25km auto delete?

[AlamoVampire]

Ok, I have a question about the distance required for auto delete of debris and so forth as the main vessel flies away.

It has been stated by any number of players and devs that 25km distance is enough to make debris and the like go poof and be auto deleted. I have trusted this number for years, but, the other day, I spotted quite accidentally something that has prompted this question.

Ok, so, here is what was going on: I was sending  up a mission to my space station, routine as routine gets. By some dumb accident of timing <I guess timing is as good as coincidence?> my boosters held out long enough to stay with the vessel almost to the point where I was ready for the coasting phase to the AP, mechjeb dumps the boosters as they burned out and 2-3 seconds later the vessel orients itself for the circularizing burn and mechjeb hits the auto-warp to take me to the the burn. I look below my vessel and I see 8 items in a neat oval below me:

As you see they range in distance from around under 20km to almost 30km away. THIS is where my question stems: I have seen things travel to 25km and delete, and now, I have seen them make it to basically 30km away <this doesnt count launch clamps as I have seen those stick to the pad with me nearly 60km away, i think, THINK they are counted differently, but, may be wrong there>, so, my question is: Is the 25km distance hard and fast, or basically an averaged distance that is a nice figure to work with? Not a pressing issue, just something I found curious and was wondering about. Thoughts? 

op 00:32:30

[Allocthonous]

Auto-delete only occurs below certain altitudes (or rather air pressures). You can find the list for different bodies here, although I can't swear to their accuracy. But it does explain what you're seeing here; your boosters almost certainly went past the auto-delete threshold above the kill line.

[Reactordrone]

I think that distance only counts inside the atmosphere. Space debris will stay flying until it re-enters and gets below about 22km.

[bewing]

There are two limits involved. There is the autodeletion altitude, and the physics bubble size. The autodeletion altitude depends on the body you are orbiting, and that body may be airless, so it does not depend on pressure.

The rule is: if any object is below the autodeletion altitude of body X, and it is also outside the physics bubble of your currently focused vessel/object then it will be autodeleted. In the flight logs, they will be listed as "crashed into terrain" generally.

The autodeletion altitude is not adjustable. The physics bubble size is -- at the bottom of your settings.cfg file.

So, on Kerbin, the autodeletion altitude is 25km and the physics bubble size in the atmosphere is also about 25km (depending on your settings).

In your picture, you are at 350km altitude, and even assuming the objects are directly below you, that puts their altitudes at 320 km or higher, which is way above the 25km autodeletion altitude. They will continue to fly around forever as debris, until they go below that 25km altitude on Kerbin -- or until the debris cleanup mechanism (a completely different topic) gets rid of them.

(Caveat that I have seen a few objects fall straight through the autodeletion altitude and impact the ground. I don't know why.)

 

 

Edited August 30, 2017 by bewing

[AlamoVampire]

@bewing Thanks for the info, makes things more clear  

op01:52:30

[Human Person]

7 hours ago, AlamoVampire said:

It has been stated by any number of players and devs that 25km distance is enough to make debris and the like go poof and be auto deleted. I have trusted this number for years

You have trusted this number for ... years. Well, there have been quite a lot of updates to KSP in ... years and at some point, the game started tracking debris instead of deleting it. The feature you describe must have been somewhere before the official release.

[AlamoVampire]

@Physics Student I have been here on KSP since version 0.21  

op 00:21:30