The Kalandan outpost was an artificial planet manufactured by the Kalandans around the 1st millennium BC. It was approximately the same size as Luna, but had a mass and atmosphere similar to that found on Earth.
During its construction, a deadly disease organism was created, killing all the Kalandans. The last survivor, Losira, enabled the outpost's automated defenses to protect it until the day when more Kalandans would arrive to secure it. This defense system killed several USS Enterprise crewmen when the ship surveyed the planet in 2268. (TOS: "That Which Survives")