"Last minute SOI change"

[Mokmo]

These images were taken an in-game hour or three apart, no maneuvers in between.

See what happened there ? Tylo can be such a troll!

But seriously, how come the map didn't show this change of SoI until i was in it ? took me about 500 dV to fix this to get my Jool aerobrake!

[Taki117]

I believe the reason is because Tylo's SoI is so large. While your Initial orbit should not have intersected the SoI Tylo's moving, along with your spacecrafts, coupled with the unusually large SoI caused you to enter it's SoI, also, if you were warping at any point your initial orbit could have been subject to rounding errors.

[Robbii6]

You were probably Right on the tip of entering tylo's SOI and it might have been spazing and not showing it. or you used physics warp or even normal warp that just edged you into the SOI.

[Mokmo]

Ok i'll keep that in mind for next time.

[Sirrobert]

Yea, it tends to do that when you are extremely close to the edge of the SOI (so only just, or just not, entering it)

Rounding errors

[BudgetHedgehog]

I don't think this is a simple fact of the game, I think this is a bug. I've had a similar one where a Minmus intercept simply would not show up. If I was on the edge of the SOI, it would, but bringing the PE down to a low altitude made the encounter disappear. I had to guess the right amount to burn in the end. Also, setting up my recent Duna mission, the intercept was flickering on and off like crazy which would be ok if it weren't for the fact I was making refinements with MJ and told it to refine closest approach to target to be a collision course.

Also, as an aside, I certainly would not call the OP intercept 'on the edge of Tylos SoI'... look at it! Yeah, the it's near-polar so the angle isn't ideal but look at how long he's in it! That kind of time does not happen if you're only just inside the SoI. Yeah, Tylo has a big gravity well but seriously now.. going that fast and staying that long inside Tylos SoI is NOT 'just inside it'.. just inside it would not affect the trajectory that much.

No, in my mind and personal experience, it's a bug. A really annoying one, too.

[Claw]

Yeah, this is really easy to recreate if you aim at the back edge of the Mun's SOI, as if you're aiming for L5. You can try to arrive behind the Mun and your orbit will show no SOI change. As you approach, it will suddenly switch to the Mun's SOI. I'm not sure what piece of the code causes this, but I agree that it can be an unpleasant surprise.

[Vector]

I have run across this bug too. Sometimes it manifests for some time warp values and if i reload and use a higher time warp then it does not occur. I believe it comes down to the PatchedConicSolver not doing a very good job.

[Boomerang]

Happens a lot to me when leaving the Mun's SoI. I'll warp until 5 or 10 seconds before the transition into Kerbin's SoI, only to have it re-plot a new escape trajectory. Does it occasionally upon returning from Minmus as well. And as was said above, it happens frequently enough to make me think it's a bug, rather than just rounding errors on trajectories that are already skirting intercepts.

[Unit327]

I don't think this is a simple fact of the game, I think this is a bug.

There's no reason it can't be both.

[Claw]

Happens a lot to me when leaving the Mun's SoI. I'll warp until 5 or 10 seconds before the transition into Kerbin's SoI, only to have it re-plot a new escape trajectory. Does it occasionally upon returning from Minmus as well. And as was said above, it happens frequently enough to make me think it's a bug, rather than just rounding errors on trajectories that are already skirting intercepts.

Warping during SOI transitions is a risky endeavour (I once flung Jeb interstellar during a return from the Mun at high warp).

My guess is because of all the calculations that are skipped during the big leaps in orbital steps. If you consider at 1000x warp, the game is calculating position and velocity 1000x less frequently. 10k warp is even worse. This means the SOI transition may occur much later than it should. Gravity is pulling the wrong way and not hard enough, velocity vectors are going astray, etc.

I find warp values of 50 or less tend to keep the errors down during transition. Although that doesn't really resolve the "surprise" SOI transition.

[Kasuha]

I have a quicksave where the ship is on collision course with Tylo and the game does not tell me it will enter its SOI until it does so. Yes it is a bug in calculating SOI intersects, it's been reported number of times, it is on bug tracker at least once and developers are definitely aware of it. The only thing we are waiting for is a fix for it.