Frontios

Located in the Veruna system.

Atmosphere is close to that of Earth - Humans, Trion and Time Lords are able to breathe without requiring special apparatus. The soil composition appears to be mostly low-level scree and porous rock. Beneath ground level there is a vast network of tunnels mined by the Tractators in an attempt to turn the planet into a gravitic motor. Stone suitable for quarrying and building material is also available.

Human Colonisation of Frontios

At the very periphery of the Time Lords sphere of knowledge, Frontios became home to a fledgling colony of human refugees who fled the collision of Earth with the sun in a ship captained by Captain Revere.

Frontios was not the original destination of the colony ship, but it was pulled off-course by the Tractators (lead by the Gravis) and crashed into the planet, where the surviving crew and colonists were bombarded with meteors, and randomly selected for enslavement in the Tractator's mining machines. ('Frontios_(TV_story)')

After the removal of the Gravis, the Tractators became harmless, earth burrowing creatures. No mention has been made of their removal from the planet, so most likely they co-habit the planet with the human colonists.