giant but rather solid, rocky planet with higher density than Mars (but lower than Earth), etc. etc. Jool would shoot it's moons in all directions, affecting all of the other planets, Kerbin would be bombed by asteroids destroying all life trees and cactuses (cause these are pretty much only life forms on a planet other than a few Kerbals)...

TL;DR: if you'd try to make kerbal system with realistic physics it'd instantly collapse.

Edited May 26, 2015 by Sky_walker

[Nansuchao]

It will not collapse so easily. Sometimes ago I saw a video on YouTube when a player did a simulation of the Kervol System in a N-Body environment. The results was that in a few years, a couple of Jool's moon went traveling around the System, and nothing more...

[Sky_walker]

It will not collapse so easily. Sometimes ago I saw a video on YouTube when a player did a simulation of the Kervol System in a N-Body environment. The results was that in a few years, a couple of Jool's moon went traveling around the System, and nothing more...

That must have been one badly made simulation if neutron stars travelling through the system didn't cause massive perturbations.

[tomf]

Planets are dense but they aren't massive. Kerbin has a smaller mass than Earth. A wandering Joolian moon isn't going to havemuch impact in the short term unless it impacts.

[Nansuchao]

Look there: http://youtu.be/qKp1M4T6z24

[Sky_walker]

Planets are dense but they aren't massive.

That's supposed to make it any better? We're talking here about system with mixed - objects being comparable to realistic, rocky planets and objects being closer to neutron stars (having neutron stars in their cores). This cannot end up being anything friendly for cactuses. Or trees.

Look there: http://youtu.be/qKp1M4T6z24

That's a very, very basic fun with n-body physics. I would be very careful calling it a "simulation".

[Findthepin1]

Ignoring the objects' densities.

[magnemoe]

That's supposed to make it any better? We're talking here about system with mixed - objects being comparable to realistic, rocky planets and objects being closer to neutron stars (having neutron stars in their cores). This cannot end up being anything friendly for cactuses. Or trees.

That's a very, very basic fun with n-body physics. I would be very careful calling it a "simulation".

It does not matter if the body is an miniature black hole or have an density less than 1 unless they get so close that tides has an serious effect, in that setting you probably had an impact with low density.

No idea how accurate it is, surprised me that Minmus was stable. Val is obviously unstable.

[Guest]

Ignoring the objects' densities.

If you go purely on body radius and correct densities to something close to what they should be you end up with a lower-end M class star orbited by a bunch of Ceres-equivalent bodies with a single Earth-sized planet with five moons. It's a dim, dismal place which is probably pretty stable orbitally-speaking.

E: Oh wait, actually it's probably not. Last time I tried the Mun was outside of Kerbin's SOI.

Edited May 26, 2015 by regex

[asmi]

Density doesn't matter for orbital mechanics (neither Keplerian nor Newtonian), only mass does, since both treats celestials as point-mass objects. Therefore the fact that celestials have unrealistic densities changes nothing regarding their orbital motion.

[soulsource]

Look there: http://youtu.be/qKp1M4T6z24

Oh, someone did that already?

*immediately stops coding and goes back to playing KSP*

[FishInferno]

The question is: Do we ignore that various bodies in the Kerbol system obviously are of a much higher density than normal matter would be under the same gravity? If not, than most bodies in KSP would probably explode, as their very fabric would try to release all strain it experiences the moment real-life physics would set in...

If we ignore this, and just assume that Kerbols planets are made out of black magic, then: Well, fellow KSP players, to the numerics mobile!

I do not think that Kerbin has the same gravity as Earth. If Kerbin has less gravity than Earth, Kerbals would only need to build rockets powerful enough to escape Kerbin's gravity, thus giving the illusion that Kerbin has the same gravity as Earth

[OhioBob]

Laythe may gain a ridiculously thick ozone layer due to ionization or whatever from Jool's radiation, etc.

There is in-game evidence that Laythe's atmosphere may have an ozone layer. Its atmosphere contains a layer where the temperature increases with increasing altitude, comparable to Earth's stratosphere. The reason for this in Earth's atmosphere is that ozone absorbs UV energy. The same could be happening at Laythe.

[magnemoe]

I do not think that Kerbin has the same gravity as Earth. If Kerbin has less gravity than Earth, Kerbals would only need to build rockets powerful enough to escape Kerbin's gravity, thus giving the illusion that Kerbin has the same gravity as Earth

Well looking at Mun an minmus orbital periods you can calculate the gravity on kerbin.

