Frontios

The TARDIS has drifted into the future and comes to rest hovering over Frontios, refuge of one group of survivors from Earth who have escaped the disintegration of their home planet.

The Doctor is reluctant to land on Frontios, as he does not wish to intervene in a moment of historical crisis - the colonists are still struggling to establish themselves and their continued existence hangs in the balance. 

But the TARDIS is forced down by what appears to be a meteor storm, and crash-lands, leaving the Doctor and his companions marooned on the hope-forsaken planet...