Parachutes not automatically deploying on non-selected craft

[Dihsael]

Using a grabber/claw probe with RCS mounted to the nose of my craft with a decoupler. Launch, retrieve the space junk, and usually decouple, then use RCS to burn retrograde and separately re-enter Kerbin atmosphere. The re-enter with the pod separately.  This occasion, I happened to burn up my RCS tank.  I then decided I would try double re-entry.  Burn retro to about 20k. Decouple, set both to SAS retrograde, check my automatic chutes were armed, focus on my grabber probe, probe successfully landed junk in the ocean, retrieve craft, done.  Go to retrieve pod, and realize I had killed 3 Kerbin. The automatic chutes did not deploy if I was not flying/watching that craft. I had also  noticed that SAS would not stay on if I switched crafts. Obviously, this would not have happened if I had not had to alter my plans. My only real question is why did the automatic chutes not deploy? Or is it as simple as "you need to be flying craft A for the chutes to deploy on Craft A. "

[Entropian]

I think the craft you weren't piloting must have exited the physics range.  When a craft leaves the physics range, the game engine stops calculating throttle, rotation, reentry heating, staging, etc. for that object.  At a certain altitude above Kerbin (the "death zone"), if a craft isn't piloted by the player, the game automatically destroys the object.  Probably your other craft fell into the "death zone" for out-of-physics-range objects and was destroyed.  Try reentering with your space junk; that probably would fix it.

Edited June 19, 2020 by Entropian

[Dihsael]

Ok. I could have three ships floating around in space for days without supervision. I figured a simple pod reentry from 40k down with SAS set and automatic chutes unsupervised was a no brainer.  Spent engines and fuel pods 20k away  on the way down keep their reentry until they crash into land or sea. Seemed odd to me. Newer to the game. Thank you for the info. Time to research the death zone and physics ranges. 

Edited June 19, 2020 by Dihsael

[Spricigo]

4 hours ago, Dihsael said:

Or is it as simple as "you need to be flying craft A for the chutes to deploy on Craft A. "

Well, with no mods, effectively it is safer to assume so. There is the physical range but if the other craft goes just a bit too far and it will not activate. 

 

[AHHans]

Hi @Dihsael, welcome to the Forums.

@Entropian already wrote the important stuff, but maybe some additional information is useful: Craft that are not within the physics range of the craft that you currently control are "put on rails", i.e. they continue on their Keplarian orbit without having any physics applied to them. This is done because the physics simulation takes the majority of the CPU time and is the single largest limitation of the game (e.g. for large craft with many parts). So without any drag being computed: if a piece of junk is place on a sub-orbital trajectory around Kerbin with a PE of 50km then it will stay there forever, the orbit will not decay unless you "take control" of it and watch it de-orbit while being focused on it. Craft that get too close to a planet or moon while "on rails" will just be considered crashed and be deleted from the game, without checking anything else. So if you have a second craft in your physics range bubble during reentry, this then deploys its parachutes before the controlled craft does, and leaves the physics range, then it will be deleted even though the parachutes were deployed!

IIRC this "death zone" is 20 km for Kerbin, and around 10 km for the Mun.