Passive imaging based multi-cue hazard detection for spacecraft safe landing

Accurate assessment of potentially damaging ground hazards during the spacecraft EDL (entry, descent, and landing) phase is crucial to insure a high probability of safe landing. A lander that encounters a large rock, falls off a cliff, or tips over on a steep slope can sustain mission-ending damage. Guided entry is expected to shrink landing ellipses from 100-300 km to ~10 km radius for the second-generation landers as early as 2009. Regardless of size and location, however, landing ellipses will almost always contain hazards such as craters, discontinuities, steep slopes, and large rocks. It is estimated that an MSL (Mars Science Laboratory)-sized lander should detect and avoid 16-150m diameter craters, vertical drops similar to the edges of 16m or 3.75m diameter crater, for high and low altitude HDA (Hazard Detection and Avoidance) respectively. It should also be able to detect slopes 20deg or steeper, and rocks 0.75m or taller. In this paper we will present a passive imaging based, multi-cue hazard detection and avoidance (HDA) system suitable for Martian and other lander missions. This is the first passively imaged HDA system that seamlessly integrates multiple algorithms - crater detection, slope estimation, rock detection and texture analysis, and multi-cues $crater morphology, rock distribution, to detect these hazards in real time