Ta was a remote frontier planet. It was a mist-shrouded desert world (PROSE: The Space Pirates) in the Pliny system. The planet had vast argonite mines owned by the Issigri Mining Company, (TV: The Space Pirates) whose head office was the most up-to-date and luxurious of all the underground installations on Ta. (PROSE: The Space Pirates)
There was no surface life on the planet as there was too much ultra-violet radiation. Milo Clancey had a secret hideout a mile underground, which was later used as a secret base by the space pirate Maurice Caven. Caven threatened to blow up Ta by detonating his atomic fuel store, "the equivalent of about eighty old-fashioned hydrogen bombs," but the Second Doctor disabled it in time. (TV: The Space Pirates)