Disappearing ships

[Thanny]

When looking to complete a contract to return science data from orbit around Bop, I found that my Bop science orbiter had disappeared. It was in a stable orbit just below the low orbit limit (so temperature scans would work). I was able to restore it from an older save file by copying and pasting the vessel definition. I then checked to make sure no other ships had disappeared, and found that one had from around Gilly. Also a science orbiter (exact same ship design, in fact - ion drive probe weighing less than a tonne), also just below the low orbit limit. I had to go further back to find that one in a previous save, so that one disappeared first.

Mods I have installed:

Toolbar

EditorExtensions

EnhancedNavBall

KerbalEngineer

PreciseNode

TacFuelBalancer

KerbalAlarmClock

TransferWindowPlanner

Is this a known intermittent bug? Is there something in particular that would lead to the game removing a ship?

[Thanny]

Figured out why one of the ships was disappearing. There must be a huge disconnect between the visual model of Gilly in the game and it's dimensions used for calculating collisions. Despite being well above any of the apparent terrain, the log shows it colliding with the planet when switching ships. So you can't actually achieve stable low orbit of Gilly, since that figure (6km) is below the highest invisible terrain (apparently around 8km).

Not sure why the Bop orbiter disappeared, since it was already above the highest recorded terrain, but I moved that to a higher orbit as well.

I also found my Gilly base deleted, and can only assume the game though it collided, despite being landed. I'll just have to keep an eye on that one. There seems to be no way to land stably, as the planet keeps torquing underneath the lander.

[TruePikachu]

For Gilly, that 8km figure for invisible terrain coincides with the minimum altitude for 5x time, and Bop has 5x at 24.5km. LGO is below 6km, and LBO is below 25km. I believe that ships which reach the 1x time limit are assumed to crash, which would suggest that it is impossible to achieve "stable" LGO, but LBO should be possible inside the 500m window.

As for the Gilly base destruction, I don't tend to leave things unattended on Gilly, but if you manage to 5x time accelerate, that pretty much guarentees that you are on the surface, and switching away might leave the base intact. You might want to look into using a grappling hook from KAS to "dock" with Gilly.