Geneva Drive

The Geneva drive or Maltese cross is a gear mechanism that translates a continuous rotation movement into intermittent rotary motion. The rotating drive wheel is usually equipped with a pin that reaches into a slot located in the other wheel (driven wheel) that advances it by one step at a time. A Geneva drive was used to change filters in the Dawn mission framing camera used to image the asteroid 4 Vesta in 2011. It was selected to ensure that should the mechanism fail at least one filter would be usable.