In Orbit Attitude Determination, Control and Stabilization Performance of the STRL 1a and 1b MicroSatellites from the UK Defence Research Agency

This paper describes the in orbit performance of the Attitude, Determination, Control and Stabilization systems employed for the Satellite Technology Research Vehicles of the United Kingdom Defence Research Agency. These two satellites will be launched in June 1994 from an Ariane 4 launcher in to Geostationary Transfer Orbit. There is a requirement to ensure that the spin axis of the satellites is maintained in a position approximately 90 degrees to the Sun vector. The satellites are spin stabilized from launch by the 3rd stage launcher rotation and additionally STRV 1a uses cold gas zenon thrusters. Each satellite has a nutation damper and is fitted with a magnetotorquer coil for control actuation since aerodynamic torque correction is required. Full attitude determination is anticipated to be accurate to +/- 1 degree from lightweight, low-cost V-split Sun and Earth sensors. Telemetered control of the actuation system will be via time tagged commands due to the restricted visibility of the satellites to the ground stations.