How to de-orbit with a docking port and a mothership with a good reaction wheel..

[Wizard Kerbal]

V: 3, 2, 1, engine off. Welcome to Ike! Bob! Are you ready?

B: Of course! 

V: Aaand You’re free. 
With that, Bob used his RCS to distance himself from the mothership, while Valentina rotated it to watch.
(1 1/2 an hour later)

V: 5 meters, 4, 3, 2, docked. 

V: Well shoot. This is a dilemma. Using only a docking port, how do we de-orbit a lander? We have a rocket engine too, but too little fuel.

B: I have an idea! Let’s try spinning! That’s a good trick.

V: Dear god. So you are a mad scientist. What did Duna and Ike do to you?

The mothership began to spin on it’s yaw axis, and when it faced retrograde, they undocked the lander. KSC checked it’s trajectory, and sure enough, it would hit the planet moon.

https://www.youtube.com/watch?v=RE0HVh-7Hns

 

Edited May 5, 2021 by Wizard Kerbal