private void Awake()
 {
     if (_rigidbody == null)
     {
         _rigidbody = GetComponent <Rigidbody>();
         if (_rigidbody == null)
         {
             _rigidbody = gameObject.AddComponent <Rigidbody>();
         }
         PointGravitySystem.AddToSystem(_rigidbody);
     }
 }
 void OnDestroy()
 {
     PointGravitySystem.RemoveMassObj(_rigidbody);
 }