Can KSP / Unity simulate Pluto & Charon orbital method?

[Sirine]

As per title. 1 more year and we will have a real close picture taken of Pluto. Cant wait to see them.

The orbit looks like this.

Edited July 15, 2014 by Sirine

[jfull]

If you mean two objects orbiting around their common center of mass, then no. I've already been told that you can't simulate that with the Patched Conics Approximation that KSP uses

[FleetAdmiralJ]

If you mean two objects orbiting around their common center of mass, then no. I've already been told that you can't simulate that with the Patched Conics Approximation that KSP uses

Could you "fake" it by having a "point" at the barycenter that acts as the SOI for the group, and the two objects are essentially treated as moons of that point? Or do the physics calculations not work like that?

[No one]

Could you "fake" it by having a "point" at the barycenter that acts as the SOI for the group, and the two objects are essentially treated as moons of that point? Or do the physics calculations not work like that?

I don't think so. Or at least, if you did, it would require different physics.

In the Pluto/Charon system, Pluto orbits much more slowly than Charon, despite being much closer to the barycenter. If you tried to treat it as a standard system where they both orbited the barycenter, Pluto would orbit much faster due to being closer.

[problemecium]

Unity can do it. KSP isn't ready yet, but perhaps it will be able to in the future, if the devs decide that realistic details like barycenters, axial tilt, etc. need to be added.

[Sirine]

One interesting point.. .Pluto and Charon are facing each other 'as always' the same direction. Like in synchronize orbit. (Check the image)

[SpaceSphereOfDeath]

One interesting point.. .Pluto and Charon are facing each other 'as always' the same direction. Like in synchronize orbit. (Check the image)

Another interesting point, Pluto has 5 moons, and they're in a 2:3:5:7 orbital resonance with Charon. (Eat that <s>joolein</s> Jovian moons!)

[boxman]

Unity can do it. KSP isn't ready yet, but perhaps it will be able to in the future, if the devs decide that realistic details like barycenters, axial tilt, etc. need to be added.

Axial tilt would for me add alot to the game. Not only would it add extra challenge, but it would also give you some kind of seasons which for me would definitely help with immersion.

[KerbMav]

KSP isn't ready yet

But it should acutally - that is if it is possible to define a gravity well (SOI) without adding a physical object with it.

[Superfluous J]

But it should acutally - that is if it is possible to define a gravity well (SOI) without adding a physical object with it.

The problem is what happens to your ship when you get close to the center of that gravity well? Gravity shoots up to infinite and your ship is teleported to the other end of the universe, that's what. The only thing keeping that from happening in the game now is before you get too close to that point source of gravity, you hit the surface of whatever planet is around it.

[nanobot]

Of course the barycenter itself is not reachable because you immediately enter the SOI of one of the "virtual moons". If you are far out, then the gravity of the barycenter will affect you instead. It's perfectly doable when using sensible SOI ranges.

[CalculusWarrior]

Man, close-up pictures of Pluto are going to be amazing. Can't wait!

I wonder how this system would look like in KSP, assuming that if you're orbiting around the Pluto analogue at the centre of the system, would you just see a tidally-locked moon in geostationary orbit going around the planet?

[KerbMav]

Let me rephrase that: Define the center of the orbit of planet and moon - because I am not sure if the planets even really orbit the star, I think they are more likely completely on rails all the time without really being affected by any SOI?

[Superfluous J]

Of course the barycenter itself is not reachable because you immediately enter the SOI of one of the "virtual moons". If you are far out, then the gravity of the barycenter will affect you instead. It's perfectly doable when using sensible SOI ranges.

Hmmm, so it'd look like a venn diagram, with a big circle for "barycenter soi"; and a fairly large circle for "pluto soi" that is centered on pluto and always within the entire barycenter soi and also covers (with a decent margin) the actualy barycenter; and another "charon soi" that is also in the barycenter soi but not touching Pluto's SOI...

I think that would work, though I'd have to play with edge cases to see. And I don't know how much it'd add over the current system.

Edited July 15, 2014 by 5thHorseman

[nanobot]

Take a look at this thread from 2013:

http://forum.kerbalspaceprogram.com/threads/39620-Barycenters-and-non-spherical-Volumes-of-Influence-%28an-idea-for-binary-planets-stars%29

[CreepyD]

One of the planet packs had two stars orbiting each other in this fashion, and used an empty point in the middle as suggested.

