Prison Station 13 was a penitentiary space station orbiting Jupiter's first moon of Io. It was colloquially known as "The Chain."
The place had a reputation for extraordinary brutality and regular human rights violations, although prisoners were permitted certain privileges - such as a weekly allowance from their private accounts to spend at the commissary.
Gail Pilgrim and her crew were imprisoned here by the Jovian Astrolaw Commission during Space Pilgrim Episode IV: Sol. At this time the station held about twenty female prisoners and more than two hundred male prisoners, most of them dangerous.
In Space Pilgrim Academy: Reunion, Sabina White mentions that The Chain doesn't exist any more.