PoSAT-1 Star Imaging System: in-flight performance

This paper describes the latest results of the performance in space of the experimental star imaging system for attitude determination based on commercially available imaging technology. The device was integrated on PoSAT-1, the first Portuguese satellite, which was launched into sunsynchronous LEO on September 26, 1993. The main features of the system are described, its data processing philosophy, attitude errors, and sensitivity analysis. The most important conclusion thus far is that low cost technology can provide attitude knowledge to within 0.05 degrees, a figure of utmost interest for small and low cost remote sensing spacecrafts.