Serac
From Tardis Wiki, the free Doctor Who reference
Serac was an ice planet located in Mutter's Spiral. The superweapon known as Thanatos was buried there.
The Sontarans once went to Serac in search of Thanatos, travelling aboard the mining vessel Betrothal of Sontar, under the command of Colonel Snathe. (COMIC: The Betrothal of Sontar)
