Desperus was an Earth prison world where the criminals were dumped to fend for themselves or die. As Bret Vyon stated, the only ships that stopped there were prison ships from Earth. There were no guards or prison warders. The Doctor crashed there on the Spar 7-40 while trying to stop the Daleks' Master Plan. They managed to take off again, although not before they had picked up a stowaway, Kirksen. (DW: The Daleks' Master Plan)