Microcosm proposes to design and develop a fully autonomous Lunar Navigator based on our MicroMak miniature star sensor and a gravity gradiometer similar to one on a ship-board celestial navigation system designed by Microcosm for the Navy. The new sensor will provide surface navigation on the Moon or Mars with accuracies comparable to state-of-the-art precision celestial navigation systems on Earth. The system can rapidly determine its location anywhere on the Moon or Mars where a large portion of the sky is visible, day or night. With the unique three field-of-view star sensor design, the sensor can also be used to provide precise surveying of surrounding terrain and, in either of two modes, can provide passive range-finding to artificial or natural objects. The entire package will be less than 10 cm on a side, weigh less than 1 kg, draw less than 10 W of power, and work in a wide range of temperature and illumination conditions. Phase I will focus on the system requirements, a preliminary navigator design, and initial performance estimate. Phase II will focus on fabricating and testing a functioning prototype of the Lunar Navigator, including ground testing with real stars at night.