The planet Adelphi Twelve, or Adelphi 12, was the designation of an unseen planet that was once colonized by the Space Corps. Adelphi 12 was the site of a penal system which held the most dangerous criminals in the Galaxy. On it's ill-fated final voyage before the radiation leak, one of the (classified) original missions of the JMC spaceship Red Dwarf was to transport 400 criminals to serve life sentences on Adelphi 12.