We visit the Thals up in orbit; the Thals are another of Terry Nation and the BBC's creations so I am not their creator. Although not explicit in the Doctor Who series itself, it seems not unreasonable to assume the Thals have deserted their home planet themselves by this point in their history. Hence in one of the Big Finish audios the Doctor mentions a new home world called New Davius (presumably after the continent from which they came on Skaro). In the original Dalek story the Thals were a peaceloving race who had renouced all forms of warfare. In later stories they are shown as possessing not only a military but interstellar travel. If the bridge owes a lot to star trek its probably because all bridges of star ships do.