Image-Based Lunar Terrain Relative Navigation Without a Map: Measurements

Image-based terrain relative navigation is expected to play an important role in the safe operation of upcoming lunar exploration missions. This work provides a detailed treatment of how visual odometry direction-of-motion measurements may be constructed using images from a monocular camera and without the need of an onboard map of the lunar surface. Substantial care is required to achieve best-possible navigation performance, which numerical studies indicate is sufficient to enable many types of autonomous navigation. Results are shown for historical Apollo images and for synthetic images. While visual odometry alone may not meet every mission’s needs, it is a powerful technique that should be a part of every professional spacecraft navigator’s toolkit.