private void OnPointerDown(Vector2 pointerScreenPosition, Vector2 lastPointerPosition, int buttonIndex)
 {
     if (buttonIndex == 0)
     {
         RaycastHit hit;
         var        ray = Camera.main.ScreenPointToRay(pointerScreenPosition);
         if (Physics.Raycast(ray, out hit))
         {
             var handle = hit.collider.GetComponent <VelocityHandle>();
             if (handle != null && handle.CelestialBodyRef != null)
             {
                 _currentTarget = handle;
             }
         }
     }
 }
 private void OnPointerUp(Vector2 pointerScreenPosition, Vector2 lastPointerPosition, int buttonIndex)
 {
     _currentTarget = null;
 }