Halo orbit, is it possible?

[tuskiomi]

can someone in KSP currently do a halo orbit between any 2 celestial bodies?

see http://spacecraftforall.com/a-new-orbit for more info

[Red Iron Crown]

No, KSP uses the patched conics model of gravity, where only one body influences a vessel gravitationally at a time. Halo orbits require the n-body model.

[tuskiomi]

is there a modification for this?

like a REAL game-altering mod?

[Red Iron Crown]

The only one I've heard of is a mod called Principia, it's in the mod development forum as it's a work in progress. Can't give you a link as I'm on my phone, nor can I speak to the mod quality as I haven't used it.

[Mr Shifty]

No, KSP uses the patched conics model of gravity, where only one body influences a vessel gravitationally at a time. Halo orbits require the n-body model.

Slight correction: Halo orbits require specifically a 3-body model (e.g. Earth, Sun, spacecraft.) They aren't stable with >2 gravitationally significant bodies.

is there a modification for this?

like a REAL game-altering mod?

eggrobin is working on [thread=68502]Principia[/thread], which will enable n-body trajectories as a side effect. (It's main goal is to increase the accuracy of KSP's forward integrators, thus enabling a host of possible activities: station keeping, time-warp under thrust, exosphere drag, non-spherical gravity, etc.) If you'd like to dabble in a space flight simulator that already has these features (and has for over a decade), try Orbiter: it's free!

[G2-]

I have often wondered if an approximation of a halo orbit can be achieved via SOI hoping. For example a L1 orbit is technically still possible in KSP although would need many small course corrections throughout a single orbit (Wouldnt be a fun expeirence). For all the others L2-L5 I believe they are unusable due to the SOI approximation.

[Red Iron Crown]

Slight correction: Halo orbits require specifically a 3-body model (e.g. Earth, Sun, spacecraft.) They aren't stable with >2 gravitationally significant bodies.

You're right of course, thanks for the correction. (I'm trying hard to refrain from pointing at ">2" and correcting it to "<2".....aw, nuts)

[Kasuha]

You can have an approximation of Halo orbit in L3 point. Just put your probe/station to a place opposite to Mun on a slightly inclined and elliptical orbit with the same orbital period as Mun and there you are - the ship will draw a closed curve around L3 in Kerbin-Mun rotational frame of reference. It will even be a reasonably stable orbit.

You could probably do something similar on Mun's SOI boundary and call them L1 and L2 but these trajectories would be extremely unstable and would require extensive maintenance.

If you try the L3, you'll probably find it boring. KSP lacks the feature of drawing the trajectory relative to Kerbin-Mun rotating reference frame so you'll see just an usual ellipse. It's the same with real halo orbits, it's just the way of displaying them in rotational reference frame what makes them look fancy.

[psyper]

Would it be possible via a mod to create a body which has gravity but no surface which can then be placed on rails in any of the L points? This will then give the illusion of being in orbit around these points - they don't even have to have a large SOI themselves - just enough to have a small orbit around them. Call them after their Ln references so they show up in the tracking station "Solsat in orbit around Kerbin-L1"?

[MarvinKitFox]

Would it be possible via a mod to create a body which has gravity but no surface which can then be placed

Bad bad BAD idea.

Any gravity source, no matter how weak, without a protective surface exposes a naked singularity to space.

If your rocket should fly through this singularity, parts of it will be subjected to ludicrous g-forces. Potentially, some order of infinity of acceleration.

It would make for a very Kerbal day, indeed.

[metaphor]

It's already possible to put spacecraft at the L3, L4, and L5 Lagrange points in game, and halo orbits around them. There's also infinitely more Lagrange points in game, all along a body's orbit and outside its SOI. If you want to approximate L1/L2, you can put a spacecraft along the same orbit as a body but right ouside its SOI. Then instead of being on the line between the moon and the planet, it will be a little to one side, but would still functionally be the same as L1/L2.

I've seen a lot of people say they want n-body gravity in order to use Lagrange points. But I haven't seen anyone use the ones that are in game already, which are functionally equivalent to the real ones.

[psyper]

Bad bad BAD idea.

Any gravity source, no matter how weak, without a protective surface exposes a naked singularity to space.

If your rocket should fly through this singularity, parts of it will be subjected to ludicrous g-forces. Potentially, some order of infinity of acceleration.

It would make for a very Kerbal day, indeed.

Yeah good call - really don't want that to happen - it'll probably start sucking in my persistence file and system32 and that would be bad!! How about a small trojan moon in there like the easter egg moon that's been mentioned a couple of times - wouldn't be at all surprising that theres a small rock hiding in kerban's L-points and it would be pretty cool to land or dock with it?

[Mesons]

Yeah good call - really don't want that to happen - it'll probably start sucking in my persistence file and system32 and that would be bad!! How about a small trojan moon in there like the easter egg moon that's been mentioned a couple of times - wouldn't be at all surprising that theres a small rock hiding in kerban's L-points and it would be pretty cool to land or dock with it?

That would be really cool! I wonder if the devs have ideas like this for more easter eggs? You could make a suggestion thread about it.

It's already possible to put spacecraft at the L3, L4, and L5 Lagrange points in game, and halo orbits around them. There's also infinitely more Lagrange points in game, all along a body's orbit and outside its SOI. If you want to approximate L1/L2, you can put a spacecraft along the same orbit as a body but right ouside its SOI. Then instead of being on the line between the moon and the planet, it will be a little to one side, but would still functionally be the same as L1/L2.

I've seen a lot of people say they want n-body gravity in order to use Lagrange points. But I haven't seen anyone use the ones that are in game already, which are functionally equivalent to the real ones.

I have to agree, and I don't know what Squad's plans are for the orbital physics in KSP, but pretty much anything besides patched conics is going to be a lot more computationally intensive, and thus slower. It would also be a lot of work to introduce n-body gravity for not a lot of gain in fun or realism. That's why eggrobin is hard at work on it! Well...sarcasm aside, some purists love maximally real physics, and why not?

[psyper]

That would be really cool! I wonder if the devs have ideas like this for more easter eggs? You could make a suggestion thread about it.

would but this ticks about 3 different points on the 'what not to suggest' post

[metaphor]

Anything in solar orbit would be extremely hard to find. There's just so much space there, even at 1/10 real scale. The magic boulder was always pretty hard to find, and it was in low orbit around a moon.

For all we know, there might already be one or a thousand easter eggs in solar orbit. Even with a million people actively playing the game, the chance that any of those easter eggs would be discovered would be miniscule (especially considering most people don't drop out of timewarp much in solar orbit).