Interplanetary Optical Navigation 101 Tutorial
Dr. William M. Owen, Jr., Dr. Shyam Bhaskaran
This tutorial presents three decades of JPL's experience with optical navigation ("opnav") techniques for interplanetary missions, from the first demonstration with Mariner 9 to the onboard algorithms developed for Deep Space 1. JPL has provided opnav services to Viking, Voyager, Galileo, and NEAR Shoemaker, in addition to DS1, and is planning to use opnav for Cassini, Deep Impact, STARDUST, and other missions.
Opnav itself consists of planning pictures to be taken by a camera on a spacecraft, analyzing the returned data to obtain precise locations of images of foreground bodies and background stars, and using these image centers to improve the spacecraft trajectory and the orbits of the imaged bodies. Several disparate disciplines come into play: optics, geometry and calculus, image analysis, filtering and data reduction techniques, and, of course, programming (including real-time command and control), to say nothing of the interpersonal skills one must have in order to work effectively within a large project.
Optical navigators must work closely with instrument designers, spacecraft engineers of all stripes, radio navigation engineers, and professional astronomers in order to achieve the goal of providing accurate and reliable information to each project. This presentation also includes an introduction to radio metric spacecraft navigation, a brief refresher on geometric optics, and the principles of positional astronomy.
The Deep Space 1 mission was the first to demonstrate a self-contained onboard navigation system for interplanetary spacecraft. For DS1, the techniques described above for ground optical navigation had to be transferred to the spacecraft. This posed some special challenges since steps in the ground opnav process generally performed with a human in the loop now had to be automated, with little margin for error. In addition, the autonomous navigation (Autonav) system also had to interact with the rest of the spacecraft. This tutorial presents details on how these challenges were met, and shows some spectacular results of the process in the flyby of a comet and asteroid.
About the speaker(s):
Dr. William M. Owen, Jr. has been a member of the Optical Navigation Group of the Navigation and Mission Design Section (312) at the Jet Propulsion Laboratory (JPL) since 1979. He has served on the navigation teams for several flight projects, including Voyager 2, Galileo, NEAR Shoemaker, and now Cassini. He is the Cognizant Engineer for JPL's Optical Measurements and Analysis Subsystem, which performs the optical navigation tasks of scene prediction, image extraction, and data analysis. His research interests include ground-based astrometry of satellites of the outer planets, comets, and asteroids. Minor planet (6135) Billowen is named in his honor. Owen received his B.S. from Caltech in 1976, and his Ph.D. from the Univerity of Florida in 1990, both in astronomy.
Dr. Shyam Bhaskaran is on staff in the Navigation and Mission Design Section (312) at the Jet Propulsion Laboratory (JPL). He started his career at JPL eleven years ago as an orbit determination specialist on the Galileo mission. Since then, he has served as a member of the Navigation Team for several missions, including Deep Space 1 and Mars Odyssey, and as the Navigation Lead for the European Mars Express and JPL's MRO missions. Bhaskaran is one of the principal architects of the autonomous navigation system used on Deep Space 1, and is currently a navigator and member of the Imaging Science Team for the STARDUST mission. He is presently also the Mission Management Office Team Chief for Guidance, Navigation and Control. Bhaskaran received a B.S. and M.S. from the University of Texas at Austin, and a Ph.D from the University of Colorado in 1991.