thanks for the answeres. I first made a small rocket just with parachute, pod, fuel and motor. But the parachute couldnt brake the rocket enough to not explode at first contact with kerbal. I was just very confused because decouplers are just so important in building rockets and I think I never built a rocket without them But now I just made a single pod, just go EVA, take some samples, go into the pod again and end the mission right on the landing pad. That gives enough research to get decouplers. But I still think Decouplers should be a starting tech, specially when you have no automated probes and want your kerbals come back save, without a big rocket under their landing pod waiting to explode