Lost ship during reentry

[sublimesc]

Hey guys,

I recently performed a rescue mission that seems to have gone awry. I sent a manned rescue ship and docked with a stranded manned command pod in orbit around the mun. I burned to a reentry trajectory while still docked, and then undocked as the ships were entering the atmosphere. I deployed my parachutes on both vessels successfully, but for some reason my second (rescued) ship seems to have disappeared.

After some research, I heard ships will despawn if they're >2.5 km away from the ship you're focused on? If this is the case with my scenario, I don't understand why ships in orbit don't disappear. Is there anyway to change this threshold? I suppose I could try to leave ships docked during reentry, but I didn't think just the magnets would be able to withstand the stress. I guess I'm just looking for confirmation of my hypothesis and ideas for how to prevent loss of ships like this in the future.

P.S. I know rescue missions normally involve kerbals just transferring to rescue, but I wanted to save the vessel too in this case.

[sewerbird]

Vessels that arrive on a point of their trajectory that passes below the surface (or the .1 pressure mark in an atmosphere, I believe) will be 'cleaned up' by KSP when they leave your physics range (which I think is 2.3km). It isn't ideal: the same thing annoys me when I make my rocket boosters 'reusable' by putting parachutes on them: they won't float down to the surface and land if I follow my actual rocket up to orbit.

[MarvinKitFox]

Any vessel that is in motion, and below ~22 km for Kerbin, needs to be within your physics 'bubble" of ~2.3km radius from your current controlling pod.

Your idea would work, but only if you ensure that the vessels never seperate more than 2.3km, while either is under 22km altitude.

[sublimesc]

Ah, I see. That's too bad. Thanks for the explanations, they were very clear.

[InF3RNo]

Hello you talk about docking, how that works? I've been not playing since a while, new features or it's a mod?

Thanks!

[Dave Kerbin]

There are two types of physics in KSP. The full simulation and 'on rails'. Whenever you are going at 4x timewarp or below you are in full simulation mode; Your ship and everything within ~2.2km is being fully simulated. Each part can exert forces on the other parts, parts can rotate, parts experience drag, engines and thrusters can fire, etc. When you timewarp to 5x or above you switch to on rails mode. On rails is a much faster type of simulation where it treats your ship as a single solid mass and simply calculates it's orbit. This is the reason you can't timewarp to 5x while your ship is in the atmosphere - it would stop simulating important things like drag.

Anything outside of the 2.2km bubble is always 'on rails' regardless of timewarp. This way you can have dozens of ships in orbit without the game slowing down. When it comes to planets objects that are on rails follow much simplier rules - drag is not simulated and anything that passes below a certain altitude (set by planet) is assumed to have crashed and is deleted. This is generally considered a good trade off, since any object you leave unattended is usually either in a stable orbit or is on a collision course (discarded boosters or other things).

[Taki117]

Hello you talk about docking, how that works? I've been not playing since a while, new features or it's a mod?

Thanks!

Docking is a feature, and we ask that you do not derail a thread for a completely separate question whose answer can be found elsewhere with a Google search.

To answer the OPs question. If you are below 22km and at a distance of greater than 2.5km any non-controlled ship (Basically the ones you aren't currently controlling) will be deleted. This is true wether the uncontrolled craft has the ability to be controlled (via probe core or manned capsule) or is simply debris.

[Pecan]

Ninja'd 10 char

[eurybaric]

Some mods do change that radius though. One example being the Lazor mod

Cheers!

[Kasuha]

I have performed parallel landings several times and the trick is to undock ships from each other when you're sufficiently low. Then they'll not drift far apart to disappear.

Here's an example.

[cantab]

The alternative would be to deorbit and land one, then the other. In your case, after getting on the return trajectory, you could have undocked and had the powered part burn to speed up its trip to Kerbin.

[Vigelius]

I've found TT NeverUnload to work great for this sort of issue. Add the NeverUnload part to both vessels and activate them both, then the 'physics bubble' can extend up to about 200km IIRC

[sublimesc]

All extremely helpful responses. I'll definitely check out that mod if I ever need to perform a parallel landing again. Thanks everyone!

[hikerchick]

Is there any way to reverse this? I just lost a 250 sp mission because of an accidental keystroke

[Claw]

Is there any way to reverse this? I just lost a 250 sp mission because of an accidental keystroke

Reverse what specifically?

If you mean "reverse the craft that was deleted outside of physics range," then unfortunately the answer is no (sorry). Unless you happen to have a quicksave available.

If it just happened, you can also ALT-F4 out of the game and it won't save the persistence. But then you are at the mercy of whenever it last auto-saved. I'm guessing this isn't an option since your post is almost 2 hours old.