It worked just fine.

So yes it's possible and has even been done.

[Sky_walker]

Man, close-up pictures of Pluto are going to be amazing. Can't wait!

Me too.

After Rosetta mission (landing on a comet and flying along it as it gets close to the sun and then flies away) it's the most interesting event in space exploration coming up the horizon

One of the planet packs had two stars orbiting each other in this fashion, and used an empty point in the middle as suggested.

It worked just fine.

So yes it's possible and has even been done.

Isn't it causing some weird artefacts? Obvious one being that there is no stable mid point between stars (cause you can't be in 2 SoI at the same time) but isn't it causing issues with ship suddenly switching it's SoI while in a middle of orbit? And do these stars actually rotate using physics engines, or is it all a usual fake, a hardcoded animation? Do these suns even have a separate SoI or are they treated as just one? Cause if so, then... well, it hasn't be done. If you got just 1 SoI than the only thing they achieved is an animation of planets, nothing particularly impressive.

[Torquemadus]

The most obvious way for Squad to implement a Pluto Charon analogue would be to use the same method they used for Duna and Ike.

[magnemoe]

Me too.

After Rosetta mission (landing on a comet and flying along it as it gets close to the sun and then flies away) it's the most interesting event in space exploration coming up the horizon

Isn't it causing some weird artefacts? Obvious one being that there is no stable mid point between stars (cause you can't be in 2 SoI at the same time) but isn't it causing issues with ship suddenly switching it's SoI while in a middle of orbit? And do these stars actually rotate using physics engines, or is it all a usual fake, a hardcoded animation? Do these suns even have a separate SoI or are they treated as just one? Cause if so, then... well, it hasn't be done. If you got just 1 SoI than the only thing they achieved is an animation of planets, nothing particularly impressive.

None of the planets and moons use the physic engines all the paths are hardcoded. I however thought you needed another body as center of rotation, has not tested the mod but the stars even have other planets around them so it has to have a SOI.

[Sky_walker]

So... both stars share the same SoI centred between 2 animated stars? Do I understand it right?

[SRV Ron]

Close up of Pluto as simulated in Space Engine;

Edit, additional info. Pluto and Charon are tidally locked by their barycenter.

Stats on the dwarf planet and the first moon

And, what it may look like on the surface with the light setting on real at sunrise.

One should note that Earth also has a berrycenter with the moon. Due to tidal forces, the Earth's moon is being slowly accelerated in its orbit at the expense of Earth's rotational speed. The results is that the moon is slowly expanding its orbit in response. Eventually, the balance will be reached when Earth's orbital speed gets locked with the Moon's rotation. It will be much further away as our day becomes several months in length.

Edited July 15, 2014 by SRV Ron

[NecroBones]

The problem is what happens to your ship when you get close to the center of that gravity well? Gravity shoots up to infinite and your ship is teleported to the other end of the universe, that's what. The only thing keeping that from happening in the game now is before you get too close to that point source of gravity, you hit the surface of whatever planet is around it.

That's true, if you assume all of the gravity is being generated at the center (mathematically/programmatically).

The difficulty here, is that when you go "inside" the radius of the gravitational mass, things can act a little differently. For instance, in a typical situation like this, where the barycenter is outside both physical bodies, the gravity is in an equilibrium here, and the pull from both bodies is about the same. If you simulate it properly, the acceleration is closer to zero, not infinity.

As another anecdote (that is less relevant), if you were to tunnel down inside the earth, the amount of gravitational acceleration you feel actually decreases with depth. You can calculate the gravitational pull based on the mass within the current radius of your depth. Everything at a higher altitude than you, cancels itself out (if you ignore differences in density, surface heights, etc). Eventually when you would reach the center, the pull toward the center would once again be zero.

[Superfluous J]

Yup. You described the real world quite well. Too bad KSP uses a point source of gravity and nothing more.

Actually that's good. It lets the game run on normal, non-water-cooled computers.

[cantab]

The mass ratio for Pluto-Charon is 8.5:1. By that point I think a spherical Charon SOI inside a spherical Pluto SOI, inside and always covering the centre of a spherical Pluto-Charon SOI, will be accurate enough.