Terrain Relative Navigation Using Crater Identification in Surface Topography Data

This paper explores three different crater identification algorithms for use in spacecraft navigation relative to a celestial body that use topography data obtained by active sensors, such as a flash LIDAR. Topography data was selected over visible images since the active sensors that produce topography data are lighting independent, and NASA desires the ability to perform precision landing at any time, and at locations such as the Lunar South Pole where the solar incidence angle is always low. Two of the algorithms explored are modified versions of existing algorithms developed for use with visible images, and one is a new method developed for topography data. Evaluation of the algorithms is made on the basis of the rate of false crater identifications and the resulting position and orientation error using test data covering eight regions within the data sets available from the Mars Orbiting Laser Altimeter and the Lunar Orbiting Laser Altimeter. All of the algorithms performed adequately, with the image morphology method performing slightly better.