Kastria

Kastria is a desolate planet inhabited by the Kastrians, first shown in The Hand of Fear. It is possibly near the Solar system, since wreckage from the explosion of a Kastrian spacecraft landed on Earth.

At its best, it was a barren and cold, though it was constantly ravaged by stellar winds. A Kastrian named Eldrad was able to create a barrier to protect Kastria and created new silicon-based bodies to deal with the environment. These efforts were for naught though, since the barrier was destroyed and the Kastrians went extinct.