I've done something similar. I built a nice system explorer ship (capable of going from planet to planet). I had built simple small landers and attached them to the ship. Went and got into orbit around Laythe, detached the lander, put Macey Kerman (I think it was him) into it and went and landed. Plopped the flag, got some samples and science, and went to get into orbit. Then I realised that the weight of the decoupler (the "attached" part of it) kept flipping the pod over, as well as the fact I didn't put an antenna on, nor a docking port to redock back to the explorer, if I could get that far. Suffice to say, Macey was a casualty of the mission after impacting into the surface of Laythe :|