sentences:  On 4 December 2006, NASA announced the conclusion of its Global Exploration Strategy and Lunar Architecture Study.The Lunar Architecture Study's purpose was to "define a series of lunar missions constituting NASA's Lunar campaign to fulfill the Lunar Exploration elements" of the Vision for Space Exploration.What resulted was a basic plan for a lunar outpost near one of the poles of the Moon, which would permanently house astronauts in six-month shifts.