Sarath

Sarath was a planet visited by the First Doctor, Susan Foreman, Ian Chesterton and Barbara Wright. The inhabitants were humans who didn't realise that they had travelled through space before because of a hazy history. The planet was soon to be destroyed by pieces of the Sarath moon breaking up and crashing to the surface after a meteor struck it. By the time the TARDIS arrived on the planet, a decade after the moon was struck, the city of Arkhaven was apparently the last surviving suitably advanced city, protected due to it being in a geologically stable area with a self-contained economy. They were building a rocket to try and escape the devastation to travel to the neighbouring planet of Mirth, with the Doctor's aid allowing a last desperate plan to save the six hundred or so final survivors of Arkhaven to depart for Mirath in relative safety. (PROSE:  City at World's End)