Undocking unmanned probe from transfer stage renders transfer stage unfindable

[formikachu]

Hello! This is my first post and first question I have not been able to resolve with Google or trial and error. I am hoping someone can shed light on my conundrum.

I have been playing KSP largely with unmanned probes. I've sent kerbals to Mun and Minmus and returned them to Kerbin successfully, but in both cases I used a lander that was also its own return vehicle, i.e. it landed with enough fuel to return to Kerbin (barely - but that's another story ).

I decided to start experimenting with a tug/transfer stage from which a lander can detach and then return to, but I can't seem to figure out how to do this with an unmanned probe. It's to the point that I wonder if it simply can't be done.

I modified one of my standard probes with a docking port on its top, and placed one on the transfer stage as well. I successfully did a flip in orbit, undocking from the launch configuration and redocking for transfer, a la the Apollo LM before TLI. I then headed out to the Mun and undocked.

At this point I can no longer find my transfer stage. I can see it visually, but I can't control it, take control of it, or find it in the Mission Tracking screen. Undocking from it pretty much rendered it a spent stage as far as KSP seemed concerned, even though I didn't actually stage - I undocked.

My hypothesis is that a decoupled stage is only "active" or "useable" if it has a kerbal on it - i.e. leaving a pilot in the command module while Jeb goes down to plant the flag. I haven't tested this yet as I'm very protective of my kerbals, having not yet lost one

Can anyone shed light on this? Is it possible to have an unmanned probe and a transfer stage in the configuration I'm describing?

[Richy teh space man]

Does it have power? Does it have a control probe on it? So long as the answer to both of those is yes then it should be controllable. If not you need to add one or both to make a stage controllable.

[Taki117]

If I understand it correctly yes, however it will be marked as Debris. To be able to see debris in map mode you need to hover near the top of the screen (Where the altimeter would be) and a drop down should appear allowing you to select the option to choose debris. You can do the same in the tracking station.

[Starstrider42]

Yes, if you're careful. I think you're seeing a combination of two issues:

1. When you undock two ships for the first time, KSP tries to figure out what type each section should be. Your stage probably got classified as debris, which isn't shown on the tracking screen by default. Right-click on the "debris" button near the top of the tracking screen, and you should see it again.

2. You cannot control *any* vehicle unless it has either a manned command pod or a probe core. Did you remember to add a second probe core to the transfer stage?

Note that you only need to solve the first issue if you just want to rendezvous and dock with the stage. The second only matters if you want to do burns with the detached stage.

[Tex]

If this is happening, I'd recommend trying to find it as debris, as the above people have said. Once you can find it, you should still be able to rendezvous with it ad hook back up to go home, or at least figure out if something happened after you left.

Of course, never count out the possibility that you'll need a rescue craft.

[formikachu]

Thank you everyone for your replies! I'm excited this problem appears to be solvable. Good thing I'm working from home today

One question: I had thought a vehicle can only have one control probe; that is, when I am in Vehicle Assembly, I can only have one, and it is the kernel of the vehicle I'm building. Is there a way I can have more than one?

[Pecan]

Yes, you can have several if you wish, just pick another one from the pods panel. For manned vehicles it's usually useful to have an okto or RGU as well so you can control the ship when/if the Kerbal(s) are on EVA. Similarly you might want one on the last stage of your launch vehicle (so you can de-orbit it after circularisation and not leave debris), and any stages which are to be left in space for later (re)docking.

[Red Iron Crown]

I've done several landing missions where having a probe core on the transfer stage in orbit has saved my bacon when the ascent didn't go as planned.

[SkyRender]

You can put as many command pods and/or probes as you'd like on your craft. KSP hasn't had a one-command-pod limit since 0.17 or so, in fact. You can even have the root of your ship be something besides a command pod or probe body now. (Though you won't be able to launch it until at least one of either is present, of course.)

[formikachu]

Thanks everyone! I am now happily attempting to dock my returning probe to the transfer stage thanks to the advice I received here. This whole rendezvous thing is tricky, but hopefully I'll figure it out

[Nepos]

Just an FYI that I learned the hard way.

Other than forgetting the second command capsule/probe (this made my first part of my space station uncontrollable) here is a tip.

Power and fuel does not always get used from the source you want. For example my capsule carry 100 unit of power and seems to use up that power BEFORE touching the batteries. As a result prepping for reentry I jettison my last stage, you know the one with the batteries. I then find myself in an un-powered capsule heading for Kerbin. Now I check my power and fuel on controllable craft before un-docking.

Good luck