Does KSP have lagrange points?

[ZooNamedGames]

Does KSP properly replicate Lagrange points? Or points in Earth's (or Kerbin's) gravity were your experiencing no gravity from neither Earth or the Sun (or so that's how I understand it- if I'm wrong please correct)? Or is this not possible?

I'm considering on sending a replica mission that will need to be placed in LP1 (Lagrange Point 1)- but first I need to know is it possible?

[Awaras]

No, unfortunately it does not.

[Randazzo]

It does not.

KSP uses a two-body simulation that does not allow for Lagrange points.

[Robotengineer]

No.

How could you have L-points with an SOI physics system?

[Musil]

As I understand it, no. Proper Lagrange points require relativistic physics, and KSP doesn't have them (for good reason). There is a Way to simulate them, I believe, but they will need correction from time to time.

[ZooNamedGames]

ahhh... that sucks :/ .

Any possibility of modding it to? (ANYTHING is possible if given the right attempt by a modder- MSS mod comes to mind when people said having more than one Solar System wouldn't work- so it IS possible... just will someone make it?)

[Stormweaver]

Someone is working on it as a mod: http://forum.kerbalspaceprogram.com/threads/68502-WIP-Principia-N-Body-Gravitation-and-Better-Integrators-for-Kerbal-Space-Program

But as above, lagrange points just don't make sense in stock KSP physics.

[bitbucket]

n-body physics would basically require a rewrite of the game that would require a supercomputer from the future to run it.

Regardless, you can still fake L3/L4/L5 Lagrange pointsâ€â€there's nothing stopping you from putting something 60° ahead/behind an object on a matching orbit (except your fuel supply), and it will stay there on its own just the same.

Edited May 12, 2015 by bitbucket

[ZooNamedGames]

Someone is working on it as a mod: http://forum.kerbalspaceprogram.com/threads/68502-WIP-Principia-N-Body-Gravitation-and-Better-Integrators-for-Kerbal-Space-Program

But as above, lagrange points just don't make sense in stock KSP.

Well they have scientific advantages- we just sent the DSCOVR spacecraft (launched aboard a F9) to L1 about a month back. It will gives us heightened advantage over seeing incoming solar flares. However in KSP this could give us the advantage of seeing more asteroids and USOs (Unknown Space Objects). It would be a great way to EARN asteroid discovery and operations. Not just HAVING it at start.

[TheMoonRover]

If you were in exactly the right orbit you could (to all intents and purposes) be sitting at a Lagrange point. Obviously not every one would be possible due to the SOI system (you can't orbit outside the SOI), but you could certainly simulate a lot of them with a precise orbit.

You could set up SOIs representing the lagrange points, however you would have to find some way around having infinite acceleration at the centre.

[Sky_walker]

No n-body physics = no Lagrange points (and few other, less obvious things).

proper Lagrange points require relativistic physics

If you were in exactly the right orbit you could (to all intents and purposes) be sitting at a Lagrange point. Obviously not every one would be possible due to the SOI system (you can't orbit outside the SOI), but you could certainly simulate a lot of them with a precise orbit.

Correct me if I'm wrong but from what I recall you can fly to L₃, L₄ and L₅. The most important points - L₁ and L₂ - are impossible to achieve in a stable matter.

n-body physics would basically require a rewrite of the game that would require a supercomputer from the future to run it.

That's ... ekhm... not true considering that there is already a mod for that.

Edited May 12, 2015 by Sky_walker

[Gerandar]

n-body physics would basically require a rewrite of the game that would require a supercomputer from the future to run it.

Regardless, you can still fake L3/L4/L5 Lagrange pointsâ€â€there's nothing stopping you from putting something 60° ahead/behind an object on a matching orbit (except your fuel supply), and it will stay there on its own just the same.

N-body physics would also tear the kerbol system apart in just a few dozen years so yeah it wouldnt really work with KSP's solar system as is anyway.

[bitbucket]

N-body physics would also tear the kerbol system apart in just a few dozen years so yeah it wouldnt really work with KSP's solar system as is anyway.

I recall a post somewhere where someone did a 100-year simulation of the system with real n-body physics, and the only notable instability that manifested was that Vall and Bop got tossed out of the Jool system into solar orbits within a few years. Otherwise, nothing else got out of line.

[Mr Shifty]

Does KSP properly replicate Lagrange points? Or points in Earth's (or Kerbin's) gravity were your experiencing no gravity from neither Earth or the Sun (or so that's how I understand it- if I'm wrong please correct)? Or is this not possible?

