1. Navigation Systems for Lunar Landing Ian J. Gravseth Ball Aerospace and Technologies Corp. March 5 th, 2007 Ian J. Gravseth Ball Aerospace and Technologies Corp. March 5 th, 2007

2. Page_2 Lunar Landing Problem Overview  What is needed ─ Navigate to the correct area  Need to know position and orientation relative to the landing site  Measure altitude and velocity  Identify Hazards in relative space ─ Land Safely  Avoid Hazards (Steep Slopes, Rocks, Holes, other structures, etc.)  Land with acceptable velocities ─ Precision Landing  Some landers require < 10 m final targeting error  Landing sites are more challenging than Apollo-era sites ─ High contrast lighting for final approach  Worse than no natural lighting ─ Rougher terrain  A robust sensor or set of sensors are needed for a high reliability landing system ─ Notional sensors include an altimeter, a velocimeter, a terrain relative navigation sensor, and a hazard relative navigation sensor

3. Page_3 Flash Lidar  Pros ─ Sensor provides all required data types  Altimetry  Velocimetry  Terrain relative navigation  Hazard detection  Precision navigation when close to the surface ─ Low mass, power and volume ─ System produces direct range measurements  The sensor provides 256 x 256 pixels, each with X, Y, Z, intensity and quality at 30 Hz.  Real time processing ─ Light insensitive ─ Self-correlated images are provided ─ Self-contained navigation algorithms are available  Cons ─ No flight heritage  TRL of the system may be advanced through other space based Lidar applications ─ Lower number of pixels than an optical camera Laser Beam Lidar FOV Flip-away Scanner

4. Page_4 Visual Cameras  Pros ─ Cameras are low mass, power and volume ─ Descent cameras have previous flight heritage (DIMES, etc.) ─ Provides estimates of horizontal position and velocity ─ High resolution image data  Cons ─ Cameras require good lighting conditions  May not work in scientifically interesting landing sites or in high contrast regions ─ Existing algorithms require an altitude estimate ─ Doesn’t provide direct 3D image data 2D image locations 3D map locations Images courtesy of JPL

5. Page_5 Radars  Pros  Sensor functions during any lighting conditions  Very accurate range and velocity measurements  Flight Heritage ─ Used on all Mars Landers  Cons  Large mass, volume and power  Hazard measurements with a phased array system are available, but are very constrained ─ Configuration, mass issues, resolution issues  Radars don’t generally perform well when they are close to landing

6. Page_6 Scanning Lidar  Pros ─ Sensor provides all required data types ─ Flight heritage for space missions  Cons ─ Challenging alignment tolerances ─ Unequal sampling distance during a scan ─ Higher power and mass than a flash system ─ Stitching data together in real time or faster required for use of data  Vehicle motion will distort the images ─ ~20% of the maximum ranging capability relative to a flash system ─ Significantly larger mass and power than a flash Lidar

7. Page_7 Geiger Counters (Kaktus Gamma Ray Altimeter)  Pros ─ Only altimeter option that is currently in use for this same problem (re-entry and landing of people on the Earth ’ s surface) ─ Extensive heritage ─ Radio source is always “ on ”, does not require power  Cons ─ Ground roughness can affect accuracy because the intensity of the reflected gamma- quantum flow is averaged over the entire diameter of the circle ─ Russian technology-politics, ITAR, contract with Energia ─ Radioactive source ─ Limited range of operation ─ Altitude and potentially velocity only Images courtesy of JPL

8. Page_8 Landing Sensor Summary  Active ─ Flash Lidar ─ Scanning Lidar ─ Radar ─ Geiger counter  Passive ─ Optical Sensors Flash Lidar Scanning Lidar Optical CameraRadar Geiger Counter Degree of Difficulty / Relative Ranking Needed Sensor Capabilities Altitude Measurement Easiest / Best Performance Velocity Measurement Medium Difficulty / Medium Performance Position and Orientation Most Difficult / Worst Performance Hazard Detection Sensor Characteristics Works in all Lighting Conditions Self-Correlated Images Light Insensitive Range of Operation Low Mass Low Power Flash Lidar is the most attractive sensor for Lunar Landing