Autonomous Star Tracker Performance
- Paper number
IAC-06-D1.2.01
- Author
Mr. James Kaidy, The John Hopkins University Applied Physics Laboratory, United States
- Coauthor
Mr. Gabe Rogers, The John Hopkins University Applied Physics Laboratory, United States
- Coauthor
Dr. Thomas Strikwerda, The John Hopkins University Applied Physics Laboratory, United States
- Coauthor
Mr. Roberto Casini, Italy
- Coauthor
Mr. Rossano Bettarini, Italy
- Coauthor
Mr. Andrea Landi, Italy
- Year
2006
- Abstract
First in NASA’s New Frontiers series of missions, the New Horizons spacecraft was launched on its way to Pluto on January 19, 2006. The overall mission description and status reports may be found at [1]. The mission design and concept of operations for New Horizons require a star tracker that operates autonomously both in a standard “staring” mode and in a spin stabilized “hibernation” mode, as described earlier in references [2, 3, 4]. This dual-mode operation is particularly important for a low-cost mission with a planned lifetime of fifteen to twenty years or more, and the capability to have accurate attitude knowledge at all times from one (redundant) sensor is especially attractive in terms of all the usual trade parameters (cost, mass, power, reliability, etc.) With the support of APL and the New Horizons Program, Galileo Avionica has redesigned the software for their ASTR star tracker to use time-delayed integration techniques (TDI) to provide autonomous spacecraft attitude estimates at 10 Hz. and at spacecraft body rates up to 10 RPM. Other trackers have used TDI to provide centroid data at rates up to 12 RPM [5] or autonomous attitude estimation at body rates of a few degrees per second [6], but we are unaware of any other implementation to provide autonomous attitude at these body rates and output frequency. While extensive testing and verification of design concepts were carried out during manufacture and test of the trackers, actual real-sky testing of the flight hardware TDI mode operation was limited to night sky test at rates of 10 deg/sec or less. Thus it was a real (but not unexpected) relief when the trackers were first powered on three days after launch and were observed to initiate tracking exactly as expected with the spacecraft spinning at 30 deg/sec! Large quantities of star tracker telemetry data are being collected during early operations and checkout of the mission. These data will be analyzed for detailed tracker performance evaluation in terms of accuracy achieved; comparison of flight results to laboratory-derived accuracy models and predictions; effects of vehicle motion on tracker performance; comparison to gyro data; effect of stray light on tracking and performance; and unanticipated “features” or characteristics of performance which may be observed. This paper will present details of these results as observed and analyzed over at least the first six months of tracker operations, and will cover performance while the spacecraft is spinning and in three-axis stabilized mode. References: 1. http://pluto.jhuapl.edu 2. Haley, D.R., et al, “Autonomous Star Tracker Development for the New Horizons Mission.” AAS-03-607, Proceedings, AAS-AIAA Astrodynamics Specialist Conference, Big Sky MT, 2003. 3. Haley, D.R., et al, “Star Tracker Scan Mode Capability for the New Horizons Mission,” Proceedings, Fifth IAA Conference on Low-cost Planetary Missions, Noordwijk NL, 2003. 4. Haley, D.R., et al, “Autonomous Star Tracker Development for the New Horizons Mission,” AAS-05-01, Proceedings, AAS Guidance and Control Conference, Breckenridge CO, 2005. 5. http://civspace.jhuapl.edu/programs/program.php?id=2 6. van Bezooijen, R., et al, “Performance of the AST-201 Star Tracker for the Microwave Anisotropy Probe,” AIAA 2002-4582, Proceedings, AIAA Guidance, Navigation and Control Conference, Monterey CA, 2002.
- Abstract document
- Manuscript document
IAC-06-D1.2.01.pdf (🔒 authorized access only).
To get the manuscript, please contact IAF Secretariat.