Advanced Celestial Navigation Systems Dr. J.P. Laine Division Leader – Positioning, Navigation and Timing DRAPER Copyright © 2018 by The Charles Stark Draper Laboratory, Inc all rights reserved The Celestial Advantage 2 Celestial Navigation • Mariners have used various celestial navigation techniques since ancient times – Sun, Polaris, the Sextant • Sextant sightings – In order to determine position with a sextant, one needs 2 stars, local vertical, and a clock. – Position accuracy reference values: • 1 arcmin ~ 1 nautical mile • 1 arcsec ~ 30 meters 3 Copyright © 2018 by The Charles Stark Draper Laboratory, Inc all rights reserved Automated Sextant – Astro-Inertial Navigation System • On a dynamic platform, the biggest challenge is determining vertical → Requires an IMU Star Tracker • Mid 20th century saw automated astro- navigation systems in aircraft use (e.g. IMU SR-71 ANS) 1 arcsecond angle error results in a 30-meter position error 4 Copyright © 2018 by The Charles Stark Draper Laboratory, Inc all rights reserved Advanced Algorithm Development STELLAR HORIZON ATMOSPHERIC REFRACTION • No local vertical required • Accuracy depends on knowledge of atmospheric density profile • Developed and published by DRAPER 5 Copyright © 2018 by The Charles Stark Draper Laboratory, Inc all rights reserved Advanced Hardware Development Shorter Optics Thin Optics DRAPER Goal: Conformal Optical Sensor, Conformal with No Focal Length Optical Flat Optic Sensors Image Readout Conventional Imaging Optic Focal Length Image Readout at Focal Plane DRAPER Goal: Conformal Optical Imaging Sensors 6 Copyright © 2018 by The Charles Stark Draper Laboratory, Inc all rights reserved Summary • Long history of Celestial Navigation • Robust techniques • Automated sextants integrated into astro-inertial navigation systems • Advanced technologies developed in past decades 7.