private void OnTriggerEnter(Collider other)
 {
     // Check if current checkpoint is active, and if the passed object was the player's ship
     if (isActiveCheckpoint && other.name == "PlayerShip")
     {
         passLight.intensity = 8.0f;
         passLight.color     = Color.green;
         // Call a function in the RaceController
         raceController.CheckpointPassed();
         isActiveCheckpoint = false;
     }
 }