Precision geolocation determination and pointing managemen for the advanced land observing satellite (ALOS)

The Advanced Land Observing Satellite (ALOS) is a NASDA’s flagship for high-resolution Earth observation. Characterized by global data collection with 2.5 m resolution, the ALOS mission requires precise geolocation determination and geometric correction without ground control points. To this end, ALOS addresses stringent pointing requirements: pointing stability (0.0004deg/5sec), pointing determination accuracy (0.0002deg), and position determination accuracy (1m). With these, the geolocation determination accuracy of 6m can be achieved from attitude and position estimates based on star tracker and GPS receiver. It can be improved to 3 m with high-bandwidth measurement. An integrated framework (i.e., pointing management) that extends from attitude control to ground systems is designed to meet these requirements. This paper presents the framework and the approaches of the ALOS’s pointing management, with an emphasis on the approaches to yield geolocation determination.