At what altitude around kerbin does the game decide that craft or debris on rails should be removed?

[Kurld]

If you play the game very long you will see it:  decoupled boosters or other garbage in map view that dips well into kerbin's atmosphere only to emerge on the other side unscathed, and since they are on rails, their orbits never decay and they don't go away until you bother to go into the tracking station and remove them manually.

How low can you go and remain safe?

[king of nowhere]

18 hours ago, Kurld said:

If you play the game very long you will see it:  decoupled boosters or other garbage in map view that dips well into kerbin's atmosphere only to emerge on the other side unscathed, and since they are on rails, their orbits never decay and they don't go away until you bother to go into the tracking station and remove them manually.

How low can you go and remain safe?

iirc, it should be 25 km, as long as you're not in physical range

[Mahnarch]

Litter bug! 

 

It is one of my mission parameters that all debris deorbits itself.

[Leganeski]

6 hours ago, king of nowhere said:

iirc, it should be 25 km, as long as you're not in physical range

In general I think it’s 0.01 atm, which on Kerbin is at an altitude of about 23 km.

[Kurld]

15 hours ago, Mahnarch said:

Litter bug!   It is one of my mission parameters that all debris deorbits itself.

Mine too   I got tired of thinking it was done only to come back and see a pesky spent stage STILL somehow keeping itself aloft.