Interstellar SOI?

[Pthigrivi]

So… what happens when you’ve exited Kerbol SOI?

[TheOrbitalMechanic]

I guess you just... float there? Somebody is 100% going to park a space station in between stars so it just hangs there forever.

[The Physics Engineer]

Given the latest episode, I assume you’d enter the galaxy’s SOI

 

[The Aziz]

Technically, a star's gravitational influence stops mattering if there's a stronger force nearby. Mind you that's overly simplified definition because there's more to it. But that brings me to my idea: while everything except Rausk twins are supposed to work in 2-body gravity system, I think the best option is to measure which star is the closest*its  gravity pull - sounds like much but it's less of a problem if the stars are static objects in the sky which I think they will be. And there's nothing to calculate because it's preprogrammed.so you'd still have virtually infinite SOIs, unless there was another SOI in the way where gravity affecting the craft would start growing back.

I guess my theory implies static Lagrange points, but then I think they'd be just that - points where multiple SOI edges meet, so practically impossible for anything to remain stable out there.

[Laxez]

Theoretically outside the SOI, there is still an influence derived from the center of the galaxy, however it is so small that it will not affect a hypothetical space station between two planetary systems.

Who knows, maybe we will also have a rogue planet!

[Ahres]

I've been wondering this ever since the game's announcement. And I've pretty well not researched much about it because I wanted to learn about interstellar travel through KSP2 like I did with orbital physics in KSP1 (I'm one of the few and the proud that didn't watch any KSP YouTube videos until after I had already gone interplanetary).

So from the standpoint of I-don't-know-anything-about-interstellar-space-physics, my intuition tells me because the super-massive blackhole at the center of the galaxy is what keeps stars in orbit around it, that same force applies to an interstellar craft as well. But the distances are so vast, and gravity is quite a weak force, so is there really any noticeable change in your velocity vector? We don't see stars (greatly) changing positions from our earthly perspective. So, I imagine while yes the center of the galaxy is tugging at you, it's not noticeable in relation to the star you left and the star you're headed toward. Which, in summary, I guess this means essentially that your vehicle will go in a "straight line" until a force vector is applied?

[The Aziz]

I found a calculator for orbital speeds/periods. Now it doesn't apply very well to Kerbol because according to the wiki, its gravity is around 1.7g - but I checked for our sun, and as it turns out, if there weren't any other objects, you could orbit the sun at ~60m/s, 4 lightyears away from it. That's Proxima Centauri distance, and it would certainly start pulling you in much further away than that. So I bet there isn't a point in Kerbal universe where you could just sort of stop moving.

Edited October 18, 2022 by The Aziz

[Pthigrivi]

8 hours ago, The Aziz said:

sounds like much but it's less of a problem if the stars are static objects in the sky which I think they will be.

I've been wondering this as well, if stars will have relative motion. They certainly do in real life but I wonder if thats worth modeling for our purposes.

[whatsEJstandfor]

14 hours ago, Pthigrivi said:

So… what happens when you’ve exited Kerbol SOI?

Wouldn't you just, by definition, enter some other star's SOI?

[The Aziz]

If they're, by old definition, still spheres of influence, there would be gaps. Can't fully fill a 3D space with only spheres, even if they're touching (at exactly one point). Hence my first post here.

[magnemoe]

2 hours ago, Ahres said:

I've been wondering this ever since the game's announcement. And I've pretty well not researched much about it because I wanted to learn about interstellar travel through KSP2 like I did with orbital physics in KSP1 (I'm one of the few and the proud that didn't watch any KSP YouTube videos until after I had already gone interplanetary).

So from the standpoint of I-don't-know-anything-about-interstellar-space-physics, my intuition tells me because the super-massive blackhole at the center of the galaxy is what keeps stars in orbit around it, that same force applies to an interstellar craft as well. But the distances are so vast, and gravity is quite a weak force, so is there really any noticeable change in your velocity vector? We don't see stars (greatly) changing positions from our earthly perspective. So, I imagine while yes the center of the galaxy is tugging at you, it's not noticeable in relation to the star you left and the star you're headed toward. Which, in summary, I guess this means essentially that your vehicle will go in a "straight line" until a force vector is applied?

Now I kind of suspect the stars in KSP 2 to be stationary. Yes real stars moves but not a lot compared to the distance, its takes probably a 1000 year to be noticeable on an star chart. 
You noticed it moved and you adjust the braking burn to correct for 100 AU  shift. I say it would be more annoying than anything. 
An central black hole has to be 2600 LY away if interstellar is scaled 1/10.  then 6-20 stars .4-5 LY from Kerbin. 
So my guess its no gravity outside of solar SOI, Stars are stationary or move at pretty random vectors, just making sure the SOI never touch even in idiotic long plays. 
It might be smart to set apart interstellar ares who are reserved for DLC and other who they ask moders to sort out between them selves. 

[pandaman]

2 hours ago, The Aziz said:

If they're, by old definition, still spheres of influence, there would be gaps. Can't fully fill a 3D space with only spheres, even if they're touching (at exactly one point). Hence my first post here.

