I really want to know how to decelerate efficient for landing.  example, landing to mum, If I decelerate too early, my vessel will drop down, and I have to decelerate again, this will waste some fuel. If I decelerate too late, It's dangerous to crash. so, How to know, what altitude is best to decelerate can save fuel? I see MechJeb didn't have this Item that can display this information. But I use its auto landing function, I see its operation, it's good, very efficient. no more r