 As the satellite moves multiple units in a frame and about 00% of the radius, the gravitational direcion have shifted alot, during this frame, but the applied force have only been "downwards". this creates a big margin of error, especially if the object is moving a big percentage of the radius.  In our example we'd probably needed our graviational direction to be based upon the average between our current position and the position at the end of this frame. 