Ship's SOI changed resulting in planetary collision

[CandyAngel]

Heyas everyone!

I was playing KSP last night and did a contract which involved putting a satellite into orbit around Kerbin. I managed to do that, but was left with too little dV to get the launcher to return to Kerbin's atmosphere (whoops!), so I used the Mun to slingshot me back.

As I warped to leaving Mun's SoI, KSP decided my satellite wasn't orbiting Kerbin anymore, but instead was orbiting the Mun.. with no orbital velocity: https://streamable.com/77nhk

Is this a known issue? Any advice how I can avoid this? I don't think I have any mods that would cause this (listed below).. these bugs (like the double-rep-consumed-by-strategy) are sucking the fun out of playing KSP :(

• ToolbarController
• KerbalAlarmClock
• KerbalEngineerRedux
• NASA-CountDown
• NavballDockAlignIndCE
• QuickBrake
• RCSBuildAidCont
• SCANsat
• ScienceAlert
• StageRecovery
• TransferWindowPlanner
• Toolbar
• ClickThroughBlocker
• EditorExtensionsRedux
• ModuleManager
• ContractsWindowPlus
• KSPLogger
• PreciseManeuver
• ProjectManager
• SmartParts
• TrimIndicator
• ProgressParser
• ContractParser
• Chatterer
• ChattererExtended

[Deddly]

Hi @CandyAngel, welcome to the forum!

I have to say I've been watching that recording you link to over and over again, and I just can't see anything unusual happening. Perhaps it's because the recording ends just before the change of SOI. Do you have a longer recording that captures the SOI change so we can see what happened?

[CandyAngel]

36 minutes ago, Deddly said:

I have to say I've been watching that recording you link to over and over again, and I just can't see anything unusual happening. Perhaps it's because the recording ends just before the change of SOI. Do you have a longer recording that captures the SOI change so we can see what happened?

The SoI change is at the halfway point in that video. If you watch the satellite to the left of the dialog box (right in line with "Add Maneuver"), you'll see its orbit switch from  Kerbin to an intercept with the Mun just before the dialog box obscures it.

Here are the two frames from the video surrounding the change. I only found out what happened after I finished streaming because I watched the recording back (initially, I thought KSP had "recovered" it as debris), so I can provide any video of that play session needed.

[4x4cheesecake]

Actually, it looks like your satellite is getting too close to the Mun and is getting caught within its SOI. Whats the Ap altitude of your satellite? If it is beyond ~8.9Mm, it will be eaten by the Mun.

[Superfluous J]

Yeah that's totally normal. You're going about the same speed and direction as the Mun. Then you get close enough to it to be within its SOI, and the game figures out your new velocity relative to the Mun which is very slow. Then you fall and die.

[Deddly]

Ah right, I was watchcing the wrong craft. Yes, that looks quite normal - the satellite has crossed over into Mün's SOI. If you were controlling that craft, it would probably have shown what was going to happen beforehand.

[CandyAngel]

Thanks everyone for explaining it, it makes sense now!

Maybe that's what the contract was for.. to understand this behaviour :)