[Geschosskopf]

If the laws of our universe were applied to the KSP universe, the KSP universe, or at least the Kerbol system, would cease to exist. Don't forget there are other fundamental forces besides gravity, and there are very significant differences in the strong and weak nuclear forces between our universe and KSP's. So if our fundamental forces were applied to the Kerbol system, all matter in it would either explode or collapse, can't tell which, because KSP matter simply cannot exist under our laws of physics.

[OhioBob]

I do not think that Kerbin has the same gravity as Earth.

Kerbin has the same surface gravity as Earth due to its absurdly high density. However, its gravitational parameter is only 3.5316 ×10¹² m³/s², which is 1/113^th of Earth.

[problemecium]

"Neutron stars" is actually overdoing it. A white dwarf is plenty dense enough for Kerbol - in fact I think of it as a D_9 (There are various letters that could go in the middle, but the 9 is the important part as it determines the color, in this case yellow). As for the planets, perhaps Kerbol was once part of a multiple system that experienced some cataclysm, so degenerate matter from one or more white dwarfs ended up scattering and reconstituting into the current planets and moons. It would also explain how every single one of them seems to have rocket fuel buried in it.

I haven't hashed this hypothesis out all the way though.

More importantly, the densities of the planets really don't matter that much as far as orbital physics are concerned. It's often said that if the Sun suddenly became a black hole, all the planets would continue orbiting unchanged. This isn't exactly true (they would be perturbed slightly), but the Solar system would remain stable and as far as orbits are concerned mostly unchanged.

With the exception of the Joolian moons, the orbiting bodies in KSP are separated plenty enough for them to affect one another basically as point masses as is the case IRL. My prediction is that if you built the system in real life, it would probably end up rather like the simulation cited above, with Jool's moons repositioning themselves but the rest staying basically where it is.

Edited May 26, 2015 by parameciumkid

[Empiro]

Alternatively, what if just the universal constant of gravitation G was much higher in the Kerbal universe? The planets and starts are made of the same stuff, have much lower mass, but the gravitational parameters would be as we see them.

I did remember hearing that the Jool system would be stable if you made the planet and moons orbit around the barycenter (center of mass) of the whole system, instead of the exact center of Jool, though I haven't actually seen a simulation of that.

[Asharad]

I'm modelling KSP in the universe sandbox. I hope I have a video soon.

- - - Updated - - -

Interesting, Jool has 70% the mass of Earth and orbits at 1/2 AU.

And the densities of the KSP planets are.... higher than anything known to man.

Edited May 26, 2015 by Asharad

[problemecium]

I recall being informed a while back that someone at SQUAD officially ruled that the KSP universe has a higher gravitational constant, but I have a hunch that simply adjusting Kerbals' perception of time would have a similar effect.

[Asharad]

I'm having problems capturing video from the Universe Sandbox model of KSP. But I can report some results:

Event #1: Vall and Laythe swapped orbits.

Event #2: Pol was absorbed by Jool

Event #3: Bop was absorbed by Tylo

Event #4: Laythe and Vall are still reacting against each other. Both are highly elliptical orbits now, and crossing each other. It's only a matter of time....

Event #5: Laythe was captured by Tylo, and then absorbed by Tylo. Vall and Tylo appear to be stable, although Vall's orbit is tight and inclined significantly.

[problemecium]

I presume all the attention you gave the Joolian moons is an indication that the rest of the system is stable?

[Asharad]

I presume all the attention you gave the Joolian moons is an indication that the rest of the system is stable?

Maybe. I need to verify my model is correct. I had several other events that didn't mention because I didn't trust them.

- Ike was ejected from Duna orbit, but I'm not sure what caused it.

- Eve and Kerbin interacted with each other, and eventually swapped orbits. I later realized that Eve's mass was too high due to clerical error.

- Mun was tossed out to sea. This was also due to Eve's erroneous mass.

I plan to check my settings sometime, and run it again. Not tonight though.

The biggest reason I focused on the Joolian moons is because the results are near instantaneous, and because the speed of the model was limited by the interaction of those moons. I have to delete Jool's moons in order to speed up the model.

Edited May 28, 2015 by Asharad