A shuttle is an oscillator in which an unstable object moves back and forth between stabilizing objects. The most well-known and first discovered examples are the queen bee shuttle (which is sometimes referred to as the shuttle) and the twin bees shuttle. A large number of T-tetromino and pre-pulsar shuttles are known, including the p30 Eureka. Reflectors can be used to construct glider shuttles (see relay).
Shuttles often utilize the same stabilization at each end, resulting in an even period oscillator; however, odd-period shuttles, such as the p25 pre-pulsar shuttle, can be formed by using different stabilizations at each end.
Glider shuttle
A glider shuttle is a shuttle in which one or more gliders bounce back and forth between two 180° reflectors.