Holistic design of a GN&C system for safe and precise autonomous landing in very challenging planetary terrains
The search for life in the solar system is one of the main driving forces behind planetary exploration. The icy moons of the giant planets are the most promising targets. Saturn's moon Enceladus in particular possesses an ocean increasingly likely to have the right conditions for microbial life...
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| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
| Published: |
2019
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| Online Access: | http://athene-forschung.unibw.de/node?id=128251 https://athene-forschung.unibw.de/doc/128251/document.pdf https://nbn-resolving.org/urn:nbn:de:bvb:706-6153 |
| Summary: | The search for life in the solar system is one of the main driving forces behind planetary exploration. The icy moons of the giant planets are the most promising targets. Saturn's moon Enceladus in particular possesses an ocean increasingly likely to have the right conditions for microbial life to emerge. Furthermore, plumes are jetting from its south pole ejecting water directly from the ocean to space. The ability to sample water from under the plumes, before any potential biosignatures are degraded by the vacuum of space would be very desirable. The German Aerospace Administration (DLR) funded Enceladus Explorer (EnEx) landing mission concept aims to deploy a melting probe to sample liquid pockets under the plumes for life. Landing there would be exceptionally challenging due to the rough canyonous topography, polar lighting conditions, the surface covered by a layer of superfine snow, and the strict planetary protection regulations. Any landing there must thus be accurate, to land near the plume for probe deployment, safe, to detect and avoid all the above hazards, and autonomous due to the long signal return times from Earth to Saturn. Past landing missions and studies, have landed blindly and with low accuracy on safe and flat terrains. Current studies for autonomous safe and accurate landing focus on the Moon or Mars, and target terrains that are still not as challenging as the one for the EnEx lander. In this work the most critical final phase of landing is investigated. A detailed landing Guidance, Navigation, and Control (GNamp;amp;C) system and operations concept is defined, encompassing the key functions necessary. For Sensing, a set of interoceptive inertial and exteroceptive cameras and lidar are used. Based on input from these sensors, an EKF-SLAM approach is followed to localize the lander and map the environment. For Hazard Detection and Avoidance (HDA), a fuzzy reasoning approach uses the uncertain sensor input to detect hazards and avoid them. For Guidance, convex optimization is used to ... |
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