- Holly (Back in the Red, Series VIII)
Adelphi Twelve, or Adelphi 12, was the designation of an unseen planet or planetoid 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.
History with Red Dwarf
The Jupiter Mining Corporation had secondary contracts for prison transport to Adelphi 12. The JMC mining freighter Red Dwarf contained a classified prison called "The Tank" on it's secretive Floor Thirteen, which had capacity to hold 400 prisoners in transit, all of whom had been sentenced to life imprisonment on Adelphi 12. Only the senior officers of Red Dwarf, and the guards of The Tank, knew of the existence of The Tank since most of the original crew were involved in off-world mining and the day-to-day running of the ship.
Red Dwarf never reached Adelphi 12 due to the accident that killed everybody aboard except Dave Lister, who was in stasis at the time. However, three million years later, the crew and criminals of Red Dwarf alike were resurrected by the nanobots. (Back in the Red)
The status of Adelphi 12 three million years into the future is uncertain, but likely long derelict. The nanobot-restored Red Dwarf of the future, now in Deep Space, instead keeps the prisoners locked up in The Tank, occasionally using them for menial labour, or as part of a volunteer convict army known as the Canaries, who are used to scout out derelict Space Corps spaceships, making them safe for the less expendable officers. (Cassandra)
- The designation of Adelphi 12 would suggest that it was the twelfth planet in the Adelphi System. If correct, this means that the planet would have been very far away from it's star, and was therefore likely very inhospitable, and certainly not an S3 Planet like Earth. This would be fitting, given that the planet was supposed to be the site of the toughest and most inescapable prison in the Galaxy.
- It is possible that Ackerman, Knot and The Tank guards were not JMC employees, but were instead employed by the same penal system which operated on Adelphi 12.