The Cylethian were an alien species from the planet Cylith.
They built distress beacons into their space ships. Once such a distess beacon was used an inter-galactic rescue team would be on it's way to the place the signal was sent from. However if it would be pressed on Earth it would take them about 100 years to go there, because Cylith was very far away. (PROSE: The Day of the Clown)