But the spheres don't just 'touch' they always intersect fully.  With the 'most powerful' one taking control in the overlapping area.

Just like The Mun SoI is entirely within Kerbin's.  The Mun gets  control once you get close enough.

[The Aziz]

Works for "entirely within". I found an unrelated but fitting picture:

Inside the green but near the edge of purple, which is the strongest? Or, in the same space, on the green edge? And we're talking in two dimensions here, add a third and there's a mess. That makes an area of fighting forces, so I say they should have a clear calculated border at which the craft starts being pulled by one or the other. It basically removes the problem of overlapping areas. A simple "if(gravitypullof(StarX)<gravitypullof(StarY)) startpullingtowards(StarY);

Forgive my terrible attempt at syntax, there's not much left of coding knowledge I had 6 years ago.

 

[Nazalassa]

29 minutes ago, pandaman said:

The Mun gets  control once you get close enough.

Interesting fact is that, if you consider that the SOI of a CB is the area in which the CB's gravitationnal attraction is higher than the one of any other CB, then the SOI of Mun, for example, wouls be egg-shaped.

[Timmon26]

You should always be in one star system's SOI, no matter where you are in interstellar space, as long as we're assuming patched conics. Although it's less of a sphere of influence now and more like a "cell" of influence. A local map of SOIs would resemble a 3D Voronoi diagram, although not exactly because the stars have different masses and the boundaries would be convex or concave.

Spoiler

 

[MK2-DroneCore]

Why not use a bigger SOI to replace the Kerbol SOI.Maybe Kerbool and Debdeb orbits the "Kalaxy" , Interstellar Transfer is just like Interplantery Transfer is Kerbool system

[tstein]

On 10/18/2022 at 12:50 PM, The Aziz said:

If they're, by old definition, still spheres of influence, there would be gaps. Can't fully fill a 3D space with only spheres, even if they're touching (at exactly one point). Hence my first post here.

They overlap each other.  So no there is no space in between them and they are not really spheres.

[GigFiz]

On 10/18/2022 at 8:09 AM, The Aziz said:

I found a calculator for orbital speeds/periods. Now it doesn't apply very well to Kerbol because according to the wiki, its gravity is around 1.7g - but I checked for our sun, and as it turns out, if there weren't any other objects, you could orbit the sun at ~60m/s, 4 lightyears away from it. That's Proxima Centauri distance, and it would certainly start pulling you in much further away than that. So I bet there isn't a point in Kerbal universe where you could just sort of stop moving.

I agree there probably isn't, but they kind of could, because the amount you move is so little as to be practically nonexistent. 

To illustrate: Sedna has a perihelion of around 76 AU and an Aphelion of just under 1k AU, which is way out there, past the Heliopause, but also only 5.5 light days, so still waaaaayyyy less than what we are talking about, plus its orbit is highly elliptical, which decreases the orbital period a great deal, and  its orbital period is still over 11,000 years. Basically, they may as well not have stuff not move outside the Kerbheliosphere, because unless you have a program going for many thousands of years, you will never even notice, even with the reduced scale.

Taking that into account, I'd say if takes relatively trivial amounts of dev time and processing power for interstellar space SOI stuff, they will do it (so I would guess there will be at least a simple version in place), but if ends up being more tricky or runtime-intensive, they won't bother, because 99.99%+ of players will never run into a situation where it would matter, or notice the difference even if they did.

Edited December 21, 2022 by GigFiz
grammar

[Lettuce]

On 10/17/2022 at 11:20 PM, TheOrbitalMechanic said:

I guess you just... float there? Somebody is 100% going to park a space station in between stars so it just hangs there forever.

This is pretty old, but I really hope that's possible. Can't wait to drag a comet to interstellar space and make it an interstellar gas station

[Jacob Kerman]

you know, I just sent a message to a dev, and then I found this thread. I really need to look at the threads first.

[darthgently]

4 minutes ago, Lettuce said:

This is pretty old, but I really hope that's possible. Can't wait to drag a comet to interstellar space and make it an interstellar gas station

The fuel and time to decelerate and reaccelerate would likely make it unviable, but maybe everyone on the crew would enjoy the pit stop and buy some touristy souvenirs

[Jacob Kerman]

45 minutes ago, darthgently said:

The fuel and time to decelerate and reaccelerate would likely make it unviable, but maybe everyone on the crew would enjoy the pit stop and buy some touristy souvenirs

Ha

 

"Comet-again soon"

Edited December 21, 2022 by Jacob Kerman

[Lettuce]

39 minutes ago, darthgently said:

The fuel and time to decelerate and reaccelerate would likely make it unviable, but maybe everyone on the crew would enjoy the pit stop and buy some touristy souvenirs

Sort of the idea I was going for, a gas station in the middle of nowhere that rarely ever has customers. A pair of kerbals waiting for their shifts to end.

[Jacob Kerman]

This now sounds sad. 

 

[darthgently]

9 minutes ago, Lettuce said:

Sort of the idea I was going for, a gas station in the middle of nowhere that rarely ever has customers. A pair of kerbals waiting for their shifts to end.

Sounds like a scene from some hypothetical sequel to Darkstar.  Or Clerks (in space?)