Metric Accuracy Improvements of Space-Based Visible Using Spacecraft Attitude Drift Corrections

TheMidcourseSpaceExperiment satellite, sponsoredbytheBallisticMissileDefenseOrganization,was launched in April 1996 into an 898-km altitude, near sun-synchronous orbit. One of the principal sensors onboard the spacecraft is the Space-Based Visible, a visible-band, electro-optical camera designed to perform the Ž rst technical and functional demonstration of space-based space surveillance. The principal task of the Space-Based Visible is to gather metric and photometric information on a wide variety of resident space objects. To assess the metric performance of the sensor, routine on-orbit metric calibration is performed. In addition, a complete independent error assessment was made using actual  ight data. The goal of producing 4-arc-s (1-sigma) observations of resident space objects was set during design, and results show that this goal is being met. A method is presented that improves the metric observations of resident space objects to better than 2-arc-s (1-sigma) by estimating the drift of the spacecraft attitude during staring events and removing the effect from the observations. Compensating for this error source brings into agreement the results of on-orbitcalibrationand the independenterror assessment.