The Kalandan outpost was an artificial planet manufactured by the Kalandans some 10,000 years ago. It was approximately the same size as Luna, but had a mass and atmosphere similar to that found on Earth.
During the construction, a deadly disease organism was created, killing all the Kalandans. The last survivor, Losira, enabled the automated defenses to protect the station until the day when more Kalandans would arrive at the outpost. This defense system killed several USS Enterprise crewmen when the ship surveyed the planet in 2268. (TOS: "That Which Survives")