Better to say that the gravity from Earth and Sun balance so that the relative geometry between the three bodies (Earth, the sun, your vessel) remains the same over time. In KSP, you can actually sort of simulate this by placing your vessel on the same orbit as, but outside the SOI of, the orbiting body.

I'm considering on sending a replica mission that will need to be placed in LP1 (Lagrange Point 1)- but first I need to know is it possible?

KS1 can't be simulated. Your vessel will pull ahead of Kerbin because of its lower orbit. KS4/5 can sort of be simulated as above, though an actual KS4/5 would not be directly on Kerbin's orbit, but slightly above it.

As I understand it, no. Proper Lagrange points require relativistic physics, and KSP doesn't have them (for good reason).

No relativistic physics required, just classic Newtonian physics with three gravitationally significant bodies.

n-body physics would basically require a rewrite of the game that would require a supercomputer from the future to run .

Nope, it wouldn't require much more than the integration methods already used to project trajectories in the game. They don't do it because n-body complicates everything (particularly time warp) and makes maneuver nodes much harder to implement and far less intuitive. In other words, it's gameplay, not technical capability that prevents it.

Two notes:

1) L-points don't work in n-body simulations. They're only actually valid for 3-body simulations.

2) Orbiter simulates n-body physics, solar radiation pressure, exosphere drag, orbital precession, gravity gradient torque, etc. If you want that stuff, head over to http://orbit.medphys.ucl.ac.uk/ and check it out.

[Sky_walker]

I recall a post somewhere where someone did a 100-year simulation of the system with real n-body physics, and the only notable instability that manifested was that Vall and Bop got tossed out of the Jool system into solar orbits within a few years. Otherwise, nothing else got out of line.

That was a very... forgiving simulation considering that KSP planets don't make much sense. Eg. Kerbin density is greater than a density of any known element and Jool density is greater than the one of Mars... sorry to disappoint you, but KSP system couldn't possibly exist.

Two notes:

1) L-points don't work in n-body simulations. They're only actually valid for 3-body simulations.

Lagrangian points do exist in real life (n-body system), but they are not perfectly stable. That said though - they are still valid and we still know how to sent satellites to them - heck, there are whole groups of asteroids located around Lagrangian points. Here you can read more about their stability: https://en.wikipedia.org/wiki/Lagrangian_point#Stability

Edited May 12, 2015 by Sky_walker

[Mr Shifty]

That was a very... forgiving simulation considering that KSP planets don't make much sense. Eg. Kerbin density is greater than a density of any known element and Jool density is greater than the one of Mars... sorry to disappoint you, but KSP system couldn't possibly exist.

bitbucket didn't say it could exist, just said it was generally gravitationally stable in an n-body paradigm.

- - - Updated - - -

Lagrangian points do exist in real life (n-body system), but they are not perfectly stable. That said though - they are still valid and we still know how to sent satellites to them - heck, there are whole groups of asteroids located around Lagrangian points. Here you can read more about their stability: https://en.wikipedia.org/wiki/Lagrangian_point#Stability

From the wikipedia article you quoted:

Although the L₁, L₂, and L₃ points are nominally unstable, it turns out that it is possible to find (unstable) periodic orbits around these points, at least in the restricted three-body problem. (emphasis added)

L₄ and L₅ are perfectly stable in a 3-body system, and as long as there are no other gravitationally significant bodies around, it's difficult to knock something at those points out of them, which is why there are Trojans at JS₄ and JS₅. (Nothing else in the solar system is gravitationally significant next to Jupiter and the sun.) But there's zero evidence of similar bodies trapped at any of the Earth-Sun or Earth-Moon triangular points. They wouldn't be stable over any long time frame because of perturbations caused by our moon, the sun, and nearby planets.

[Sky_walker]

Re-read my post. I specifically pointed out that they are not stable. But nice you found out quote from wikipedia confirming what I just said. It doesn't mean however that they are "invalid". Also Earth Trojans do exist (or at least one of them )

Edited May 12, 2015 by Sky_walker

[Mr Shifty]

Also Earth Trojans do exist (or at least one of them )

Interesting. I hadn't known that; thanks for the link! Compared to the more than one million Jupiter trojans though...

[Vanamonde]

KSP does not simulate Lagrange points. Furthermore, this is a subject that has been talked to death and tends to cause arguments, earning it a place on the What Not to Suggest list. Let's please not get into it again, whether as a suggestion or not.