Sanctuary Base 6

Sanctuary Base 6 was a huge base that contained humans and Ood on Krop Tor. Sanctuary bases could be situated in any enivironment, and any lifeforms could survive on hostile habitats using sanctuary bases.

Sanctuary Base 6 was created by the Walker Expedition, where the scientists involved where studying K37 Gem 5, a black hole and the power source keeping Krop Tor from getting sucked in.

The base was destroyed when the planet it was situated on was consumed by the black hole. (DW: The Impossible Planet / The Satan Pit)

The Doctor kept his Sanctuary Base 6 spacesuit in the TARDIS, eventually using it to save Martha from falling into a sun (DW: 42), then, long after, to stroll on the surface of Mars, the helmet was damaged in the escape from Bowie Base One, and left by the Doctor shortly after. (DW: The Waters of Mars)