Does the change in acceleration along the path of a space flight to the moon, for example, get taken into account when planning initial velocity? I would imagine that the initial velocity leaving earth will be decelerating and the deceleration will increase the further it gets until another bodies gravitation compels it? How is this change in acceleration taken into account? I am especially wondering if it is an average value of the acceleration function over the radius, or if an average doesn't work in this case? Any input would be appreciated Thanks!