In atmosphere deletion of spacecraft with Kerbals?

[heya4000]

Today I was deorbiting an apollo style moon lander which had 2 pods. So I undock each pod and activated the chutes. But after the other one got 2.5km away, it got deleted. The thing is, it had a kerbal inside it. I thought the deletion thing only applied to debris and such, not to active spacecraft? Is there any way to prevent this and keep all kerbals alive?

RIP Bill.

[M4ck]

Well, AFAIK you simply cannot leave a vessel moving through atmosphere, like it is impossible to quicksave or return to Space Center when rolling a rover or dropping on a chute. What happens to vessels farther than about 2km from your active vessel, they are treated like a single point on its current trajectory(like all the stuff you see in map view).

Such "simplified" trajectories won't be calculated in atmosphere, as that would require calculating air resistance etc. They are usually simply destroyed upon reaching atmosphere - try by launching two ships to a stable orbit, then lowering the periapsis of one to like 10km about Kerbin surface. If you switch to the other ship, open map view and wait until the other one gets to around 65 km altitude, you will see it disappear, even though it clearly couldn't have crashed into terrain(at least it happens to me). Even if you create some solid metal cube ship that can somehow survive impact at extreme speeds, so it would not be destroyed if you manually crashed it into a planet, it will still go bye-bye when "simplified" and below some pre-set altitude

The pod that disappeared wasn't "another active vessel", you can only have one active vessel at a time. When it got far enough, it got "simplified", marked as currently in atmosphere and removed. I don't think there is anything to be done about it, it's just the way game engine works.

Edited August 6, 2013 by M4ck

[T-Pilot395]

Romfaror's Lazorsystem curbs this if you increase the draw distance. But depending on how close they were it might not be needed.

I just splashed down my rescue lander with 2 pods, which separated and deployed their own chutes.

[Francesco]

it's 23 km.

that is, the altitude where Kerbin's atmo pressure is 0.01

[Tiron]

Here's what's happening: The game doesn't fully simulate everything. Once something gets outside a certain range of your focused craft (about 2.4KM is the default range but as pointed out the Lazor system can alter it), that object is put 'on rails', just like when you start using non-physical timewarps. While on-rails, the physics aren't actually being simulated. It just locks the craft onto its current orbit, as if it were a train on an invisible set of rails. One of the interesting things about this state is that objects that are on-rails can't collide with anything, they just pass right through it. And because the Physics aren't being simulated, anything that's on-rails inside an atmosphere doesn't get slowed by drag, either.

One of the effects of this is that any empty stages you drop, once they get outside of simulation range, go on-rails. If this puts them on a sub-orbital trajectory (as during a launch), this actually puts them on a defined orbit around a point at the exact center of Kerbin. Without any intervention, they'd actually fall through the surface clear down to the center of the planet, then come flying back out of the planet up to their maximum altitude. And keep doing that forever.

What the game designers did to prevent that was to set it up so that ANY object which is on-rails below a particular altitude (Around 20km at least for Kerbin) immediately despawns. This makes it seem like it 'hit the planet' in the case of debris. Trick being, it applies to ANYTHING. If you airdrop a rover with a parachute and try to fly away, the rover will despawn the second you get more than 2.4KM away from it unless it's already resting on the ground when you fly off. This also goes for manned pods: If they get 2.4km away from the focused craft while under 20km, they instantly despawn. Because the game can't have their parachutes open and lower them safely to the surface while they're on-rails.

The Lazor System has built in features that allow you to change the distance at which things go on rails, mitigating this somewhat at the price of having to simulate more objects for longer.

Given that the current behavior would cause some pretty major problems with career mode (Can't recover a stage that's been despawned), I'm expecting some kind of alterations to it in future. Otherwise, the change they made several versions back that allowed parachutes to be deployed on a dropped stage would be kinda moot.

[metaphor]

To prevent this happening, wait until you're closer to the ground before you separate the two craft, so that they won't have time to go 2.5 km away.