Optical Tracking of Artificial Earth Satellites with COTS Sensors

摘要

Tracking of artificial Earth satellites is typically performed with ground based radar but newer commercial off-the-shelf (COTS) optical sensors are a valuable complementary technique. Optical sensors are sensitive to the weather but newer systems are inexpensive, can be operated autonomously and while they not only can perform initial orbit determination (IOD) they also add the benefit of providing rotational information via photometry. This makes the ability to track and observe Earth satellites much more accessible to the research and academic community. In this paper we present our automatic astrometry pipeline for reducing COTS optical sensor data from three main orbital regimes (low, medium, and geosynchronous). We present the successful pipeline with preliminary observations of multiple artificial Earth satellites, including the now defunct Chinese space station, Tiangong 1, shortly before atmospheric reentry. Development and calibration of the pipeline continues, with the most important focus being characterization of the sources of error to improve our astrometric and photometric accuracy. Observations of the geostationary telecommunication satellites GALAXY 15 and ANIK FIR are compared to predicted locations using published ephemeris showing a good characterization of the errors present in our system. Our astrometric solutions for Tiangong 1 are compared to predicted locations using less accurate, two-line element (TLE) data since no published ephemerides are available. This type of analysis gives a qualitative characterization of systematic errors in our process. Finally, we compare our astrometric solutions to catalog star positions to characterize the limiting positional noise in our current system so that we have a baseline metric to which we can compare future improvements.