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

Sanctuary Base 6 was built by the Walker Expedition. The scientists involved were 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 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. He wore it to stroll on the surface of Mars. The helmet was damaged in the escape from Bowie Base One and abandoned shortly after. (DW: The Waters of Mars)