Sanctuary Base 6
Sanctuary Base 6 was a huge base staffed with humans and Ood on Krop Tor.
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. (TV: The Impossible Planet / The Satan Pit)
The Tenth Doctor kept his Sanctuary Base 6 space suit 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. (TV: The Waters of Mars) The Eleventh Doctor had replaced the helmet by the time he wore the suit on primordial Earth. (TV: Hide) The Twelfth Doctor later wore this same spacesuit along with similar ones being worn by Clara Oswald and Courtney Woods during their trip to the moon. (TV: Kill the Moon) Clara then wore this spacesuit on a trip with the Doctor and continued to wear it throughout their subsequent adventure with Vikings. The wiring on this spacesuit is later used to channel electricity from electric eels to immobilise the Mire suits. (TV: The Girl Who Died)