I have a few satellites and stations orbiting my planets, but I'd like to add onto them. I've seen numerous videos on using docking clamps to attach my new ship to the existing station, but can I do that on a part-by-part basis? For example, I take an extra fuel tank up there, can I attach just the tank to my station, then send my vessel back to Kerbin? I'm not talking about refueling, but rather transferring individual parts from my ship to the station in orbit.

I'd prefer to not have to use an unmanned probe and jettison everything but the desired part in space after docking if possible, but if that's the only way I guess I don't have a choice.

  • 2
    In the stock game, nope. You'll need docking ports.
    – Frank
    Mar 20, 2015 at 18:09

2 Answers 2


Kerbal Attachment System gives you a limited ability to do this, but probably not to the extent that you want. You can only move and attach parts that are Kerbal sized or smaller, and are radially attachable. Unfortunately, this doesn't include fuel tanks (other than monopropellant and xenon). The only other option that I know of is to use docking ports.

  • 2
    I've successfully used KAS to refuel and dead ship. You have to EVA and attach a pipe end point to the dead ship, then connect a pipe between rescue and dead ships and transfer fuel. Once enough fuel is transfered, unlink the pipe and fly both ships home. I have a probe with excess fuel and ~6 pipe end points in high orbit. It's saved more returning-but-not-quite-going-to-make-it ships than I ought to admit in public...
    – Grhm
    Apr 28, 2015 at 10:35

When you want to dock with a vessel which hasn't got docking ports, you can use the Advanced Grabbing Unit. This gadget can grab onto any part of other vessels and then works just like a docking connection. You can use this to transfer resources or gain control of an uncontrolled vessel.

You can also use this to add new parts to an existing ship, as long as you are OK with having the AGU as an adapter. Here are instructions for how to attach a new fuel tank to an existing ship:

  1. Build a new ship with a detachable fuel tank and add an AGU to the tank.
  2. Rendezvous with the target.
  3. Arm the AGU
  4. Attach the AGU to the target ship by tenderly pushing it onto a surface
  5. undock the tank.

You now have the tank attached to the ship with the AGU in between.

Supply-ship approaching target with armed claw: Supply-ship approaching target with armed claw

Supply ship exchanging fuel with target through claw: Supply ship exchanging fuel with target through claw

Supply ship decouples the fuel tank with the AGU. The tank keeps being attached to the target: The tank keeps being attached to the target

Unfortunately the fuel in the tank won't be used automatically because the AGU doesn't provide automatic fuel crossfeed, but you can pump the fuel from the new tank to the existing one manually. Also, this craft has some issues flying straight due to the asymmetrically attached mass of its new tank. But besides these minor inconveniences, it works.

  • completely forgot about the grabber.
    – MBraedley
    Mar 21, 2015 at 1:33
  • So it seems like this may solve another problem I have -- I have a ship in orbit around the sun that ran out of fuel, but like a tool I accidentally decoupled my last fuel tank, which I would normally do during re-entry to Kerbin. So if I can use this to attach a new fuel tank to my orbiting pod, that could help out immensely. I'd hate to see Jebidiah's journey end in tragedy.... thanks!
    – Tim S.
    Mar 29, 2015 at 3:02

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