Target Pointing of the BIRD Spacecraft via Ground in the Loop Attitude Control - Manfred Schneller

Kurzfassung

BIRD, a Bi-spectral Infra-Red Detector is located on a micro-satellite mission launched on Oct. 22, 2001 on a PSLV–C3 from Sriharikota, India, into a sun-synchronous orbit with a height of 563 km and an inclination of 97.775º. The major attitude control modes during nominal operations are Sun pointing for battery charging (satellite -z-axis points towards the Sun), and target pointing for data-takes and for downlinking of high rate data to the ground (satellite +z-axis points towards a ground observation target). Since launch attitude determination, prediction and attitude maneuver design is performed on-ground filling in for an incomplete onboard attitude control system not yet implemented to its full extent. Continuous development of the on-ground attitude software and procedures, has made it possible to achieve an accuracy in target pointing of less than two degrees. Special effort has been spent on the development of the maneuver design software to keep it user friendly in an operational environment.