ESA GNC Conference Papers Repository

Terma has developed a next generation star tracker optical head (OH) and accompanying electronics unit (EU) supported by two ESA projects; '2nd generation APS STR - Optical Head ' and 'Miniature APS based star tracker engineering qualification model development'. The paper will present the qualified OH featuring: - Fully integrated single chip APS sensor (Faintstar or LCMS) - Designed for low cost, mass production and automated testing with high reliability using a minimum number of components - Miniaturized mechanical outline with outstanding thermo-mechanical stability suitable for integration in close proximity to the satellite payload - Very low power consumption (< 0.75 W) with no need for thermo-electrical cooling - Compact single stage straylight baffle completely mechanical decoupled - Spacewire interface and single 5 VDC supply A modular software library has been developed supporting space and power critical missions, allowing the software to be hosted on a central OBC. Major features are already flying on-board the ESA CryoSat2 and Lisa Pathfinder satellite star trackers and guarantees high accuracy and robustness in the most demanding environment (10 years 1000 km LEO, 15 years GEO) comprising solar flare events, presence of moon/earth limb in the field-of-view and high slew rate. The paper will also outline the newly developed EU enabling a fully autonomous star tracker. The EU features: - LEON3 based design using space qualified components only - Less than 0.5 U miniaturised design and low power - Two OH interfaces - Up to 10 Hz attitude update rate - Redundant Spacewire or RS-422 interface and 28 VDC supply - Wireless test interface